JP2001007767A - Optical communication system, optical receiver and the optical communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost of an optical communication system as a whole and to miniaturize an optical transmitter by sharing an optical branching unit for feedback-controlling the outputs of the optical signals of respective wavelengths with the parts of an optical reception circuit side. SOLUTION: The optical branching unit 2b of a receiver 200-side branches a wavelength multiplex optical signal and outputs it to a designated port during an operation. Optical reception circuits 9a to 9d are connected to the operating port, to which the operating wavelength is outputted, and optical signals are received. Opto-electric transducer 6a to 6d are connected to the idle port for receiving a leakage optical signal from the adjacent operating wavelength. When outputs are simultaneously dropped in the idle ports on both sides of the operating port receiving the wavelength which is an object of monitoring, a comparison control circuit 5 judges that the output of the optical signal of the wavelength which is the monitoring object is dropped. The result of monitoring is transmitted to a transmitter 100-side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an optical communication system,
The present invention relates to an optical receiver and an optical communication method, in particular, in an optical communication system for transmitting a wavelength-division multiplexed optical signal in which a plurality of signals having different wavelengths are multiplexed, the output and the wavelength of the optical signal transmitted from the optical transmitter are automatically adjusted. TECHNICAL FIELD The present invention relates to an optical communication system, an optical receiver, and an optical communication method which are adjusted in an appropriate manner.

[0002]

2. Description of the Related Art In an optical communication system for transmitting a wavelength multiplexed optical signal in which a plurality of signals having different wavelengths are multiplexed,
When controlling the optical output of each wavelength or the optical signal of each wavelength,
Conventionally, a wavelength-locker for the number of wavelengths to be multiplexed is provided, or a part of a wavelength-division multiplexed optical signal, which is a main signal, is branched by an optical coupler and then a part of the main signal is branched. To the Arrayed Wave Guide
The wavelength is separated using veguide grating (AWG) or the like, and the output of each wavelength is compared and controlled.

FIG. 2 shows a conventional optical communication system for transmitting a wavelength-division multiplexed optical signal, for example, as disclosed in Japanese Unexamined Patent Publication No. Hei.
1 shows an optical communication device disclosed in Japanese Unexamined Patent Application Publication No. H10-26095. In FIG. 2, reference numerals 1a, 1b and 1c denote optical transmission circuits for converting the electric signals 10, 12 or 14 into optical signals, respectively, and 2a denotes each wavelength (λ) of the optical signal output from the optical transmission circuits 1a to 1c.
1, λ2 or λ3), an optical fiber amplifier for amplifying a wavelength multiplexed optical signal, 4a an optical splitter for splitting a wavelength multiplexed optical signal, and 2b for demultiplexing the split optical signal. The second optical branch, 6a, 6b or 6c,
Each wavelength (λ1, λ2 or λ3) by the optical splitter 2b
An optical-to-electrical converter (also referred to as an “O / E converter”) for converting the optical signal demultiplexed into an optical signal as a measurement result, and a measurement result output from the optical-to-electrical converters 6a to 6c. A comparison control circuit for comparing with a predetermined threshold, 11, 13 or 15 is provided from the comparison control circuit 7 to the optical transmission circuits 1a to 1c.
8a is a control signal for performing feedback control to the optical fiber connecting the transmitter and the opposite station (receiver).
c is the received optical signal at each wavelength (λ1, λ2 or λ3)
The first optical splitter 9a, 9b, or 9c in the receiver that splits the light into a light is a light receiving circuit in the receiver connected to the first optical splitter.

Next, the operation will be described. Optical transmission circuit 1
The optical signals of each wavelength (λ1, λ2, or λ3) output from a to 1c are multiplexed by the optical splitter 2a.
The wavelength-division multiplexed optical signal is amplified by the optical fiber amplifier 3a, and a part of the signal light is split by the optical splitter 4 and input to the second optical splitter 2b. The wavelength multiplexed optical signal is the second
Of each wavelength (λ1, λ2 or λ)
The signal is demultiplexed every 3), converted from an optical signal to an electric signal by the optical / electrical conversion element converters 6a to 6c, and then compared with a predetermined threshold value by the comparison control circuit 7. The control signal 11 is sent to the optical transmission circuits 1a to 1c based on the result of comparison with the predetermined threshold.
To 15 and feedback control is performed so that the output signal light of the optical amplifier 3a becomes substantially constant.

[0005]

However, the above-mentioned conventional optical communication system for wavelength division multiplex transmission has a problem in an optical transmitter.
A dedicated optical splitter was required to feedback-control the output of each wavelength or an optical signal of each wavelength, and an optical-to-electrical converter for the number of wavelength multiplexes was required. Therefore, there is a problem that the optical transmitter used in the optical communication system becomes large.
Therefore, an object of the present invention is to solve the above problem, and shares an optical splitter for feedback-controlling the output of an optical signal of each wavelength or each wavelength with components on the optical receiving circuit side. Accordingly, an object of the present invention is to provide an optical communication system, an optical receiver, and an optical communication method that can reduce the cost of an optical communication system as a whole and reduce the size of an optical transmitter.

[0006]

An optical communication system according to the present invention is an optical communication system for transmitting a wavelength multiplexed optical signal in which a plurality of signals having different wavelengths are multiplexed from an optical transmitter to an optical receiver. The optical receiver, an optical demultiplexing unit that demultiplexes the wavelength-multiplexed optical signal transmitted from the optical transmitter for each wavelength and outputs the demultiplexed optical signal to an operating port, and an operating port of the optical demultiplexing unit. An optical receiving circuit unit connected to receive the demultiplexed optical signal, and a length of the optical signal demultiplexed to the optical receiving circuit unit connected to a port different from the operating port of the optical demultiplexing unit. The optical-to-electrical conversion circuit unit on the long wavelength side, which inputs the crosstalk light on the wavelength side and converts it into an electric signal, is connected to a port different from the operating port of the optical demultiplexing unit, and is connected to the optical reception circuit unit. The short-wavelength side that inputs the crosstalk light on the short-wavelength side of the demultiplexed optical signal and converts it into an electric signal When the output of the signal converted by the optical-to-electrical conversion circuit unit on the long wavelength side and the output of the signal converted by the optical-to-electrical conversion circuit unit on the short wavelength side both increase and decrease. A control circuit unit that determines that the signal output of the wavelength demultiplexed to the optical receiving circuit unit has increased or decreased and outputs a control signal as a result of the determination, and the optical transmitter includes an output from the control circuit unit. If the control signal indicates an increase in the signal output of the wavelength demultiplexed to the optical receiving circuit unit, the output of the optical signal to be transmitted to the optical receiver is reduced, the signal is demultiplexed to the optical receiving circuit unit When the decrease in the wavelength signal output is indicated, the output of the optical signal transmitted to the optical receiver is increased.

Here, in the optical communication system of the present invention, the control circuit section outputs a signal converted by the long-wavelength-side optical-to-electrical conversion circuit section or the short-wavelength-side optical-to-electrical conversion circuit section. If one of the output of the signal converted by the above increases and the other decreases, the signal output of the wavelength demultiplexed to the optical receiving circuit shifts toward the increased optical / electrical conversion circuit. The optical transmitter outputs a control signal of the determination result, and the control signal output from the control circuit unit detects the deviation of the signal output of the wavelength demultiplexed to the optical reception circuit unit. In the case shown, the deviation of the output of the optical signal transmitted to the optical receiver can be adjusted.

Here, in the optical communication system of the present invention, the wavelength interval between the ports of the optical demultiplexing unit can be made smaller than the wavelength interval of the optical signal multiplexed on the wavelength-multiplexed optical signal to be transmitted. It is.

Here, in the optical communication system of the present invention, the wavelength multiplexed optical signal in which a plurality of signals having different wavelengths are multiplexed can be assumed to be multiplexed with a predetermined number of wavelengths. .

Here, in the optical communication system of the present invention, the optical demultiplexing unit has a structure in which a plurality of waveguides having different lengths are regularly arranged, and a two-dimensional optical waveguide is provided at an input / output end of the waveguide. It can perform multi-beam interference type light demultiplexing (preferably using AWG).

Here, in the optical communication system according to the present invention, the control circuit unit can intensity-modulate the control signal as a result of the determination, and superimpose the control signal on the main signal, and output the superposed control signal.

An optical receiver according to the present invention is an optical receiver in an optical communication system for transmitting a wavelength division multiplexed optical signal in which a plurality of signals having different wavelengths are multiplexed. An optical demultiplexing unit that demultiplexes the optical signal to an operating port; an optical receiving circuit unit that is connected to the operating port of the optical demultiplexing unit and receives the demultiplexed optical signal; A long wavelength side optical / electrical device which is connected to a port different from the operating port of the wave unit and receives the long wavelength side crosstalk light of the demultiplexed optical signal to the optical receiving circuit unit and converts it into an electric signal; A conversion circuit unit, which is connected to a port different from the operating port of the optical demultiplexing unit, inputs crosstalk light on the short wavelength side of the demultiplexed optical signal to the optical reception circuit unit, and converts it into an electric signal. The short-wavelength-side optical-to-electrical conversion circuit unit and the long-wavelength-side optical-to-electrical conversion circuit unit When both the output of the converted signal and the output of the signal converted by the optical / electrical conversion circuit on the short wavelength side increase or decrease, the signal output of the wavelength demultiplexed to the optical receiving circuit increases or decreases. And a control circuit for outputting a control signal as a result of the determination.

Here, in the optical receiver according to the present invention, the control circuit section may output a signal converted by the long-wavelength-side optical / electrical conversion circuit section or the short-wavelength-side optical / electrical conversion circuit section. If one of the output of the signal converted by the above increases and the other decreases, the signal output of the wavelength demultiplexed to the optical receiving circuit shifts toward the increased optical / electrical conversion circuit. The control signal can be output as a result of the determination.

Here, in the optical receiver according to the present invention, the wavelength interval between the ports of the optical demultiplexing unit can be made smaller than the wavelength interval of the optical signal multiplexed on the transmitted wavelength multiplexed optical signal. It is.

Here, in the optical receiver according to the present invention, in the optical demultiplexing section, a plurality of waveguides having different lengths are regularly arranged, and a two-dimensional optical waveguide is provided at an input / output end of the waveguide. It can perform multi-beam interference type light demultiplexing.

An optical communication method according to the present invention is an optical communication method for transmitting a wavelength multiplexed optical signal in which a plurality of signals having different wavelengths are multiplexed from an optical transmitter to an optical receiver. An optical demultiplexing step of demultiplexing the wavelength division multiplexed optical signal transmitted from the optical transmitter for each wavelength and outputting the demultiplexed optical signal to an operating port of the optical demultiplexing unit; To the connected optical receiving circuit unit, an optical receiving step of outputting a demultiplexed optical signal, and to an optical-electrical conversion circuit unit connected to a port different from the operating port of the optical demultiplexing unit, The optical / electrical conversion step on the long wavelength side for inputting the long wavelength crosstalk light on the optical signal output to the optical receiving circuit section and converting it into an electric signal is different from the operating port of the optical demultiplexing section. The light output to the optical receiving circuit unit is transmitted to the optical / electrical conversion circuit unit connected to the port. A light-electricity conversion step of a short wavelength side be converted into electrical signals by entering the crosstalk light on the short wavelength side of the item,
When both the output of the signal converted by the optical / electrical conversion step on the long wavelength side and the output of the signal converted by the optical / electrical conversion step on the short wavelength side increase or decrease, the signal is output to the optical receiving circuit unit. A control step of determining that the signal output of the wavelength has increased or decreased and outputting a control signal as a result of the determination, wherein the optical transmitter side transmits the control signal output by the control step to the optical receiving circuit unit. The output of the optical signal transmitted to the optical receiver side is reduced when the output of the signal of the output wavelength is increased, and the optical receiver is output when the output of the signal of the wavelength output to the optical receiving circuit unit is reduced. This increases the output of the optical signal transmitted to the side.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

Embodiment 1 FIG. 1 shows an optical communication system according to Embodiment 1 of the present invention. Optical transmitter 1 of FIG.
On the 00 side, reference numerals 1a, 1b and 1c denote optical transmission circuits for converting electrical signals 10, 12 or 14 into optical signals, respectively, and 2a denote respective wavelengths (λ1, λ2) of the optical signals output from the optical transmission circuits 1a to 1c. Or λ3), an optical fiber amplifier for amplifying the wavelength multiplexed optical signal, 3a an optical receiving circuit for receiving a control signal from the optical receiver 200, and 20 an optical fiber amplifier for detecting a control signal from the optical receiving circuit 9d. A transmitter control circuit that compares a control signal with a predetermined threshold,
On the optical receiver 200 side, reference numeral 2b denotes an optical branching device such as an AWG for demultiplexing the amplified wavelength-division multiplexed optical signal, 6a, 6
b, 6c or 6d is connected to an empty port where the optical branching device 2b is not in operation, and each wavelength (λ1, λ2 or λ3)
Optical-electrical converter 9a, 9b or 9c for measuring an optical signal demultiplexed into an optical signal and converting it into an electric signal.
b, the optical receiving circuit connected to the operating port,
A comparison control circuit 1d for comparing the result measured and converted by the electric converters 6a to 6d with a predetermined threshold value, and 1d is an optical transmission circuit for transmitting the comparison result of the comparison control circuit 5 to the transmitter 100 side.

Next, the operation will be described. Optical transmission circuit 1
The optical signals of each wavelength (λ1, λ2, or λ3) output from a to 1c are multiplexed by the optical splitter 2a.
The wavelength multiplexed optical signal is amplified by the optical fiber amplifier 3a and transmitted to the receiver 200. The optical splitter 2b on the receiver 200 side demultiplexes the wavelength-division multiplexed optical signal and outputs it to the designated port in operation. In this case, if the wavelength interval of the port of the optical branching device 2b is set to be, for example, の of the wavelength interval of the wavelength multiplexed optical signal as the main signal, the wavelength output to the operating port and the idle port Are alternately arranged. The optical receiving circuits 9a to 9d are connected to the operating ports to which the operating wavelengths are output to receive optical signals. Since a crosstalk characteristic causes a crosstalk light signal to be output from an adjacent operating wavelength to an empty port, the optical-to-electrical converters 6a to 6d receive the optical signal having the crosstalk characteristic. Thus, the output of the operating port can be monitored as a monitoring target.

For example, an optical signal having the wavelength λ1 is
When the signal is received by the optical signal a, the crosstalk light signal on the short wavelength side of the signal can be received by the optical / electrical converter 6a, and the crosstalk optical signal on the long wavelength side can be received by the optical / electrical converter 6b. In this case, when the output simultaneously decreases in the empty ports on both sides of the operating port that receives the wavelength λ1 to be monitored, the output of the optical signal of the wavelength λ1 to be monitored decreases in the comparison control circuit 5. Can be determined. Therefore, the monitoring result can be written on data to be transmitted to the transmitter 100 and transmitted, and the transmitter control circuit 20 of the transmitter 100 can adjust the output of the optical transmission circuits 1a to 1c. Therefore, an optical splitter for feedback-controlling the output of the optical signal is provided by the optical transmitter 1.
The optical communication system can be reduced in size as a whole and the optical transmitter can be reduced in size by not using it exclusively on the 00 side but instead sharing it with components on the optical receiving circuit side.

As described above, according to the first embodiment, the optical branching unit of the optical receiver causes the operating port to receive the demultiplexed optical signal, and the free port receives the crosstalk optical signal for monitoring. By doing so, the optical splitter for feedback-controlling the output of the optical signal can be shared with the components on the optical receiving circuit side, so that the cost of the optical communication system as a whole is reduced and the optical transmitter is downsized. be able to.

Embodiment 2. In Embodiment 1,
When the output simultaneously decreases in the empty ports on both sides of the operating port to be monitored, the comparison control circuit 5 determines that the output of the optical signal of the wavelength λ1 or the like to be monitored has decreased. In the second embodiment, the vacant ports on both sides of the operating port to be monitored are monitored, and the output at one vacant port increases and the output at the other vacant port decreases with respect to a predetermined threshold. When the output balance between the two ports is lost, for example, when it is performed, the comparison control circuit 5 determines that the optical wavelength such as the wavelength λ1 to be monitored is shifted. Specifically, it is determined that the optical wavelength such as the wavelength λ1 to be monitored is shifted to the free port side of the output whose output has increased, and the determination result is written on data for the transmitter 100 and transmitted. The output wavelength of the optical transmission circuit 1a and the like is adjusted by the transmitter control circuit 20 on the transmission circuit 100 side.

As described above, according to the second embodiment, the optical branching unit of the optical receiver causes the operating port to receive the demultiplexed optical signal, and the unoccupied port receives the crosstalk optical signal for monitoring. By doing so, it is possible to determine that the wavelength of the optical signal to be monitored has shifted, so that the determination result can be sent to the transmitter side and the output wavelength can be adjusted.

Embodiment 3 In the above-described Embodiments 1 and 2, the number of wavelength intervals of the optical branching device 2b, that is, the number of ports is set to の of the operating wavelength, but the number of ports is set arbitrarily. can do.

As described above, according to the third embodiment, the number of ports can be set to an arbitrary value, so that the number of available ports can be increased, and the optical signal of the wavelength to be monitored is monitored in more detail. be able to.

Embodiment 4 In the above-described Embodiments 1 to 3, the number of wavelengths is set to 3, but the number of wavelengths can be set arbitrarily.

As described above, according to the fourth embodiment, the number of wavelengths can be arbitrarily set, so that a multiplexed wavelength-multiplexed optical signal can be transmitted.

Embodiment 5 In the above-described Embodiments 1 to 4, the AWG is used as the optical splitter.
The same effect can be obtained by using a WDM coupler or a dielectric multilayer filter.

As described above, according to the fifth embodiment, the same effects as in the first to fourth embodiments can be obtained by using a WDM coupler or a dielectric multilayer filter as the optical branching device.

Embodiment 6 In the above-described Embodiments 1 to 5, the transmitter 10 output from the comparison control circuit 5
For writing the control signal to the 0 side, the intensity-modulated control signal can be transmitted by being superimposed on the main signal.

As described above, according to the sixth embodiment, the control signal output from the comparison control circuit 5 can be transmitted by superposing the intensity-modulated control signal on the main signal.
It can be written and transmitted on data intended for the transmitter.

[0032]

As described above, according to the optical communication system, the optical receiver, and the optical communication method of the present invention, the optical splitter for feedback-controlling the output of each wavelength or the optical signal of each wavelength is provided. It is possible to provide an optical communication system, an optical receiver, and an optical communication method that can reduce the cost of an optical communication system as a whole and reduce the size of an optical transmitter by being shared with components on the receiving circuit side. it can.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an optical communication system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a conventional optical communication system for transmitting a wavelength multiplexed optical signal.

[Explanation of symbols]

1a, 1b, 1c Optical transmission circuit, 2a, 2b, 2c
Optical splitter, 3a, 3b Optical fiber amplifier, 5, 7
Comparison control circuit, 6a, 6b, 6c, 6d optical / electrical converter, 8a, 8b optical fiber, 9a, 9b, 9c
Optical receiving circuit, 10, 12, 14 Electric signal, 1
1, 13, 15 control signal, 20 transmitter control circuit,
100 transmitters, 200 receivers.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04J 14/02

Claims (11)

[Claims] 1. An optical communication system for transmitting a wavelength-division multiplexed optical signal in which a plurality of signals having different wavelengths are multiplexed from an optical transmitter to an optical receiver, wherein the optical receiver transmits from the optical transmitter. An optical demultiplexing unit that demultiplexes the wavelength-division multiplexed optical signal for each wavelength and outputs the demultiplexed optical signal to an operating port, and is connected to the operating port of the optical demultiplexing unit and receives the demultiplexed optical signal. An optical receiving circuit unit, which is connected to a port different from the operating port of the optical demultiplexing unit, inputs the crosstalk light on the long wavelength side of the demultiplexed optical signal to the optical receiving circuit unit, and converts the optical signal into an electric signal. Long wavelength light to be converted
An electric conversion circuit unit, which is connected to a port different from the operating port of the optical demultiplexing unit, inputs crosstalk light on the short wavelength side of the demultiplexed optical signal to the optical receiving circuit unit, and converts it into an electric signal. Short wavelength light to be converted
When the output of the signal converted by the optical-to-electrical conversion circuit unit on the long wavelength side and the output of the signal converted by the optical-to-electrical conversion circuit unit on the short wavelength side both increase and decrease, A control circuit unit that determines that the signal output of the wavelength demultiplexed to the optical receiving circuit unit has increased or decreased and outputs a control signal of a determination result, wherein the optical transmitter is output from the control circuit unit. When the control signal indicates an increase in the signal output of the wavelength demultiplexed to the optical receiving circuit unit, the output of the optical signal transmitted to the optical receiver is reduced, and the wavelength of the wavelength demultiplexed to the optical receiving circuit unit is reduced. An optical communication system characterized by increasing the output of an optical signal transmitted to an optical receiver when a decrease in signal output is indicated. 2. The method according to claim 1, wherein the control circuit is configured to control the light on the long wavelength side.
If either the output of the signal converted by the electrical conversion circuit or the output of the signal converted by the short-wavelength optical-electrical conversion circuit increases and the other decreases, the increased optical / electrical Towards the conversion circuit unit, it is determined that the signal output of the wavelength demultiplexed to the optical receiving circuit unit is shifted and outputs a control signal of the determination result, the optical transmitter, the output from the control circuit unit 2. The method according to claim 1, wherein when the control signal indicates a shift in the signal output of the wavelength demultiplexed to the optical receiving circuit unit, the shift in the output of the optical signal transmitted to the optical receiver is adjusted. An optical communication system according to claim 1. 3. A wavelength interval between ports of the optical demultiplexing unit,
3. The optical communication system according to claim 1, wherein a wavelength interval of the optical signal multiplexed with the wavelength-division multiplexed optical signal to be transmitted is smaller than a wavelength interval. 4. The optical communication according to claim 1, wherein said wavelength multiplexed optical signal in which a plurality of signals having different wavelengths are multiplexed is multiplexed with a predetermined number of wavelengths. system. 5. The multi-beam interference type optical demultiplexer in which a plurality of waveguides having different lengths are regularly aligned and a two-dimensional optical waveguide is provided at an input / output end of the waveguide. The optical communication system according to claim 1, wherein the communication is performed. 6. The optical communication system according to claim 1, wherein the control circuit unit performs intensity modulation on the control signal as a result of the determination, superimposes the control signal on a main signal, and outputs the resultant signal. 7. An optical receiver in an optical communication system for transmitting a wavelength multiplexed optical signal in which a plurality of signals having different wavelengths are multiplexed, wherein the transmitted wavelength multiplexed optical signal is demultiplexed for each wavelength and operated. An optical demultiplexing unit that outputs to the middle port, an optical receiving circuit unit that is connected to the operating port of the optical demultiplexing unit and receives the demultiplexed optical signal, and that the optical demultiplexing unit is operating. A long-wavelength light that is connected to a port different from the port and that inputs the long-wavelength crosstalk light of the demultiplexed optical signal to the optical receiving circuit unit and converts it into an electric signal;
An electric conversion circuit unit, which is connected to a port different from the operating port of the optical demultiplexing unit, inputs crosstalk light on the short wavelength side of the demultiplexed optical signal to the optical receiving circuit unit, and converts it into an electric signal. Short wavelength light to be converted
When the output of the signal converted by the optical-to-electrical conversion circuit unit on the long wavelength side and the output of the signal converted by the optical-to-electrical conversion circuit unit on the short wavelength side both increase and decrease, An optical receiver comprising: a control circuit unit that determines that the signal output of the wavelength demultiplexed to the optical receiving circuit unit has increased or decreased and outputs a control signal as a determination result. 8. The control circuit section comprises:
If either the output of the signal converted by the electrical conversion circuit or the output of the signal converted by the short-wavelength optical-electrical conversion circuit increases and the other decreases, the increased optical / electrical 8. The control circuit according to claim 7, wherein it is determined that the signal output of the wavelength demultiplexed to said optical receiving circuit is shifted to said optical receiving circuit, and a control signal as a result of the determination is output.
An optical receiver as described. 9. A wavelength interval between ports of the optical demultiplexing unit,
9. The optical receiver according to claim 7, wherein the wavelength interval is smaller than the wavelength interval of the optical signal multiplexed on the wavelength-multiplexed optical signal to be transmitted. 10. The multi-beam interference type optical demultiplexer, wherein a plurality of waveguides having different lengths are regularly aligned and a two-dimensional optical waveguide is provided at an input / output end of the waveguide. The optical receiver according to any one of claims 7 to 9, wherein the operation is performed. 11. An optical communication method for transmitting a wavelength multiplexed optical signal in which a plurality of signals having different wavelengths are multiplexed from an optical transmitter to an optical receiver, wherein the optical receiver side comprises: An optical demultiplexing step of demultiplexing the transmitted wavelength division multiplexed optical signal for each wavelength and outputting the demultiplexed optical signal to an operating port of the optical demultiplexing unit, and an optical receiving circuit connected to the operating port of the optical demultiplexing unit An optical receiving step of outputting a demultiplexed optical signal to the optical demultiplexing unit, to an optical / electrical conversion circuit unit connected to a port different from the operating port of the optical demultiplexing unit, and to the optical receiving circuit unit A long-wavelength-side optical / electrical conversion step of inputting the long-wavelength crosstalk light of the input optical signal and converting it into an electric signal; and a light connected to a port different from the operating port of the optical demultiplexing unit. -To the electric conversion circuit unit, on the short wavelength side of the optical signal output to the optical receiving circuit unit A short-wavelength-side optical-electrical conversion step of inputting talking light and converting it into an electric signal; an output of a signal converted by the long-wavelength-side optical-electrical conversion step and the short-wavelength-side optical-electrical conversion step A control step of determining that the signal output of the wavelength output to the optical receiving circuit unit has increased or decreased, and outputting a control signal of a determination result when the output of the signal converted by both increases and decreases, The transmitter side reduces the output of the optical signal transmitted to the optical receiver side when the control signal output in the control step indicates an increase in the signal output of the wavelength output to the optical receiving circuit section, An optical communication method comprising: increasing the output of an optical signal to be transmitted to an optical receiver when the signal output of the wavelength output to the optical receiving circuit unit decreases.