JPH1022979A - Light transmission device for wavelength multiplex light transmission and light reception device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically obtain appropriate light output in spite of the multiplex number of wavelengths and to simplify constitution by comparing reference voltage corresponding to the number of channels with total power detected in a light receiver and controlling output light to be constant. SOLUTION: A wavelength multiplex light transmitter 1 is provided with a means 7 for overlapping channel data of the multiplexed channel with LD6 of the wavelength different from the main signal, synthesizing it with the main signal and transmitting it to a transmission line. Respective optical amplifiers 8 are provided with control means 16 terminating channel data signal components synthesized in the wavelength multiplex light transmitter 1, detecting the number of multiplexed channels, varying reference voltage in accordance with the number of the channels, comparing reference voltage with total power detected in the light receiver and making output light to be constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical direct amplifier, and more particularly, to an optical direct amplifier for amplifying an optical signal multiplexed with an optical wavelength.

[0001]

2. Description of the Related Art FIG. 4 shows an example of a constant optical output control method of a first conventional optical direct amplifier. The input optical signal is directly amplified in the EDF 61 by the pumping light from the pumping LD 69 injected through the WDM coupler 62, and output through the optical branching coupler 63. In order to keep the output light constant, the output of the optical direct amplifier is branched by the optical branch coupler 63, and the output light power is monitored by the optical receiver 64 on one side. The light receiver 64 performs light / electric conversion, and the current / voltage conversion circuit 65 performs current / voltage conversion, and outputs the result to the constant light output control circuit 67. In the optical output constant control circuit 67,
The reference voltage (Vref) from the reference voltage generation circuit 66 is compared with the output voltage from the current / voltage conversion circuit 65, and Vref
The LD drive circuit 68 is controlled so as to have the same voltage as
The output of the excitation LD 69 to be injected into the DF 61 is controlled.
As a result, a constant light output is always maintained.

In the case where a wavelength-multiplexed optical signal is input to the input, in the system shown in FIG. 4, since the photodetector 64 for monitoring the output light has a wide band, if Vref is constant, the channel to be multiplexed is The output light power varies depending on the number (FIG. 5). When the signal to be multiplexed changes, it is necessary to change the value of Vref accordingly.

FIG. 6 shows an example of a constant optical output control method of a second conventional optical direct amplifier. One of the wavelength multiplexed channels between the optical branch coupler having the configuration of FIG.
Narrow band optical filter 73 for extracting only the wavelength component of the channel
Is added, and the other channels are controlled in accordance with the output of the monitored channel, so that the optical output can be controlled to be constant regardless of the number of input channels (FIG. 7). . However, when the channel to be monitored is not received, there is a problem that the optical output constant control cannot be performed.

FIG. 8 shows an example of a constant optical output control method of an optical direct amplifier of a third conventional configuration. In FIG. 8, the modulators 83-1 to 83-n of the wavelength multiplexing optical transmitter 80 include respective LDs.
The control signals of the frequencies f1 to fn output from the control signal generation circuits 82-1 to 82-n are superimposed on the signal lights of the wavelengths λ1 to λn output from 81-1 to 81-n, respectively. Multiplexed and transmitted to the transmission path. The wavelength-multiplexed optical signal is input to the optical direct amplification unit 85 via a transmission line,
The optical output is split by an optical splitter 88. One of the branches is input to the output, and the other is input to the other optical branch coupler 89.

[0005] One of the outputs from the optical branching coupler 89 is input to a light receiver 90 and the other is input to a demultiplexer 96. The optical signal of each wavelength that has been wavelength-divided by the demultiplexer 96 counts the number of channels input by the wave number counter 97 and outputs it to the reference voltage generator 92. Since the reference voltage generator 92 changes the value of Vref based on the signal from the wave number counter 97, the output can be controlled to be constant regardless of the number of input channels.

FIG. 9 shows an example of the configuration of the wave number counter 97. The optical signal of each channel from the duplexer 96 in FIG. 8 is optically / electrically converted by the optical receivers 98-1 to 98-n, and the control signal components are extracted by the bandpass filters 99-1 to 99-n, and added. Output to the container 100. The adder 100 outputs an output signal corresponding to the number of input channels to the reference voltage generator 92 in FIG.

[0007]

In the case of the conventional configuration as shown in FIG. 4, since the photodetector for monitoring the output light has a wide band, if the Vref is constant, the output light power is determined by the number of multiplexed channels. There is a problem that there is a difference between the two.

As shown in FIG. 5, the receiver monitors the total power, not the peak power of the channel, and therefore looks large. If the value of Vref is constant, 1
The output peak power per wave is smaller in the case of two-wave input than in the case of wave input.

In the case of the conventional configuration shown in FIG. 6 in which a narrow-band optical filter is added to the configuration shown in FIG. 4, only the wavelength component of one channel of the wavelength-multiplexed optical signal is extracted by the narrow-band optical filter, and the output of the channel is output. Since the output of other channels is also controlled according to the power, the optical output can be controlled to be constant regardless of the change in the number of channels. However, there is a problem that the control cannot be performed if the monitored channel is not received.

In the case of the conventional configuration shown in FIG. 8, a control signal is superimposed on each channel signal in advance at a different frequency, a control signal is received on the receiving side, and the number of received channels is counted by a wave number counter. The output voltage of the reference voltage generator is varied according to the number of channels. For this reason, the output can be controlled to be constant irrespective of the number of received channels, but on the transmitting side, control signals must be superimposed on all channels to be multiplexed. On the receiving side, the output side temporarily separates the signal of each channel and further extracts the control signal component from each channel, so that the configuration scale is considerably large.

The present invention relates to an optical direct amplifier for amplifying an optical signal subjected to optical wavelength multiplexing, and an object thereof is to provide a system which can automatically obtain an appropriate optical output irrespective of the number of multiplexed wavelengths and has a simple configuration. And

[0012]

In order to eliminate the above-mentioned drawbacks of the conventional wavelength division multiplexing optical transmission apparatus, the wavelength division multiplexing optical transmission apparatus and the optical reception apparatus of the present invention have the following features. ing. That is, the optical transmission device of the present invention includes:
A plurality of optical signal units for transmitting optical signals having different wavelengths from each other, an optical multiplexer for wavelength-multiplexing these optical signals to output a multiplexed optical signal, and an optical amplifier for amplifying the multiplexed optical signal and optically amplifying the amplified optical signal A first optical amplifier for transmitting to a transmission line, a channel data generating circuit for detecting each of the lights output from the optical transmitter and generating channel data including the number of channels of the wavelength-multiplexed optical signal; And a channel data superimposing circuit that superimposes on the amplified optical signal.

Here, the first optical amplifier comprises a rare earth element-doped optical fiber, a pump light source for outputting pump light, and an optical multiplex for multiplexing the multiplexed optical signal and the pump light into the rare earth element-doped optical fiber and outputting the multiplexed optical signal. And a container.

The channel data superimposing circuit includes a channel optical transmitter for transmitting a channel optical signal having a wavelength different from the optical signal based on the channel data, and a channel optical signal multiplexing device for multiplexing the channel optical signal into an amplified optical signal. And a container. Alternatively, the channel data superimposing circuit may be constituted by an optical modulation circuit that optically modulates an amplified optical signal and superimposes a modulation signal composed of channel data.

The transmitting apparatus for wavelength-division multiplexed optical transmission according to the present invention further comprises a first reference value setting circuit for setting a reference value according to the number of channels, and an output of the amplified optical signal so as to match the reference value. And a first optical amplification control circuit. Here, the reference value is characterized by being set discretely according to the number of channels.

Further, an optical receiver for wavelength-division multiplexed optical transmission according to the present invention comprises: a channel number identification circuit for detecting channel data from a received optical signal output from the optical transmission line to identify the number of channels; Set the reference value according to the second
Reference value setting circuit, a second optical amplifier circuit that amplifies the received optical signal and outputs the received amplified optical signal, and a second optical amplifier that controls the output of the received amplified optical signal so as to match the reference value. An amplification control circuit. Here, the second optical amplifier includes a rare earth element-doped optical fiber, a pump light source that outputs pump light, and an optical multiplexer that multiplexes the multiplexed optical signal and the pump light into the rare earth element-doped optical fiber and outputs the multiplexed optical signal and the pump light. Have. The channel data is a modulation signal emitted by the optical transmission device, and the channel number identification circuit includes a demodulation circuit for demodulating the modulation signal.

According to a first aspect of the present invention, there is provided a wavelength multiplexing optical amplifying and relaying transmission system for optically amplifying and relaying a wavelength multiplexed optical transmission signal. Means for superimposing the channel data of the selected channel on an LD (6 in FIG. 1) having a wavelength different from that of the main signal, multiplexing with the main signal and transmitting the multiplexed signal to the transmission line. Terminates the channel data signal component multiplexed by the wavelength multiplexing optical transmitter (22 in FIG. 1), detects the number of multiplexed channels, and varies the reference voltage according to the number of channels.
It is characterized by comprising control means for comparing the reference voltage with the total power detected by the light receiver to control the output light to be constant.

According to a seventh aspect of the present invention, in a wavelength division multiplexing optical amplifying and relaying transmission system for optically amplifying and relaying a wavelength multiplexed optical transmission signal, a wavelength division multiplexing optical transmitter (26 in FIG. 2) is provided with multiplexing. Means for superimposing the channel data of the channel on the pumping LD (31 in FIG. 2) of the optical amplifying unit of the wavelength multiplexing optical transmitter, thereby superimposing the data on the main signal, and transmitting the signal to the transmission line. At 34 in FIG. 2, the channel data superimposed by the wavelength multiplexing optical transmitter is terminated (4 in FIG. 2).
0), a control means for detecting the number of multiplexed channels, varying the reference voltage according to the number of channels, comparing the reference voltage with the total power detected by the light receiver, and controlling the output light to be constant. It is characterized by the following.

According to a third aspect of the present invention, in a wavelength division multiplexing optical amplifying and relaying transmission system for optically amplifying and relaying a wavelength multiplexed optical transmission signal, the wavelength multiplexing optical transmitter (45 in FIG. 3) includes:
Means for superimposing channel data of the multiplexed channel on the main signal using a modulator (49 in FIG. 3) at the output stage of the wavelength multiplexing optical transmitter and transmitting the signal to the transmission line; In 50), the channel data superimposed by the wavelength multiplexing optical transmitter is terminated (56 in FIG. 3), the number of multiplexed channels is detected, and the reference voltage is varied according to the number of channels. It is characterized by comprising control means for comparing output power with the total power detected by the light receiver to control output light to be constant.

According to the present invention, channel data is superimposed in a wavelength division multiplexing optical transmitter, channel data is terminated in each optical amplifier, the number of multiplexed channels is detected, and a reference voltage is varied according to the number of channels. To control the output light by comparing the reference voltage with the total power detected by the receiver,
The optical output level can be controlled to be constant regardless of the number of multiplexed channels.

In the first to sixth aspects of the present invention, the wavelength multiplexed optical transmitter superimposes channel data of the multiplexed channel on an LD having a wavelength different from that of the main signal and multiplexes the data with the main signal. To the transmission line, each optical amplifier terminates the channel data signal component multiplexed by the wavelength multiplexing optical transmitter,
By detecting the number of multiplexed channels, varying the reference voltage according to the number of channels, and comparing the reference voltage with the total power detected by the light receiver to control the output light to be constant,
The optical output level can be controlled to be constant regardless of the number of multiplexed channels.

In the seventh to ninth aspects of the present invention, the wavelength multiplexing optical transmitter mainly has the channel data of the multiplexed channel superimposed on the pumping LD of the optical amplifier of the wavelength multiplexing optical transmitter. The signal is superimposed on the signal and transmitted to the transmission line. Each optical amplifier terminates the channel data superimposed by the wavelength multiplexing optical transmitter, detects the number of multiplexed channels, and varies the reference voltage according to the number of channels. By comparing the reference voltage with the total power detected by the light receiver and controlling the output light to be constant, the light output level can be controlled to be constant regardless of the number of multiplexed channels.

According to the third aspect of the present invention, in the wavelength division multiplexing optical transmitter, the channel data of the multiplexed channel is superimposed on the main signal using a modulator at the output stage of the wavelength division multiplexing optical transmitter. The wavelength-multiplexed optical transmitter terminates the channel data superimposed by the wavelength multiplexing optical transmitter, detects the number of multiplexed channels, and varies the reference voltage according to the number of channels. By controlling the output light to be constant by comparing the total power detected by the light receiver, the optical output level can be controlled to be constant regardless of the number of multiplexed channels.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical transmitter and an optical receiver for wavelength multiplexing optical transmission according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of an optical transmitter and an optical receiver for wavelength multiplexed optical transmission according to the present invention. In a wavelength division multiplexing optical transmission system, a channel data generation circuit 4 for generating channel data of a plurality of wavelength-multiplexed optical signals, and channel data for generating an optical signal having a wavelength different from that of the main signal based on data from the channel data generation circuit 4 A wavelength multiplexing optical transmitter including an LD for signal superposition, an LD drive circuit for driving the LD for channel data signal superimposition, and a multiplexer for multiplexing an optical signal from the LD for signal superimposition with a main signal. 1 is used. An EDF 10 for directly amplifying an optical signal from the wavelength multiplexing optical transmitter 1, a pumping semiconductor LD 18,
An LD driving circuit 17 for driving the pumping LD 18;
In an optical direct amplifying unit configured by a WDM coupler 11 input to the optical amplifier 10, an optical branching coupler 12 that branches the output light of the optical direct amplifying unit, and a light receiving device that optically / electrically converts one output light of the optical branching coupler 12 13 and a current / voltage conversion circuit 14 for current / voltage conversion of the output current from the light receiver 13
And a constant optical output control circuit 16 that monitors the output of the current / voltage conversion circuit 14 and controls the output to be equal to the reference voltage (Vref).

A narrow band optical filter 19 for extracting only a wavelength component of an optical signal on which a channel data signal is superimposed from an optical signal received from the wavelength multiplexing optical transmitter 1 and an output light from the narrow band optical filter 19 / Electric conversion light receiver 20
And a current / voltage conversion circuit 21 for current / voltage conversion of the output current from the light receiver 20, and terminating the channel data from the output signal of the current / voltage conversion circuit 21 and identifying the number of wavelength-multiplexed channels based on the channel data Then, the output signal to the reference voltage generation circuit 15 is varied according to the number of channels,
Further, the channel data termination / generation circuit 22 for further generating channel data from the terminated channel data, and the value of Vref to the optical output constant control circuit 16 in accordance with a signal from the channel data termination / generation circuit 22 are discretely set. A reference voltage generating circuit 15 for changing the
LD 24 for channel data signal superposition for generating an optical signal having a wavelength different from the main signal based on data from generation circuit 22
For driving the channel data signal superimposing LD 24
It has a drive circuit 23 and a multiplexer 25 for multiplexing an optical signal from the channel data signal superimposing LD 24 with a main signal.

FIG. 2 is a block diagram showing a second embodiment of the optical transmission apparatus for wavelength multiplexed optical transmission according to the present invention. In a wavelength division multiplexing optical transmission system, a channel data generation circuit 29 for generating channel data of a plurality of wavelength multiplexed optical signals.
And an excitation LD 31 for using data from the channel data generation circuit 29 in an optical direct amplification unit in a transmitter output stage.
And a wavelength multiplexing optical transmitter 26 for superimposing a channel data signal on a main signal.

An EDF 35 for directly amplifying an optical signal from the wavelength multiplexing optical transmitter 26, an excitation LD 44, an LD drive circuit 43 for driving the excitation LD 44, and an excitation L
In an optical direct amplifier composed of a WDM coupler 36 which wavelength division multiplexes the output light of D44 and inputs the wavelength division multiplexed light to the EDF 35, one of the optical branch coupler 37 for branching the output light of the optical direct amplifier and one of the optical branch couplers 37 A photodetector 38 for optically / electrically converting output light; a current / voltage conversion circuit 39 for current / voltage conversion of an output current from the photodetector 38;
One output of the voltage conversion circuit 39 is monitored, and a reference voltage (V
ref), and a channel data terminal for terminating a channel data signal superimposed by the wavelength division multiplexing optical transmitter 26 from the other output of the current / voltage conversion circuit 39. The circuit 40 and the channel data from the channel data termination circuit 40 identify the number of wavelength-multiplexed channels based on the channel data.
A reference voltage generation circuit 41 that discretely changes the value of f is provided.

FIG. 3 is a block diagram showing a second embodiment of the optical output constant control method of the optical transmitter and the optical receiver for wavelength multiplexed optical transmission according to the present invention. In a wavelength division multiplexing optical transmission system, a channel data generation circuit 48 for generating channel data of a plurality of wavelength-multiplexed optical signals, and a modulator 49 for superimposing data from the channel data generation circuit 48 on a main signal at a transmitter output stage. And a wavelength multiplexing optical transmitter 45 for superimposing a channel data signal on a main signal is used.

The EDF 51 for directly amplifying the optical signal from the wavelength multiplexing optical transmitter 45, the pumping LD 60, and the pumping L
LD drive circuit 59 for driving D60, LD60 for excitation
In the optical direct amplifier composed of the WDM coupler 52 which wavelength division multiplexes the output light of the optical fiber and inputs the wavelength division multiplexed light to the EDF 51, the optical branching coupler 53 for branching the output light of the optical direct amplifier
A photodetector 54 for optically / electrically converting one output light of the optical branching coupler 53, and an output current from the photodetector 54
A current / voltage conversion circuit 55 for voltage conversion and one output of the current / voltage conversion circuit 55 are monitored, and a reference voltage (Vref) is monitored.
And a constant light output control circuit 58 for performing control so as to coincide with.

A channel data terminating circuit 56 for terminating the channel data signal superimposed by the wavelength multiplexing optical transmitter 45 from the other output of the current / voltage converting circuit 55, and wavelength multiplexing by the channel data from the channel data terminating circuit 56. The number of channels is identified, and according to the number of channels, V
A reference voltage generating circuit 57 that discretely changes the value of ref is provided.

[0032]

The first effect of the optical transmitter and the optical receiver for wavelength division multiplexing optical transmission of the present invention relates to an optical direct amplifier for amplifying an optical signal subjected to optical wavelength division multiplexing. That is, an appropriate light output can be obtained.
In a wavelength division multiplexing optical transmitter, when the number of multiplexed channels is generated as a channel data signal, the channel data signal is superimposed on a main signal or a signal having a wavelength different from the main signal, transmitted to a transmission line, and received by an optical amplifier. This is for extracting the channel data signal, identifying the number of multiplexed channels, and discretely changing the reference voltage of the optical output constant control circuit according to the number of channels.

A second effect is that the configuration scale of the present invention is smaller than that of the prior art.

According to the configuration of the prior art, in a wavelength multiplexing optical transmitter, a control signal is superimposed on all channels to be multiplexed, and in an optical amplifier, a signal of each channel is once separated, and further, control is performed from each channel. On the other hand, in the wavelength division multiplexing optical transmitter, the channel data signal is superimposed on the main signal or a signal different from the main signal, and the optical amplifier extracts the signal component from the main signal. Alternatively, the extraction is performed after wavelength-separating a signal having a wavelength different from the multiplexed main signal.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of an optical transmitter and an optical receiver for wavelength multiplexed optical transmission according to the present invention.

FIG. 2 is a block diagram showing a configuration of a second embodiment of the optical transmitter and the optical receiver for wavelength division multiplexing optical transmission according to the present invention.

FIG. 3 is a block diagram showing a configuration of a third embodiment of the optical transmitter and the optical receiver for wavelength multiplexing optical transmission according to the present invention.

FIG. 4 is a block diagram showing a configuration of an example of a conventional optical transmission device for wavelength multiplexing optical transmission and an optical receiving device.

FIG. 5 is a diagram showing an input / output spectrum in the configuration shown in FIG. 4;

FIG. 6 is a block diagram showing the configuration of another example of a conventional optical transmission device for wavelength multiplexing optical transmission and an optical receiving device.

FIG. 7 is a diagram showing an input / output spectrum in the configuration shown in FIG. 6;

FIG. 8 is a block diagram showing another example of a configuration of a conventional optical transmission device for wavelength multiplexing optical transmission and an optical receiving device.

FIG. 9 is a block diagram showing one embodiment of a configuration of a reciprocal counter.

[Explanation of symbols]

1, 26, 45, 80 WDM optical transmitters 2-1 to 2-n, 27-1 to 27-n, 46-1 to 46
-N, 81-1 to 81-n Semiconductor laser (LD) 3, 7, 25, 28, 47, 84 multiplexer 4, 29, 48 channel data generation circuit 5, 17, 23, 30, 43, 59, 68, 78, 94
LD drive circuit 6, 24 Channel data superimposing LD 8, 34, 50, 85 Optical direct amplifier 9, 12, 37, 53, 63, 72, 88, 89 Optical branching coupler 10, 32, 35, 51, 61, 70 , 86 Erbium-doped fiber (EDF) 11, 33, 36, 52, 62, 71, 87 Wavelength division multiplexing coupler (WDM coupler) 13, 20, 38, 54, 64, 74, 90, 98-1
~ 98-n photodetector 14,21,39,55,65,75,91
Voltage conversion circuit 15, 41, 57, 66, 76, 92 Reference voltage generation circuit 16, 42, 58, 67, 77, 93 Constant light output control circuit 18, 31, 44, 60, 69, 79, 95 LD for excitation 19, 73 Narrow band optical filter 22 Channel data termination / generation circuit 40, 56 Channel data termination circuit 49, 83-1 to 83-n Modulator 82-1 to 82-n Control signal generation circuit 96 Demultiplexer 97 Wavenumber counting Devices 99-1 to 99-n band pass filters 100 adders

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Reference number in the agency FI Technical display location H04B 10/04

Claims (10)

[Claims] A plurality of optical signal transmitting means for transmitting optical signals having mutually different wavelengths; an optical multiplexer for wavelength-multiplexing the optical signals to output a multiplexed optical signal; and an optical amplifier for amplifying the multiplexed optical signal. First optical amplifying means for transmitting an amplified optical signal to an optical transmission line, and detecting channel light including the number of channels of the wavelength-multiplexed optical signal by detecting each of the lights output from the optical signal transmitting means. An optical receiver for wavelength-division multiplexing optical transmission, comprising: channel data generating means for generating; and channel data superimposing means for superimposing the channel data on the amplified optical signal. 2. The first optical amplification means includes: a rare earth element-doped optical fiber; an excitation light source that outputs excitation light; and a light source that multiplexes the multiplexed optical signal and the excitation light with the rare earth element-doped optical fiber. 2. The optical transmission device for wavelength-division multiplexed optical transmission according to claim 1, further comprising an optical multiplexer for outputting. 3. The channel data superimposing means: a channel optical signal transmitting means for transmitting a channel optical signal having a wavelength different from the optical signal based on the channel data; and the channel optical signal to the amplified optical signal. 3. The optical transmission device for wavelength multiplexed optical transmission according to claim 1, further comprising a channel optical signal multiplexing unit for multiplexing. 4. The apparatus according to claim 1, wherein the channel data superimposing means includes an optical modulating means for optically modulating the amplified optical signal and superimposing a modulated signal composed of the channel data. The optical transmission device for wavelength-division multiplexed optical transmission according to the above. 5. The transmission device for wavelength multiplexing optical transmission further comprises: first reference value setting means for setting a reference value according to the number of channels; 3. The optical transmitter according to claim 1, further comprising first optical amplification control means for controlling an output. 6. The optical transmitter according to claim 4, wherein the reference value is set discretely according to the number of channels. 7. A channel number identifying means for detecting the channel data from a received optical signal output from the optical transmission line according to claim 1 to identify the number of channels, and for setting a reference value according to the number of channels. Second reference value setting means for setting; second optical amplification means for amplifying the received optical signal to output a received amplified optical signal; and outputting the received amplified optical signal so as to match the reference value. An optical receiver for wavelength-division multiplexed optical transmission, comprising: a second optical amplification controller for controlling. 8. The second optical amplifying means includes: a rare earth element-doped optical fiber, an excitation light source that outputs excitation light, and a light source that multiplexes the multiplexed optical signal and the excitation light with the rare earth element-doped optical fiber. The optical receiver for wavelength-division multiplexed optical transmission according to claim 7, further comprising an optical multiplexer for outputting. 9. The wavelength according to claim 7, wherein said channel data is a modulated signal according to claim 4, and said channel number identifying means includes demodulating means for demodulating said modulated signal. Optical receiver for multiplex optical transmission. 10. The optical receiving apparatus for wavelength multiplexed optical transmission according to claim 7, further comprising channel data superimposing means for superimposing said channel data on said amplified optical signal. Optical receiver for wavelength multiplexed optical transmission.