CN101110761A - Optical Packet Switching System Based on Wavelength and Polarization Hybrid Labeling - Google Patents

Abstract

An optical packet switching system with mixed marking of wavelength and polarization uses an optical letter head to carry optical routing, and the routing information is marked by wavelength and polarization state. Under the unified control of the edge node optical label control module, the wavelength label generation module outputs optical pulses of different wavelengths, the polarization label generation module controls the polarization state of the optical pulse, and the optical header and optical packet carrying wavelength and polarization information are wavelength division multiplexed sent to the core node. The core node separates the optical signal head from the optical packet, and inputs the optical pulses of different wavelengths of the optical signal head to the wavelength mark detection module, detects the polarization information carried by the polarization mark detection module, and identifies its polarization state by the polarization mark detection module to obtain the route information. The core node controls the switching matrix to perform optical packet switching according to the obtained routing information. The invention solves the problem of limited amount of information that can be carried by the header due to the limited number of usable wavelengths in the same channel of the multi-wavelength label, and solves the problem of inconsistency in the direction of the polarization axis in optical transmission.

Description

Optical Packet Switching System Based on Wavelength and Polarization Hybrid Labeling

technical field

The present invention relates to an optical packet switching system, in particular to an optical packet switching system based on mixed marking of optical wavelength and polarization state, which solves the problems of optical packet header composition, routing information bearing, and switching information processing, and belongs to optical communication technology field.

Background technique

In the optical switching technology that has been researched, according to the different switching methods, the optical switching technology is usually divided into three categories, optical circuit switching OCS (Optical Circuit Switching), optical packet (packet) switching OPS (Optical Packet Switching) and between The optical burst switching OBS (Optical Burst Switching) between the two. The optical switching mode studied earlier is optical line switching, the basic switching unit calls, and the bandwidth of the entire call is reserved in the dual process. Its main defect is that a wavelength routing channel must be established before data transmission, and the channel wavelength is always occupied until a call is completed before being released. In Optical Burst Switching (OBS), signals are divided into control packets containing routing information and data packets carrying traffic. The control information of the control packet is electronically processed by the router, while the data packet is directly transmitted in the end-to-end transparent transmission channel without photoelectric conversion. The communication bandwidth of OBS only needs to be reserved in one direction, and the switching granularity is better than optical line switching, but the control information needs to occupy additional channel resources. More ideal is Optical Packet Switching (OPS). OPS divides optical information into fixed optical loads and optical headers carrying routing information to form optical packets with a fixed format for transmission. It is a connectionless (Connectionless) automatic In the transmission mode of routing (Self-routing), there is no need to wait for the information to be sent directly before sending, and the storage and forwarding (S&F) is performed at the optical switching node, and the original data flow is restored by sorting each packet at the target node. This technology attempts to implement small-grained packet switching directly on the optical layer, and has the advantages of less overhead, high bandwidth utilization, and transparent transmission information format.

With the development of MPLS (Multi-Protocol Label Switching) technology, people have introduced the idea of label switching into OPS, and divided the Optical Packet into an Optical Header carrying routing information and an Optical Header with a fixed time length. Optical packet (Optical Payload), the optical packet completes the identification and routing search of the optical letter header (mark) at the OPS switching node, and the updated (switched) optical letter header and optical packet (load) form a new optical packet and continue to enter the next level of optical payload. network transmission. In this way, optical tags are identified and processed in the electrical domain, and the load is transparently transmitted throughout the optical network. There are also many articles reporting the research of optical label switching technology, and the research results have attracted widespread attention. It is worth noting a method of optical packet switching in a multi-wavelength optical marking mode. "Realization of Multi-wavelength Label Optical Packet Switching" (multi-wavelength label optical grouping) published by Shilin Xiao et al. Realization of Switching) A specific implementation method of OPS technology for in-band wavelength marking is proposed, and a simple optical label switching system is realized.

In this system, the optical letter head is composed of several optical pulses with different wavelengths, and different combinations of these optical pulses represent different routing information. The wavelength of the optical pulse in the optical signal head and the carrier wave of the optical packet belong to the same wavelength channel, and no additional wavelength resources are occupied. At the switching node, the optical wave routing is realized by judging the combination of different wavelengths of the optical pulses in the optical letter head. Since the marked wavelengths of the optical pulses that make up the optical signal head can only take values within the passband of the communication channel, and optical pulses of different wavelengths occupy a certain bandwidth, too many wavelength marks will cause cross-talk between each other, which limits The number of pulses available for marking places a limit on the amount of information that can be carried by the optical head.

In addition to amplitude, phase, and frequency, light has another characteristic, which is polarization. Polarized light can be divided into elliptically polarized light and linearly polarized light. If the light only vibrates in a certain direction during the propagation process, this light is called linearly polarized light. Elliptically polarized light can be decomposed into any two linearly polarized lights whose directions are perpendicular to each other. When the amplitudes of these two components are equal, it is circularly polarized light. According to the polarization characteristics of light, a digital transmission technology called Polarization Shift Keying (POLSK) has been proposed in recent years, which generates two orthogonal polarization states by adjusting the external polarization controller, representing data "1" and "0", information transmission is carried out by modulating the two linear orthogonal polarization states of the transmission signal. Sergio Benedetto explained the principle of Polarization Shift Keying (Polarization Shift Keying, PolSK) technology in "Theory of Polarization Shift Keying Modulation" published on "IEEE TRANSACTIONS ONCOMMUNICATIONS" VOL.40, NO.4, APRIL1992. Polarization shift keying technology has the characteristics of being less affected by the phase noise of the light source and can effectively suppress the nonlinear effect in the optical fiber transmission process. However, due to the influence of the polarization state dispersion of the optical fiber, the polarization information will The polarization direction will change, and the structure of the receiver (Stokes receiver) is relatively complex, requiring the polarization axis of the receiving module to be consistent with the polarization axis of the sending module, which is difficult to implement and limits the application of this modulation method in high-speed data transmission to a certain extent. in the application.

Contents of the invention

The object of the present invention is to address the deficiencies in the prior art, to propose an optical packet switching system with mixed wavelength and polarization markings, to increase the amount of information that can be carried by the optical header, thereby improving the performance of the entire optical label switching network.

To achieve this purpose, the present invention uses the optical letterhead to carry routing information, and uses both wavelength and polarization state as marking parameters. Under the unified control of the optical label control module in the optical label switching edge node, the optical pulses of different wavelengths output by the wavelength label generation module are loaded with polarization labels in the polarization label generation module, and the optical headers and optical packets carrying wavelength and polarization information are timed and After wavelength division multiplexing, it is sent to the core node. The wavelength mark detection module separates the optical pulses of different wavelengths in the optical letter head, and then detects the routing information carried by the polarization mark detection module. The optical marking core control unit controls the optical switch matrix to perform optical packet switching through the obtained routing information.

The scheme of the present invention is specifically described as follows:

The system includes an optical label switching edge node and an optical label switching core node. The connection relationship is: the computer user terminal used for demonstration is connected to the OLS edge node through a cable, the OLS edge node is connected to the OLS core node through an optical fiber, and the OLS core node and the OLS core node are connected via Fiber optic interconnect.

The main functional modules of the optical label switching edge node include: electronic input and output line cards, optical packet packaging and unpacking processors, optical label control modules, wavelength label generation modules, polarization label generation modules and wavelength division multiplexers. The electronic input and output line card is connected to the user terminal, the output of the electronic input and output line card is respectively connected to the optical packet packaging and unpacking processor and the optical marking control module, the output of the electronic input and output line card is connected to the optical marking control module, and the optical packet packaging and unpacking process The control signal output and optical packet output of the device are respectively connected to the optical label control module and the wavelength division multiplexer, the output of the optical label control module is connected to the wavelength label generation module and the polarization label production module respectively, and the output of the wavelength label production module is connected to the polarization label The generation modules are connected, the output of the polarization mark generation module is connected to the wavelength division multiplexer, and the output of the wavelength division multiplexer is connected to the optical label switching core node.

The main functional modules of the optical label switching core node include: wavelength label detection module, polarization label detection module composed of several single-channel optical polarization detection units, optical label core control unit, optical switch matrix, optical label generation module and output wave Demultiplexer; the wavelength mark detection module is connected to the output of the optical mark edge node, the wavelength mark detection module separates the optical letter head and the optical packet, the output of the optical letter head is connected to the polarization mark detection module, the optical packet output is connected to the optical switch matrix, and the polarization The mark detection module is connected with the optical mark core control unit, the routing control output of the optical mark core control unit is connected to the optical switch switching matrix, and the optical mark core control unit controls the optical mark generation module to generate the output of the next optical letter head, and the optical switch switches The optical packets output by the matrix are connected to the output wavelength division multiplexer together with the new optical signal head of the optical mark generating module.

In the solution of the present invention, a new marking method of the optical letter head is adopted, that is, the information carried by the optical letter head is composed of the wavelength and polarization state of the optical pulse in the channel band. The composition of the optical packet in the wavelength polarization hybrid marking optical switching is described as follows: In the time domain, the optical header and the optical packet have a sequence, and each optical header carries the routing information of its corresponding optical packet. The optical packets carrying effective communication information work on a carrier of a specified wavelength, such as the wavelength λ ₀ in the DWDM wavelength series compliant with the ITUT. The routing information carried by the optical letter head is composed of the wavelength and polarization state of the optical pulse. The pulse wavelength of the optical letter head refers to the wavelength in the same communication channel as the optical packet. The polarization state used as the polarization mark refers to the circular polarization state or the linear polarization state. Each optical letter head is composed of several optical pulses of different wavelengths, and each optical pulse has a polarization state.

At the edge node of optical label switching, the electronic input and output line card transmits the data information of the user terminal service flow to the optical packet packaging and unpacking processor, and at the same time notifies the routing information of the service flow to the optical label control module. According to the routing information of the input service flow, the optical label control module controls the wavelength label generation module and the polarization label generation module to generate a corresponding optical letter head composed of optical pulses of different wavelengths and their polarization states, and the optical packet packaging and unpacking processor When an optical packet is generated, a signal is sent to notify the optical marking control module, and the optical letter head after strict queuing and timing control is connected to the wavelength division multiplexer together with the optical packet, and the optical packet generated by multiplexing is sent to the remote optical packet through the optical fiber. Label the exchange core node.

At the core node of optical label switching, the wavelength label detection module separates the optical letterhead of the optical packet arriving at the core node from the optical packet, and the optical signals of different wavelengths that make up the optical letterhead are input to the polarization label detection module. These optical signals carrying routing information pass through The polarization mark detection module detects the polarization information in it, and then outputs the complete optical routing information to the core control unit; the optical mark core control unit controls the optical switch switching matrix according to the detected optical routing information, and completes the exchange of optical packets , while controlling the optical label generation unit connected to it, and the optical label generation module generates the next-hop optical signal head; the optical packet passes through the optical switch matrix and then is connected to the wavelength division multiplexer of the corresponding output port together with the new optical signal head , the output port of the WDM is connected to the destination node.

The present invention greatly increases the amount of information that can be carried by the header by introducing a special optical polarization state into the wavelength label, and the information that can be carried by n wavelengths will be expanded by 1.5 ⁿ times, improving the performance of the entire optical label switching network , and at the same time retain the advantages of the multi-wavelength optical label switching method without occupying additional wavelength resources, and the optical letter head is easy to process. The invention can effectively reduce the influence of the change of the polarization axis direction caused by long-distance optical fiber transmission, because the polarization marks used are linear polarization state and circular polarization state, which overcomes the rotation of the polarization axis direction during transmission to a certain extent lack of. And with the development of related technologies, it can be well integrated with the existing label switching technology, and smoothly transition to the ideal optical packet switching technology, which can be put into practical use quickly, with low cost, simple structure and easy implementation.

Description of drawings

FIG. 1 is a structural diagram of an edge node of a wavelength polarization hybrid mark in the present invention.

Fig. 2 is a structural diagram of the core node of the wavelength polarization hybrid label in the present invention.

Fig. 3 is an illustration of loading and depolarization of polarized markers in the present invention.

Fig. 4 is a schematic structural diagram of a polarization mark generating module of the present invention.

Fig. 5 is a schematic structural diagram of a single-channel polarization mark detection module of the present invention.

Detailed ways

In order to better understand the technical solution of the present invention, the implementation manner will be further described below in conjunction with the accompanying drawings.

The optical packet switching system of the wavelength polarization mixed label of the present invention comprises: an optical label switching edge node and an optical label switching core node. The connection relationship is: the computer user terminal used for demonstration is connected to the OLS edge node through a cable, the OLS edge node is connected to the OLS core node through an optical fiber, and the OLS core node and the OLS core node are connected via Fiber optic interconnect.

Fig. 1 has provided the schematic diagram of the structure of the optical label switching edge node in the present invention, the optical label switching edge node generates optical packets, and its main functional modules include: electronic input and output line card, optical packet packaging and unpacking processor, optical label control module , a wavelength mark generation module, a polarization mark generation module and a wavelength division multiplexer.

The user terminal is connected to the electronic input and output line card, the output of the electronic input and output line card is respectively connected to the optical packet packaging and unpacking processor and the optical marking control module, the output of the electronic input and output line card is connected to the optical marking control module, and the optical packet packaging and unpacking process The output of the device is respectively connected to the optical label control module and the wavelength division multiplexer, the output of the optical label control module is connected to the wavelength label production module and the polarization label production module respectively, and the output of the wavelength label production module is connected to the polarization label production module, The output of the polarization mark generating module is connected to the wavelength division multiplexer, and the output of the wavelength division multiplexer is connected to the core node of optical label switching.

The electronic input and output line card transmits the data information of the service flow of the user terminal to the optical packet packaging and unpacking processor, and at the same time notifies the routing information of the service flow to the optical marking control module. The optical label control module controls the wavelength label generation module and the polarization label generation module to generate a corresponding optical signal head according to the routing information of the input service flow, and the optical signal head is composed of optical pulses of different wavelengths and their polarization states. Every time the optical packet packaging and unpacking processor generates an optical packet, it sends a signal to notify the optical marking control module, and connects the optical letter head after strict queuing and timing control together with the optical packet to the wavelength division multiplexer, and multiplexes the generated optical signal. The packet is sent to the remote optical label switching core node through the optical fiber.

Fig. 2 is a structure diagram of the optical label switching core node of the present invention. As shown in Figure 2, the main functional modules of the optical label switching core node include: a wavelength label detection module, a polarization label detection module composed of several single-channel optical polarization detection units, an optical label core control unit, an optical switch matrix, an optical A marker generation module and an output wavelength division multiplexer.

The wavelength mark detection module is connected to the output of the optical label switching edge node, the wavelength mark detection module separates the optical letter head and the optical packet, the output of the optical letter head is connected to the polarization mark detection module, the output of the optical packet is connected to the optical switch matrix, and the polarization mark detection module is connected to The optical label core control units are connected, the routing control output of the optical label core control unit is connected to the optical switch matrix, the control output of the next optical signal head generated by the optical label core control unit is connected to the optical label generation module, and the optical switch matrix The output is connected to the output wavelength division multiplexer together with the output of the optical label generating module.

The wavelength mark detection module separates the optical header of the optical packet arriving at the core node from the optical packet, and the optical signals of different wavelengths forming the optical header are input to the polarization mark detection module. These optical signals carrying (wavelength) routing information are detected by the polarization mark detection module, and then the polarization mark detection module outputs complete optical routing information to the core control unit. The optical marking core control unit mainly completes the detection of routing optical information, the control of the optical switch matrix and the generation of new routing information, that is, controls the optical switch switching matrix according to the detected optical routing information, and completes the exchange of optical loads. The optical label generation unit connected to it generates the next-hop optical header by the optical label generation module. After the optical packet passes through the optical switch matrix, it is connected with the new optical signal head to the output wavelength division multiplexer corresponding to the output port. The output port of the output wavelength division multiplexer is connected to the destination node.

Fig. 3 illustrates in detail the loading and extraction process of the polarization marker of the present invention. The wavelength mark generation module uses a distributed feedback (DFB) laser to generate linearly polarized light of different wavelengths, which is input to the polarization mark generation module, and the polarization mark generation module determines the polarization state of each output light according to the control information input by the optical mark control module (including linear polarization state, circular polarization state). The polarization mark detection module is composed of several single-channel light polarization detection units, and the polarization state of the corresponding wavelength pulse is extracted by the single-channel light polarization detection unit.

Fig. 4 is a schematic structural diagram of a polarization mark generating module. As shown in Figure 4, the polarization mark generation module includes a high-speed optical switch, three 1×2 polarization-maintaining couplers, and a 90° rotator. The three 1×2 polarization-maintaining couplers are respectively an input coupler, an intermediate stage coupler, and an output coupler.

According to the principle structure of outputting circularly polarized light or linearly polarized light at the control level, the signal is transmitted from left to right. Because the output light of the wavelength mark generation module is generated by a DFB laser with high linear polarization characteristics, the input light of the polarization mark generation module is actually linearly polarized light, and the high-speed optical switch in the polarization mark generation module is controlled by the level of the optical mark control module , if the output of linearly polarized light is required, the optical path is controlled to pass through, and if the output of circularly polarized light is required, the optical path is controlled to pass through obliquely. The straight-through output of the high-speed optical switch is directly connected to the output coupler, and the oblique output of the high-speed optical switch is connected to the input coupler. The output of the coupler is two lines of linearly polarized light with parallel polarization directions. One line is directly connected to the intermediate stage coupler, and the other path is connected to the intermediate stage output coupler after passing through a 90° rotator. The optical path is controlled so that the phase difference between the two lines of light is just right. is π/2, the output of the intermediate stage coupler is connected to the other input of the output coupler. All fibers in this module use polarization-maintaining fibers.

Fig. 5 is a schematic structural diagram of a single-channel light polarization detection unit in the present invention. As shown in Figure 5, the single-channel light polarization detection unit is composed of a beam splitter and two polarization beam splitters (PBS) whose main axes are at 45°.

The input light (linear polarization state or circular polarization state) passes through the beam splitter to two polarization beam splitters PBS whose main axes are 45°, and the PBS splits the input light into two paths of light with orthogonal polarization directions. If it is a circularly polarized light input, the light intensity of the two outputs should be equal; if it is a linearly polarized light input, the two signals should have unequal light intensities. When the ratio of the two signal powers is within the threshold range (such as around 1 When the ratio is outside this range, it is judged as circularly polarized light, and when the ratio is outside this range, it is judged as linearly polarized light.

Considering that the polarization direction of the input light is exactly 45° to the polarization direction of the two polarizers in the PBS, the light intensity ratio is also 1, and two sets of PBS with the polarization axes at 45° are used for two-way comparison, so that even if the direction of the linearly polarized light is the same as that of one of the PBSs The angle between the two polarization axes is 45°, and the other path can also effectively detect its polarization state, thereby extracting the polarization mark.

In the present invention, the user terminal transmits and receives high-speed service flow through the cable and the optical label switching edge node, and the electronic input and output line card is directly connected to the user terminal in the optical label switching edge node, and the line card is responsible for receiving data from the computer terminal. The 10M/100M electrical Ethernet data packet is responsible for forwarding the data information to the optical packet packaging and unpacking processor, and at the same time notifying the optical label control module of the destination address corresponding to the service flow, the optical label control module performs table lookup according to the received routing information, And prepare the control information of the optical routing, and wait for the notification from the optical packing and unpacking processor. The optical packet packaging and unpacking processor allocates the data packets to the corresponding queues in the data set according to the business priority and destination address of the data packets. When an optical packet is encapsulated, the optical packet packaging and unpacking processor sends a notification to the optical label control module, and drives It generates the photomarker control signal. The optical mark control module is connected with the wavelength mark generation module and the polarization mark generation module. The wavelength mark generation module generates light pulses with different wavelength combinations according to the level of the control line. These light pulses are then connected to the polarization mark generation module through a polarization-maintaining fiber. The label generation module also controls the polarization state of the optical pulse according to the control information. The polarization state is defined by the designer and corresponds to the polarization label detection module of the optical label switching core node. After the generated optical header and optical packet are strictly timed and separated, the transmitted optical packet and the optical header are multiplexed into the wavelength division multiplexer and output through the optical fiber.

At the core node of optical label switching, the input light first passes through the wavelength label detection module to separate the optical letter head and the optical packet, and the optical pulses of different wavelengths in the optical letter head are also shunted to different optical fibers. The light pulses of different wavelengths are sent to the polarization mark detection module. The polarization mark module is composed of multiple single-channel light polarization detection units, which respectively detect the polarization states of light pulses of different wavelengths. Different polarization states represent different routing information. The core node detects the depolarized routing information through the photodetector, obtains the routing information carried by the header, and generates the control level control switching matrix according to the routing information, and establishes the output optical path corresponding to the optical packet, and the optical packet is switched by the optical switch. The matrix is switched to the output port, and after being multiplexed with the next-hop optical signal head, it is output to the next-hop optical label switching core node or receiving optical label switching edge node.

The invention greatly increases the amount of information that can be carried by the letter head, and effectively reduces the influence brought by the change of the polarization axis direction caused by the long-distance optical fiber transmission. Because the polarization states used as polarization marks are circular polarization states and linear polarization states, the detection end can adopt a direct detection method. The polarization mark detection module uses the method of firstly letting the input light pulse pass through the polarization beam splitter, and then compares the light intensity of the two output lights whose polarization directions are perpendicular to each other, which shields the optical fiber bending and dispersion to a certain extent. Impact.

Claims (4)

1. An optical packet switching system of wavelength polarization hybrid marking, comprising an optical label switching edge node and an optical label switching core node, characterized in that: The optical label switching edge node includes an electronic input and output line card, an optical packet packing and unpacking processor, an optical label control module, a wavelength label generation module, a polarization label generation module and a wavelength division multiplexer; the electronic input and output line card is connected with the user Terminal connection, the output of the electronic input and output line card is respectively connected to the optical packet packing and unpacking processor and the optical marking control module, the output of the electronic input and output line card is connected to the optical marking control module, and the output of the optical packet packing and unpacking processor is respectively connected to the optical marking The control module and the wavelength division multiplexer, the output of the optical mark control module are respectively connected with the wavelength mark generation module and the polarization mark generation module, the output of the wavelength mark generation module is connected with the polarization mark generation module, and the output of the polarization mark generation module is connected To the wavelength division multiplexer, the output of the wavelength division multiplexer is connected to the optical label switching core node; The electronic input and output line card transmits the data information of the user terminal service flow to the optical packet packaging and unpacking processor, and at the same time notifies the routing information of the service flow to the optical label control module, and the optical label control module, according to the input service flow routing information, Control the wavelength mark generation module and the polarization mark generation module to generate corresponding optical letterheads composed of optical pulses of different wavelengths and their polarization states, and the optical packet packing and unpacking processor sends a signal to notify the optical mark control module every time an optical packet is generated , the optical signal head and the optical packet after strict queuing and timing control are connected to the wavelength division multiplexer, and the optical packet generated by multiplexing is sent to the remote optical label switching core node through the optical fiber; The optical label switching core node includes a wavelength label detection module, a polarization label detection module composed of several single-channel optical polarization detection units, an optical label core control unit, an optical switch matrix, an optical label generation module and an output wavelength division multiplexing The wavelength mark detection module is connected to the output of the optical mark edge node, the wavelength mark detection module separates the optical letter head and the optical packet, the output of the optical letter head is connected to the polarization mark detection module, the optical packet output is connected to the optical switch matrix, and the polarization mark detection module It is connected with the optical label core control unit, the routing control output of the optical label core control unit is connected to the optical switch matrix, the next letter header control output generated by the optical label core control unit is connected to the optical label generation module, and the optical switch matrix The output and the output of the optical mark generating module are connected to the output wavelength division multiplexer together; The wavelength mark detection module separates the optical letter head and the optical packet of the optical packet arriving at the core node, and the optical signals of different wavelengths that make up the optical letter head are input to the polarization mark detection module, and these optical signals carrying routing information are detected by the polarization mark detection module. Polarization information, and then the polarization mark detection module outputs complete optical routing information to the core control unit; the optical marking core control unit controls the optical switch switching matrix according to the detected optical routing information, completes the exchange of optical loads, and controls the connected The optical label generation module generates the next-hop optical signal head by the optical label generation module; the optical packet passes through the optical switch matrix and then is connected to the output wavelength division multiplexer of the corresponding output port together with the new optical signal head, and the output wavelength division multiplexer The output port of the device is connected to the destination node. 2. The optical packet switching system for wavelength polarization hybrid marking according to claim 1, characterized in that said polarization state is circular polarization or linear polarization. 3. The optical packet switching system according to claim 1 or 2, characterized in that said polarization mark generation module comprises a high-speed optical switch, three 1×2 polarization-maintaining couplers, and a 90° rotator; 1×2 polarization maintaining couplers are input coupler, intermediate stage coupler and output coupler respectively; the straight-through output of the high-speed optical switch is directly connected to the output coupler, the oblique output of the high-speed optical switch is connected to the input coupler, and the input coupler The output of the filter is two lines of linearly polarized light with parallel polarization directions, one of which is directly connected to the intermediate stage coupler, and the other is connected to the intermediate stage coupler after being passed through a 90° rotator, and the output of the intermediate stage coupler is connected to the output coupler. 4. The optical packet switching system according to claim 1 or 2, wherein the wavelength polarization mixing label is characterized in that the single-path optical polarization detection unit is composed of a beam splitter and two polarization beam splitters whose main axes are 45°, and the input light After passing through the beam splitter to the polarization beam splitter with two main axes at 45°, it is divided into two paths of light with orthogonal polarization directions, and the polarization state of the light is determined according to whether the ratio of the signal power of the two paths is within the threshold range, thereby extracting Polarization marks.

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