CN100432819C

CN100432819C - Optical device and measurement system using several tunable polarizers

Info

Publication number: CN100432819C
Application number: CNB2005100752926A
Authority: CN
Inventors: 姚晓天
Original assignee: BEIJING GAOGUANG TECHNOLOGY Co Ltd; General Photonics Optoelectronic Technology (beijing) Co Ltd
Current assignee: Yueshen Innovation Co ltd
Priority date: 2004-06-10
Filing date: 2005-06-10
Publication date: 2008-11-12
Anticipated expiration: 2025-06-10
Also published as: CN1766725A

Abstract

The present invention relates to an optical device and a measurement system using several adjustable polarizers, belonging to the technical field of generating and analyzing the polarization state of light. The device includes: at least four adjustable polarizers placed to form an optical channel; and a light polarizing device placed in the light channel at one end of the rotator. The method comprises: using at least four adjustable polarizers to transmit light in the optical channel and controlling one polarization state of the transmitted light beam; controlling each polarizer to rotate the polarization state by two different preset angles; and At least four polarizers are controlled to work under different settings of the polarizers to generate at least four different polarization states. In the present invention, various polarizations can be generated with high precision. The repetition accuracy is better than 0.1°, the insertion loss is less than 0.9dB, and the return loss is better than 55dB. The invention can be used as a Miller matrix polarization analyzer, and can be applied to polarization analysis, scanning wavelength measurement, polarization related parameters and signal-to-noise ratio monitoring of optical networks.

Description

Optical device and measurement system using several tunable polarizers

本发明是以2004年6月10日递交的美国专利申请号No.60/578,700题目为“利用可调旋光器产生和分析偏振态”的专利，(律师档案号No.12361-033P01)。及2004年8月9日递交美国专利申请号No.10/914,592题目为“利用可调旋光器产生和分析偏振态”(律师档案号NO.12361-033001)两项专利申请的优先权为基础的申请。This invention is based on US Patent Application No. 60/578,700, filed June 10, 2004, entitled "Generation and Analysis of Polarization States Using a Tunable Optical Rotator," (Attorney Docket No. 12361-033P01). and U.S. Patent Application No. 10/914,592 filed on August 9, 2004, entitled "Generating and Analyzing Polarization States Using a Tunable Optical Rotator" (Attorney Docket No. 12361-033001) based on the priority of two patent applications application.

技术领域 technical field

本发明属于光偏振实现技术及其在偏振光监测装置和系统中的应用技术领域。The invention belongs to the technical field of light polarization realization technology and its application in polarized light monitoring device and system.

背景技术 Background technique

在一个光学装置或系统中，光的光学性质或参数因为多种目的被测量。例如，光学测量可用来确定装置或系统的性能和工作条件。光的光学性质或参数包括光偏振，信噪比，两正交偏振态的差分群延时，等等。In an optical device or system, optical properties or parameters of light are measured for various purposes. For example, optical measurements can be used to determine the performance and operating condition of a device or system. Optical properties or parameters of light include light polarization, signal-to-noise ratio, differential group delay of two orthogonal polarization states, and so on.

在多种光学系统中光偏振是一个光信号的重要参数。在光通信系统中，光纤和其他装置的偏振相关效应--如偏振相关损耗(PDL)、偏振模色散(PDM)，对光学装置和系统的性能和正常工作有很大的伤害。因此，最好对这些系统中的偏振态(SOP)和偏振度(DOP)进行测量和监测。Optical polarization is an important parameter of optical signals in various optical systems. In optical communication systems, the polarization-dependent effects of optical fibers and other devices—such as polarization-dependent loss (PDL), polarization-mode dispersion (PDM), have great damage to the performance and normal operation of optical devices and systems. Therefore, it is desirable to measure and monitor the state of polarization (SOP) and degree of polarization (DOP) in these systems.

同样的，光信号的信噪比(SNR)和差分群延迟(DGD)对于多种光学装置和系统也同样是重要的参数，因此在一定情况下最好对这些参数进行监测。Similarly, the signal-to-noise ratio (SNR) and differential group delay (DGD) of optical signals are also important parameters for various optical devices and systems, so it is best to monitor these parameters under certain circumstances.

发明内容 Contents of the invention

本发明的目的是提出一种利用可调旋偏器产生和分析偏振态的光学装置及其方法。本发明的装置能够高精度地在邦加球上产生多种偏振态。其重复精度高，还可预测的波长和温度依赖度。器件光纤至光纤的插入损耗小。本发明可用作米勒矩阵偏振分析器，可应用于偏振分析，扫描波长测量，偏振相关参数和光网络的信噪比监测。The object of the present invention is to propose an optical device and method for generating and analyzing polarization states using an adjustable polarizer. The device of the invention can generate various polarization states on the Poincare sphere with high precision. It has high repeatability and predictable wavelength and temperature dependence. Device fiber-to-fiber insertion loss is low. The invention can be used as a Miller matrix polarization analyzer, and can be applied to polarization analysis, scanning wavelength measurement, polarization related parameters and signal-to-noise ratio monitoring of optical networks.

本发明提出的一种产生和分析偏振态的装置，其特征在于，该装置包括：A device for generating and analyzing polarization states proposed by the present invention is characterized in that the device includes:

至少4个旋偏器，放置形成一个光通道；各旋偏器是可调节的，用于改变穿过光通道中的光的偏振旋转度；和at least four rotators positioned to form an optical channel; each rotator is adjustable for varying the degree of polarization rotation of light passing through the optical channel; and

一个光偏振装置，放置在旋偏器的一端的光通道中，用于传输一束线偏振经过选择的光。A light polarizing device, placed in the light channel at one end of the polarizer, is used to transmit a beam of linearly polarized selected light.

本发明提出的另一种产生和分析偏振态的装置，其特征在于，该装置包括：Another device for generating and analyzing the polarization state proposed by the present invention is characterized in that the device includes:

至少2个旋偏器，放置形成一个光通道；各旋偏器是可调节的，用于改变穿过光通道中的光的偏振旋转度；和at least two rotators positioned to form an optical channel; each rotator is adjustable for varying the degree of polarization rotation of light passing through the optical channel; and

本发明提出的一种产生和分析偏振态的方法，其特征在于，包括以下步骤：A method for generating and analyzing the polarization state proposed by the present invention is characterized in that it comprises the following steps:

利用至少四个可调旋偏器在光通道中传输光并且控制传输光束的一个偏振态；using at least four adjustable polarizers to transmit light in the optical channel and to control a polarization state of the transmitted beam;

控制所述各旋偏器旋转偏振两个不同的预定的角度；并且controlling each of said rotators to rotate polarization by two different predetermined angles; and

控制至少四个旋偏器在不同旋偏器设置下并且产生至少四个不同的偏振态。At least four polarizers are controlled at different polarizer settings and at least four different polarization states are produced.

本发明提出的另一种产生和分析偏振态的方法，其特征在于，包括以下步骤：Another method for generating and analyzing the polarization state proposed by the present invention is characterized in that it comprises the following steps:

利用至少两个可调旋偏器在光通道中传输光并且控制传输光束的一个偏振态；using at least two adjustable rotators to transmit light in the optical channel and to control a polarization state of the transmitted beam;

控制至少两个旋偏器在不同旋偏器设置下并且产生至少三个不同的偏振态。At least two polarizers are controlled at different polarizer settings and at least three different polarization states are produced.

本发明包括多种监测一个或多个光信号SNR、DOP和DGD及产生多种偏振态的装置和技术的实现方案和例子。一种实现方案是，可在光通道中利用一个扰偏器和一个起偏器进行测量。另一种实现方案是，可在光通道中利用一个可旋转的四分之一波片和可旋转的二分之一波片进行测量。在其它实现方案中，可利用一个偏振态发生器和线偏振起偏器进行测量。本发明描述的光监测装置可用来测量WDM通道。The present invention includes implementations and examples of various devices and techniques for monitoring one or more optical signals SNR, DOP and DGD and generating multiple polarization states. In one implementation, measurements can be made with a polarization scrambler and a polarizer in the optical channel. As another implementation, a rotatable quarter-wave plate and a rotatable half-wave plate can be used in the optical channel for measurements. In other implementations, measurements can be made using a polarization state generator and linear polarizer. The optical monitoring device described in this invention can be used to measure WDM channels.

以下包括多种实现方案的例子。Examples of various implementations are included below.

在一个例子中，一个装置，它包括一个光纤回路，在上述光纤回路的一个光耦合器，用于将输入光耦合到上述的光纤回路中作为上述光纤回路中两反向传播的波并且耦合上述光纤回路的光作为一个输出光束输出，一个在上述光纤回路的偏振装置用于改变上述光纤回路中光的偏振态使上述输出光束达到一个最大功率大小和最小功率大小，一个光探测器用于接受上述输出光束产生一个探测器信号；和一个电路用于处理上述探测器信号，产生一个代表上述输入信号在上述最大和最小功率大小下的一个信噪比或一个偏振度的输出。In one example, an apparatus comprising a fiber optic loop, an optical coupler in said fiber optic loop for coupling input light into said fiber optic loop as two counterpropagating waves in said fiber optic loop and coupling said The light of the optical fiber loop is output as an output beam. A polarization device in the above-mentioned optical fiber loop is used to change the polarization state of the light in the above-mentioned optical fiber loop to make the above-mentioned output beam reach a maximum power level and a minimum power level. An optical detector is used to receive the above-mentioned the output beam produces a detector signal; and a circuit for processing said detector signal to produce an output representative of a signal-to-noise ratio or a degree of polarization of said input signal at said maximum and minimum power levels.

在另一个例子中，一个装置，它包括一个扰偏器用于扰乱接收光的偏振态产生一个响应控制信号的受控的输出光，一个起偏器用来接收上述扰偏器的输出光产生一个传输光束，一个光探测器用于接收上述传输光束产生一个探测器信号，和一个控制单元用于产生上述扰偏器的上述控制信号，并产生一个代表上述输入光的一个信噪比或一个偏振度的输出。In another example, an apparatus comprising a polarization scrambler for disturbing the polarization state of received light to produce a controlled output light responsive to a control signal, a polarizer for receiving the output light of said polarization scrambler to produce a transmitted light beam, an optical detector is used to receive the above-mentioned transmitted light beam to generate a detector signal, and a control unit is used to generate the above-mentioned control signal of the above-mentioned polarization scrambler, and generate a signal-to-noise ratio or a polarization degree representing the above-mentioned input light output.

在另一个例子中，一个装置，它包括一个偏振装置用于调节接收光的偏振，产生输出光，利用此输出光寻找上述接收光的不同WDM通道的各WDM通道的最大和最小功率大小，一个WDM解复器用于接受上述输出光并且分别分离上述输出光的不同WDM通道；多个光探测器用于分别接收传输经过上述起偏器后的上述不同WDM通道；和一个电路用于处理上述光探测器的输出信号，利用上述最大最小功率大小为各WDM通道产生一个代表上述各WDM通道信噪比或偏振度的输出。偏振装置能是一个在搜索上述最大最小功率大小时随机改变上述偏振的扰偏器。偏振装置还可能是一个偏振控制器。In another example, a device, which includes a polarizing device for adjusting the polarization of received light to generate output light, using this output light to find the maximum and minimum power levels of each WDM channel of the different WDM channels of the above-mentioned received light, a The WDM demultiplexer is used to receive the above-mentioned output light and separate the different WDM channels of the above-mentioned output light respectively; multiple photodetectors are used to respectively receive the above-mentioned different WDM channels after passing through the above-mentioned polarizer; and a circuit is used to process the above-mentioned light detection The output signal of the device is used to generate an output representing the signal-to-noise ratio or polarization degree of each WDM channel for each WDM channel by using the above-mentioned maximum and minimum power levels. The polarizing means can be a polarization scrambler that randomly changes said polarization while searching for said maximum and minimum power magnitudes. The polarization device may also be a polarization controller.

在另一个例子中，一个装置，它包括一个偏振装置用来扰乱调节接收光的偏振产生一个输出光，利用这个输出光寻找上述接收光的不同WDM通道的各WDM通道的一个最大和一个最小功率大小。一个起偏器，在上述偏振装置和WDM解复用器之间的输出光的光通道中用于传输上述输出光到上述WDM解复器，多个光探测器分别接收经过上述起偏器后的上述不同WDM通道，和一个电路，用于处理上述光探测器的输出信号，利用上述最大最小功率大小为各WDM通道产生一个代表上述各WDM通道信噪比或偏振度的输出。偏振装置可能是一个在搜索上述最大最小功率大小时随机改变上述偏振的扰偏器，还可能是一个偏振控制器。In another example, an apparatus comprising a polarizing means for disturbing and adjusting the polarization of received light to produce an output light is used to find a maximum and a minimum power of each WDM channel of the different WDM channels of said received light size. A polarizer is used to transmit the above-mentioned output light to the above-mentioned WDM demultiplexer in the optical channel of the output light between the above-mentioned polarization device and the WDM demultiplexer, and a plurality of photodetectors respectively receive and pass through the above-mentioned polarizer The above-mentioned different WDM channels, and a circuit are used to process the output signals of the above-mentioned optical detectors, and use the above-mentioned maximum and minimum power levels to generate an output representing the signal-to-noise ratio or polarization degree of each WDM channel for each WDM channel. The polarization device may be a polarization scrambler that randomly changes the above-mentioned polarization while searching for the above-mentioned maximum and minimum power levels, and may also be a polarization controller.

在另一个例子中，一个装置，它包括一个偏振装置，用于改变接收光的偏振态产生输出光，此输出光用于寻找上述接受光的不同WDM通道的各通道的一个最大功率大小和一个最小功率大小；一个光起偏器，用于接收上述输出光产生一个光束；一个衍射光栅，用于使上述光束发生衍射成为空间上分离的不同WDM通道；一个透镜，用于传输上述不同WDM通道；多个光探测器，用于从上述透镜分别接收上述不同WDM通道；和一个电路，用于处理上述光探测器的输出信号，为各WDM通道产生一个代表上述各WDM通道噪比或偏振度的输出。偏振装置可能是一个在搜索上述最大和上述最小功率大小时随机改变上述偏振的扰偏器，还可能是一个偏振控制器。In another example, a device comprising a polarizer for changing the polarization state of received light to generate output light for finding a maximum power level and a Minimum power level; an optical polarizer, used to receive the above output light to generate a beam; a diffraction grating, used to diffract the above beam into different spatially separated WDM channels; a lens, used to transmit the above different WDM channels ; a plurality of photodetectors, used to respectively receive the above-mentioned different WDM channels from the above-mentioned lens; and a circuit, used to process the output signals of the above-mentioned photodetectors, for each WDM channel to generate a signal representing the above-mentioned WDM channel-to-noise ratio or degree of polarization Output. The polarizing means may be a polarization scrambler randomly changing said polarization while searching for said maximum and said minimum power levels, and may also be a polarization controller.

在另一个例子中，一个装置，它包括一个偏振装置用于改变接收光的偏振态产生输出光，这个输出光用于寻找上述接收光不同WDM通道中各WDM通道的一个最大功率大小和一个最小功率大小；一个WDM解复器用于接受上述输出光分离上述接收光的不同WDM通道；多个偏振分束器分别放置在上述不同WDM通道的光通道中，其中各偏振分束器将相应的WDM通道分离成两个具有正交偏振的监测光束；多个滤波片分别放置于上述不同WDM通道的上述两个监测光束中的一个光束中，每个滤波片可以通过操作在不影响上述各WDM通道的信号功率大小的情况下，为各WDM通道产生一个上述两监测光束噪声功率大小之间的差值功率；多个光探测器提供给不同WDM通道，其中每对光探测器的两个探测器分别接受相应WDM通道的上述两监测光束，为上述WDM通道产生两个探测器信号；和一个控制单元用于产生上述控制信号并且处理探测器信号，为各WDM通道产生一个代表上述各WDM通道的一个信噪比或偏振度的输出。偏振装置可能是一个在搜索上述最大和上述最小功率大小时随机改变上述偏振的扰偏器，还可能是一个偏振控制器。In another example, a device, which includes a polarizing device for changing the polarization state of received light to generate output light, this output light is used to find a maximum power level and a minimum power level of each WDM channel in the different WDM channels of the above-mentioned received light Power level; a WDM demultiplexer is used to accept the above-mentioned output light and separate the different WDM channels of the above-mentioned received light; multiple polarization beam splitters are respectively placed in the optical channels of the above-mentioned different WDM channels, and each polarization beam splitter divides the corresponding WDM The channel is separated into two monitoring beams with orthogonal polarization; multiple filters are respectively placed in one of the above two monitoring beams of the above-mentioned different WDM channels, and each filter can be operated without affecting the above-mentioned WDM channels In the case of the signal power level, the difference power between the noise power of the above two monitoring beams is generated for each WDM channel; multiple optical detectors are provided to different WDM channels, and two detectors of each pair of optical detectors Respectively accept the above two monitoring light beams of the corresponding WDM channels, generate two detector signals for the above WDM channels; A signal-to-noise ratio or degree of polarization output. The polarizing means may be a polarization scrambler randomly changing said polarization while searching for said maximum and said minimum power levels, and may also be a polarization controller.

在另一个例子中，一个装置，它包括一个偏振装置用于改变接收光的偏振产生输出光，这个输出光用于寻找上述接收光的不同WDM通道的各通道的一个最大功率大小和一个最小功率大小；一个偏振分束器用于将上述输出光分离成偏振相互正交的第一和第二个光束；第一个WDM解复器，用于接受上述第一个光束分离上述第一个光束的不同WDM通道；第二个WDM解复器，用于接受上述第二个光束分离上述第一个光束的不同WDM通道，其中的上述第一个WDM解偏器和第二个解偏器不同，其不同在于上述的第一个WDM解偏器的一个输出WDM通道的噪声功率大小和上述的第二个WDM解复器不同；第一个光探测器用于接收上述第一个WDM解复器的不同WDM通道；第二个光探测器用于接收上述第二个WDM解复器的不同WDM通道；和一个控制单元用于产生上述控制信号并且处理来自上述第一个光探测器的探测信号为各WDM通道产生一个代表上述各WDM通道的一个信噪比或偏振态的输出。偏振装置可能是一个在搜索上述最大和上述最小功率大小时随机改变上述偏振的扰偏器并且还可能是一个偏振控制器。In another example, a device comprising a polarizer for changing the polarization of received light to generate output light for finding a maximum power level and a minimum power level for each of the different WDM channels of said received light size; a polarization beam splitter is used to separate the above output light into the first and second beams whose polarizations are orthogonal to each other; the first WDM demultiplexer is used to accept the above first beam and split the above first beam Different WDM channels; the second WDM demultiplexer is used to accept the above-mentioned second beam to separate the above-mentioned first beam of different WDM channels, wherein the above-mentioned first WDM depolarizer and the second depolarizer are different, The difference is that the noise power of an output WDM channel of the above-mentioned first WDM depolarizer is different from that of the above-mentioned second WDM demultiplexer; Different WDM channels; the second optical detector is used to receive the different WDM channels of the second WDM demultiplexer; and a control unit is used to generate the above-mentioned control signal and process the detection signal from the above-mentioned first optical detector for each The WDM channels produce an output representative of a signal-to-noise ratio or state of polarization for each of the above-mentioned WDM channels. The polarizing means may be a polarization scrambler randomly changing said polarization while searching said maximum and said minimum power levels and may also be a polarization controller.

在另外一个例子中，一个装置，它包括一个偏振元件可用于调节输入光的偏振；一个起偏器，用于接收上述偏振元件的输出光产生一个传输光束；一个光探测器，用于接收上述起偏器的上述传输光束；和一个信号运算电路，用于处理上述光探测器的输出，提取上述输入光的偏振态信息。偏振元件可利用一个偏振控制器实现，一个可旋转的四分之一波片，或SOP发生器来实现。In another example, an apparatus comprising a polarizing element operable to adjust the polarization of input light; a polarizer for receiving output light from said polarizing element to produce a transmitted light beam; a photodetector for receiving said The above-mentioned transmission light beam of the polarizer; and a signal operation circuit for processing the output of the above-mentioned photodetector to extract the polarization state information of the above-mentioned input light. The polarizing element can be implemented using a polarization controller, a rotatable quarter-wave plate, or an SOP generator.

还描述了一个方法用于得到来自一个光纤链路承载的WDM通道的监测信号；空间上分离来自上述监测光束的WDM通道；将WDM通道分离成具有正交偏振的第一个光束和第二个光束，利用上述第一个光束的噪声功率大小和上述第二个光束不同的方法；在分离上述第一和上述第二个光束之前调节各WDM通道的偏振，寻找上述第一和上述第二个光束的一个最大功率大小和一个最小功率大小；并且测定上述监测光束中各WDM通道的一个信噪比和一个偏振度。Also described is a method for obtaining a monitoring signal from a WDM channel carried by an optical fiber link; spatially separating the WDM channel from said monitoring beam; separating the WDM channel into a first beam and a second beam with orthogonal polarizations Beams, using the method that the noise power of the first beam is different from that of the second beam; before separating the first and second beams, adjust the polarization of each WDM channel to find the first and second a maximum power level and a minimum power level of the beam; and determining a signal-to-noise ratio and a degree of polarization of each WDM channel in the monitor beam.

这里还描述了其他的例子和实现方案。Other examples and implementations are also described herein.

这里描述的一个装置的例子，它包括第一和第二个旋偏器相继放置在一个光通道中，一个四分之一波片在光通道中用于接收来自第一和第二旋偏器的输出光，并且第三和第四旋偏器相继放置在光通道中用于接收来自四分之一波片的输出光。各旋偏器可通过控制信号调节并且可工作在两个旋偏角度下。An example of a device is described here, which includes first and second polarizers placed sequentially in an optical channel, and a quarter-wave plate in the optical channel for receiving signals from the first and second polarizers. output light, and the third and fourth polarizers are successively placed in the optical channel for receiving the output light from the quarter-wave plate. Each deviator can be adjusted by a control signal and can work at two deflection angles.

在另一个例子中，一个装置，它包括至少四个旋偏器在光通道中，并且各旋偏器通过响应一个控制信号调节偏振旋转+22.5°或-22.5°。这个装置还包括一个四分之一波片在光通道中。In another example, an apparatus includes at least four rotators in an optical channel, and each rotator adjusts the polarization rotation by +22.5° or -22.5° in response to a control signal. The device also includes a quarter-wave plate in the optical channel.

产生和分析偏振的方法在这里也有描述。在一个例子中，一个装置，它包括至少四个旋偏器放置形成一个光通道，各旋偏器可通过调节改变通过光通道的光的偏振旋转角度，和一个光偏振装置在旋偏器一端的光通道中，用于传输经过挑选的线偏振光。作为另外一个例子，至少4个可调的旋偏器在光通道中用于传输光并且控制传输光的一个偏振态。各旋偏器通过控制将偏振旋转两个预定的不同的角度；和至少四个旋偏器通过控制在不同旋偏设置下工作，产生至少四个不同的偏振态。Methods for generating and analyzing polarization are also described here. In one example, a device comprising at least four polarizers placed to form an optical channel, each polarizer can be adjusted to change the polarization rotation angle of light passing through the optical channel, and a light polarizer at one end of the polarizer In the optical channel, it is used to transmit selected linearly polarized light. As another example, at least four tunable polarizers are used in the optical channel to transmit light and control one polarization state of the transmitted light. Each rotator is controlled to rotate the polarization by two predetermined different angles; and at least four rotators are controlled to operate at different rotator settings to generate at least four different polarization states.

另一个例子利用至少四个旋偏器和一个四分之一波片在一个传输光的光通道中。各旋偏器通过控制将偏振态旋转两个预定的不同的角度。这至少四个旋偏器通过控制在不同旋偏设置下工作产生至少四个不同的偏振态。Another example utilizes at least four polarizers and a quarter wave plate in an optical channel that transmits light. Each rotator is controlled to rotate the polarization state by two predetermined different angles. The at least four rotators are controlled to work under different rotator settings to generate at least four different polarization states.

这些和其他实现方案在附图、细节描述和权利要求中有更详细地描述。These and other implementations are described in more detail in the drawings, detailed description, and claims.

本发明技术特点及效果：Technical features and effects of the present invention:

如果利用米勒矩阵的方法分析光器件或系统的偏振性能，非常关键的一步是沿邦加球能否产生至少4个独立的具有高重复精度的偏振态，如0°线偏振，+/-45°线偏振，90°线偏振，右旋圆偏振(RHC)和左旋圆偏振(LHC)。从这些分析中得到的信息还可用于进一步测量其他参数，如双折射，偏振模色散(PMD)，偏振相关损耗(PDL)，偏振度(DOP)，信噪比(SNR)和偏振态。本发明中的装置能够高精度地在邦加球上产生0°线偏振，+/-45°线偏振，90°线偏振，右旋圆偏振和左旋圆偏振。测量结果显示在邦加球上的重复精度优于0.1°，器件的另外一个优点是它可预测的波长和温度依赖度，典型值分别为-0.067°/nm和0.1°/C。器件光纤至光纤的插入损耗为小于0.9dB，回程损耗优于55dB。该器件同样可用作米勒矩阵偏振分析器，可应用于偏振分析，扫描波长测量，偏振相关参数和光网络的信噪比监测。If the Miller matrix method is used to analyze the polarization performance of optical devices or systems, a very critical step is whether at least 4 independent polarization states with high repeatability can be produced along the Poincare sphere, such as 0° linear polarization, +/- 45° linear polarization, 90° linear polarization, right-handed circular polarization (RHC) and left-handed circular polarization (LHC). The information obtained from these analyzes can also be used to further measure other parameters such as birefringence, polarization mode dispersion (PMD), polarization dependent loss (PDL), degree of polarization (DOP), signal-to-noise ratio (SNR) and state of polarization. The device in the present invention can generate 0° linear polarization, +/-45° linear polarization, 90° linear polarization, right-handed circular polarization and left-handed circular polarization on the Poincare sphere with high precision. Measurements show a repeatability of better than 0.1° on a Poincare sphere. Another advantage of the device is its predictable wavelength and temperature dependence, with typical values of -0.067°/nm and 0.1°/C, respectively. The fiber-to-fiber insertion loss of the device is less than 0.9dB, and the return loss is better than 55dB. The device can also be used as a Miller matrix polarization analyzer, which can be applied to polarization analysis, scanning wavelength measurement, polarization related parameters and signal-to-noise ratio monitoring of optical networks.

附图说明 Description of drawings

图1和图2展示了两个带有扰偏器或偏振控制器的光监测装置。Figures 1 and 2 illustrate two optical monitoring setups with polarization scramblers or polarization controllers.

图3展示了一个应用了图2中的监测装置的传输系统。Fig. 3 shows a transmission system using the monitoring device in Fig. 2.

图4展示了一个波分复用(WDM)传输线路的监测装置，其中波分复用传输线的输入包括不同WDM波长的信号。FIG. 4 shows a monitoring device for a wavelength division multiplexing (WDM) transmission line, wherein the input of the wavelength division multiplexing transmission line includes signals of different WDM wavelengths.

图5展示了一个基于上述监测技术的一个全光纤动态PMD控制器500的实现方案。FIG. 5 shows an implementation scheme of an all-fiber dynamic PMD controller 500 based on the above monitoring technology.

图6展示了一个基于微处理器的监测装置的实现方案。Figure 6 shows an implementation of a microprocessor-based monitoring device.

图7展示了一个在扰偏器或偏振控制器的输出利用一个波分解复器分离不同WDM通道的监测装置。Figure 7 shows a monitoring setup using a wavelength division multiplexer at the output of a polarization scrambler or polarization controller to separate the different WDM channels.

图8展示了另一个利用衍射光栅分离不同WDM通道的实现方案。Figure 8 shows another implementation using a diffraction grating to separate different WDM channels.

图9展示了一个PMD非敏感监测装置，用于所有波长通道只利用一个扰偏器的WDM应用。Figure 9 shows a PMD-insensitive monitoring setup for WDM applications using only one polarization scrambler for all wavelength channels.

图10展示了另一个WDM监测装置的实现方案，其中包括了一个结合了两个WDM解复器的偏振分束器。Figure 10 shows another implementation of a WDM monitoring device, which includes a polarization beam splitter combined with two WDM demultiplexers.

图11展示了一个具有实时DGD监测装置和一个动态PMD补偿器的系统。Figure 11 shows a system with real-time DGD monitoring and a dynamic PMD compensator.

图12举例说明了图11中的DGD运算电路进行偏振处理的参考邦加球。FIG. 12 illustrates a reference Poincare sphere for polarization processing performed by the DGD operation circuit in FIG. 11 .

图13，14和15展示了三个光监测装置的例子，这些装置将一个可旋转的四分之一波片和一个可旋转的起偏器用作一个扰偏器。Figures 13, 14 and 15 show three examples of optical monitoring devices using a rotatable quarter wave plate and a rotatable polarizer as a scrambler.

图16展示了一个光纤系统，它利用法布里-泊罗滤波器和连续或者并联的多通道偏光计监测各通道的SOP.Figure 16 shows a fiber optic system that uses Fabry-Perot filters and continuous or parallel multi-channel polarimeters to monitor the SOP of each channel.

图17举例说明了图16中法布里-泊罗滤波器的操作。FIG. 17 illustrates the operation of the Fabry-Perot filter in FIG. 16 .

图18A和18B展示了两个WDM系统光监测装置的例子，它利用了一个可旋转四分之一波片和一个可旋转的二分之一波片作为装置的一部分。Figures 18A and 18B show two examples of optical monitoring devices for WDM systems utilizing a rotatable quarter wave plate and a rotatable half wave plate as part of the device.

图19A，19B，19C，19D，和19E举例说明了利用一个SOP发生器和一个固定的起偏镜的光监测装置。Figures 19A, 19B, 19C, 19D, and 19E illustrate optical monitoring devices utilizing a SOP generator and a fixed polarizer.

图20和21展示了一个SOP发生器的实现方案。Figures 20 and 21 show an implementation of a SOP generator.

图22展示了一个将SOP发生器用作SOP分析仪测量光偏振度的装置。Figure 22 shows a setup for measuring the degree of polarization of light using a SOP generator as a SOP analyzer.

图23展示了一个含有一个控制和处理单元的具有4个旋偏器的装置的例子。Figure 23 shows an example of a device with 4 deviators including a control and processing unit.

图24和25展示了利用光纤的具有4个旋偏器和具有6个旋偏器的装置的例子。Figures 24 and 25 show examples of devices with 4 and 6 deviators using optical fibers.

图26展示了另一个具有6个旋偏器的装置的例子。Figure 26 shows another example of a setup with 6 deviators.

图27展示了一个具有8个旋偏器的例子。Figure 27 shows an example with 8 rotators.

图28展示了为测试上述多旋偏器的测试系统。Figure 28 shows the test system for testing the above-mentioned multirotator.

图29，30，31，32A，和32B展示了基于具有4个旋偏器的和具有6个旋偏器的装置的多旋偏器装置的测量。Figures 29, 30, 31, 32A, and 32B illustrate measurements of multi-rotator devices based on devices with 4 and devices with 6 rotators.

图33展示了一个利用多旋偏SOP发生器和分离的多旋偏器测量偏振特性的系统。Figure 33 shows a system for measuring polarization characteristics using a multirotator SOP generator and a separate multirotator.

图34A，34B，35和36展示了测量一个样品或装置偏振特性的系统，这个系统基于利用多旋偏器的光反射使用单一的设置同时产生SOP和分析样品和装置的输出的一个折叠设计。Figures 34A, 34B, 35 and 36 illustrate systems for measuring the polarization properties of a sample or device based on a folded design utilizing light reflection from multiple rotators to simultaneously generate SOPs and analyze the output of the sample and device using a single setup.

图37A和37B展示了两个多通道SOP分析仪的例子。Figures 37A and 37B show two examples of multi-channel SOP analyzers.

图38举例说明了图37A和37B中多通道SOP分析仪的使用。Figure 38 illustrates the use of the multi-channel SOP analyzer of Figures 37A and 37B.

具体实施方式 Detailed ways

本发明的技术方案结合附图及实施例进一步详细说明如下：The technical scheme of the present invention is described in further detail as follows in conjunction with accompanying drawing and embodiment:

图1举例说明了一个监测器100的实现方案，它可以用来监测接收光的SNR和DOP。监测器100利用一段光纤接收一个被监测光信号101，和一个光回路120例如一个光纤回路用于实现监测。一个光耦合器110，例如一个50％的光纤耦合器，耦合于光纤回路120的两端，分离输入信号110成为回路120中两个反向传输的光束，并且耦合两反向传输的光束产生一个输出光束140。因此，耦合器110和回路120提供了一个反射装置。一个扰偏器或偏振控制器130在光纤回路120中随机打乱回路120中光的偏振态，或系统的控制偏振态在所有可能的偏振态范围内变化，从而测量得到输出光束140的一个最大功率大小和一个最小功率大小。扰偏器或偏振控制器130可以选择通过响应一个控制信号163的方法，调节通过光的偏振态。FIG. 1 illustrates an implementation of a monitor 100 that can be used to monitor the SNR and DOP of received light. The monitor 100 utilizes a section of optical fiber to receive a monitored optical signal 101, and an optical circuit 120 such as an optical fiber circuit for monitoring. An optical coupler 110, such as a 50% optical fiber coupler, is coupled at both ends of the optical fiber loop 120, splits the input signal 110 into two counter-propagating beams in the loop 120, and couples the two counter-propagating beams to generate a output beam 140 . Thus, coupler 110 and loop 120 provide a reflective means. A polarization scrambler or polarization controller 130 randomly scrambles the polarization state of the light in the loop 120 in the fiber loop 120, or the control polarization state of the system changes in all possible polarization state ranges, thereby measuring a maximum of the output beam 140 power size and a minimum power size. The polarization scrambler or polarization controller 130 can optionally adjust the polarization state of the passing light by responding to a control signal 163 .

如图1所示的装置130的一个实现方案是，利用分别包括两个或更多在控制器133和134控制下的光纤挤压器131和132型扰偏器或偏振控制器130。光纤挤压器131和132的挤压方向的方位互相成45度角用于实现扰偏操作。One implementation of apparatus 130 as shown in FIG. 1 utilizes a polarization scrambler or polarization controller 130 comprising two or more fiber squeezers 131 and 132 under the control of controllers 133 and 134, respectively. The extrusion directions of the fiber squeezers 131 and 132 are oriented at an angle of 45 degrees to each other for scrambling operation.

一个光探测器150用于接收来自回路120的耦合输出光140。一个光隔离器103放置在输入光101的光通道中，用于防止任何输入光通道内的光反馈。一个运算电路160用于接收来自光探测器150的探测信号产生一个输出信号162，它包括SNR或DOP的信息。A photodetector 150 is used to receive the outcoupled light 140 from the loop 120 . An optical isolator 103 is placed in the optical channel of the input light 101 to prevent any optical feedback in the input optical channel. An arithmetic circuit 160 is used to receive the detection signal from the photodetector 150 to generate an output signal 162, which includes SNR or DOP information.

在操作过程中，光探测器150探测输出信号140的最大和最小光功率大小。运算电路160计算基于测量得到的最大和最小光功率大小的消光比。在多种应用中，信号101一般是偏振的但噪声是非偏振的。因此，消光比直接和SNR及DOP相关。消光比增大，DOP和SOP也相应的增大，反之亦然。运算电路160还包括一个控制单元控制扰偏器130的工作。During operation, optical detector 150 detects the maximum and minimum optical power levels of output signal 140 . The arithmetic circuit 160 calculates an extinction ratio based on the measured maximum and minimum optical power levels. In many applications, the signal 101 is generally polarized but the noise is unpolarized. Therefore, the extinction ratio is directly related to SNR and DOP. As the extinction ratio increases, DOP and SOP also increase accordingly, and vice versa. The arithmetic circuit 160 also includes a control unit to control the operation of the scrambler 130 .

图2展示了一个基于其他实现方案的监测装置200。扰偏器130用于打乱输入光101的偏振，和一个起偏器210用于传输来自扰偏器130的输出光。起偏器在这里用于代替图1中监测装置100的反射回路120。光探测器150用于接收来自起偏器210的传输光。运算电路160接收和处理探测器的输出产生输出162。Fig. 2 shows a monitoring device 200 based on other implementation schemes. A polarizer 130 is used to scramble the polarization of the input light 101 , and a polarizer 210 is used to transmit the output light from the scrambler 130 . A polarizer is used here instead of the reflection circuit 120 of the monitoring device 100 in FIG. 1 . The light detector 150 is used to receive the transmitted light from the polarizer 210 . Arithmetic circuitry 160 receives and processes the detector output to produce output 162 .

图3展示了在传输系统300中监测装置200的一个使用方法。一个光耦合器310放置在输入光束301的光通道中，将一部分输入光耦合器310的光分流成为一个监测光束320，和输入光束301剩下的光302继续沿输入通道传播作为系统300的一个输出。监测装置200通过耦合接收监测光束320完成测量过程。特别的是，用一个机架303封装了耦合器310，监测光束320的光通道，和监测装置200。组成所有光通道的是光纤，绝缘波导，或一个光纤通道和波导通道的组合。这个密封的机架提供了可供光纤传输链路或系统使用的集成模块。一个基片用来将波导和其他光学部分制作成为一个单一芯片封装在机架303中。在图1中的监测装置100可以用来代替图3中的装置200和在这个申请中展示的其它系统。FIG. 3 illustrates a method of using the monitoring device 200 in a transport system 300 . An optical coupler 310 is placed in the optical channel of the input beam 301, splitting a portion of the light input into the optical coupler 310 into a monitor beam 320, and the remaining light 302 of the input beam 301 continues to propagate along the input channel as a part of the system 300 output. The monitoring device 200 completes the measurement process by coupling and receiving the monitoring beam 320 . In particular, a housing 303 encloses the coupler 310 , the optical path of the monitoring beam 320 , and the monitoring device 200 . All optical channels are composed of optical fibers, dielectric waveguides, or a combination of optical fiber channels and waveguide channels. This sealed rack provides integrated modules for use with fiber optic transport links or systems. A substrate is used to make the waveguide and other optical parts into a single chip packaged in the chassis 303 . The monitoring device 100 in FIG. 1 may be used in place of the device 200 in FIG. 3 and other systems presented in this application.

图4展示了一个波分复用(WDM)传输链路的监测装置，这里输入301包括不同WDM波长的信号。耦合器310分离输入的所有WDM信号产生监测光束320。把一个WDM耦合器用作耦合器310。一个可调滤波器410耦合在耦合器310和监测装置200或100之间，对WDM信号进行滤波，从而使每次只有在一个WDM波长的一个信号能够传输到装置200或100。滤波器410在所有信号波长范围内一次一个连续可调的进行滤波，并且通过装置200或100测量各个WDM信号。一个控制装置420耦合到滤波器410和监测装置200或100中控制这种连续的滤波和监测操作。可调滤波器410可利用许多结构实现，例如一个可调法布里-泊罗滤波器，或一个可调光纤光栅滤波器(例如，与一个光线拉伸器耦合)，或一个可通过一个进步马达，或其他装置控制的旋转轴上的传输不同波长的若干滤波器。Fig. 4 shows a monitoring device for a wavelength division multiplexing (WDM) transmission link, where the input 301 includes signals of different WDM wavelengths. Coupler 310 splits all incoming WDM signals to generate monitor beam 320 . As the coupler 310, a WDM coupler is used. A tunable filter 410 coupled between the coupler 310 and the monitoring device 200 or 100 filters the WDM signal so that only one signal at one WDM wavelength is transmitted to the device 200 or 100 at a time. The filter 410 filters continuously tunable one at a time all signal wavelength ranges and each WDM signal is measured by the device 200 or 100 . A control unit 420 coupled to filter 410 and monitoring unit 200 or 100 controls the continuous filtering and monitoring operations. The tunable filter 410 can be implemented using many structures, such as a tunable Fabry-Perot filter, or a tunable fiber grating filter (e.g., coupled with a light stretcher), or one can be achieved by a progressive Several filters transmitting different wavelengths on a rotating shaft controlled by a motor, or other device.

图5展示了一个基于上述监测技术的全光纤动态PMD控制器500的实现方案。一个可调偏振控制器510耦合于输入光纤用于控制输入光束501的偏振。一个保偏光纤部分520耦合于偏振控制器510的输出，用于产生来自控制器510的输出光需要的差分群延时。熔接光纤用于连接PM光纤部分510。一个光线耦合器310用于分离可调偏振控制器510的输出成为一个在输入光纤内的输出光束502和一个监测光束320到图2中的监测装置200(或图1中的装置100)用于监测偏振度。电路160通过耦合提供输出162，控制偏振控制器510，因此可调偏振控制器510能通过响应电路160的测量进行动态的调节。可调偏振控制器510可通过许多结构实现。PMD控制器500包括多个，例如，3个或更多的光纤挤压器。美国专利号No.6,493,474在2002年12月10号准子姚公开一些基于四个连续光纤挤压器的例子并且在这里结合它的全部内容作为本申请的一个特殊部分。FIG. 5 shows an implementation scheme of an all-fiber dynamic PMD controller 500 based on the above monitoring technology. A tunable polarization controller 510 is coupled to the input fiber for controlling the polarization of the input beam 501 . A polarization maintaining fiber section 520 is coupled to the output of the polarization controller 510 for generating the required differential group delay of the output light from the controller 510 . Fused fibers are used to connect PM fiber sections 510 . An optical coupler 310 is used to split the output of the adjustable polarization controller 510 into an output beam 502 and a monitoring beam 320 in the input fiber to the monitoring device 200 in FIG. 2 (or the device 100 in FIG. 1 ) for Monitor the degree of polarization. Circuit 160 provides output 162 via coupling to control polarization controller 510 , so adjustable polarization controller 510 can be dynamically adjusted in response to measurements from circuit 160 . Tunable polarization controller 510 can be realized by many structures. PMD controller 500 includes a plurality, eg, 3 or more, of fiber squeezers. US Patent No. 6,493,474 issued Dec. 10, 2002 to Zhunzi Yao discloses some examples based on four continuous fiber squeezers and is hereby incorporated in its entirety as a special part of this application.

图5中的系统有许多优点，例如少于0.5dB的低光损和由基于简单光学设计和简单器件的独特设计得到的低成本。可用图中所示的一个密封的机架530封装整个装置。The system in Fig. 5 has many advantages such as low optical loss of less than 0.5dB and low cost resulting from a unique design based on simple optical design and simple components. The entire apparatus can be enclosed in a sealed chassis 530 as shown in the figure.

图6展示了一个基于微处理器的监测装置600的实现方案。一个偏振控制器630用于调节被测输入光612的SOP，和一个起偏器210用于传输来自控制器630的输出光到一个光探测器150中。来自探测器150的输出信号152可被电放大器660放大并且这个放大的信号发送到一个基于微处理器的运算电路650。运算电路650将各接收到的各模拟信号转换为数字位并且通过利用一个数字的微处理器实现信号处理操作，产生一个代表输入光612的DOP或SNR监测结果的输出651。如图6所示，可用一个激光器610或其它光源产生输入光612。FIG. 6 shows an implementation of a microprocessor-based monitoring device 600 . A polarization controller 630 is used to adjust the SOP of the measured input light 612 , and a polarizer 210 is used to transmit the output light from the controller 630 into a photodetector 150 . The output signal 152 from the detector 150 may be amplified by an electrical amplifier 660 and this amplified signal sent to a microprocessor based arithmetic circuit 650 . Arithmetic circuit 650 converts each received analog signal to digital bits and generates an output 651 representative of the DOP or SNR monitoring result of input light 612 by utilizing a digital microprocessor to perform signal processing operations. As shown in FIG. 6, input light 612 may be generated by a laser 610 or other light source.

可供选择的，一个分光器620，例如一个光纤耦合器，用于分离输入光束612的一部分作为一个参考光束622到第二个光探测器640中去。此分光器620因该是对光偏振不敏感的。第二个探测器640的输出642被反馈回电路650进行处理。这个参考光束622提供了一个测量输入光束612功率变化的测量方法，所以由功率变化引起的接收信号152的一部分的变化可由扰偏器630引起的偏振变化推导出来。Optionally, a beam splitter 620 , such as a fiber coupler, is used to split a portion of the input beam 612 into a second photodetector 640 as a reference beam 622 . The beam splitter 620 should therefore be insensitive to light polarization. The output 642 of the second detector 640 is fed back to the circuit 650 for processing. This reference beam 622 provides a measure of the change in power of the input beam 612, so changes in the portion of the received signal 152 caused by power changes can be derived from the polarization changes caused by the scrambler 630.

在操作中，电路650产生一个控制信号652用于调节控制器630寻找探测器150的最大功率(V_max)和最小功率(V_min)。控制信号652首先是通过微处理器产生的数字的信号，并且随后转换成为模拟信号。电路650中的运算器基于测量得到的Vman和Vmin计算光的DOP或SNR。DOP可通过下式计算得到：In operation, the circuit 650 generates a control signal 652 for regulating the maximum power (V _max ) and minimum power (V _min ) at which the controller 630 seeks the detector 150 . The control signal 652 is first a digital signal generated by a microprocessor and then converted to an analog signal. The arithmetic unit in the circuit 650 calculates the DOP or SNR of the light based on the measured Vman and Vmin. DOP can be calculated by the following formula:

$DOP DOP = = \frac{{V V}_{max max} - - {V V}_{min min}}{{V V}_{max max} + + {V V}_{min min}} . .$

偏振控制器630利用如图1中元件130的两挤压器设计或图6中的三挤压器设计，或5，6个挤压器给输入光提供更多控制。图6展示了一个终端的设计，它的输入光完全利用于监测操作。同样，监测装置600可用作一个线内装置，和图3附加一个分光器310的设计相似，用于将主输入光301分束产生监测装置600的输入和继续传输在传输系统中的主输入光。Polarization controller 630 utilizes a two-squeezer design as element 130 in FIG. 1 or a three-squeezer design in FIG. 6, or 5 or 6 squeezers to provide more control over the input light. Figure 6 shows a terminal design whose input light is fully utilized for monitoring operations. Similarly, the monitoring device 600 can be used as an in-line device, similar to the design of Figure 3 with an additional optical splitter 310, used to split the main input light 301 to generate the input of the monitoring device 600 and continue to transmit the main input in the transmission system Light.

在这个申请中的以上和其他监测装置中，可利用一个可调光滤波器插入输入光通道实现对输入的不同WIM通道进行连续监测。图4展示了一个例子。这种基于一个可调滤波器的多通道技术可用于本申请的很多监测装置的实现方案中。但是，这种技术受限于只能连续的一次监测一个通道。In the above and other monitoring devices in this application, a tunable optical filter can be inserted into the input optical channel to realize continuous monitoring of different input WIM channels. Figure 4 shows an example. This multi-channel technique based on an adjustable filter can be used in many implementations of monitoring devices of the present application. However, this technique is limited to continuous monitoring of one channel at a time.

图7和8展示了两个同时监测不同WDM通道的多通道监测技术。这种技术允许在同一时刻监测不同通道。Figures 7 and 8 show two multi-channel monitoring techniques that simultaneously monitor different WDM channels. This technique allows monitoring of different channels at the same time.

图7展示了一个监测装置700，它利用一个WDM解复器710在扰偏器或偏振控制器130后分离不同WDM通道。在各分离的WDM光通道中，一个起偏器210和一个光探测器150用于接收和探测各通道的功率大小。因此，不同通道的功率大小在同一时刻得到了测量。探测器150的输出信号随后被反馈到电路160中，用于通过数据处理来监测WDM通道。若干个起偏器210放置在解复器710和探测器150的光通道之间。同样的，可用一个单一起偏器放置在扰偏器130和WDM解复器710之间代替探测器150前的若干起偏器210。FIG. 7 shows a monitoring device 700 that utilizes a WDM demultiplexer 710 after the polarization scrambler or polarization controller 130 to separate the different WDM channels. In each separated WDM optical channel, a polarizer 210 and an optical detector 150 are used to receive and detect the power of each channel. Therefore, the power levels of different channels are measured at the same time. The output signal of the detector 150 is then fed back into the circuit 160 for monitoring the WDM channel through data processing. Several polarizers 210 are placed between the demultiplexer 710 and the optical channel of the detector 150 . Likewise, a single polarizer can be placed between the polarizer 130 and the WDM demultiplexer 710 to replace several polarizers 210 in front of the detector 150 .

图8展示了另一个实现方案800，它利用一个衍射光栅820分离不同WDM通道。一个准直器810用于接收扰偏器130的输出产生一个准直后的输出。一个起偏器210放置在扰偏器130和准直器810之间。光栅820通过使输入光发生衍射得到具有不同衍射角的不同WDM波长。这个衍射空间上分离了不同WDM通道。第二个准直器830，例如一个透镜，用于收集不同波长的不同光束并且聚焦衍射光束到光探测器阵列840的不同探测器元件上。一个可选的运算电路850用于调整进入电路160之前的探测输出。FIG. 8 shows another implementation 800 that utilizes a diffraction grating 820 to separate different WDM channels. A collimator 810 is used to receive the output of the scrambler 130 to generate a collimated output. A polarizer 210 is placed between the polarizer 130 and the collimator 810 . The grating 820 diffracts the input light to obtain different WDM wavelengths with different diffraction angles. This diffraction spatially separates the different WDM channels. A second collimator 830 , such as a lens, is used to collect different beams of different wavelengths and focus the diffracted beams onto different detector elements of the photodetector array 840 . An optional arithmetic circuit 850 is used to adjust the detection output prior to entering circuit 160 .

以上基于一个扰偏器的监测信号可能会对包括两个或更多WDM通道的输入信号的PMD敏感。这种PMD敏感性会造成一个测量误差。通常，输入的PMD越大，监测装置的误差越大。因此，最好在监测DOP或SNR的时候消除这种PMD效应。The above monitoring signal based on a polarization scrambler may be sensitive to PMD of an input signal comprising two or more WDM channels. This PMD sensitivity can cause a measurement error. Generally, the larger the input PMD, the larger the error of the monitoring device. Therefore, it is best to eliminate this PMD effect when monitoring DOP or SNR.

图9展示了一个针对与WDM应用的PMD非敏感监测装置900的实现方案，它只使用一个扰偏器作用于所有波长通道。装置900包括一个通用扰偏器910用于接收输入光纤901的输入WDM通道。一个或更多光放大器902用在输入光通道中放大输入的WDM通道。一个WDM解复器920用于接收来自扰偏器910的输出并且分离不同波长的WDM通道成为分离的光信号输出922。在各光输出中，一个偏振分束器(PBS)930或一个合适的偏振装置用于分离基于具有两正交偏振态的接收光产生两个具有正交偏振的光束。一个滤波器940用于过滤PBS 930两个输出中的一个，所以两输出光的噪声功率大小不同，同时输出光束的信号功率大小本质上不会受滤波影响。如图示，滤波器940从沿输入光束方向传输的光的端口过滤光。FIG. 9 shows an implementation scheme of a PMD non-sensitive monitoring device 900 for WDM applications, which uses only one polarization scrambler to act on all wavelength channels. Apparatus 900 includes a universal scrambler 910 for receiving input WDM channels of input fiber 901 . One or more optical amplifiers 902 are used in the input optical channels to amplify the incoming WDM channels. A WDM demultiplexer 920 is used to receive the output from the scrambler 910 and separate the WDM channels of different wavelengths into separate optical signal outputs 922 . In each light output, a polarizing beam splitter (PBS) 930 or a suitable polarizing device is used to split the received light with two orthogonal polarization states to generate two beams with orthogonal polarizations. A filter 940 is used to filter one of the two outputs of the PBS 930, so the noise power of the two output lights is different, and the signal power of the output beam is essentially not affected by the filter. As shown, filter 940 filters light from the port of light transmitted in the direction of the input beam.

以上光滤波器导致了两正交偏振的输出光的噪声信号不平衡。这个不平衡用于同时并且独立的监测SNR和DOP。可选用两正交方位角的起偏器941和942放置在PBS 930的两输出端口用于保证输出光束是正交偏振的。放置两个光探测器951和952用于分别接收PBS 930的输出光。探测器951和952的输出信号反馈回一个运算电路970用于测量和数据处理。可选的两电放大器961和962用于在运算电路970之前分别放大探测输出。The above optical filter causes the noise signal imbalance of the two orthogonally polarized output lights. This imbalance is used to monitor SNR and DOP simultaneously and independently. Polarizers 941 and 942 with two orthogonal azimuth angles can be selected to be placed on the two output ports of the PBS 930 to ensure that the output beams are orthogonally polarized. Two light detectors 951 and 952 are placed for receiving the output light of the PBS 930 respectively. The output signals of the detectors 951 and 952 are fed back to an arithmetic circuit 970 for measurement and data processing. Optional two electric amplifiers 961 and 962 are used to respectively amplify the detection output before the operation circuit 970 .

在一个实现方案中，带通滤波器940具有一个比各信号实际带宽更宽的带宽来允许各信道不被滤波的穿过滤波器，但是比EDM装置的各通道带宽要窄因为要滤掉一部分噪声以产生噪声功率不均衡的两个输出光束。例如，对一个通道间隔为100GHz和通道带宽为10GHz的WDM通道来说，WDM解复器920的带宽可以被设计为50GHz。带通滤波器940的带宽可以是25GHz，在10-GHz通道带宽和50-GHz装置通道带宽之间，以允许一个通道不被滤波的穿过滤波器。但是25GHz窗口外的噪声分量被滤波器从PBS 930传输光束中滤出。In one implementation, the bandpass filter 940 has a bandwidth wider than the actual bandwidth of each signal to allow each channel to pass through the filter unfiltered, but narrower than the bandwidth of each channel of the EDM device because a portion is filtered out. noise to produce two output beams with unbalanced noise power. For example, for a WDM channel with a channel spacing of 100 GHz and a channel bandwidth of 10 GHz, the bandwidth of the WDM demultiplexer 920 can be designed to be 50 GHz. Bandpass filter 940 may have a bandwidth of 25 GHz, between the 10-GHz channel bandwidth and the 50-GHz device channel bandwidth, to allow one channel to pass through the filter unfiltered. But the noise components outside the 25GHz window are filtered out from the PBS 930 transmission beam by the filter.

两探测器951和952探测的所有SOP的得到的最大最小功率为：The obtained maximum and minimum powers of all SOPs detected by the two detectors 951 and 952 are:

$\{\begin{matrix} {V V}_{11}^{max max} = = {G G}_{11} [[{P P}_{s the s} ((11 - - δ δ)) + + 0.5 0.5 {P P}_{N N}]] & ((11)) \\ {V V}_{11}^{min min} = = {G G}_{11} [[{P P}_{s the s} δ δ + + 0.5 0.5 {P P}_{N N}]] & ((22)) \\ {V V}_{22}^{max max} = = {G G}_{22} [[{P P}_{s the s} ((11 - - δ δ)) + + 0.5 0.5 α α {P P}_{N N}]] & ((33)) \\ {V V}_{22}^{min min} = = {G G}_{22} [[{P P}_{s the s} δ δ + + 0.5 0.5 α α {P P}_{N N}]] & ((44)) \end{matrix}$

这里P_s为信号功率，P_N为噪声功率，α小于1并且是带通滤波器940的噪声功率滤波系数，和δ消偏系数，它产生于，例如，输入信号的PMD，非线性双折射，和PBS 930的非完美。特别是，在没有产生PBS 930两输出光束非平衡输出的的滤波器940的情况下，等式(1)和(2)和等式(3)和(4)是相等的。滤波器940是专门用来破坏简并和提供SOP和DOP的分别测量的。Here _Ps is the signal power, P _N is the noise power, α is less than 1 and is the noise power filter coefficient of the bandpass filter 940, and δ depolarization coefficient, which results from, for example, the PMD of the input signal, nonlinear birefringence , and PBS 930's Imperfect. In particular, equations (1) and (2) and equations (3) and (4) are equivalent in the absence of filter 940 that produces an unbalanced output of the two output beams of PBS 930 . Filter 940 is designed to destroy degeneracy and provide separate measurements of SOP and DOP.

等式(1)和(2)相加得到：Adding equations (1) and (2) yields:

${V V}_{11}^{max max} + + {V V}_{11}^{min min} = = {G G}_{11} (({P P}_{S S} + + {P P}_{N N})) - - - - - - ((55)),,$

等式(1)和(2)相减得到：Subtracting equations (1) and (2) yields:

${V V}_{11}^{max max} - - {V V}_{11}^{min min} = = {G G}_{11} {P P}_{S S} ((11 - - 22 δ δ)) - - - - - - ((66)) . .$

等式(3)和(4)经过同样的运算得到：Equations (3) and (4) are obtained through the same operation:

${V V}_{22}^{max max} + + {V V}_{22}^{min min} = = {G G}_{22} (({P P}_{s the s} + + α α {P P}_{N N})) - - - - - - ((77))$

${V V}_{22}^{max max} - - {V V}_{22}^{min min} = = {G G}_{22} {P P}_{S S} ((11 - - 22 δ δ)) - - - - - - ((88))$

另外，通过如下的信号运算：In addition, through the following signal operation:

${G G}_{22} \cdot &Center Dot; Eq Eq . . ((55)) - - {G G}_{i i} \cdot &Center Dot; Eq Eq . . ((77)) = = {G G}_{22} (({V V}_{11}^{max max} + + {V V}_{11}^{min min})) - - {G G}_{11} (({V V}_{22}^{max max} + + {V V}_{22}^{min min}))$

$= = {G G}_{11} {G G}_{22} {P P}_{S S} + + {G G}_{11} {G G}_{22} {P P}_{N N} - - {G G}_{11} {G G}_{22} {P P}_{S S} - - α α {G G}_{11} {G G}_{22} {P P}_{N N} . .$

因此，可得到如下结果：Therefore, the following results can be obtained:

$G_{1} G_{2} (1 - α) P_{N} = G_{2} (V_{1}^{\max} + V_{1}^{\min}) - G_{1} (V_{2}^{\max} + V_{2}^{\min}),$ and $G_{1} G_{2} (1 - α) P_{N} = G_{2} (V_{1}^{\max} + V_{1}^{\min}) - G_{1} (V_{2}^{\max} + V_{2}^{\min}),$ and

${P P}_{N N} = = \frac{11}{11 - - α α} [[\frac{{V V}_{11}^{max max} + + {V V}_{a a}^{min min}}{{G G}_{11}} - - \frac{{V V}_{22}^{max max} + + {V V}_{22}^{min min}}{{G G}_{22}}]] - - - - - - ((99))$

从等式(5)可推导出：From equation (5), it can be deduced that:

${G G}_{11} {P P}_{S S} = = (({V V}_{11}^{max max} + + {V V}_{11}^{min min})) - - {G G}_{11} {P P}_{N N}$

$= = (({V V}_{11}^{max max} + + {V V}_{11}^{min min})) - - \frac{11}{11 - - α α} [[(({V V}_{11}^{max max} + + {V V}_{11}^{min min})) - - \frac{{G G}_{11}}{{G G}_{22}} (({V V}_{22}^{max max} + + {V V}_{22}^{min min}))]]$

$= = ((11 - - \frac{11}{11 - - α α})) (({V V}_{11}^{max max} + + {V V}_{11}^{min min})) + + \frac{{G G}_{11} / / {G G}_{22}}{11 - - α α} (({V V}_{22}^{max max} + + {V V}_{22}^{min min}))$

$= = \frac{11}{11 - - α α} [[\frac{{G G}_{11}}{{G G}_{22}} (({V V}_{22}^{max max} + + {V V}_{22}^{min min})) - - α α (({V V}_{11}^{max max} + + {V V}_{11}^{min min}))]] . .$

所以，可推出如下表达式：Therefore, the following expression can be deduced:

${P P}_{S S} = = \frac{11}{11 - - α α} [[\frac{{V V}_{22}^{max max} + + {V V}_{22}^{min min}}{{G G}_{22}} - - \frac{α α}{{G G}_{11}} (({V V}_{11}^{max max} + + {V V}_{11}^{min min}))]] - - - - - - ((1010))$

$S S / / N N = = \frac{{P P}_{s the s}}{{P P}_{N N}}$

$= = \frac{\frac{{V V}_{22}^{max max} + + {V V}_{22}^{min min}}{{G G}_{22}} - - \frac{α α}{{G G}_{11}} (({V V}_{11}^{max max} + + {V V}_{11}^{min min}))}{\frac{{V V}_{11}^{max max} + + {V V}_{11}^{min min}}{{G G}_{11}} - - \frac{{V V}_{22}^{max max} + + {V V}_{22}^{min min}}{}}$

$= = \frac{{G G}_{11} (({V V}_{22}^{max max} + + {V V}_{22}^{min min})) - - α α {G G}_{22} (({V V}_{11}^{max max} + + {V V}_{11}^{min min}))}{{G G}_{22} (({V V}_{11}^{max max} + + {V V}_{11}^{min min})) - - {G G}_{11} (({V V}_{22}^{max max} + + {V V}_{22}^{min min}))} . .$

取 $\overset{&OverBar;}{V_{1}} = \frac{1}{2} (V_{1}^{\max} + V_{1}^{\min}),$ 并且Pick $V$ $\overset{&OverBar;}{_{1}} = \frac{1}{2} (V_{1}^{\max} + V_{1}^{\min}),$ and

${\overset{&OverBar; &OverBar;}{V V}}_{22} = = \frac{11}{22} (({V V}_{22}^{max max} + + {V V}_{22}^{min min})),,$

SNR可通过下式计算得到：SNR can be calculated by the following formula:

$\frac{S S}{N N} = = \frac{{G G}_{11} {\overset{&OverBar; &OverBar;}{V V}}_{22} - - α α {G G}_{22} {\overset{&OverBar; &OverBar;}{V V}}_{11}}{{G G}_{22} {\overset{&OverBar; &OverBar;}{V V}}_{11} - - {G G}_{11} {\overset{&OverBar; &OverBar;}{V V}}_{22}} . . - - - - - - ((1212))$

如果G₁＝G₂，那么SNR为If G ₁ =G ₂ , then the SNR is

$\frac{S S}{N N} = = \frac{{\overset{&OverBar; &OverBar;}{V V}}_{22} - - α α {\overset{&OverBar; &OverBar;}{V V}}_{11}}{{\overset{&OverBar; &OverBar;}{V V}}_{11} - - {\overset{&OverBar; &OverBar;}{V V}}_{22}} . .$

因此，信噪比只和V₁、V₂的平均值有关。这种推导本质上排除了所有PMD效应，非线性双折射，和PBS的非完美性。Therefore, the signal-to-noise ratio is only related to the average value of V ₁ and V ₂ . This derivation essentially rules out all PMD effects, nonlinear birefringence, and PBS imperfections.

由公式(6)，(9)，和(10)可得消偏系数δ为：From formulas (6), (9), and (10), the depolarization coefficient δ can be obtained as:

${G G}_{11} {P P}_{S S} ((11 - - 22 δ δ)) = = {V V}_{11}^{max max} - - {V V}_{11}^{min min},,$

$1 - 2 δ = \frac{1}{G_{1} P_{S}} (V_{1}^{\max} - V_{1}^{\min}),$ and $1 - 2 δ = \frac{1}{G_{1} P_{S}} (V_{1}^{\max} - V_{1}^{\min}),$ and

$δ δ = = \frac{11}{22} [[11 - - \frac{11}{{G G}_{11} {P P}_{S S}} (({V V}_{11}^{max max} - - {V V}_{11}^{min min}))]] = = \frac{11}{22} [[11 - - \frac{((11 - - α α)) (({V V}_{11}^{max max} - - {V V}_{11}^{min min}))}{\frac{{G G}_{11}}{{G G}_{22}} (({V V}_{22}^{max max} + + {V V}_{22}^{min min})) - - α α (({V V}_{11}^{max max} + + {V V}_{11}^{min min}))}]] . .$

如果G₁＝G₂，消偏系数可简化为：If G ₁ =G ₂ , the depolarization coefficient can be simplified as:

$δ δ = = \frac{11}{22} [[11 - - \frac{((11 - - α α)) (({V V}_{11}^{max max} - - {V V}_{11}^{mim mime}))}{22 (({\overset{&OverBar; &OverBar;}{V V}}_{22} - - α α {\overset{&OverBar; &OverBar;}{V V}}_{11}))}]] . .$

由不完美的PBS 930带来的δ可通过在图9中的PBS 930输出放置起偏器941和942来消除。因此，由PMD带来的消偏可得到精确的测量。这个机制还能用于监测PMD效应。The delta introduced by the imperfect PBS 930 can be eliminated by placing polarizers 941 and 942 at the output of PBS 930 in FIG. 9 . Therefore, the depolarization brought about by PMD can be accurately measured. This mechanism can also be used to monitor PMD effects.

图9中的装置利用若干PBS分离WDM通道。同样的，图10展示了用了一个PBS 930结合两个WDM解复器1010和1020的另一个实现方案1000。在这个设计中，两解复器1010和1020刻意的设计为不同的，以产生噪声功率不平衡，不平衡系数为α(λi)(i＝1，2，…，N)。例如，两解复器1010和1020的通道带宽不同，一个为50GHz另一个为75GHz，在WDM信号通道带宽10GHz和100GHz通道间距的情况下，各WDM通道无衰减的传输但是解复器1010和1020输出的噪声功率大小不同。因此，可以除去图9中的滤波器940。如果两解复器1010和1020是一致的，那么需要用一个滤波器产生噪声功率不平衡。The arrangement in Figure 9 utilizes several PBSs to separate the WDM channels. Likewise, FIG. 10 shows another implementation 1000 using a PBS 930 combined with two WDM demultiplexers 1010 and 1020. In this design, the two demultiplexers 1010 and 1020 are intentionally designed differently to generate noise power imbalance with an imbalance coefficient of α(λi) (i=1, 2, . . . , N). For example, the channel bandwidths of the two demultiplexers 1010 and 1020 are different, one is 50 GHz and the other is 75 GHz. In the case of WDM signal channel bandwidths of 10 GHz and 100 GHz channel spacing, each WDM channel can transmit without attenuation but the demultiplexers 1010 and 1020 The output noise power is different. Therefore, filter 940 in FIG. 9 can be eliminated. If the two demultiplexers 1010 and 1020 are identical, then a filter is required to create the noise power imbalance.

参见图11，展示了光纤系统1100中的一个实时DGD监测装置，它和动态PMD补偿器连接在一起使用。这个光纤系统包括三个主要模块：一个发射终端，光纤传输线1103，它可能包括一个带有光放大器的光线链路，和一个接收终端。发射终端包括若干不同通道波长的光发射器1101和一个WDM复用器1102用于复用不同通道使之在光纤链路1103中传输。接收终端包括一个DGD监测器，一个解复用器1120，不同通道的动态PMD补偿器，和不同通道的光接收器。一个光耦合器1110，例如一个光纤耦合器，放置在解复器1120的输入端用于分离输入信号的一部分作为监测光束1112发送到DGD监测器，和解复器1120接收到的主输入信号。Referring to FIG. 11 , a real-time DGD monitoring device in an optical fiber system 1100 is shown, which is used in connection with a dynamic PMD compensator. This fiber optic system consists of three main modules: a transmitting terminal, fiber optic transmission line 1103, which may include an optical fiber link with optical amplifiers, and a receiving terminal. The transmitting terminal includes several optical transmitters 1101 with different channel wavelengths and a WDM multiplexer 1102 for multiplexing different channels for transmission in the optical fiber link 1103 . The receiving terminal includes a DGD monitor, a demultiplexer 1120, dynamic PMD compensators for different channels, and optical receivers for different channels. An optical coupler 1110 , such as a fiber optic coupler, is placed at the input of the demultiplexer 1120 to separate a portion of the input signal sent to the DGD monitor as a monitoring beam 1112 , and the main input signal received by the demultiplexer 1120 .

系统1100中的DGD监测器包括一个可调滤波器1130，一个偏光计1140，和一个控制单元1190中的一个DGD运算电路。可调滤波器1130用于相继的扫描不同WDM或DWDM通道使不同通道依次到达偏光计1140。可调滤波器1130的带宽远远小于各通道的带宽。偏光计1140用于高速测量SOP作为实时的监测。在控制单元1190中的DGD运算电路接收并处理由偏光计1140产生的SOP信号确定各通道的DGD。The DGD monitor in system 1100 includes a tunable filter 1130 , a polarimeter 1140 , and a DGD arithmetic circuit in a control unit 1190 . The tunable filter 1130 is used to sequentially scan different WDM or DWDM channels so that different channels reach the polarimeter 1140 sequentially. The bandwidth of the tunable filter 1130 is much smaller than the bandwidth of each channel. The polarimeter 1140 is used to measure SOP at high speed as a real-time monitor. The DGD arithmetic circuit in the control unit 1190 receives and processes the SOP signal generated by the polarimeter 1140 to determine the DGD of each channel.

在操作中，可调滤波器1130用于调谐一个通道到它的中心波长λi，并且在λi附近扫描一段比偏光计测量通道SOP长的时间。在扫描λi附近的信号的过程中，偏光计处理λi的输入光信号产生这个通道的SOP信息。In operation, tunable filter 1130 is used to tune a channel to its center wavelength λi, and scan around λi for a time longer than the polarimeter measures the channel SOP. In the process of scanning the signal near λi, the polarimeter processes the input optical signal of λi to generate the SOP information of this channel.

图12举例说明了DGD运算电路的运算操作，它在偏振上是以邦加球为参考的。设定通道λi的SOP围绕主光轴Ω变化的角度为Δθi，并且围绕中心波长λi的频率变换为Afi，DGD可通过下示计算得到：Fig. 12 illustrates the operation of the DGD operation circuit, which is referenced to the Poincare sphere in polarization. Assuming that the SOP of the channel λi changes around the main optical axis Ω at an angle of Δθi, and the frequency conversion around the central wavelength λi is Afi, DGD can be calculated as follows:

$Δ Δ {τ τ}_{i i} = = \frac{Δ Δ {θ θ}_{i i}}{22 πΔ πΔ {f f}_{i i}} . .$

这个计算是通过DGD运算电路完成的。图12中展示的，DGD和主光轴Ω的方向都能够由此确定下来。This calculation is done by the DGD arithmetic circuit. As shown in Fig. 12, both the DGD and the direction of the principal optical axis Ω can be determined from this.

接下来，控制单元1190利用DGD信息控制PMD补偿器产生一个和测量得到的DGD相反的DGD。这样就完成了一个通道的监测和控制。然后，控制单元1190命令滤波器1130跳到下一个通道重复这个监测和补偿操作。这个过程相继重复于所有通道。Next, the control unit 1190 uses the DGD information to control the PMD compensator to generate a DGD opposite to the measured DGD. This completes the monitoring and control of a channel. Then, the control unit 1190 commands the filter 1130 to skip to the next channel to repeat this monitoring and compensation operation. This process is repeated for all channels in succession.

图11中的DGD监测装置共享于所有通道。但是PMD补偿是各通道分别实现的。因此，图11中利用若干PMD补偿器对各通道分别进行补偿。为了简化只描述了通道λ1的补偿。The DGD monitoring device in Figure 11 is shared by all channels. However, PMD compensation is implemented separately for each channel. Therefore, in Fig. 11, several PMD compensators are used to compensate each channel separately. For simplicity, only the compensation of channel λ1 is described.

在解复器1120后的各通道的光通道中，通道的PMD补偿器放置在各自的通道接收器1180之前。PMD补偿器包括一个偏振控制器(PC)1150，一个可调DGD(VDGD)元件1160产生一个可调的DGD，一个DOP监测器用于测量光的偏振度，和控制单元1190中的一个PMD控制电路。偏振控制器1150可通过多种方法实现，包括结合的美国专利号No.6,493,474的专利中公开的光纤挤压器型控制器。DOP监测器1170通过设置，分流一部分信号提供给监测操作并且将剩下的信号传送到通道接收器1180中。如图例，PMD控制电路响应监测器1170测量得到的DOP，控制偏振控制器1150和可调DGD元件1160。因此，这个控制为一个反馈控制并且动态的操作产生实时PMD补偿。在实现方案中，一个微处理器在控制单元1190中用于完成DGD测量的计算和PMD补偿。In the optical channel of each channel after the demultiplexer 1120 , the channel's PMD compensator is placed before the respective channel receiver 1180 . The PMD compensator includes a polarization controller (PC) 1150, an adjustable DGD (VDGD) element 1160 produces an adjustable DGD, a DOP monitor is used to measure the degree of polarization of light, and a PMD control circuit in the control unit 1190 . Polarization controller 1150 can be implemented in a variety of ways, including the fiber squeezer type controller disclosed in incorporated US Patent No. 6,493,474. The DOP monitor 1170 is configured to shunt a portion of the signal for monitoring operations and pass the remaining signal to the channel receiver 1180 . As illustrated, the PMD control circuit controls the polarization controller 1150 and the adjustable DGD element 1160 in response to the DOP measured by the monitor 1170 . Therefore, this control is a feedback control and the dynamic operation produces real-time PMD compensation. In an implementation, a microprocessor is used in the control unit 1190 to perform calculations for DGD measurements and PMD compensation.

图11中的偏光计1140可通过多种方法实现。图13展示了一个利用一个可旋转的四分之一波片1310和一个可旋转的起偏器1320处理输入光的实现方案1300。波片1310和1320是受控制的，例如，电路1350，使它在不同旋转速度或频率下旋转。在这个和其他实现方案中，可旋转的波片可替换为一个偏振控制器例如美国专利号No.6,493,474公开的光纤挤压型控制器。一个光探测器1330用于转换这个经过处理后的光成为一个探测信号，以及一个信号运算电路1350进一步处理这个探测信号测量光的SOP。一个可选的信号放大器1340耦合在探测器1330和电路1350之间用于放大信号。因此，在图11的结构中，滤波器扫描通过不同通道，偏光器1300一次一个的测量通道的SOP。同样的，图11中的结构中可调整滤波器1130的位置，把它放置在探测器1330和偏光计1300的起偏器1320之间。The polarimeter 1140 in FIG. 11 can be implemented in a variety of ways. FIG. 13 shows an implementation 1300 of processing input light using a rotatable quarter-wave plate 1310 and a rotatable polarizer 1320 . Wave plates 1310 and 1320 are controlled, eg, by circuitry 1350, to rotate at different rotational speeds or frequencies. In this and other implementations, the rotatable waveplate can be replaced with a polarization controller such as the fiber extrusion type controller disclosed in US Patent No. 6,493,474. A light detector 1330 is used to convert the processed light into a detection signal, and a signal operation circuit 1350 further processes the detection signal to measure the SOP of the light. An optional signal amplifier 1340 is coupled between detector 1330 and circuit 1350 for amplifying the signal. Thus, in the configuration of FIG. 11 , the filter is scanned through the different channels, and the polarizer 1300 measures the SOP of the channels one at a time. Similarly, the position of the filter 1130 can be adjusted in the structure in FIG. 11 , and it is placed between the detector 1330 and the polarizer 1320 of the polarimeter 1300 .

同时一个偏光计还可用于平行的多通道SOP的测量。图14和15展示了两个例子。在图14中，偏光计1400利用一个解复器1120分离来自四分之一波片1310和起偏器1320输出的不同通道。各通道利用一个光探测器1330和一个信号运算电路1350处理通道信号，确定通道的SOP。因此，并行监测了同一时刻的所有通道。At the same time, a polarimeter can also be used for parallel multi-channel SOP measurement. Figures 14 and 15 show two examples. In FIG. 14 , a polarimeter 1400 utilizes a demultiplexer 1120 to separate the different channels from the quarter wave plate 1310 and polarizer 1320 outputs. Each channel uses a photodetector 1330 and a signal operation circuit 1350 to process the channel signal to determine the SOP of the channel. Therefore, all channels at the same time are monitored in parallel.

图15展示了一个不同的设计1500，它使用一个衍射光栅820和一个准直透镜830空间分离不同通道，它的设计和图8近似的但是应用不同。一个运算电路1520用于处理探测输出产生不同通道的SOP信号。Figure 15 shows a different design 1500 that uses a diffraction grating 820 and a collimating lens 830 to spatially separate the different channels, similar in design to Figure 8 but with a different application. An arithmetic circuit 1520 is used to process the detection output to generate SOP signals of different channels.

在当输入信号不存在PMD时，信号的SNR能直接从DOP测量中得到。假设P_s为偏振的信号的功率P_n为非偏振的噪声的功率。DOP可通过如下公式计算：When there is no PMD in the input signal, the SNR of the signal can be obtained directly from the DOP measurement. Suppose P _s is the power of the polarized signal and P _n is the power of the unpolarized noise. DOP can be calculated by the following formula:

$DOP DOP = = \frac{{P P}_{s the s}}{{P P}_{s the s} + + {P P}_{n no}} = = \frac{{P P}_{s the s} / / {P P}_{n no}}{11 + + {P P}_{s the s} / / {p p}_{n no}} . .$

因此，SNR能通过DOP计算得到：Therefore, SNR can be calculated by DOP:

$SNR SNR = = \frac{{P P}_{s the s}}{{P P}_{n no}} = = \frac{DOP DOP}{11 - - DOP DOP} . .$

这里，DOP可以通过计算测量得到的最大和最小功率大小得到。当DOP为1的时候，SNR为无穷，当DOP为0的时候，SNR为0。Here, DOP can be obtained by calculating the measured maximum and minimum power levels. When the DOP is 1, the SNR is infinite, and when the DOP is 0, the SNR is 0.

图16展示了光纤系统1600，它用到以上的连续或平行的多通道偏光计监测各通道的SOP。一个光纤耦合器1110用于分离多通道的输入光的一部分产生一个监测信号1112。一个可调法布里-泊罗滤波器1610用于过滤监测光束1112同时传输所有WDM通道到一个多通道偏光计1620。这个可以通过使法布里-泊罗滤波器1610产生具有一个等子WDM通道间隔或通道间隔倍数的自由谱范围(FSR)实现。在操作中通过调节可调法布里-泊罗滤波器1610的中心波长，利用图12所示的邦加球对DGD进行测量。图17进一步展示了滤波器1610的光谱，滤波器1610的一个调节引起所有传输通道的相同量的频移。如图14和15所示，偏光计1620可以是一个含有一个可调滤波器的按时序测量的多通道偏光计也可以是一个平行的多通道偏光计。Figure 16 shows a fiber optic system 1600 that uses the above sequential or parallel multi-channel polarimeters to monitor the SOP of each channel. A fiber coupler 1110 is used to split a part of the input light of multiple channels to generate a monitoring signal 1112 . A tunable Fabry-Perot filter 1610 is used to filter the monitoring beam 1112 while transmitting all WDM channels to a multi-channel polarimeter 1620 . This can be achieved by having the Fabry-Perot filter 1610 produce a free spectral range (FSR) with an equal sub-WDM channel spacing or a multiple of the channel spacing. In operation, by adjusting the central wavelength of the tunable Fabry-Perot filter 1610, the DGD is measured using the Poincare sphere shown in FIG. 12 . Figure 17 further illustrates the spectrum of filter 1610, one adjustment of filter 1610 causes the same amount of frequency shift for all transmission channels. As shown in Figures 14 and 15, the polarimeter 1620 can be a sequentially measuring multi-channel polarimeter with a tunable filter or a parallel multi-channel polarimeter.

在一些WDM系统中，通道间距为50GHz，100GHz，或200GHz。假设滤波器1610的精细度为100，则滤波器的分辨率带宽为1GHz并且足够分辨10Gb/s信号的光谱。如上所述，各通道的DGD可通过基于如图12所示的各通道SOP的测量计算得到。In some WDM systems, the channel spacing is 50GHz, 100GHz, or 200GHz. Assuming that the fineness of the filter 1610 is 100, the resolution bandwidth of the filter is 1 GHz and is sufficient to resolve the spectrum of a 10 Gb/s signal. As described above, the DGD of each channel can be calculated based on the measurement of the SOP of each channel as shown in FIG. 12 .

图18A和18B展示了两个独立监测WDM系统的信噪比(SNR)和DGD的实现方案1801和1802。在两系统中，输入光相继经过一个可旋转的四分之一波片1310和一个可旋转的二分之一波片1810。波片1310和1810具有不同旋转速度。在两系统中，各通道被分解成两个具有正交偏振的光束并且具有不同功率大小。在系统1801中，可通过利用两个具有不同通道带宽的不同解复器1010和1020得到。在系统1802中，用一个滤波器940插入两束光中的一束来产生差异。这里可应用结合图9和10的处理技术。Figures 18A and 18B illustrate two implementations 1801 and 1802 for independently monitoring the signal-to-noise ratio (SNR) and DGD of a WDM system. In both systems, input light passes through a rotatable quarter-wave plate 1310 and a rotatable half-wave plate 1810 sequentially. Wave plates 1310 and 1810 have different rotational speeds. In both systems, each channel is split into two beams with orthogonal polarizations and different power levels. In system 1801, this can be obtained by utilizing two different demultiplexers 1010 and 1020 with different channel bandwidths. In system 1802, a filter 940 is used to interpolate one of the two beams to create a difference. Here the processing techniques combined with Figures 9 and 10 can be applied.

在以上图13，14，15，18A和188中描述的例子中，由可旋转波片1310和可旋转起偏器1320构成的扰偏器可由一个SOP发生器和一个在光通道下游的固定方向的起偏器代替。SOP发生器用于控制接收光的偏振产生邦加球上预设的任何SOP中所需的SOP。In the examples described above in Figures 13, 14, 15, 18A and 188, the scrambler consisting of the rotatable wave plate 1310 and the rotatable polarizer 1320 can be composed of a SOP generator and a fixed direction downstream of the optical path polarizer instead. The SOP generator is used to control the polarization of the received light to generate the desired SOP in any SOP preset on the Poincare sphere.

图19A，19B，19C，19D，和19E用1901，1902，1903，1904，和1905的例子说明了用一个SOP发生器1910和一个特定起偏器210的光监测装置。SOP发生器通过设置可调节产生多种SOP。一个外控制信号用于控制SOP发生器1910产生SOP。在实际操作中，控制信号包括SOP发生器1910中不同旋偏器的各自的控制信号。Figures 19A, 19B, 19C, 19D, and 19E illustrate an optical monitoring device using a SOP generator 1910 and a specific polarizer 210 using examples 1901, 1902, 1903, 1904, and 1905. The SOP generator can be adjusted to generate various SOPs through settings. An external control signal is used to control the SOP generator 1910 to generate SOP. In actual operation, the control signals include the respective control signals of different rotators in the SOP generator 1910 .

图20展示了一个SOP发生器的例子。在这个例子中，SOP发生器包括4个可控制的旋偏器1，2，3，和4相继放置在光通道中。一个四分之一波片放置在旋偏器2和3之间用于将4个旋偏器分成两对：旋偏器1和2为一对，旋偏器3和4为另一对。此外，一个可选的输入起偏器放置在第一个旋偏器之前用于将输入偏振和λ/4波片相关光轴(c-axis)对齐。输入起偏器可有多种方位角，例如，λ/4波片与c-轴方向，或与c-轴成45°角方向或其与它预定的角度对齐。图20中的各旋偏器如图所示可通过各自的控制信号控制。产生需要的SOP输出。Figure 20 shows an example of a SOP generator. In this example, the SOP generator consists of four controllable rotators 1, 2, 3, and 4 placed sequentially in the optical channel. A quarter-wave plate is placed between depolarizers 2 and 3 to divide the 4 depolarizers into two pairs: depolarizers 1 and 2 as one pair, and depolarizers 3 and 4 as another pair. In addition, an optional input polarizer is placed before the first rotator to align the input polarization with the relative optical axis (c-axis) of the λ/4 plate. The input polarizer can have a variety of azimuths, for example, a lambda/4 plate aligned with the c-axis, or oriented at a 45° angle to the c-axis, or aligned at other predetermined angles. Each rotator in Fig. 20 can be controlled by a respective control signal as shown. Generate the required SOP output.

特别的是，图20中的SOP发生器可使输入的一个线偏振的输入光束产生至少4个和一般多于4个不同的偏振态。图20中的SOP发生器的这种特点主要因为光的任何偏振态可由4个Stockes参量表示。所以，当能够从光样品，一个光装置，或一个光模块得到的至少4个测量得到光的4个不同偏振态时，通过求解一个四元线性方程确定4个Stockes参量，从而确定被测样品装置或模块的偏振特性。In particular, the SOP generator of FIG. 20 can generate at least 4 and generally more than 4 different polarization states from a linearly polarized input beam. This characteristic of the SOP generator in Fig. 20 is mainly because any polarization state of light can be represented by 4 Stockes parameters. Therefore, when 4 different polarization states of light can be obtained from at least 4 measurements obtained from an optical sample, an optical device, or an optical module, the four Stockes parameters are determined by solving a four-element linear equation, thereby determining the measured sample Polarization characteristics of the device or module.

此外，图20中的SOP发生器还可用作SOP分析仪或偏光计来确定任何接收光的SOP，它是通过对输入光进行至少4次不同的测量，求解输入光的4个Stockes参量得到的。In addition, the SOP generator in Figure 20 can also be used as a SOP analyzer or polarimeter to determine the SOP of any received light, which is obtained by solving the 4 Stockes parameters of the input light by making at least 4 different measurements of the input light of.

众所周知，邦加球可用于表示所有偏振态。邦加球上的各点有一个唯一的坐标值，这个值是由球的3维轴S₁，S₂和S₃确定的。一个Stokes矢量是一个结合4个Stokes参量(S₀，S₁，S₂，S₃)的4×1实矩阵，可完全的描述光的SOP。例如，邦加球赤道上的点表示的是线偏振态，两极表示右旋圆偏振和左旋圆偏振，邦加球上的其它点表示椭圆偏振态。It is well known that the Poincare sphere can be used to represent all polarization states. Each point on the Poincare sphere has a unique coordinate value, which is determined by the 3-dimensional axes S ₁ , S ₂ and S ₃ of the sphere. A Stokes vector is a 4×1 real matrix combining 4 Stokes parameters (S ₀ , S ₁ , S ₂ , S ₃ ), which can fully describe the SOP of light. For example, points on the equator of the Poincare sphere represent linear polarization states, the poles represent right-handed and left-handed circular polarization, and other points on the Poincare sphere represent elliptical polarization states.

从数学上讲，至少4个相互不同的偏振测量可用来测量确定Stockes参量。从理论上讲，对一个特定的应用总会有一个比较合适的方法来得到这4个相互不同偏振测量。例如，一个未知SOP的光束的四个Stockes参量，可以用以下方法通过测量功率大小得到：1)将一个0°起偏器(例如，沿水平方向)放置在输入光通道中并且测量通过起偏器后的光功率；2)接下来，旋转起偏器45°然后测量通过起偏器后的相应的光功率；3)然后再旋转起偏器至90度(或-45°)后测量通过起偏器后的光功率；4)最后，插入一个左旋圆偏振或右旋圆偏振起偏器，测量通过左旋圆偏振或右旋圆偏振起偏器之后的光功率。Mathematically, at least 4 mutually different polarization measurements can be used to determine the Stockes parameters. Theoretically, there is always a more appropriate way to obtain these four mutually different polarization measurements for a specific application. For example, the four Stockes parameters of a beam of unknown SOP can be obtained by measuring the power level in the following way: 1) Place a 0° polarizer (for example, along the horizontal direction) in the input optical channel and measure 2) Next, rotate the polarizer 45° and then measure the corresponding optical power after passing through the polarizer; 3) Then rotate the polarizer to 90° (or -45°) and measure through Optical power after the polarizer; 4) Finally, insert a left-handed or right-handed circular polarizer, and measure the optical power after passing through the left-handed or right-handed circular polarizer.

以上功率测量可通过以下方法确定输入SOP的Stockes参量：S₀为整个光束(I)的平均功率；S₁为光束的水平(0度)和垂直(90度)线偏振分量之差(I₀-1₉₀)；S₂表示+45度和-45度线偏振功率之差，(1₄₅-I-₄₅)；和S₃为左旋圆偏振光和右旋圆偏振光功率之差：(I_RCP-I_LCP)。Stokes矢量的大小等于(s₁ ²+s₂ ²+s₃ ²)^1/2并且以邦加球圆心为起点。这三个Stokes参量可通过归一化得到相对功率值(s₁＝S₁/S₀，s₂＝S₂/S₀，s₃＝S₃/S₀)。The above power measurement can be determined by the following method to determine the Stockes parameters of the input SOP: S ₀ is the average power of the entire beam (I); S ₁ is the difference between the horizontal (0 degree) and vertical (90 degree) linear polarization components of the beam (I ₀ -1 ₉₀ ); S ₂ represents the difference between +45 degrees and -45 degrees linearly polarized power, (1 ₄₅ -I- ₄₅ ); and S ₃ is the difference between left-handed circularly polarized light and right-handed circularly polarized light power: (I _RCP -I _LCP ). The size of the Stokes vector is equal to (s ₁ ² +s ₂ ² +s ₃ ² ) ^1/2 and originates from the center of the Poincare sphere. These three Stokes parameters can be normalized to obtain relative power values (s ₁ =S ₁ /S ₀ , s ₂ =S ₂ /S ₀ , s ₃ =S ₃ /S ₀ ).

图20中的SOP发生器的一个实现方案为，各旋偏器为一个磁-光(MO)旋偏器用于消除SOP发生器中任何机械移动部分。这种运用没有可移动部分的MO旋偏器或其它旋偏器的方法能改进装置的可靠性和使用寿命。In one implementation of the SOP generator in Figure 20, each depolarizer is a magneto-optical (MO) depolarizer to eliminate any mechanically moving parts in the SOP generator. This method of using an MO deviator or other deviator with no moving parts can improve the reliability and lifetime of the device.

一个旋偏器，例如一个MO旋偏器，适合用作图20中的SOP发生器，它包含了以下性质：(1)当给MO旋片器加一个高于MO旋偏器饱和电压Vsat的正电压时(例如，V≥+Vsat)，MO旋偏器使光的SOP旋转+22.5°；(2)当给MO旋片器加一个低于MO旋偏器饱和电压Vsat的负电压时(例如，V≤-Vsat)，旋偏器使光的SOP旋转-22.5°；(3)当旋偏器1和2(或者3和4)相同方向旋转时，旋偏器1和2(或3和4)总的旋偏角为45°；(4)当旋偏器1和2(或者3和4)向相反方向旋转，旋偏器对的总旋偏角为0°。同时，其它类型的旋偏器例如液晶旋偏器和固态双折射晶体型旋偏器也可通过适当的控制信号产生以上工作偏振态。A polarizer, such as an MO rotator, is suitable for use as the SOP generator in Figure 20, and it includes the following properties: (1) When a MO rotator is added with a voltage higher than the saturation voltage Vsat of the MO rotator When the voltage is positive (for example, V≥+Vsat), the MO rotator rotates the SOP of the light by +22.5°; (2) When a negative voltage lower than the saturation voltage Vsat of the MO rotator is applied to the MO rotator ( For example, V≤-Vsat), the polarizer rotates the SOP of the light by -22.5°; (3) When the polarizers 1 and 2 (or 3 and 4) rotate in the same direction, the polarizers 1 and 2 (or 3 and 4) the total deflection angle is 45°; (4) when the deviator 1 and 2 (or 3 and 4) rotate in opposite directions, the total deflection angle of the deviator pair is 0°. Meanwhile, other types of polarizers such as liquid crystal polarizers and solid birefringent crystal polarizers can also generate the above working polarization states through appropriate control signals.

因此，这个SOP发生器，在输入SOP是线偏振并且与λ/4波片的C-轴对齐的情况下产生至少以下5种特殊不同的偏振态：Therefore, this SOP generator, given that the input SOP is linearly polarized and aligned with the C-axis of the λ/4 waveplate, produces at least the following 5 specific different polarization states:

当旋偏器1和2向相反方向旋偏，并且旋偏器3和4也向相反方向旋偏时产生一个0°线SOP；When rotators 1 and 2 are rotating in opposite directions, and rotators 3 and 4 are also rotating in opposite directions, a 0° line SOP is generated;

当旋偏器1和2向相反方向旋偏，但是旋偏器3和4各旋偏+22.5°时产生一个+45°的线SOP；A line SOP of +45° is generated when the deviators 1 and 2 are deviating in opposite directions, but the deviators 3 and 4 are each deviating by +22.5°;

当旋偏器1和2向相反方向旋偏，但是旋偏器3和4各旋偏-22.5°时产生一个-45°的SOP；When the deviators 1 and 2 are deviating in opposite directions, but the deviators 3 and 4 are each deviating by -22.5°, a SOP of -45° is generated;

当旋偏器1和2各旋偏+22.5°时产生一个右旋圆偏振态(RHC)；和A right-handed circular polarization state (RHC) is produced when rotators 1 and 2 are each rotated by +22.5°; and

当旋偏器1和2各旋偏-22.5°时产生一个左旋圆偏振态(LHC)。A left-handed circular polarization state (LHC) is produced when rotators 1 and 2 are each deviated by -22.5°.

表1和2为图20中两种结构的SOP发生器的旋偏器1，2，3，4在不同设置下的输出SOP逻辑表。各表中的第一行显示四个旋偏器中每个旋偏器的旋偏方向和旋偏角度，剩下的行只显示了旋偏器的旋偏方向并且旋偏角固定为22.5度。表2中具有45度配置的SOP发生器有6个不同的特定偏振态。这两个结构下的SOP具有简并偏振态，简并偏振态指的是两个不同旋偏器设置产生同一个偏振态输出。例如，最上面的四个不同设置的4个旋偏器都产生同样的0度线偏振输出。Tables 1 and 2 are the output SOP logic tables of the SOP generators 1, 2, 3, 4 of the two structures in Fig. 20 under different settings. The first row in each table shows the direction of rotation and the angle of rotation for each of the four polarizers, and the remaining rows only show the direction of rotation of the polarizer and the angle of rotation is fixed at 22.5 degrees . The SOP generator in Table 2 with the 45 degree configuration has 6 different specific polarization states. The SOPs under these two structures have degenerate polarization states, which means that two different rotator settings produce the same polarization state output. For example, the top four rotators with different settings all produce the same 0° linearly polarized output.

表1当输入SOP与四分之一被片对齐时的输出SOPTable 1 Output SOP when input SOP is aligned with quarter slice

旋偏器1 Rotator 1 旋偏器2 Rotator 2 旋偏器3 Rotator 3 旋偏器4 Rotator 4 SOP SOP +22.5° +22.5° -22.5° -22.5° +22.5° +22.5° -22.5° -22.5° 0°线偏振 0° linear polarization + + - - - - + + 0°线偏振 0° linear polarization - - + + + + - - n°线偏振 n° linear polarization - - + + - - + + 0°线偏振 0° linear polarization + + - - + + + + 45°线偏振 45° linear polarization - - + + + + + + 45°线偏振 45° linear polarization + + - - - - - - -45°线偏振 -45° linear polarization - - + + - - - - -45°线偏振 -45° linear polarization + + + + + + + + RHC RHC + + + + - - + + RHC RHC + + + + + + - - RHC RHC + + + + - - - - RHC RHC - - - - + + + + LHC LHC - - - - - - + + LHC LHC - - + + - - LHC LHC - - - - - - - - LHC LHC

表2输入SOP与四分之一被片的e-轴成45度角时的SOP输出Table 2 SOP output when the input SOP is at a 45-degree angle to the e-axis of the quarter sheet

旋偏器1 Rotator 1 旋偏器2 Rotator 2 旋偏器3 Rotator 3 旋偏器4 Rotator 4 SOP SOP +22.5° +22.5° -22.5° -22.5° +22.5° +22.5° -22.5° -22.5° RHC RHC + + - - - - + + RHC RHC - - + + + + - - RHC RHC - - + + - - + + RHC RHC + + - - + + + + RHC RHC - - + + + + + + RHC RHC + + - - - - - - RHC RHC - - + + - - - - RHC RHC + + + + + + + + 90°线偏振 90° linear polarization + + + + - - + + 45°线偏振 45° linear polarization + + + + + + - - 45°线偏振 45° linear polarization + + + + - - - - 0°线偏振 0° linear polarization - - - - + + + + 0°线偏振 0° linear polarization - - - - - - + + -45°线偏振 -45° linear polarization - - - - + + - - -45°线偏振 -45° linear polarization - - - - - - - - -90°线偏振 -90° linear polarization

图21举例说明了一个基于图20设计的封装了的SOP发生器的例子，发生器利用保偏(PM)或单模(SM)光纤作为输出封装。如图所示，用一个机架承载旋偏器和波片还有可选的起偏器。用两个光纤准直器在SOP发生器输入输出端口并且耦合于输入和输出PM或SM光纤中。光纤准直器也是单模或PM光纤。Figure 21 illustrates an example of a packaged SOP generator based on the design of Figure 20, utilizing either polarization-maintaining (PM) or single-mode (SM) fiber as the output package. As shown, a rack holds the polarizer, wave plate and optional polarizer. Use two fiber collimators at the input and output ports of the SOP generator and couple into the input and output PM or SM fibers. Fiber collimators are also single mode or PM fiber.

在工作情况下图20或21的SOP发生器用于产生不同SOP输出，首先确定一个线偏振的输入光信号然后设置好输入SOP和四分之一波片之之间的相对方位角，例如，在如表1中的0度或表2中的45度。In working conditions, the SOP generator of Fig. 20 or 21 is used to generate different SOP outputs, first determine a linearly polarized input optical signal and then set the relative azimuth between the input SOP and the quarter-wave plate, for example, in Such as 0 degrees in Table 1 or 45 degrees in Table 2.

当图20或图21中的SOP发生器被用作SOP分析仪测量光的SOP和DOP时，一个来自图20中右端口(旋偏器4)的未知SOP的输入光束发送到SOP发生器中和一个在图20中左端口(旋偏器1)的光探测器用于接收传输经过SOP发生器后的光束。图22展示了一个可实现SOP发生器用作SOP分析仪的装置。一个具有特定线偏振的输出起偏器放置在SOP发生器输出和光探测器之间用于过滤来自SOP发生器的输出光，所以光探测器接受到的光是被特定起偏器起偏后的光。起偏器的输出功率经过测量并且测量结果用来确定输入光的SOP。When the SOP generator in Figure 20 or Figure 21 is used as a SOP analyzer to measure the SOP and DOP of light, an input beam of unknown SOP from the right port (rotator 4) in Figure 20 is sent to the SOP generator and a photodetector at the left port (rotator 1) in Fig. 20 is used to receive the light beam transmitted through the SOP generator. Figure 22 shows a setup that enables the SOP generator to be used as a SOP analyzer. An output polarizer with a specific linear polarization is placed between the output of the SOP generator and the photodetector to filter the output light from the SOP generator, so the light received by the photodetector is polarized by the specific polarizer Light. The output power of the polarizer is measured and the measurement is used to determine the SOP of the input light.

在这种操作中，SOP发生器用于给起偏器产生最少4个不同偏振态，通过旋转起偏器分析输入光的SOP。因此，图22中用于分析输入光未知SOP的SOP发生器的4个旋偏器通过控制，旋转SOP为测量产生4个不同输出态。和之前通过旋转起偏器和用RHC或LHC起偏器确定4个Stokes系数的4个不同偏振态测量的例子相比，图22中的SOP起偏器通过旋转输入光的偏振态代替之前的4个等价功率的测量：1)通过控制4个旋偏器使输入SOP不变并且直接送入光探测器前的起偏器中并且测量起偏器后的光功率；2)通过控制4个旋偏器旋转SOP45°并且再次测量起偏器后的光功率；3)通过控制4个起偏器旋转输入SOP 90或-45°，第三次测量起偏器后的光功率；和4)通过控制4个旋偏器将输入SOP转换为RHC(或LHC)并且测量起偏器后的光功率。以上步骤用来说明图22中的SOP发生器是用于将输入SOP转换为4个不同SOP得到4个不同的功率实现测量的。图22中的SOP发生器在实际操作中，可利用4个或更多设置来产生不同SOP输出实现不同测量。例如，如果图22中光探测器前的起偏器的方向是与SOP发生器中λ/4波片的光轴对齐时，4个旋偏器可通过表1中4种不同的组合产生不同SOP输出实现4个功率测量。当图22中光探测器前的起偏器的方向是与SOP发生器中的λ/4波片成45度角时，这4个旋偏器可通过表2中4个不同设置产生表2中不同SOP输出实现4个功率测量。In this operation, the SOP generator is used to generate a minimum of 4 different polarization states to the polarizer, and the SOP of the input light is analyzed by rotating the polarizer. Therefore, the 4 rotators of the SOP generator used to analyze the unknown SOP of the input light in Fig. 22 are controlled to rotate the SOP to generate 4 different output states for the measurement. Compared to the previous example of measuring 4 different polarization states by rotating the polarizer and determining the 4 Stokes coefficients with RHC or LHC polarizers, the SOP polarizer in Figure 22 replaces the previous one by rotating the polarization state of the input light Measurement of 4 equivalent powers: 1) by controlling 4 polarizers to keep the input SOP constant and directly sending it into the polarizer in front of the photodetector and measuring the optical power behind the polarizer; 2) by controlling 4 A polarizer is rotated by SOP45° and the optical power after the polarizer is measured again; 3) by controlling 4 polarizers to rotate the input SOP 90 or -45°, the optical power behind the polarizer is measured for the third time; and 4 ) convert the input SOP to RHC (or LHC) by controlling 4 rotators and measure the optical power after the polarizers. The above steps are used to illustrate that the SOP generator in Figure 22 is used to convert the input SOP into 4 different SOPs to obtain 4 different powers for measurement. In actual operation, the SOP generator in Figure 22 can use 4 or more settings to generate different SOP outputs to achieve different measurements. For example, if the direction of the polarizer in front of the photodetector in Figure 22 is aligned with the optical axis of the λ/4 wave plate in the SOP generator, the four polarizers can produce different The SOP output enables 4 power measurements. When the direction of the polarizer in front of the photodetector in Figure 22 is at a 45-degree angle to the λ/4 wave plate in the SOP generator, these 4 polarizers can be generated by using the 4 different settings in Table 2. Table 2 4 power measurements are realized with different SOP outputs.

图23进一步展示了一个基于图22设计的偏光计，它在光探测器之前并且平行对齐于λ/4波片的慢轴。假设这4个旋偏器1，2，3，和4分别工作在旋偏角α，β，γ，和δ下，并且在传输经过偏光计的过程中不存在光损耗，偏光计的Mueller矩阵可用如下4×4矩阵M(T)表示：Figure 23 further shows a polarimeter based on the design of Figure 22, before the photodetector and aligned parallel to the slow axis of the λ/4 waveplate. Assuming that the four rotators 1, 2, 3, and 4 work under the declination angles α, β, γ, and δ respectively, and there is no optical loss during transmission through the polarizer, the Mueller matrix of the polarizer It can be represented by the following 4×4 matrix M(T):

$M m ((T T)) = = (\begin{matrix} 11 & cos cos 22 ((α α + + β β)) cos cos 22 ((γ γ + + δ δ)) & sin sin 22 ((α α + + β β)) cos cos 22 ((γ γ + + δ δ)) & sin sin 22 ((γ γ + + δ δ)) \\ 11 & cos cos 22 ((α α + + β β)) cos cos 22 ((γ γ + + δ δ)) & sin sin 22 ((α α + + β β)) cos cos 22 ((γ γ + + δ δ)) & sin sin 22 ((γ γ + + δ δ)) \\ 00 & 00 & 00 & 00 \\ 00 & 00 & 00 & 00 \end{matrix}),,$

当利用Stokes矢量S＝(S₀，S₁，S₂，S₃)描述输入光的偏振态时，输出光功率(S₀′)为：When using the Stokes vector S=(S ₀ , S ₁ , S ₂ , S ₃ ) to describe the polarization state of the input light, the output optical power (S ₀ ′) is:

${S S}_{00}^{' '} = = \frac{11}{22} [[{S S}_{00} + + cos cos 22 ((α α + + β β)) cos cos 22 ((γ γ + + δ δ)) {S S}_{11} + + sin sin 22 ((α α + + β β)) cos cos 22 ((γ γ + + δ δ)) {S S}_{22} + + sin sin 22 ((γ γ + + δ δ)) {S S}_{33}]] . .$

在偏光计输出光功率表达式中，旋偏器的4个不同旋转角是成对出现的，在λ/4波片一边的旋偏器1和2的旋偏角度体现为(α+β)之和并且在λ/4另一边的旋偏器3和5的旋偏角体现为(γ+δ)之和。因此，两个双级旋转角θ

定义用来分别代表着两个和：In the expression of the output optical power of the polarizer, the four different rotation angles of the polarizer appear in pairs, and the deflection angles of the

polarizers

1 and 2 on one side of the λ/4 wave plate are expressed as (α+β) The sum and the declination angles of the deviators 3 and 5 on the other side of λ/4 are expressed as the sum of (γ+δ). Therefore, the two-stage rotation angle θ

The definitions are used to represent two sums respectively:

θ＝α+β，和θ = α + β, and

在图20-22中可效仿的设计中，旋偏器，例如磁光晶体，假设具有以下二元静态值In an exemplary design in Figs. 20-22, a polarizer, such as a magneto-optic crystal, is assumed to have the following binary static values

α＝β＝γ＝δ＝±22.5°.α=β=γ=δ=±22.5°.

在这个条件下，可能的双级旋偏角组合为：Under this condition, the possible dual-stage spin angle combinations are:

因此，光的输出S₀′，双级旋偏角θ和

，和4个旋偏器的二元旋偏角可用来展示在所有可能的θ和

的组合中能得到总共5个不同输出功率值。上述任意4个组合产生足够计算输入SOP的信息。Therefore, the light output S ₀ ′, the two-stage declination angle θ and

, and the binary declination angles of the 4 delectors can be used to show that at all possible θ and

A total of 5 different output power values can be obtained in the combination. Any combination of the above 4 yields enough information to calculate the input SOP.

更特别的是，光的输出S₀′可表示为角θand

的一个函数：More specifically, the light output S ₀ ′ can be expressed as the angle θ and

A function of:

因此输出S₀′的以下输出态能通过控制旋偏器得到：Therefore the following output states of the output S ₀ ′ can be obtained by controlling the rotator:

and，

and,

因此，偏光计中未知SOP的输入光的Stockes参量可用下示确定：Therefore, the Stockes parameter of the input light with unknown SOP in the polarimeter can be determined as follows:

S₀＝S₀′(θ，45°)+S₀′(θ，，-45°)＝S₀′(45°，0°)+S₀′(-45°，0°)，S ₀ ＝S ₀ ′(θ, 45°)+S ₀ ′(θ,,-45°)=S ₀ ′(45°, 0°)+S ₀ ′(-45°, 0°),

S₁＝2S₀′-S₀′(45°，0°)-S₀′(- 45°，0°)S ₁ =2S ₀ ′-S ₀ ′(45°, 0°)-S ₀ ′(- 45°, 0°)

S₂＝S₀′(45°，0°)-S₀′(-45°，0°)，S ₂ =S ₀ ′(45°, 0°)-S ₀ ′(-45°, 0°),

S₃＝S₀′(θ，45°)-S₀′(θ，-45°).S ₃ ＝S ₀ ′(θ, 45°)-S ₀ ′(θ, -45°).

在偏光计的实际操作中，一个控制和运算单元用来产生控制信号1，2，3和4用于分别控制旋偏器并且处理来自相应不同旋偏器组合的光探测器的探测输出。一个微处理器或电脑在控制和运算单元中编程实现某些控制和数据处理操作。然后通过求解基于探测器输出的Mul ler矩阵方程确定接收光的SOP。然后输入光的DOP可通过SOP确定下来。输入信号的信噪比同样也通过SNR＝(DOP)/(1-DOP)的关系得到。In the actual operation of the polarizer, a control and arithmetic unit is used to generate control signals 1, 2, 3 and 4 for respectively controlling the polarizers and processing the detection outputs from the photodetectors corresponding to different combinations of polarizers. A microprocessor or computer is programmed in the control and arithmetic unit to perform certain control and data processing operations. The SOP of the received light is then determined by solving the Muller matrix equation based on the detector output. The DOP of the input light can then be determined by the SOP. The signal-to-noise ratio of the input signal is also obtained through the relationship of SNR=(DOP)/(1-DOP).

图24展示了一个利用光纤实现图23中的偏光计的例子，一个输入光纤用于传输输入光和一个输出光纤用于接收输出光。分别耦合光纤准直器C1和C2到偏光计的输入和输出端。Figure 24 shows an example of implementing the polarimeter in Figure 23 using optical fibers, an input fiber for transmitting input light and an output fiber for receiving output light. Couple fiber collimators C1 and C2 to the input and output of the polarimeter, respectively.

在以上SOP发生器和基于SOP的偏光计中，用4个旋偏器组成两对旋偏器对。可通过增加旋偏器对进一步增加这些SOP发生器和偏光计的不同的SOP输出。四分之一波片(QWP)可放置在任意两旋偏器对之间。In the above SOP generator and SOP-based polarimeter, four polarizers are used to form two pairs of polarizers. The different SOP outputs of these SOP generators and polarimeters can be further increased by adding pairs of rotators. A quarter-wave plate (QWP) can be placed between any two pairs of polarizers.

图25展示了一个总共具有6个旋偏器R1，R2，R3，R4，R5，和R6，形成3对旋偏器(R1，R2)，(R3，R4)，和(R5，R6)的偏光计的例子。四分之一波片放置在(R3，R4)和(R5，R6)旋偏器对之间。同样的，四分之一波片还可放置在(R1，R2)和(R3，R4)旋偏器对之间。此外，假设各旋偏器设定工作在二元旋偏角±22.5°下，这个具有3对旋偏器的SOP发生器能在线偏振输入时产生6个不同偏振态。Figure 25 shows a total of 6 polarizers R1, R2, R3, R4, R5, and R6, forming 3 pairs of polarizers (R1, R2), (R3, R4), and (R5, R6) Example of a polarimeter. A quarter-wave plate is placed between the (R3, R4) and (R5, R6) polarizer pairs. Likewise, a quarter-wave plate can also be placed between the (R1, R2) and (R3, R4) polarizer pairs. In addition, assuming that each polarizer is set to work at a binary declination angle of ±22.5°, this SOP generator with 3 pairs of polarizers can generate 6 different polarization states when input with linear polarization.

表3为当一个输入光具有一个对齐于四分之一波片慢轴的线偏振时，图25中具有3对旋偏器的偏光计的SOP发生器的输出SOP的逻辑表。这6个特定的不同SOP是4个不同线偏振态--0，+45，-45和+/-90度线偏振，和两个圆偏振态--RHC和LHC。Table 3 is a logical table of the output SOP of the SOP generator of the polarimeter with 3 pairs of rotators in FIG. 25 when an input light has a linear polarization aligned with the slow axis of the quarter-wave plate. The 6 specific different SOPs are 4 different linear polarization states - 0, +45, -45 and +/-90 degree linear polarization, and two circular polarization states - RHC and LHC.

表3具有6个旋偏器的偏振发生器逻辑表Table 3 Polarization generator logic table with 6 rotators

(0，+45，-45，+/-90，RHC，和LHC)(0, +45, -45, +/-90, RHC, and LHC)

旋偏器1 Rotator 1 旋偏器2 Rotator 2 旋偏器3 Rotator 3 旋偏器4 Rotator 4 旋偏器5 Rotator 5 旋偏器6 Rotator 6 输出SOP Output SOP +22.5 +22.5 -22.5 -22.5 +22.5 +22.5 -22.5 -22.5 +22.5 +22.5 -22.5 -22.5 0 0 + + - - + + + + - - - - 0 0 + + - - + + - - - - + + 0 0 + + - - - - - - + + + + 0 0

+ + - - - - + + - - + + 0 0 + + - - - - + + + + - - 0 0 + + - - + + + + + + - - 45 45 + + - - + + + + - - + + 45 45 + + - - + + - - + + + + 45 45 + + - - - - + + + + + + 45 45 + + - - - - - - + + - - -45 -45 + + - - - - - - - - + + -45 -45 + + - - - - + + - - - - -45 -45 + + - - + + - - - - - - -45 -45 + + - - + + + + + + + + 90 90 + + - - - - - - - - - - -90 -90 - - + + + + - - + + - - 0 0 - - + + + + + + - - - - 0 0 - - + + + + - - - - + + 0 0 - - + + - - - - + + + + 0 0 - - + + - - + + - - + + 0 0 - - + + - - + + + + - - 0 0 - - + + + + + + + + - - 45 45 - - + + + + + + - - + + 45 45 - - + + + + - - + + + + 45 45 - - + + - - + + + + + + 45 45 - - + + - - - - + + - - -45 -45 - - + + - - - - - - + + -45 -45 - - + + - - + + - - - - -45 -45 - - + + + + - - - - - - -45 -45 - - + + + + + + + + + + 90 90 - - + + - - - - - - - - -90 -90 + + + + + + - - + + - - RHC RHC + + + + + + + + - - - - RHC RHC + + + + + + - - - - + + RHC RHC + + + + - - - - + + + + RHC RHC + + + + - - + + - - + + RHC RHC + + + + - - + + + + - - RHC RHC + + + + + + + + + + - - RHC RHC + + + + + + + + - - + + RHC RHC + + + + + + - - + + + + RHC RHC + + + + - - + + + + + + RHC RHC + + + + - - - - + + - - RHC RHC + + + + - - - - - - + + RHC RHC + + + + - - + + - - - - RHC RHC + + + + + + - - - - - - RHC RHC + + + + + + + + + + + + RHC RHC + + + + - - - - - - - - RHC RHC - - - - + + - - + + - - LHC LHC - - - - + + + + - - - - LHC LHC - - - - + + - - - - + + LHC LHC - - - - - - - - + + + + LHC LHC - - - - - - + + - - + + LHC LHC - - - - - - + + + + - - LHC LHC - - - - + + + + + + - - LHC LHC - - - - + + + + - - + + LHC LHC - - - - + + - - + + + + LHC LHC - - - - - - + + + + + + LHC LHC - - - - - - - - + + - - LHC LHC - - - - - - - - - - + + LHC LHC - - - - - - + + - - - - LHC LHC - - - - + + - - - - - - LHC LHC

- - - - + + + + + + + + LHC LHC - - - - - - - - - - - - LHC LHC

和具有4旋偏器的SOP发生器一样，图25中的偏光计中的SOP发生器具有很多简并的SOP，它们是通过不同旋偏器设置的组合产生的。旋偏器的设置和相应的SOP可以在6个不同的SOP下，根据各旋偏器对的不同组合和旋转角进行分类。因为旋偏器对(R1，R2)和(R3，R4)位于四分之一波片的同一边，前四个旋偏器R1，R2，R3，和R4的总旋偏被用作一个独立的控制参数，并且四分之一波片另一边的旋偏器对(R5and R6)被用作另一个独立的控制参数。这6个不同SOP的两个总旋偏参数组合在表4中列出。Like the SOP generator with 4 rotators, the SOP generator in the polarimeter in Figure 25 has many degenerate SOPs, which are generated by combinations of different rotator settings. The settings of the polarizers and the corresponding SOPs can be classified under 6 different SOPs according to the different combinations and rotation angles of each polarizer pair. Because the polarizer pairs (R1, R2) and (R3, R4) are on the same side of the quarter-wave plate, the total rotation of the first four polarizers R1, R2, R3, and R4 is used as an independent control parameter, and the polarizer pair (R5 and R6) on the other side of the quarter-wave plate is used as another independent control parameter. The two total rotation parameter combinations for these 6 different SOPs are listed in Table 4.

表4.图25中SOP发生器产生6个不同SOPTable 4. The SOP generator in Figure 25 produces 6 different SOPs

同样的，图24中具有4个旋偏器的偏光计的SOP发生器能通过表5中两旋偏对(R1，R2)和(R3，R4)的组合，控制产生5个SOP。Similarly, the SOP generator of the polarizer with 4 rotators in FIG. 24 can be controlled to generate 5 SOPs through the combination of the two rotators (R1, R2) and (R3, R4) in Table 5.

表5图24中的SOP发生器产生的5个不同SOPTable 5 Five different SOPs generated by the SOP generator in Figure 24

图26展示了另一个具有6个旋偏器的SOP发生器，它的四分之一波片位于前两对旋偏器对(R1，R2)和(R3，R4)之间。图27展示了一个利用了具有8个旋偏器的SOP发生器的例子。Figure 26 shows another SOP generator with 6 polarizers, with the quarter-wave plate placed between the first two polarizer pairs (R1, R2) and (R3, R4). Figure 27 shows an example using a SOP generator with 8 rotators.

在上述例子中，四分之一波片被放置于不同旋偏器对之间，例如，在第二和第三个旋偏器之间。这个位置使系统操作的分析更加直观。但是，四分之一波片可以放置于4个或更多旋偏器之间的任何位置，例如，第一个旋偏器之前，最后一个旋偏器之后，或之间的任意位置。另外，旋偏器的数量可以为4，5，6，7，8等等。而且，以上二元的旋偏角度可以设置为不同于22.5度的角。例如，要增加偏振态的数量，可选择小一些的旋偏角或其它合适的角度值。In the above example, the quarter-wave plates are placed between different pairs of polarizers, for example, between the second and third polarizers. This location makes the analysis of system operation more intuitive. However, the quarter-wave plate can be placed anywhere between 4 or more depolarizers, for example, before the first depolarizer, after the last depolarizer, or anywhere in between. In addition, the number of deviators can be 4, 5, 6, 7, 8 and so on. Also, the above binary rotation angle can be set to an angle other than 22.5 degrees. For example, to increase the number of polarization states, a smaller declination angle or other suitable angle value can be selected.

以上4，6，和8旋偏的SOP发生器用于产生至少4个不同SOP来求解Muller矩阵方程，得到的结果用于确定输入光的SOP或测量光装置或模块或一个双折射材料的偏振特性。具有4个旋偏器的的SOP发生器在理论上足够得到4个不同SOP。但是，多于4个旋偏器可用于产生更多特殊SOP帮助在有由于许多光元件的非理想造成的附加的不确定元素的偏振测量。例如，用于测量的线起偏器可能没有和四分之一波片的快轴或慢轴完全对齐，而是相对于四分之一波片的轴有一个偏置角。作为另一个例子，旋偏器的旋偏角可能和想要的角之间存在着一定的偏差。The above 4, 6, and 8 SOP generators are used to generate at least 4 different SOPs to solve the Muller matrix equation, and the results obtained are used to determine the SOP of the input light or measure the polarization characteristics of an optical device or module or a birefringent material . A SOP generator with 4 rotators is theoretically sufficient to obtain 4 different SOPs. However, more than 4 polarizers can be used to generate more specific SOPs to aid in polarization measurements where there are additional elements of uncertainty due to non-idealities of many optical elements. For example, a linear polarizer used for measurements may not be perfectly aligned with the fast or slow axis of the quarter-wave plate, but rather be at an offset angle with respect to the quarter-wave plate's axis. As another example, there may be some deviation between the declination angle of the deviator and the desired angle.

具有4个或更多旋偏器的SOP发生器设计用于产生邦加球上不同SOP，为了精确的测量，尽可能多的覆盖球上的偏振态。在一些实现方案中不同偏振态均一的分布在邦加球上。具有4个旋偏器的SOP发生器提供了邦加球赤道上的3个SOP和两极上的两个SOP，具有6个旋偏器的SOP发生器还提供了赤道上另外一个SOP。当存在3个以上不同偏振态时，可通过结合4个SOP进行测量，不同结合方法的测量结果取平均得到最后结果。SOP generators with 4 or more rotators are designed to generate different SOPs on the Poincare sphere, covering as many polarization states on the sphere as possible for accurate measurements. In some implementations the different polarization states are uniformly distributed on the Poincare sphere. The SOP generator with 4 rotators provides 3 SOPs at the equator and 2 SOPs at the poles of the Poincar sphere, and the SOP generator with 6 rotators provides an additional SOP at the equator. When there are more than 3 different polarization states, it can be measured by combining 4 SOPs, and the measurement results of different combining methods are averaged to obtain the final result.

利用光纤实现的图24中的具有4个旋偏器的设计和图25中的具有6个旋偏器的装置的测量的方法为，输入光束耦合与C1和C2端口的任意一端。但是，装置对光从不同端口输入有不同的功能表现。当输入光束耦合于端口C1，C2后的起偏器只允许和它透过轴同向的偏振态传输到C2。因此，C2输出的不同旋转角的光功率是输入偏振态的函数。这个特点可用于构造一个偏振分析仪获偏光计用来测量输入光的SOP。另一方面，当输入光束耦合于C2端口并且对齐于起偏器的透光轴，C1端口的输出光保持一个固定的输出功率(和装置的PDL有关)，但是SOP在这里是MO旋偏器旋转角的一个函数。由于各MO旋偏器的二元(饱和)性，产生分离的SOP的数量相关于旋偏器的数量和各旋偏器的旋偏角。在测试装置中，各个旋偏器完全相同并且旋偏角当在±z轴方向加磁场的情况下都设置在±22.5度。在C2端口的起偏器可通过对齐于其它角产生一个不同的SOP。以上的表4和5展示了当C2用作输入口C1输出的SOP。当光进入图24和25中各装置的端口C2并且传输通过C1端口后的一断单模光纤，由于SM光纤的双折射，输出SOP变换成与表4和表5中所列的不同的SOP。但是，不同SOP的相对角，换而言之，邦加球上任意两个不同SOP之间的夹角，会保持不变。The design with 4 rotators in FIG. 24 and the device with 6 rotators in FIG. 25 are measured using optical fibers by coupling the input beam to either end of the C1 and C2 ports. However, the device behaves differently for light input from different ports. When an input beam is coupled to port C1, the polarizer after C2 allows only the polarization state in the same direction as its transmission axis to be transmitted to C2. Therefore, the optical power at different rotation angles output by C2 is a function of the input polarization state. This feature can be used to construct a polarization analyzer or polarimeter to measure the SOP of the input light. On the other hand, when the input beam is coupled to the C2 port and aligned to the transmission axis of the polarizer, the output light at the C1 port maintains a fixed output power (related to the PDL of the device), but the SOP here is the MO rotator A function of the rotation angle. Due to the duality (saturation) nature of each MO spinner, the number of SOPs that generate separation is related to the number of spinners and the spin angle of each spinner. In the test setup, the deviators are identical and the declination angles are all set at ±22.5 degrees when a magnetic field is applied in the ±z-axis direction. The polarizer at the C2 port can produce a different SOP by aligning to other corners. Tables 4 and 5 above show the SOP of C1 output when C2 is used as input port. When the light enters the port C2 of each device in Figures 24 and 25 and transmits through a broken single-mode fiber after the C1 port, due to the birefringence of the SM fiber, the output SOP is transformed into a different SOP than that listed in Table 4 and Table 5 . However, the relative angles of different SOPs, in other words, the angle between any two different SOPs on the Poincar sphere, will remain unchanged.

图28展示了一个测量具有4个旋偏器的和具有6个旋偏器的装置，在一个有″PSG-4S/6S″标签的装置中。被测偏振控制器#1和#2放置于该装置的两边。一个激光光源，例如一个可调激光器(Agilent 81680TSL)用于产生输入光；第一个偏振控制器#1控制进入被测装置的光束的偏振，用于将输出光功率最大化，最大功率产生在输入偏振态与内部起偏器对齐的时候。第二个偏振控制器#2为可选的，用于移动邦加球上的SOP来方便显示。一个偏振分析仪，例如Agilent 8509C光波偏振分析仪，用于分析光束通过被测装置的光的SOP。一个9伏的DC电源用来给被测装置中的MO旋偏器供电。被测装置的控制单元包括一个为MO旋偏器驱动控制设计的驱动卡。一台个人电脑(PC)用作被测装置的控制和运算单元。具有6个旋偏器的装置被组合在一个光学头模块中并且安装在驱动板上提供以供测量。具有4个旋偏器的装置和具有6个旋偏器的装置的测试步骤有些细微的不同，因为它们的测试步骤与学头和驱动卡之间的连接方式有关。Figure 28 shows a measurement of a device with 4 and a device with 6 polarizers, in a device labeled "PSG-4S/6S". Polarization controllers #1 and #2 under test were placed on either side of the device. A laser light source, such as a tunable laser (Agilent 81680TSL) is used to generate the input light; the first polarization controller #1 controls the polarization of the beam entering the device under test to maximize the output light power, which is generated at When the input polarization state is aligned with the internal polarizer. A second Polarization Controller #2 is optional and is used to move the SOP on the Poincare Sphere for easy display. A polarization analyzer, such as the Agilent 8509C Lightwave Polarization Analyzer, is used to analyze the SOP of the light passing through the device under test. A 9 V DC power supply was used to power the MO rotator in the device under test. The control unit of the device under test includes a drive card designed for the drive control of the MO rotator. A personal computer (PC) was used as the control and arithmetic unit of the device under test. A device with 6 polarizers combined in an optical head module and mounted on a driver board is provided for measurement. The test procedure for a device with 4 rotators and a device with 6 rotators is slightly different, because their test procedures are related to the connection between the learning head and the driver card.

具有6个旋偏器的的装置按如下方法测试。测试之前，启动预运行可调激光器光源(例如，2小时)。在连接线缆之前，将DC电源设置为9V并且电源处于关闭状态。接下来，连接电源线并且具有6个旋偏器的装置相应的位1到位6线通过数据I/O卡输出块连接在一起。还可用其它方法得到6位TTL控制信号。具有6个旋偏器的装置连接好后，打开9VDC电源。默认的设置是所有LED显示器在开启状态。要得到更好的SOP重复性，建议预运行被测具有6个旋偏器的装置20分钟。A device with 6 deviators was tested as follows. Before testing, start the pre-running tunable laser light source (eg, 2 hours). Before connecting the cables, set the DC power supply to 9V and turn off the power. Next, the power wires are connected and the corresponding bit 1 to bit 6 wires of the device with 6 rotators are connected together through the data I/O card output block. The 6-bit TTL control signal can also be obtained by other methods. Once the unit with 6 rotators is connected, turn on the 9VDC power supply. The default setting is that all LED indicators are on. For better SOP repeatability, it is recommended to pre-run the unit under test with 6 deviators for 20 minutes.

总共6个不同SOP态可通过一个6位高低数字信号产生。各位的高低逻辑信号能直接通过观察模块面板上的相应LED显示器确认。一个LED“开”代表逻辑表中的“1”；LED“关”代表逻辑表中的“0”。A total of 6 different SOP states can be generated by a 6-bit high and low digital signal. The high and low logic signals of each bit can be confirmed directly by observing the corresponding LED display on the module panel. An LED "on" represents a "1" in the logic table; an LED "off" represents a "0" in the logic table.

逻辑表 SOP Logic table SOP

(000101) State 1(000101) State 1

(001101) State 2(001101) State 2

(011101) State 3(011101) State 3

(011100) State 4(011100) State 4

(111101) State 5(111101) State 5

(111011) State 6(111011) State 6

在以上逻辑表中，比特的次序从左到右数为位1到位6。当用到这个逻辑表时，态[1，3]，[2，5]和[4，6]形成正交态对。这里用来控制具有6个旋偏器的逻辑表并不是唯一的，它是能够产生6个不同态的许多组合中的一个。在一个有6位二进制TTL码中可以有64种组合，但只有6种不同偏振态。因此，在64种组合一些输出SOP是简并的或接近简并的。不同的逻辑表也可以通过用一个偏振分析仪监视输出偏振态得到。In the above logical table, the order of the bits is bit 1 to bit 6 from left to right. When this logic table is used, the states [1,3], [2,5] and [4,6] form an orthogonal state pair. The logic table used here to control the 6 rotators is not unique, it is one of many combinations that can produce 6 different states. There can be 64 combinations in a 6-bit binary TTL code, but only 6 different polarization states. Therefore, some output SOPs are degenerate or close to degenerate in 64 combinations. Different logic tables can also be obtained by monitoring the output polarization state with a polarization analyzer.

接下来，由逻辑表引入控制程序和测试TTL。当给模块输入TTL控制信号时检查PSG-6S板上的6个绿色LED是否在闪烁。如果LED闪烁则说明逻辑的高(LED开)和低(LED关)已经成功的从控制器发送到模块中了。另外检查连接确保电脑和模块是正确连接的。来自激光器的光信号从合适的输入和合适的输出导入装置，因为这个装置作为一个偏振发生器是没有方向性的。之后通过依照以上逻辑表控制SOP值，测量光的插入损耗，切换态相关损耗，和切换瞬时损耗。.Next, the control program and test TTL are introduced by the logic table. Check if the 6 green LEDs on the PSG-6S board are blinking when the TTL control signal is input to the module. If the LED blinks it means that logic high (LED on) and low (LED off) has been successfully sent from the controller to the module. Also check the connections to make sure the computer and the module are properly connected. The optical signal from the laser is directed into the device from a suitable input and a suitable output, since the device is non-directional as a polarization generator. Then by controlling the SOP value according to the above logic table, the insertion loss of the light, the switching state dependent loss, and the switching instantaneous loss are measured. .

没有任何连接器时的插入损耗是在制作装置的时候测量得到的。一个偏振控制器用于将输出偏振态和起偏器的透光轴P对齐。测量得到的1550nm波长的光的具有4个旋偏器的和具有6个旋偏器的装置的插入损耗和理论值0.65dB和0.75dB相比分别为0.83dB和0.90dB。Insertion loss without any connectors is measured during fabrication of the device. A polarization controller is used to align the output polarization state with the pass axis P of the polarizer. The measured insertion losses of the devices with 4 and 6 rotators for light with a wavelength of 1550nm are 0.83dB and 0.90dB, respectively, compared with the theoretical values of 0.65dB and 0.75dB.

SOP相关损耗是通过记录测量不同SOP的输出光功率得到的。在测量之前，各旋偏器的切换时间设置为1秒，所以可得到一个稳定的功率读数。最大和最小读数之差为SOP相关损耗，它在1550nm的具有4个旋偏器的和具有6个旋偏器的装置中分别为0.06dB和0.08dB。The SOP-related loss is obtained by recording and measuring the output optical power of different SOPs. The switching time of each rotator was set to 1 second before the measurement, so a stable power reading was obtained. The difference between the maximum and minimum readings is the SOP related loss which is 0.06dB and 0.08dB at 1550nm for the 4 and 6 rotators, respectively.

在被测的具有4个旋偏器的和具有6个旋偏器的装置中，当进行切换过程中反转加在旋偏器MO晶体上的磁场时，当磁场通过0点时有一个短暂的插入损耗。这个损耗增加通常被描述为切换瞬时损耗(或简单的讲成瞬时损耗)并且能用一个快速光探测器和一个示波器测量出来。瞬时损耗可表示为In the tested devices with 4 rotators and 6 rotators, when the magnetic field applied to the MO crystal of the rotator is reversed during the switching process, there is a brief moment when the magnetic field passes through 0 insertion loss. This loss increase is usually described as switching transient loss (or simply transient loss) and can be measured with a fast photodetector and an oscilloscope. The instantaneous loss can be expressed as

这里的ΔV_s为切换过程中的电压凹陷，V_DC为没有切换时候的DC电压输出水平。Here, ΔV _s is the voltage sag during the switching process, and V _DC is the DC voltage output level when there is no switching.

${IL IL}_{tr tr} = = - - 1010 \cdot &Center Dot; log log ((11 - - \frac{Δ Δ {V V}_{s the s}}{{V V}_{DC DC}}))$

图29的左边展示了测量得到的一个MO旋偏器的瞬时损耗，右边展示了没有切换时的光信号水平的相应DC电压。基于测量得到的单级切换ΔVs(图左边的通道1的峰-峰值)和VDC(图右边的Cursor Delta)，计算得到的瞬时损耗为各级0.37dB。在一个典型的任意2态切换中，能够进行切换的级数达到了5个，如以上逻辑表中从000101到111011之间的切换。The left side of Figure 29 shows the measured instantaneous loss of an MO rotator, and the right side shows the corresponding DC voltage for the optical signal level without switching. Based on the measured single-stage switching ΔVs (peak-peak value of channel 1 on the left of the figure) and VDC (Cursor Delta on the right of the figure), the calculated instantaneous loss is 0.37dB for each level. In a typical arbitrary 2-state switching, the number of stages that can be switched reaches 5, such as the switching from 000101 to 111011 in the above logic table.

被测的具有4个旋偏器的和具有6个旋偏器的装置的SOP切换时间是通过利用一个TEK210数字示波器测量得到的。各被测装置的切换时间包括两个主要的构成部分：一个大约100μs的时延和一个大约50μs的上升时间。The measured SOP switching times of the 4- and 6-declulator devices were measured using a TEK210 digital oscilloscope. The switching time of each device under test consists of two main components: a delay of approximately 100 μs and a rise time of approximately 50 μs.

一个SOP发生器，可以被设计用来产生均匀分布在邦加球上的互不相同的偏振态并且两不同偏振态之间夹角互成90度。这些偏振态能满足高精度的测量。在实际装置中，SOP的精确度可能被装置的一些因素限制住，例如，MO晶体的切换角度。MO晶体的旋偏角度为晶体厚度，光的波长，环境温度，和晶体方位角的函数。当晶体厚度和方位角有很好地控制并且是均匀的情况下，SOP的绝对精确度主要相关于光波长和环境温度。A SOP generator can be designed to generate different polarization states uniformly distributed on the Poincare sphere and the angle between the two different polarization states is 90 degrees to each other. These polarization states can satisfy high-precision measurement. In practical devices, the accuracy of SOP may be limited by some factors of the device, for example, the switching angle of the MO crystal. The rotation angle of an MO crystal is a function of crystal thickness, wavelength of light, ambient temperature, and crystal azimuth. When the crystal thickness and azimuth are well controlled and uniform, the absolute accuracy of SOP is mainly related to the light wavelength and ambient temperature.

图30展示了被测具有6个旋偏器的装置的邦加球上旋偏角的波长相关性。实际旋偏角为这些邦加球测量值得一半。实际MO晶体的波长相关斜率为0.0668deg./nm，在制造商提供的数据(-0.068deg./nm)的2％范围内。Figure 30 shows the wavelength dependence of the upswirling angle of the Poincare sphere for the tested device with 6 deviators. The actual spin is half the measured value for these Poincarballs. The wavelength-dependent slope of the actual MO crystal is 0.0668 deg./nm, which is within 2% of the data provided by the manufacturer (-0.068 deg./nm).

另一个SOP发生器的性能参数是产生的SOP的重复性。产生的SOP的重复性可以通过重复的切换两个任意的SOP来得到。一个典型的两SOP之间的切换路径如图31所示。这些点描绘的初态和终态保持为两个非常清晰的定义的点，说明了装置优秀的SOP重复性。图31同样展示了从SA切换到SB和从sB切换到SA的路径不同，是交织在一起的。Another performance parameter of an SOP generator is the repeatability of the SOPs generated. The repeatability of the generated SOP can be obtained by repeatedly switching between two arbitrary SOPs. A typical switching path between two SOPs is shown in Figure 31. The initial and final states delineated by these points remain as two very clearly defined points, illustrating the excellent SOP repeatability of the device. Figure 31 also shows that the paths from SA to SB and from sB to SA are different and intertwined.

回到参考图5，一个理想的具有4个旋偏器的装置能产生5个不同偏振态。在本发明的SOP覆盖测量中，来自驱动卡的全部的64个二元态都可用于驱动具有4个旋偏器的装置和具有6个旋偏器的装置。图32A和32B分别展示了具有4个旋偏器的和具有6个旋偏器的装置中在邦加球上的SOP的截图。在图32A中，标记了具有4个旋偏器的装置产生的5个不同的偏振态。显而易见的，在SOP A和C附近，有一些接近A和C的偏振态。这些点为什么没有交叠在点A和C上的原因尚不清楚。图38B展示了由一个被测的具有6个旋偏器的装置产生的邦加球上A-F所示的6个不同偏振态。偏振态B，C和F散布的比较少，而A，D，和E有一些接近简并的态，这些态的位置取决于与初始和最后的态。比较图32A和32B，很明显的，具有4个旋偏器的装置只覆盖了邦加球的一部分(例如，只有半个邦加球)，而具有6个旋偏器的装置对称的覆盖了整个邦加球的SOP，能提供更精确的测量。Referring back to Figure 5, an ideal setup with 4 rotators can generate 5 different polarization states. In the SOP coverage measurement of the present invention, all 64 binary states from the driver card can be used to drive the device with 4 rotators and the device with 6 rotators. Figures 32A and 32B show screenshots of the SOP on a Poincare sphere in devices with 4 and 6 deviators, respectively. In Fig. 32A, 5 different polarization states produced by a device with 4 rotators are marked. Obviously, near SOP A and C, there are some polarization states close to A and C. The reason why these points do not overlap on points A and C is unclear. Figure 38B shows the six different polarization states shown in A-F on the Poincare sphere produced by a tested device with six rotators. Polarization states B, C, and F are less spread out, while A, D, and E have some near-degenerate states whose positions depend on the initial and final states. Comparing Figures 32A and 32B, it is clear that the device with 4 deviators covered only a portion of the Poincare sphere (e.g., only half of the Poincare sphere), while the device with 6 deviators symmetrically covered The SOP of the entire Poincarball provides more accurate measurements.

以上多旋偏SOP发生器可用于产生不同SOP和分析输入光的SOP。在某些应用中，可以通过一个光系统测量得到光元件，装置，模块和双折射材料的偏振特性，这个光系统包括一个多旋偏SOP发生器(例如，一个偏振态发生器或PSG)用于产生具有不同SOP的探测光照亮被测装置或样品，和一个SOP分析仪或偏光计(例如，一个偏振态分析仪或PSA)利用另一个多旋偏SOP发生器来测量来自被测装置或样品的输出光。因为这个系统的输入SOP和输出SOP为已知的，装置或样品的偏振参数可以通过求解Muller矩阵方程得到。在这个系统中，可以利用偏振态分析仪(PSA)分析样品的双折射性质。PSG和PSA可以通过4个或更多片具有+/-22.5度旋转角的法拉第旋偏器构成。还可以利用其他旋偏装置，例如，旋偏器还可以由液晶单元构成。基本上，PSG能产生邦加球上4个特定偏振态。如以上的描述，PSA仅仅是在输出端利用起偏器光学翻转的PSG和一个用于接收光的光探测器。在这个设计中，PSA还可以产生具有邦加球上4个特定偏振态的光束，它的功率通过起偏器进行分析。利用四个SOP相应的四个功率读数确定引入光的SOP。The above multi-rotational SOP generator can be used to generate different SOPs and analyze the SOP of the input light. In some applications, the polarization properties of optical components, devices, modules, and birefringent materials can be measured with an optical system that includes a multirotational SOP generator (e.g., a polarization state generator or PSG) for To generate probe light with different SOPs to illuminate the device under test or sample, and an SOP analyzer or polarimeter (for example, a polarization analyzer or PSA) utilizes another multi-rotational SOP generator to measure the or the output light of the sample. Since the input SOP and output SOP of this system are known, the polarization parameters of the device or sample can be obtained by solving the Muller matrix equation. In this system, the birefringent properties of the sample can be analyzed using a polarization state analyzer (PSA). PSG and PSA can be constructed by 4 or more Faraday rotators with +/-22.5 degree rotation angle. Other rotators can also be used, for example, the rotator can also be formed by a liquid crystal cell. Basically, PSG can generate 4 specific polarization states on the Poincare sphere. As described above, the PSA is just a PSG optically flipped with a polarizer at the output and a photodetector for receiving light. In this design, the PSA can also generate beams with 4 specific polarization states on the Poincare sphere, and its power is analyzed by a polarizer. The SOP of the incoming light was determined using four power readings corresponding to the four SOPs.

图33举例说明了测量样品或光装置的系统。它提供了一个支架用于固定将被测样品或装置。一个放置在输入光通道中的PSG用于控制输入SOP和一个放置在输出光通道的PSA用于分析传输光束的SOP。在PSG中，可利用一个输入线起偏器来控制输入的偏振。Figure 33 illustrates a system for measuring samples or light devices. It provides a bracket for holding the sample or device to be tested. A PSG placed in the input optical channel is used to control the input SOP and a PSA placed in the output optical channel is used to analyze the SOP of the transmitted beam. In a PSG, an input linear polarizer can be used to control the polarization of the input.

特别是，当PSG和PSA基于同一个多旋偏器的设计时，PSA实质上是PSG的镜像。所以，在被测样品或装置中可以用一个镜子或反射镜将传输经过样品的光返回样品，并且在探测在回转方向的PSG的SOP时不需要另一个PSA。这种SOP系统可被看作折叠了图33中系统的折叠系统。In particular, when the PSG and PSA are based on the same multirotator design, the PSA is essentially a mirror image of the PSG. Therefore, a mirror or mirror can be used in the sample or device under test to return the light transmitted through the sample back to the sample, and another PSA is not needed to detect the SOP of the PSG in the rotational direction. This SOP system can be seen as a folded system that folds the system in FIG. 33 .

这种折叠系统有许多优点。例如，在系统中只有一个PSA装置，如具有4个旋偏器的或具有6个旋偏器的PSG，简化了系统并且降低了系统成本。另一个例子，与图33中的非折叠系统相比，折叠系统相对的SOP误差能够明显的减少或消除，因为发生器和分析仪经历了完全相同的不完美或偏移量。而且，折叠系统比图33中的非折叠系统有更简单的样品放置方法，尤其是样品更容易在x-y移动台上放置，探测光在折叠系统的样品中传输两次并且在样品互感厚度中完成两折叠增加用于改进测量和信噪比。这个折叠系统还有一个比图33中非折叠系统小巧的设计，适合在多种便携式的装置中应用。This folding system has many advantages. For example, having only one PSA device in the system, like a PSG with 4 rotators or a PSG with 6 rotators, simplifies the system and reduces system cost. As another example, the relative SOP error of the folded system can be significantly reduced or eliminated compared to the non-folded system in Figure 33 because the generator and analyzer experience exactly the same imperfections or offsets. Moreover, the folded system has a simpler sample placement method than the non-folded system in Fig. 33, especially the sample is easier to place on the x-y moving stage, the probing light is transmitted twice in the sample of the folded system and completed in the sample mutual inductance thickness Two folds were added for improved measurements and signal-to-noise ratio. This folding system also has a smaller design than the non-folding system in Figure 33, suitable for use in various portable devices.

图34A，34B，35和36展示了折叠系统的例子。在各例子中，将一个偏振分束器(PBS)用作为产生沿着一个方向的SOP的输入起偏器，和沿着这个偏振正交方向的输出起偏器实现SOP分析的操作。在图34中，一个准直透镜用于使输入光通过PBS进入测量装置，光探测器用于直接接收来自测量装置，经过PBS后的反射光。在图34B中，第二个准直透镜放置在PBS和光探测器之间用于校准反射光。在图35和36中，被测的样品为一卷光纤，第三个放置于旋偏器和光纤卷之间的准直透镜用于校准进入和从光纤卷反射回来的光。Figures 34A, 34B, 35 and 36 show examples of folding systems. In each example, a polarizing beam splitter (PBS) is used as an input polarizer to generate a SOP along one direction, and an output polarizer along this polarization orthogonal direction enables operation of the SOP analysis. In Fig. 34, a collimating lens is used to make the input light enter the measurement device through the PBS, and the light detector is used to directly receive the reflected light from the measurement device after passing through the PBS. In Figure 34B, a second collimating lens is placed between the PBS and the photodetector for collimating the reflected light. In Figures 35 and 36, the sample under test is a coil of fiber, and a third collimating lens placed between the polarizer and the coil is used to collimate the light entering and returning from the coil.

如图35所示的装置，能够在单一或者多波长的情况下测量被测样品或装置。图35中用了一个宽谱光源产生不同波长的输入光。作为选择，还可用不同的单波长光源产生不同波长的光，并且耦合不同波长的光束送入系统中。在探测时，输出光可通过滤波器空间上分离开来，例如，利用一个波长解复器或一个光谱分析仪分离光。接下来探测器接收不同波长的输出光束。因此，被测样品或装置的不同波长的偏振特性能够同时地被测量出来。The device shown in FIG. 35 can measure the sample or device under test at single or multiple wavelengths. In Fig. 35, a broadband light source is used to generate input light of different wavelengths. Alternatively, different single-wavelength light sources can be used to generate light of different wavelengths, and the beams of different wavelengths can be coupled into the system. Upon detection, the output light can be spatially separated by filters, for example, using a wavelength demultiplexer or an optical spectrum analyzer to separate the light. Next the detector receives the output beams at different wavelengths. Therefore, the polarization characteristics of different wavelengths of the tested sample or device can be measured simultaneously.

以上和其他描述的折叠系统可有许多应用，包括小型双折射分析仪，测量水果，甘蔗，和糖尿病的糖分的便携式糖份分析仪(糖具有旋光性能够使SOP发生旋转，并且SOP旋转的量和含糖量有关)，和光窗的双折射分析。Folding systems described above and elsewhere can have many applications, including small birefringence analyzers, portable sugar analyzers for measuring sugars in fruit, sugarcane, and diabetes (sugar has optical rotation that rotates the SOP, and the amount of rotation of the SOP related to the sugar content), and the birefringence analysis of the light window.

图37A和37B展示了两个具有四个或更多旋偏器的多波长偏振分析仪的例子。这种系统可应用在同时进行WDM多通道测量的情况中。Figures 37A and 37B show two examples of multi-wavelength polarization analyzers with four or more polarizers. This system can be applied in the case of simultaneous WDM multi-channel measurements.

图37A展示了一个利用一个衍射光栅和一个透镜分离光的不同波长的装置。通过起偏器后的光在波长上被衍射光栅分离，通过透镜聚焦在一个光探测器阵列的不同位置上。分析不同通道的光功率能得到各通道的SOP，DOP，PMD值。在图37B中，输入的具有所有不同通道的光在穿过起偏器后被一个WDM或密集型WDM解复器分离开来。接下来监测具有不同SOP的各通道的光功率大小，得到各通道的SOP，DOP，和PMD的全部信息。Figure 37A shows a device that uses a diffraction grating and a lens to separate different wavelengths of light. The light passing through the polarizer is separated in wavelength by a diffraction grating, and focused on different positions of a photodetector array through a lens. By analyzing the optical power of different channels, the SOP, DOP, and PMD values of each channel can be obtained. In Fig. 37B, the input light with all the different channels is separated by a WDM or dense WDM demultiplexer after passing through the polarizer. Next, monitor the optical power of each channel with different SOPs, and get all the information of SOP, DOP, and PMD of each channel.

要改进光谱的分辨率，可在光被光栅和透镜或解复器空间分离之前利用一个可调谐的法布里-泊罗过滤起偏器的输出。可调滤波器的自由谱宽度与WDM或DWDM信号的多波长通道间隔相同。例如，一个具有100GHz频率间隔的DWDM系统，它的滤波器的自由谱宽度(FSR)也同样选择为100GHz。分辨率随滤波器的精细度(F)增加。例如，一个精细度为100的法布里-泊罗滤波器相应的光谱分辨率为1GHz。精细度为1000时，光谱分辨率为0.1GHz。一个10Gb/s的信号的带宽大约为10GHz。F-P滤波器扫描整个信号谱并且测量各频率分量的SOP得到光纤的差分群延时(DGD)和光纤的主偏振态(PSP)方向。图38举例说明了这种多通道分析仪的操作流程。To improve spectral resolution, a tunable Fabry-Perot filter can be used to filter the output of the polarizer before the light is spatially separated by a grating and lens or a demultiplexer. The free spectral width of the tunable filter is the same as the multi-wavelength channel spacing of the WDM or DWDM signal. For example, for a DWDM system with a frequency interval of 100 GHz, the free spectrum width (FSR) of its filter is also selected as 100 GHz. Resolution increases with the fineness (F) of the filter. For example, a Fabry-Perot filter with a fineness of 100 corresponds to a spectral resolution of 1 GHz. When the fineness is 1000, the spectral resolution is 0.1GHz. The bandwidth of a 10Gb/s signal is about 10GHz. The F-P filter scans the entire signal spectrum and measures the SOP of each frequency component to obtain the differential group delay (DGD) of the fiber and the main polarization state (PSP) direction of the fiber. Figure 38 illustrates the flow of operation of such a multi-channel analyzer.

在没有消偏的情况下，光信噪比(OSNR)直接相关于各通道的DOP：OSNR＝DOP/(1-DOP)。因此，这个装置可以当作各通道的光谱，OSNR，DOP和PSP的性能监测仪使用。因为光谱分辨率非常高，OSNR也可以通过F-P滤波器扫描各通道直接得到。各频率扫描得到的最小探测功率相当于各通道的噪声功率p_n(v)。各频率v的信号功率p_s(v)等于测量得到的功率p(v)减去噪声功率p_n(v)：In the absence of depolarization, the optical signal-to-noise ratio (OSNR) is directly related to the DOP of each channel: OSNR=DOP/(1-DOP). Therefore, this device can be used as a performance monitor for spectrum, OSNR, DOP and PSP of each channel. Because the spectral resolution is very high, OSNR can also be obtained directly by scanning each channel with an FP filter. The minimum detection power obtained by each frequency scan is equivalent to the noise power p _n (v) of each channel. The signal power p _s (v) at each frequency v is equal to the measured power p(v) minus the noise power p _n (v):

p_s(v)＝p(v)-p_n(v)p _s (v)=p(v)-p _n (v)

$OSNR OSNR = = \frac{{&Integral; &Integral;}_{- - Δ Δ}^{Δ Δ} p p ((v v)) - - {p p}_{n no} ((v v))}{{&Integral; &Integral;}_{- - Δ Δ}^{Δ Δ} {p p}_{n no} ((v v))}$

没有消偏的情况下，通过DOP测量的得到的OSNR结果和通过光谱扫描测量得到的结果应该是一致的。因此，利用一个DGD可忽略的短光纤得到测量结果之间的一个校准系数。In the absence of depolarization, the OSNR results measured by DOP and the results obtained by spectral scanning measurements should be consistent. Therefore, using a short fiber with negligible DGD results in a calibration factor between the measurements.

存在PMD(消偏)时的DOP可表示为：DOP in the presence of PMD (depolarization) can be expressed as:

$DOP DOP = = \frac{{P P}_{pol pol}}{{P P}_{pol pol} + + {P P}_{nonpol nonpol}} = = \frac{((11 - - δ δ)) {P P}_{s the s}}{{P P}_{s the s} + + {P P}_{n no}}$

这里的Ps和Pn为给定带宽的信号和噪声的功率，δ为消偏系数，在没有消偏的情况下为0，完全消偏的情况下为1。OSNR和DOP有如下关系：Here Ps and Pn are the signal and noise power of a given bandwidth, and δ is the depolarization coefficient, which is 0 in the case of no depolarization and 1 in the case of complete depolarization. OSNR and DOP have the following relationship:

$SNR SNR = = {P P}_{s the s} / / {P P}_{n no} = = \frac{DOP DOP}{11 - - δ δ - - DOP DOP}$

所以，通过独立的测量DOP和OSNR，计算得到消偏系数Therefore, by measuring DOP and OSNR independently, the depolarization coefficient is calculated

δ＝1-DOP-DOP/SNRδ=1-DOP-DOP/SNR

这里描述的SOP发生器能用于取代图13，14，和15中的多通道偏光计/偏振分析仪中的可旋转的四分之一波片和起偏器集合。这种SOP发生器还可用于其它的应用。The SOP generator described here can be used to replace the rotatable quarter wave plate and polarizer set in the multi-channel polarimeter/polarization analyzer of Figures 13, 14, and 15. This SOP generator can also be used in other applications.

上述基于PSG装置的例子用到四个或更多旋偏器和一个四分之一波片的组合。但是，一些实现方案中我们可以去掉四分之一波片。所以在另一些实现方案中，也可以会用一个两主偏振相对相位延迟与四分之一波片延迟不同的波片代替四分之一波片。和四分之一波片相同，这个非四分之一波片也可放置于相对于旋偏器的任何位置。The above example of a PSG-based device uses a combination of four or more polarizers and a quarter-wave plate. However, in some implementations we can eliminate the quarter-wave plate. Therefore, in other implementation schemes, the quarter-wave plate may also be replaced by a wave plate whose relative phase delay of the two main polarizations is different from that of the quarter-wave plate. Like the quarter-wave plate, this non-quarter-wave plate can also be placed anywhere relative to the polarizer.

这个发明的另一个实现方案是，只利用两个旋偏器产生至少三个偏振态，例如0，+45°，和-45°的线SOP。所以一般而言，可以利用这个发明的概念叠加两个或更多的旋偏器产生一些需要的SOP。Another implementation of this invention is to use only two rotators to generate at least three polarization states, such as 0, +45°, and -45° linear SOP. So in general, the concept of this invention can be used to stack two or more polarizers to produce some desired SOP.

虽然这里只描述了少数例子和实现方案，但是其它的实现方案，变更，修正，和完善都是可能的。Although only a few examples and implementations are described here, other implementations, variations, modifications, and enhancements are possible.

Claims

1. device that produces and analyze polarization state is characterized in that this device comprises:

At least 4 inclined to one side device groups of revolving of revolving inclined to one side device composition are placed and are formed an optical channel; It is adjustable respectively revolving inclined to one side device, is used for changing the polarisation of light rotation angle of passing optical channel, and the polarization rotation angle is changed between two different predetermined angle; With

A light polarization device is placed in the optical channel of a described end that revolves inclined to one side device group, is used to transmit a branch of linearly polarized light through selecting.

2. device as claimed in claim 1, it is characterized in that, described light polarization device is placed on to be used in the optical channel receive and passes the described light that revolves after the inclined to one side device group and produce an output beam, and this device comprises that also a photo-detector is used to measure the watt level of an output beam.

3. device as claimed in claim 2 is characterized in that, also comprises:

A control module is used to control and revolves inclined to one side device and make and pass the described light beam that revolves after the inclined to one side device group and produce 4 different polarization states; With

A mechanism is used to handle the watt level of the output beam of four different polarization states, thereby determines that this revolves a polarization state of the light that inclined to one side device winding receives.

4. device as claimed in claim 1, it is characterized in that, described light polarization device is placed on is used to receive an input beam in the optical channel, and revolve inclined to one side device group and be used to receive the light that passes the light polarization device and produce an output beam after being placed on the light polarization device described.

5. device as claimed in claim 4 is characterized in that, comprises that also a control module is used for controlling each and revolves inclined to one side device in polarization state of output beam generation.

6. device as claimed in claim 4 is characterized in that, also comprises:

A catoptron is used for that output beam is reflexed to this and revolves inclined to one side device group, and produces a folded light beam along optical channel,

Described light polarization device is a polarization beam apparatus, is used for being reflected in folded light beam and that part through the polarization direction of the linear polarization quadrature selected; With

A photo-detector is used for measuring the watt level of described polarization beam apparatus reflecting part.

7. device as claimed in claim 6 is characterized in that, also comprises optical devices, and it is placed between optical polarization beam splitter and the photo-detector, is used for the reflecting part is separated into light beams of different wavelengths.

8. device as claimed in claim 6 is characterized in that, also comprises:

A control module is used to control and revolves inclined to one side device and make and pass the described light beam that revolves after the inclined to one side device group and produce at least four different polarization states; With

A mechanism is used to handle the watt level of the reflecting part that measures, and determines to be placed on catoptron and this revolves the polarization characteristic of the sample between the inclined to one side device group.

9. device as claimed in claim 6 is characterized in that, also comprises a wave plate that is placed in the optical channel.

10. device as claimed in claim 9 is characterized in that, described wave plate is a quarter-wave plate.

11. device as claimed in claim 1 is characterized in that, it is to be placed in succession in the optical channel that described first and second of revolving in the inclined to one side device group are revolved inclined to one side device;

Also comprise a quarter-wave plate, in optical channel, be used to receive first and second above-mentioned output light that revolve inclined to one side device; And

It is to be placed in succession in the optical channel that described third and fourth of revolving in the inclined to one side device group revolved inclined to one side device, is used to receive the output light of described quarter-wave plate.

12. device as claimed in claim 11, it is characterized in that, it is described that respectively to revolve inclined to one side device be mutually alignment, described first and second revolve inclined to one side device and revolve oblique presentation to equidirectional and give birth to one total 45 ° and revolve the drift angle, described third and fourth revolves inclined to one side device and revolves oblique presentation to equidirectional and give birth to one total 45 ° and revolve the drift angle, and described first and second revolve inclined to one side device and revolve oblique presentation round about and give birth to one total 0 ° and revolve the drift angle, the described the 3rd and above-mentioned the 4th revolve inclined to one side device and revolve oblique presentation round about and give birth to one total 0 ° and revolve the drift angle.

13. device as claimed in claim 1 is characterized in that, described respectively to revolve inclined to one side device be that a magnetic-light revolves inclined to one side device.

14. device as claimed in claim 1 is characterized in that, describedly respectively revolves inclined to one side device and responds first control signal and produce+22.5 ° and revolve the drift angle, and respond second control signal and produce-22.5 ° and revolve the drift angle.

15. device as claimed in claim 1 is characterized in that, describedly respectively revolves inclined to one side device and responds first control signal and produce 11.125 ° and revolve the drift angle, and respond second control signal and produce-11.125 ° and revolve the drift angle.

16. device as claimed in claim 1 is characterized in that, also comprises:

A grating is placed on and is used to receive the light that passes the described light that revolves inclined to one side device group and separate different wave length in the optical channel to different directions; With

Lens are used for the light of the different wave length diverse location from the photodetection plane of grating guiding.

17. device as claimed in claim 17 is characterized in that, also comprises a tunable Fabry Perot wave filter in optical channel, is used to filter enter pass the described light that revolves after the inclined to one side device group before the described grating.

18. device as claimed in claim 1, its characteristics are, comprise that also a wavelength demultiplexer is placed in the optical channel, are used for receiving passing the described light that revolves the light after the inclined to one side device group and separate different wave length to different light beams.

19. device as claimed in claim 1, its characteristics be, described respectively to revolve inclined to one side device be a liquid crystal cell.

20. device as claimed in claim 1 is characterized in that, also comprises: described light polarization device, be placed on the described front end that revolves inclined to one side device group, filter to pass and describedly revolve the incident light of inclined to one side device group and produce an output light.

21. device as claimed in claim 1 is characterized in that, also comprises a wave plate that is placed in the optical channel.

22. device is characterized in that this device also comprises a wave plate according to claim 1, is placed in the optical channel, this wave plate is a quarter-wave plate.

23. install according to claim 1, it is characterized in that, described light polarization device is a polarization beam apparatus, be placed on described revolving before the inclined to one side device group, be used for revolving an input of inclined to one side device transmission light to first, and reflects one polarization, to revolve the polarization direction of polarizing beam of inclined to one side device vertical with being transferred to first in the polarization direction of this reflect polarized light; Also comprise:

A specimen holder is installed in the described optical channel, and the back that all revolve inclined to one side device is used for fixing the spin sample of output light of inclined to one side device of conduction;

A catoptron is installed in the described optical channel, is used for reflecting back into sample and revolving inclined to one side device passing the light that revolves inclined to one side device and sample;

Photo-detector is used for accepting the reflection output beam from polarization beam apparatus.

24. device is characterized in that according to claim 1,

This device also comprises a reverberator, and the output light of this device is produced a reflected light reflection inclined to one side device that circles round along light path.

25. a method that produces and analyze polarization state is characterized in that, may further comprise the steps:

Utilize at least four adjustablely to revolve inclined to one side device and form adjustable inclined to one side device group is transmitted light and control transmission light beam in optical channel the polarization state of revolving;

Control the described adjustable inclined to one side device group of revolving, make two different default angles of polarization state rotation; And

Control this and adjustablely revolve inclined to one side device group and be operated in difference and revolve inclined to one side device and be provided with down, produce at least four different polarization states.

26. method as claimed in claim 25, its characteristics be, described two different predetermined angle are successively+and 22.5 ° and-22.5 °.

27. method as claimed in claim 25, its characteristics are, also comprise:

Light is transmitted under at least four different polarization states sample to be measured is arranged through a polarization characteristic;

Measure the corresponding output polarization attitude of transmission through the light behind the sample; And

Utilize at least four different polarization states of the light of importing sample and the polarization characteristic that corresponding output polarization attitude is determined sample.

28. method as claimed in claim 27, its characteristics are, also comprise:

Make light after transmission has sample to be measured through a polarization characteristic under at least four different polarization states, the more former road of this light is reflected;

The light that reflects is as a folded light beam transmission process sample and this adjustable inclined to one side device group and quarter-wave plate of revolving;

Under a specific polarization output, measure the watt level of folded light beam; And

The watt level that utilization measures is determined the corresponding output polarization attitude of transmission through the light of sample.

29. method as claimed in claim 25, its characteristics are, also comprise:

The light beam of a polarization state the unknown is transmitted in optical channel through this adjustablely revolve inclined to one side device group;

Control this and adjustablely revolve inclined to one side device group and be operated in difference and revolve partially and be provided with down, produce the polarization that at least four different polarization states are used for control bundle;

Make light beam pass through a fixing polarizer;

Measure different revolving the luminous power size of transmitting through behind this fixing polarizer is set down partially; And

The watt level that utilization measures is provided with the polarization state of determining light beam partially with different revolving.

30. method as claimed in claim 29 is characterized in that, comprises that also the polarization state of utilizing fixed light beam determines the degree of polarization of light beam.

31. method as claimed in claim 29 is characterized in that, comprises that also the polarization state of utilizing fixed light beam determines a signal to noise ratio (S/N ratio) of light beam.

32. method as claimed in claim 25, its characteristics are, also comprise: utilize in addition at least four revolve that inclined to one side device forms another revolve inclined to one side device group and be placed on light by the other quarter-wave plate in the light path of sample;

Control this another revolve inclined to one side device group at least four different swing settings, produce at least four different polarization states;

Utilize a fixing linear polarizer, filter pass at least this another revolve the light of inclined to one side device group and another quarter-wave plate;

Measure the watt level of the light that filters by the static line polarizer;

The watt level that utilization measures is with the corresponding output polarization attitude of the light of determining to pass sample.