JP2005223418A - Wavelength router and optical wavelength multiplex transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wavelength router having a low loss and a wide pass band in a CWDM system, a wavelength group routing system and a high-speed transmission system by relieving a crosstalk characteristic between ports. <P>SOLUTION: This wavelength router is provided with N pieces of input ports and output ports, and has first and second optical multiplexing/demultiplexing circuits and N sets of optical multiplexing circuits. The first and second optical multiplexing/demultiplexing circuits are provided with N pieces of input ports and output ports, and output inputted wavelength multiplexing optical signals to a predetermined output port depending on a wavelength. The optical multiplexing circuit is provided with two input ports and one output port. The M-th (1≤M≤N) input port of a wavelength router is connected to the M-th input port of the first optical multiplexing/demultiplexing circuit if M is an odd number, and connected to the M-th input port of the second optical multiplexing/demultiplexing circuit if M is an even number. The M-th output ports of the two optical multiplexing/demultiplexing circuits have been connected to the input port of the M-th optical multiplexing/demultiplexing circuit, and the output port of the M-th optical multiplexing/demultiplexing circuit has been connected to the M-th output port of the wavelength router. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wavelength router that distributes a plurality of optical signals that have been subjected to optical wavelength division multiplexing according to the wavelength, and an optical wavelength division multiplexing communication system that uses the wavelength router to transmit between a plurality of transmission / reception apparatuses.

An optical wavelength division multiplexing (WDM) transmission system not only greatly increases the transmission capacity that can be transmitted by one optical fiber by assigning a plurality of optical signals to different optical frequencies, but also the destination of the signal with respect to the wavelength. Wavelength addressing for assigning information is possible.
Further, the star-type optical wavelength division multiplexing network system is arranged so that N transmission / reception devices are connected around a wavelength router having a demultiplexing characteristic of a periodic input / output relationship. It is possible to realize an optical wavelength division multiplexing communication system capable of independently connecting full-mesh N × N signal paths interconnecting devices only by using the above optical signal (see Patent Document 1).

FIG. 5 is a schematic diagram showing an optical wavelength division multiplexing communication system configured using the conventional wavelength router described above.
In FIG. 5, reference numerals 501 to 507 denote transmission / reception apparatuses that transmit and receive WDM signals (signals obtained by combining optical signals of wavelengths λ1 to λn), and reference numeral 508 denotes a periodic input / output relationship having N port inputs and outputs. This is a wavelength router having the following demultiplexing characteristics.
In the example of FIG. 5, an arrayed waveguide grating type multiplexer / demultiplexer (AWG) is used as the wavelength router 508, and the wavelength router 508 and each of the transmission / reception devices 501 to 507 each have two light beams, upstream and downstream. Connected with fiber.

Next, FIG. 6 is a conceptual diagram illustrating a schematic configuration of the optical wavelength multiplexing communication system shown in FIG. 6, reference numerals 601 to 604 denote transmission / reception apparatuses, reference numeral 605 denotes a reception apparatus that receives a WDM signal (a signal obtained by combining optical signals having wavelengths λ1 to λn), and reference numeral 606 denotes a WDM signal (wavelengths λ1 to λn). 607 is a demultiplexer for demultiplexing a WDM signal wavelength-multiplexed on one optical fiber, and 608 is a transmitter 606. Is a multiplexer for multiplexing a plurality of optical signals having different wavelengths to one optical fiber, reference numeral 609 is a wavelength router (AWG), reference numerals 610 to 613 are transmission and reception apparatuses 601 to 604 and wavelengths. This is an optical fiber that optically connects an input / output port with the router 609.
Note that the configuration of the transmission / reception devices 602 to 604 is the same as that of the transmission / reception device 601. One transmission / reception apparatus and the wavelength router 609 are connected by two optical fibers, both upstream and downstream.
JP 2002-201112 A

In the optical wavelength division multiplexing communication system configured using the conventional wavelength router described above, it is necessary to prevent signal degradation due to crosstalk from the ports of adjacent transmitting / receiving devices in this wavelength router.
Further, the wavelength router in the communication system is designed so that the transmission loss is minimized and the crosstalk is minimized at the center wavelength of the transmission band.
Here, when the signal wavelength deviates from the center wavelength of the transmission band, the loss increases, and at the same time, the crosstalk to the adjacent channel increases.

In particular, in a CWDM (Coarse WDM) system that does not control the temperature of the laser, as shown in FIG. 7, the light emission wavelength of the laser in the transmitter shifts due to a change in the environmental temperature, and the light to the adjacent port of the wavelength router Crosstalk occurs in the signal.
In order to avoid this, in order to reduce the crosstalk in the wavelength router, it is necessary to narrow the transmission band of the wavelength router.
However, when the transmission band is narrowed, the transmission loss of the optical signal increases, and in the CWDM system, measures such as limiting the ambient environmental temperature to be used are required.

In addition, a signal group (wavelength group) of a plurality of wavelengths is assigned to the transmission band of the wavelength router as shown in the literature (2002 Electronic Information Communication Society Society B-12-2), and routing is performed simultaneously. There is a wavelength group routing.
In this wavelength group routing, since an optical signal having a wavelength deviating from the center of the transmission band of the wavelength router is used, a crosstalk component to an adjacent channel increases.
In this case, if the transmission band of the wavelength router is narrowed in order to obtain a desired crosstalk characteristic, it is necessary to reduce the number of wavelengths that can be used, thereby reducing the transmission efficiency.
Further, in a high light-shielding transmission system such as a transmission speed of 40 Gbit / s, there is a problem that when a wavelength router with a narrow transmission band is used, a modulation sideband is distorted, thereby causing an optical signal transmission error.

  The present invention has been made in view of such circumstances, and relaxes the crosstalk characteristics required for wavelength routing circuits. In a CWDM system, a wavelength group routing system, or a high-speed transmission system, the present invention has a low loss and a transmission band. An object of the present invention is to provide a wide wavelength router and to provide a high-performance optical wavelength division multiplexing communication system at a low cost.

  The wavelength router of the present invention includes N (N is an integer of 1 or more) input ports and N output ports, and includes a first optical multiplexing / demultiplexing circuit, a second optical multiplexing / demultiplexing circuit, and N optical multiplexing / demultiplexing circuits. A wavelength router having a wave circuit, wherein the first optical multiplexing / demultiplexing circuit and the second optical multiplexing / demultiplexing circuit each include N input ports and N output ports, and are input wavelength multiplexing A function of outputting an optical signal to a predetermined output port according to a wavelength, wherein the optical multiplexing circuit includes two input ports and one output port, and the Mth (M is 1 ≦ M ≦) of the wavelength router; N) is connected to the Mth input port of the first optical multiplexing / demultiplexing circuit when M is an odd number, and when M is an even number, the input port of the second optical multiplexing / demultiplexing circuit is connected. An Mth output port of the two optical multiplexing / demultiplexing circuits is connected to the Mth input port. The input port of the serial optical multiplexing circuit are connected respectively, and wherein the output ports of the M-th of said optical multiplexing circuit is connected to the M-th output ports of the wavelength router.

The wavelength router of the present invention is characterized in that the optical multiplexing circuit is composed of an interleaver.
The wavelength router according to the present invention is characterized in that the optical multiplexing / demultiplexing circuit includes an optical demultiplexing circuit including N input ports and 2N output ports, and N optical combining circuits. To do.
In the wavelength router of the present invention, the optical multiplexing / demultiplexing circuit is an arrayed waveguide diffraction grating.

  An optical wavelength division multiplexing transmission system of the present invention includes a plurality of optical transmitters that generate optical signals having different wavelengths, and an optical transmission unit that includes a multiplexer that multiplexes output optical signals of the plurality of optical transmitters, An optical fiber transmission line to which the output optical signal of this optical transmission means is input, a wavelength router that routes the optical signal in this optical fiber transmission line by wavelength, and an optical signal transmitted by this optical fiber transmission line for each wavelength In the optical wavelength division multiplex transmission system, the optical wavelength multiplex transmission system includes: an optical demultiplexer that demultiplexes the optical signal; and a plurality of optical receivers that receive optical signals for each wavelength demultiplexed by the demultiplexer. The router includes N (N is an integer) input ports and N output ports, and includes a first optical multiplexing / demultiplexing circuit, a second optical multiplexing / demultiplexing circuit, and N optical multiplexing circuits. And the first optical multiplexing / demultiplexing circuit and The second optical multiplexing / demultiplexing circuit includes N input ports and N output ports, respectively, and has a function of outputting an input wavelength-multiplexed optical signal to a predetermined output port according to wavelength, When the optical multiplexing circuit includes two input ports and one output port, and the Mth input port of the wavelength router (M is an integer in the range of 1 ≦ M ≦ N), M is an odd number. M is connected to the Mth input port of one optical multiplexing / demultiplexing circuit. When M is an even number, it is connected to the Mth input port of the second optical multiplexing / demultiplexing circuit. The output port of the Mth optical multiplexing circuit is connected to the Mth output port of the wavelength router, and the output port of the Mth optical multiplexing circuit is connected to the Mth output port of the wavelength router. And

  As described above, according to the wavelength router of the present invention, the crosstalk characteristic required for the wavelength routing circuit is alleviated, a low-loss wavelength router is provided in a CWDM system and a wavelength group routing system, and a high performance It becomes possible to provide an inexpensive optical wavelength division multiplexing communication system at a low cost.

The wavelength router of the present invention includes N (N is an integer equal to or greater than 1) input ports and N output ports, and includes two first optical multiplexing / demultiplexing circuits and two optical multiplexing / demultiplexing circuits. An optical multiplexing / demultiplexing circuit and N optical multiplexing circuits are provided.
The first optical multiplexing / demultiplexing circuit and the second optical multiplexing / demultiplexing circuit each have N input ports and N output ports, and input wavelength-multiplexed optical signals are predetermined according to the wavelength. It has a function to output to the output port.
Each of the optical multiplexing circuits includes two input ports and one output port, and the Mth input port (M is an integer in the range of 1 ≦ M ≦ N) of the wavelength router is M Is connected to the Mth input port of the first optical multiplexing / demultiplexing circuit, and when M is an even number, it is connected to the Mth input port of the second optical multiplexing / demultiplexing circuit. The Mth output port of the two optical multiplexing / demultiplexing circuits is connected to the input port of the Mth optical multiplexing circuit, and the output port of the Mth optical multiplexing circuit is connected to the Mth output port of the wavelength router. Has been.

  The router of the present invention generates optical signals having different wavelengths from each other as shown in FIG. 6, for example, and at least some of the optical transmission devices (606) having different transmission speeds. An optical transmitter (not shown) including a multiplexer (608) that multiplexes the output optical signal of the transmitter, and an amplifying means that amplifies the multiplexed optical signal, and an output optical signal of the optical transmitting means An input optical fiber transmission line (optical fibers 610 to 613), a wavelength router (using the wavelength router of the present invention) that distributes the optical signal in the optical fiber transmission line according to the wavelength, and the optical fiber transmission line An optical wavelength provided with a demultiplexer (607) for demultiplexing the transmitted optical signal for each wavelength and a plurality of optical receiving devices (605) for receiving the optical signal for each wavelength demultiplexed by the demultiplexer. Wavelength router for multiplex transmission system Used in.

<First Embodiment>
A wavelength router according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration example of an optical wavelength division multiplexing communication system using the wavelength router according to the first embodiment.
In this figure, reference numerals 101 to 104 denote transmitters that transmit WDM signals (signals obtained by combining optical signals having wavelengths λ1 to λ4), and 105 to 108 denote WDM signals (multiplexing optical signals having wavelengths λ1 to λ4). Signal).
Reference numeral 123 denotes a 4 × 4 wavelength router having input / output of four ports, that is, input ports II1 to II4 and output ports OO1 to OO4, and having a demultiplexing characteristic of a periodic input / output relationship. .
Reference numerals 109 to 116 denote optical fibers that connect the transmission / reception apparatuses 101 to 108 and the wavelength router 123.
The configuration of the transmission / reception devices 101 to 108 is the same as that of the conventional transmission / reception devices 801 to 804 shown in FIG.

Here, in the wavelength router 123 of this embodiment, the transmission / reception apparatuses 101 to 108 are different from the conventional example shown in FIG. 5 in that two optical multiplexing / demultiplexing circuits 117 and 118 and optical multiplexing circuits 119 to 122 are provided. Have.
For example, in FIG. 1, a wavelength-circulating arrayed waveguide diffraction grating type multiplexing / demultiplexing circuit (AWG) is used as the optical multiplexing / demultiplexing circuits 117 and 118, and an interleaver (waveguide type wavelength splitter) is used as the optical multiplexing circuits 119 to 122. ) Is used.
The optical multiplexing / demultiplexing circuits 117 and 118 demultiplex the input WDM signal into individual optical signals based on the relationship between the wavelength of the table shown in FIG. 2, which will be described later, and the input and output ports. The demultiplexed optical signals are multiplexed and output so as to correspond to the above relationship.

Here, in the wavelength router 123, the first input port II1 is connected to the first input port I1 of the first optical multiplexing / demultiplexing circuit 117, and the second input port II2 is connected to the second optical multiplexing / demultiplexing circuit. 118 is connected to the second input port I2.
In each of the two optical multiplexing / demultiplexing circuits 117 and 118, the first output port O1 is connected to the input port of the first optical multiplexing circuit 119.
Here, the first output port O1 of the first optical multiplexing / demultiplexing circuit 117 corresponds to the wavelength λ1,3, and corresponds to the first output port O1 wavelength λ2,4 of the second optical multiplexing / demultiplexing circuit 118. doing.
The first optical multiplexing circuit 119 has an output port connected to the first output port OO 1 of the wavelength router 123.
Similarly, the second, third, and fourth optical multiplexing circuits 120, 121, and 122 are connected to the second, third, and fourth output ports OO2, OO3, and OO4 of the wavelength router 123, respectively.

FIG. 2 shows the relationship between the wavelengths at the input port and the output port according to the present invention, that is, the correspondence between the wavelength input from the input port and the wavelength output from the output port in the optical multiplexing / demultiplexing circuits 117 and 118. It is a table which shows a relationship.
The numbers I1 to I4 described in the vertical column are the input port numbers of the optical multiplexing / demultiplexing circuits 117 and 118, and the numbers O1 to O4 described in the horizontal column are the output port numbers of the optical multiplexing / demultiplexing circuits 117 and 118. is there.
For example, the optical multiplexing / demultiplexing circuits 117 and 118 use the optical signal of wavelength λ2 from the table shown in FIG. 2 to transmit the optical signal from the input port I1 to the output port O2, and conversely from the input port I2. It can be seen that the wavelength λ2 may be used to send an optical signal to the output port O1. The same applies to other input and output ports in the optical multiplexing / demultiplexing circuits 117 and 118.

In the embodiment of FIG. 1, the WDM signals sent from the transmission apparatuses 101 (node 1) and 103 (node 3) are input to the optical multiplexing / demultiplexing circuit 117, while the transmission apparatuses 102 (node 2) and 104 (nodes). The WDM signal sent from 4) enters the optical multiplexing / demultiplexing circuit 118 and is wavelength-routed respectively.
Here, the input ports II1, II2, II3, and II4 of the wavelength router 123 are connected to the transmission devices 101, 102, 103, and 104, respectively.
The interleavers 119 to 122 multiplex the wavelength-routed WDM signals and transmit the multiplexed signals to the corresponding receiving apparatuses 105 to 108.

Here, since WDM signals from adjacent nodes (for example, node 1 and node 2) are wavelength-routed by different optical multiplexing / demultiplexing circuits 117 and 118, crosstalk components from adjacent ports in the wavelength router 123 are Are removed by the interleaving function of the optical multiplexing circuits 119-122. As the adjacent ports, for example, as shown in FIG. 1, the input ports II1 and II2 or the input ports II3 and II4 correspond to each other.
In addition, since the characteristic of shielding the crosstalk from the non-adjacent port to -40 dB or less can be easily realized, signal degradation due to the crosstalk does not occur. As the non-adjacent ports, for example, as shown in FIG. 1, input ports II1 and II3, input ports II2 and II4, or input ports II1 and II4 correspond to each other.

<Second Embodiment>
FIG. 3 is a block diagram showing a configuration example of an optical wavelength division multiplexing communication system configured using the wavelength router according to the second embodiment of the present invention.
In this figure, reference numerals 231 to 304 denote transmission apparatuses that transmit WDM signals (signals obtained by combining optical signals having wavelengths λ1 to λ4).
Reference numerals 305 to 308 denote receiving apparatuses that receive WDM signals (signals obtained by combining optical signals having wavelengths λ1 to λ4).
Reference numeral 331 is a 4 × 4 wavelength router having input / output of four ports, that is, input ports II1 to II4 and output ports OO1 to OO4, and having a demultiplexing characteristic of a periodic input / output relationship.

Reference numerals 309 to 316 denote optical fibers that connect the transmission / reception apparatuses 301 to 308 and the wavelength router 331.
The configuration of the transmission / reception devices 301 to 308 is the same as that of the conventional transmission / reception devices 601 to 604 shown in FIG.
Here, the wavelength router 331 includes two optical multiplexing / demultiplexing circuits 317 and 318 and optical combining circuits 319 to 330 for multiplexing a plurality of input optical signals.
In the configuration example shown in FIG. 3, a 4 × 8 array waveguide diffraction grating type multiplexing / demultiplexing circuit (AWG) is used as the optical multiplexing / demultiplexing circuits 317 and 318, and an interleaver is used as the optical multiplexing circuits 329 to 322. Optical couplers are used as the circuits 323 to 330.
The optical multiplexing / demultiplexing circuits 317 and 318 are provided with N input ports and 2N output ports, and the input WDM signal is converted based on the relationship between the wavelength and the input and output ports in the table shown in FIG. At one end, the optical signals are demultiplexed into individual optical signals, and the optical signals thus demultiplexed are multiplexed and output so as to correspond to the relationship of this table.

Here, in the wavelength router 331, the first input port II1 is connected to the first input port I1 of the first optical multiplexing / demultiplexing circuit 317, and the second input port II2 is connected to the second optical multiplexing / demultiplexing circuit. 318 is connected to the second input port I2.
On the other hand, in the optical multiplexing / demultiplexing circuit 317, the first and fifth output ports O 1 and O 5 are connected to the input port of the first optical combining circuit 323.
In the optical multiplexing / demultiplexing circuit 318, the first and fifth output ports O1, O5 are connected to the input port of the fifth optical combining circuit 327.
Furthermore, the output ports of the first optical combining circuit 323 and the fifth optical combining circuit 327 are connected to the input ports of the first optical combining circuit 319, and the output ports of the first optical combining circuit 319 are: The wavelength router 123 is connected to the first output port OO1.

FIG. 4 shows the wavelength relationship between the input port and the output port in the optical multiplexing / demultiplexing circuits 217 and 318 according to the present invention, that is, the wavelength input from the input port and the output from the output port in the optical multiplexing / demultiplexing circuits 117 and 118. It is a table which shows a corresponding relationship with the wavelength to be performed.
Numbers II1 to II4 are input port numbers of the wavelength router, and numbers OO1 to OO4 are output port numbers.
Based on the table shown in FIG. 4, the optical multiplexing / demultiplexing circuit 217 sequentially outputs optical signals of wavelengths λ 1 to λ 4 to the output ports O 5 to O 8 in the WDM signal input from the input port I 1.
Similarly, the optical multiplexing / demultiplexing circuit 217 sequentially outputs optical signals of wavelengths λ1 to λ4 to the output ports O4 to O7 in the WDM signal input from the input port I2.

In FIG. 3, WDM signals transmitted from the respective nodes (transmission / reception devices 301 to 304) are demultiplexed by optical multiplexing / demultiplexing circuits 317 and 318, multiplexed by optical couplers 323 to 330, and further combined by interleavers 319 to 322. The WDM signal is generated and output to each of the output optical fibers 313 to 316.
Here, WDM signals from adjacent nodes (for example, node 1 and node 2) are wavelength-routed by different optical multiplexing / demultiplexing circuits 317 and 318, respectively.
Thereby, in the wavelength router 123, the crosstalk component from the adjacent port as described in FIG. 7 is removed by the interleaving function of the optical multiplexing circuits 319 to 322. As the adjacent ports, for example, as shown in FIG. 3, the input ports II1 and II2 or the input ports II3 and II4 correspond to each other.

In addition, since the characteristic of shielding the crosstalk from the non-adjacent port to -40 dB or less can be easily realized, signal degradation due to the crosstalk does not occur. As the non-adjacent ports, for example, as shown in FIG. 1, input ports II1 and II3, input ports II2 and II4, or input ports II1 and II4 correspond to each other. .
Here, an interleaver can be used as the optical combining circuits 323 to 330 in place of the optical coupler.
In the first and second embodiments described above, a single element AWG is used as the optical multiplexing circuit or the optical multiplexing / demultiplexing circuit. However, other elements, for example, a combination of the demultiplexing AWG and fiber wiring, or a dielectric multilayer The same effect can be obtained by combining a multiplexing / demultiplexing circuit using a film and fiber wiring.

It is the schematic which shows the optical wavelength division multiplexing communication system comprised using the wavelength router by the 1st Embodiment of this invention. It is a table which shows the relationship of the wavelength of the input and output port of the wavelength router by the 1st Embodiment of this invention. It is the schematic which shows the optical wavelength division multiplexing communication system comprised using the wavelength router by the 2nd Embodiment of this invention. It is a table | surface which shows the relationship of the wavelength of the input / output port of the wavelength router by the 2nd Embodiment of this invention. It is the schematic which shows the optical wavelength division multiplexing communication system comprised using the conventional wavelength router. It is a block diagram which shows the schematic structural example of the optical wavelength division multiplexing communication system using the conventional wavelength router. It is a figure explaining the crosstalk to the adjacent channel in the conventional wavelength router.

Explanation of symbols

101, 102, 103, 104 ... transmitting device 105, 106, 107, 108 ... receiving device 109, 110, 111, 112, 113, 114, 115, 116 ... optical fiber 117, 118 ... optical multiplexing / demultiplexing circuit 119, 120, 121, 122 ... Optical multiplexing circuit 301, 302, 303, 304 ... Transmitting device 305, 306, 307, 308 ... Receiving device 309, 310, 311, 312, 313, 314, 315, 316 ... Optical fiber 317, 318 ... Optical multiplexing Demultiplexing circuit 319, 320, 321, 322 ... Optical multiplexing circuit

Claims (5)

A wavelength router having N (N is an integer of 1 or more) input ports and N output ports, and having a first optical multiplexing / demultiplexing circuit, a second optical multiplexing / demultiplexing circuit, and N optical multiplexing / demultiplexing circuits Because
Each of the first optical multiplexing / demultiplexing circuit and the second optical multiplexing / demultiplexing circuit includes N input ports and N output ports, and outputs an input wavelength multiplexed optical signal to a predetermined output port according to a wavelength. Has the function to
The optical multiplexing circuit includes two input ports and one output port;
The Mth input port (M is an integer in the range of 1 ≦ M ≦ N) of the wavelength router is connected to the Mth input port of the first optical multiplexing / demultiplexing circuit when M is an odd number. If it is an even number, it is connected to the Mth input port of the second optical multiplexing / demultiplexing circuit,
M-th output ports of the two optical multiplexing / demultiplexing circuits are respectively connected to input ports of the M-th optical multiplexing / demultiplexing circuit,
The wavelength router, wherein an output port of the Mth optical multiplexing circuit is connected to an Mth output port of the wavelength router.   The wavelength router according to claim 1, wherein the optical multiplexing circuit includes an interleaver.   The optical multiplexing / demultiplexing circuit includes an optical demultiplexing circuit including N input ports and 2N output ports, and N optical combining circuits. 2. The wavelength router according to 2.   4. The wavelength router according to claim 3, wherein the optical multiplexing / demultiplexing circuit is an arrayed waveguide diffraction grating. Optical transmission means including a plurality of optical transmitters that generate optical signals having different wavelengths, and a multiplexer that multiplexes output optical signals of the plurality of optical transmitters, and an output optical signal of the optical transmission means is input An optical fiber transmission line, a wavelength router that distributes the optical signal in the optical fiber transmission line according to the wavelength, a demultiplexer that demultiplexes the optical signal transmitted by the optical fiber transmission line for each wavelength, In an optical wavelength division multiplex transmission system comprising: an optical receiving means including a plurality of optical receivers that receive optical signals for each wavelength demultiplexed by a demultiplexer;
The wavelength router includes N (N is an integer) input ports and N output ports, and includes a first optical multiplexing / demultiplexing circuit, a second optical multiplexing / demultiplexing circuit, and N optical multiplexing circuits. A wavelength router,
Each of the first optical multiplexing / demultiplexing circuit and the second optical multiplexing / demultiplexing circuit includes N input ports and N output ports, and outputs an input wavelength multiplexed optical signal to a predetermined output port according to a wavelength. Has the function to
The optical multiplexing circuit includes two input ports and one output port;
The Mth input port (M is an integer in the range of 1 ≦ M ≦ N) of the wavelength router is connected to the Mth input port of the first optical multiplexing / demultiplexing circuit when M is an odd number. If it is an even number, it is connected to the Mth input port of the second optical multiplexing / demultiplexing circuit,
M-th output ports of the two optical multiplexing / demultiplexing circuits are respectively connected to input ports of the M-th optical multiplexing / demultiplexing circuit,
An optical wavelength division multiplexing transmission system, wherein an output port of the Mth optical multiplexing circuit is connected to an Mth output port of the wavelength router.

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