JP2006119464A - Single core bidirectional optical transceiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable optical transmission and reception through a single optical fiber, and to enable the transmission and reception at low costs and at a high bit rate by suppressing an influence of cross-talk between the optical transmission and reception parts. <P>SOLUTION: The single core bidirectional optical transceiver is characterized in that an optical transmitter element 28 and an optical receiver element 32 having two different oscillation wavelengths, and a wavelength multiplexing/demultiplexing filter 26 are built in one transceiver optical system 21, and the optical transmission and reception is performed by connecting one optical fiber with an optical connector to this transceiver optical system 21. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a single-core bidirectional optical transceiver used for optical communication.

  Conventionally, an optical transceiver equipped with a VCSEL (Vertical-Cavity Surface Emitting Laser) performs optical communication by connecting an optical fiber with an optical connector for each of optical transmission and reception. . As conventional optical transmission / reception transceivers, for example, those having the structures shown in FIGS. 3A, 3B and 4 are known. 3A is a plan view of the transceiver, FIG. 3B is a cross-sectional view taken along line XX of FIG. 3A, and FIG. 4 is a block diagram of the transceiver.

  The optical transceiver 1 includes a first optical system 2 called TOSA (Transmitter Optical Sub Assembly) and a second optical system 3 called ROSA (Receiver Optical Sub Assembly). The first optical system 2 includes an optical transmission element (VCSEL) 5 and an optical monitor optical reception element 6 as optical transmission units mounted on the stem 4 and a resin sleeve 10a. A cap 7 with a glass window is attached to the stem 4 so as to hermetically seal the light transmitting element 5 and the light monitor light receiving element 6. The resin sleeve 10a is disposed on the optical fiber connector side of the cap 7, and has a lens portion 8 and a through hole (receptacle portion) 9 for the optical fiber connector.

  The second optical system 3 includes a light receiving element 11 and a transimpedance amplifier 12 as a light receiving portion mounted on the stem 4 and a resin sleeve 10b. A cap 7 with a glass window is attached to the stem 4 so as to hermetically seal the light receiving element 11 and the transimpedance amplifier 12. The resin sleeve 10b is disposed on the optical fiber connector side of the cap 7, and a lens portion 8 and a through hole 9 for an optical fiber connector are formed.

  Reference numeral 13 in FIG. 3 denotes a control board on which the driver IC 14 and the limiting amplifier 15 for driving the TOSA are mounted. The control board 13 is connected to a first optical system 2 called TOSA and a second optical system 3 called ROSA, and the control board 13 and the first and second optical systems 2 and 3 are envelopes. 18.

  By the way, in an optical communication system using a conventional optical transceiver, two optical fibers for transmission and reception are required for optical transmission as shown in FIG. Here, considering the demands for reducing communication costs and simplifying the system configuration, optical transmission / reception transmission with a single optical fiber has been economical. However, it has been difficult to achieve this requirement with the conventional optical transceiver.

Conventionally, as an optical module mainly used for optical communication and optically connecting a semiconductor optical device and an optical fiber, for example, Patent Document 1 is known.
JP 2004-20851 A

  The present invention has been made in order to solve the conventional problems. By mounting an optical transmission element having two different oscillation wavelengths, an optical reception element, and a wavelength multiplexing / demultiplexing filter so as to be incorporated in one optical system. Provides a single-core bidirectional optical transceiver that enables optical transmission / reception transmission with a single optical fiber, enables transmission at a low bit rate, and suppresses the influence of crosstalk between the optical transmission unit and optical reception unit at a high bit rate. The purpose is to do.

  The single-core bidirectional optical transceiver according to the present invention incorporates an optical transmission element having two different oscillation wavelengths, an optical reception element, and a wavelength multiplexing / demultiplexing filter in one transmission / reception optical system. An optical fiber with an optical connector is connected to perform optical transmission / reception transmission.

  According to the present invention, single-core bidirectional transmission that enables optical transmission / reception transmission with a single optical fiber, can be performed at a low cost, and can be transmitted at a high bit rate while suppressing the influence of crosstalk between the optical transmission unit and the optical reception unit. An optical transceiver can be provided.

Hereinafter, the present invention will be described in more detail.
In the present invention, the transmitting / receiving optical system includes a resin sleeve having a refractive index of substantially 1.6. It is preferable that the optical transmission element, the optical reception element, and the wavelength multiplexing / demultiplexing filter are integrally held on the resin sleeve.

  In the present invention, the core diameter of the optical fiber with an optical connector connected to the transmission / reception optical system is preferably 50 μm or more. That is, the single-core bidirectional optical transceiver according to the present invention is compatible with multimode fiber. Therefore, by setting the core diameter to 50 μm or more as described above, the core diameter standard of multimode fiber is 50 μm. Two types of φ62.5μm can be covered.

  In the present invention, it is preferable to use VCSELs with oscillation peak wavelengths of 820 nm and 850 nm, and to set the wavelength range to 820 nm + 5 / −10 nm and 850 nm + 10 / −5 nm in terms of the characteristics of the wavelength multiplexing / demultiplexing filter. Here, “+ 5 / −10 nm” means that the tolerance at 820 nm is +5 nm to −10 nm, and “+ 10 / −5 nm” means that the tolerance at 850 nm is +10 to −5 nm.

Next, specific embodiments of the present invention will be described.
(Example)
Please refer to FIG. 1 and FIG. Here, FIG. 1 is a plan view of a single-core bidirectional optical transceiver according to this embodiment, and FIG. 2 is an enlarged view of a main part of FIG. This example shows a case where light having an optical oscillation peak wavelength of 820 nm is transmitted and light having an optical oscillation peak wavelength of 850 nm is received (upstream 820 nm / downstream 850 nm).

  Reference numeral 21 in the figure indicates a resin sleeve as a transmission / reception optical system formed of an optical resin having a refractive index of about 1.6 (for example, trade name: Udel manufactured by Solvay Advanced Polymers Co., Ltd.). The resin sleeve 21 is formed with a receptacle portion 22 to which an optical fiber (not shown) with an optical connector is fixed, and a lens portion 23 for collimating light emitted from the optical fiber.

  An optical transmitter 24 is disposed at the end of the resin sleeve 21 opposite to the optical fiber, and an optical receiver 25 is disposed at the periphery of the resin sleeve 21. A wavelength multiplexing / demultiplexing filter 26 is disposed inside the resin sleeve 21 and is inclined and fixed at an angle of 30 degrees (θ) with respect to the axial direction of the resin sleeve 21.

  The optical transmission unit 24 includes an optical transmission element (VCSEL) 28 having an oscillation wavelength of 820 nm and a monitor light reception element 29, which are mounted on a stem 27, respectively. A cap 31 with a glass window having a hemispherical lens 30 is attached to the stem 27 so as to hermetically seal the light transmitting element 28 and the monitor light receiving element 29.

  The optical receiving unit 25 includes an optical receiving element 32 and a transimpedance amplifier 33 mounted on a stem 27, respectively. A glass window cap 31 having a hemispherical lens 30 is attached to the stem 27 so as to hermetically seal the light receiving element 32 and the transimpedance amplifier 33. The number 34 indicates a plate-shaped glass window, and the number 35 indicates a lead.

  In FIG. 1, reference numeral 36 indicates a control board on which a drive IC 37 and a limiting amplifier 38 are mounted. Leads 35 from the optical transmitter 24 and the optical receiver 25 are fixed to the control board 36. The control board 36, the optical transmitter 24 and the optical receiver 25 are surrounded by an envelope 40.

The upstream and downstream operations of the single-core bidirectional optical transceiver having such a configuration are as follows.
Ascending: The emitted light having an angle of 10 to 30 degrees of the light transmitting element 28 mounted on the stem 27 of the light transmitting unit 24 is collimated by the hemispherical lens 30, passes through the wavelength multiplexing / demultiplexing filter 26, and resin The light is condensed by the lens portion 23 of the sleeve 21 and coupled to an optical fiber (multimode fiber).
Downstream: The light emitted from the optical fiber (multimode fiber) is collimated by the lens portion 23 of the resin sleeve 21, and the light reflected by the wavelength multiplexing / demultiplexing filter 26 is collected by the hemispherical lens 30 on the light receiving portion 25 side to receive light. Coupled to element 32.

  As described above, according to the single-core bidirectional optical transceiver according to the above embodiment, the VCSEL emission light is collimated by the hemispherical lens 30 and the optical fiber emission light is collimated by the lens portion 23 of the resin sleeve 21. The incident angle with respect to the multiplexing / demultiplexing filter 26 is optimized, and the optical transmission characteristics due to variations in the fixed angle of the wavelength multiplexing / demultiplexing filter 26, the fixed angle deviation between the resin sleeve 21 and the stem 27, and variations in the VCSEL oscillation wavelength. Resistance to deterioration can be increased.

  In addition, optical transmission / reception transmission is achieved by mounting the optical transmission element 28 having two different transmission wavelengths (820 nm, 850 nm), the optical reception element 32 and the wavelength multiplexing / demultiplexing filter 26 so as to be incorporated in one optical system. As shown in FIG. 5, transmission with a high bit rate can be realized by using a single optical fiber at low cost and suppressing the influence of crosstalk between the optical transmitter 24 and the optical receiver 25.

Table 1 below summarizes the transmission test results of the single-core bidirectional optical transceiver according to the present invention. That is, an upstream 820 nm / downstream 850 nm and an upstream 850 nm / downstream 820 nm of this product were connected by an optical fiber, and a transmission test was performed at a bit rate of 1.25 Gbps and 2.5 Gbps. FIG. 6 is a characteristic diagram in which the data in Table 1 is plotted with the optical power as the horizontal axis and the bit error rate as the vertical axis.

In Table 1, “Δ” indicates a difference in minimum reception sensitivity. “Ref.” Uses the OFF state (uppermost stage) as a reference value in order to obtain the difference in minimum reception sensitivity when the built-in optical transmission unit is ON / OFF. “1.25 Gbps” indicates the minimum reception sensitivity standard of Gigabit Ethernet SX. Although there is no standard for “2.5 Gbps”, the standard of 2.1 Gb / s Fiber Channel is described.

  From the above Table 1 and FIG. 6, using a VCSEL having two different oscillation wavelengths for upstream and downstream of the present invention, optical transmission / reception mounted in one optical system incorporating an optical transmission element, a reception element, and a wavelength multiplexing / demultiplexing filter It has been found that an optical transmission / reception transceiver that can transmit light with a single fiber is obtained.

  In addition, in the said Example, although the fixed angle of the wavelength multiplexing / demultiplexing filter was 30 degree | times, it may be the range of 20 degree | times-45 degree | times not only in this but on the characteristic. However, when the angle is 20 degrees, it is difficult to reduce the size, and it is difficult to mount the optical transceiver. Further, at 45 degrees, the number of dielectric multilayer films of the wavelength multiplexing / demultiplexing filter has to be increased, resulting in an increase in cost.

  In addition, this invention is not limited to the said embodiment as it is, It can implement by changing a component in the range which does not deviate from the summary in an implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

Explanatory drawing of the single core bidirectional | two-way optical transmission / reception transceiver based on the Example of this invention. The enlarged view of the principal part of FIG. Explanatory drawing of the conventional optical transmission / reception transceiver. FIG. 4 is a block diagram of the optical transceiver shown in FIG. 3. The block diagram of the single core bidirectional | two-way optical transmission / reception transceiver of FIG. The characteristic view which shows the transmission test result by the single core bidirectional | two-way optical transmission / reception transceiver based on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 21 ... Resin sleeve (optical transmission / reception optical system), 22 ... Re-sectorable part, 23 ... Lens part, 24 ... Optical transmission part, 25 ... Optical reception part, 26 ... Wavelength multiplexing / demultiplexing filter, 27 ... Stem, 28 ... Optical transmission element , 29 ... Monitor light receiving element, 32 ... Light receiving element, 30 ... Hemispherical lens, 31 ... Cap with glass window, 33 ... Transimpedance amplifier, 34 ... Glass window, 35 ... Lead, 36 ... Control board, 37 ... Driver IC 38 ... Limiting amplifier.

Claims (3)

An optical transmitter / receiver and a wavelength multiplexing / demultiplexing filter having two different oscillation wavelengths are built in one transmission / reception optical system, and an optical fiber with one optical connector is connected to the transmission / reception optical system to transmit / receive optical signals. A single-core bidirectional optical transmission / reception transceiver. The transmission / reception optical system is a resin sleeve having a refractive index of substantially 1.6, and the optical transmission element, the optical reception element, and the wavelength multiplexing / demultiplexing filter are integrally held in the resin sleeve. The single-core bidirectional optical transceiver according to claim 1. 2. The single-core bidirectional optical transceiver according to claim 1, wherein the optical fiber with an optical connector has a core diameter of 50 [mu] m or more.

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