JPH11331126A - Optical transmitter and its wavelength maintenance device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the state of a wavelength detector in an in-service state from the outside by providing a reference wavelength optical input circuit for maintenance for inputting the reference wavelength light for maintenance of a reference wavelength for maintenance to the wavelength detector and a wavelength detector output extracting circuit for extracting the output of the wavelength detector to the outside. SOLUTION: During the keeping of the wavelength of a transmission light source 3, reference wavelength light for maintenance outputted from a light source for maintenance 14 is made incident on a wavelength detector 6, and a detecting part 15 detects an output to the reference wavelength light for maintenance of the light source for maintenance 14. Although an error amplifier 8 outputs a difference signal at the time, feedback control is not executed since a switch 11 is switched to the side of a former value holding circuit 10. A voltage obtained by the detector 15 is compared with an output voltage in the reference wavelength for maintenance of the detector 6 stored in a memory in a signal processing part 16. When the difference is smaller than a prescribed value as the result of comparison, the detector 6 decided that it is normal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmitter in a wavelength division multiplexing optical communication system and a wavelength maintenance device for maintaining the wavelength of an optical signal output from the optical transmitter.

[0002]

2. Description of the Related Art In recent years, wavelength multiplexing technology has been widely used as a means for increasing the capacity of an optical communication system. By arranging light sources of different N wavelengths and modulating each with a data signal of bit rate B, the transmission capacity is N ×
B. The number of wavelengths increased from 32 at the beginning of the study to 32 and 64 at the beginning.
As the wavelength interval, ITU (International
al Telecommunications Unio
n) (0.8 GHz (100 GHz))
z) is common.

[0003] When the number of wavelengths increases, it is necessary to widen the band of the optical amplification repeater used in the transmission line. However, it is not easy to reduce the wavelength interval. In the case of the intensity modulation method, the wavelength interval Δλ must be at least Δλ> 2B in order to avoid inter-channel interference.
On the other hand, in the case of a 1.55 μm band InGaAsP distributed feedback type semiconductor laser, the wavelength of the semiconductor laser (hereinafter referred to as a transmission light source) fluctuates at about 10 GHz / ° C. Controlled. However, even if the temperature is kept constant, it is inevitable that the wavelength changes due to aging, so in order to keep the wavelength stable over a long period of time, a wavelength stabilization method using a wavelength detector or a wavelength stabilization device Is being considered.

FIG. 11 is a block diagram showing a schematic configuration of a wavelength stabilizing device for a semiconductor laser disclosed in Japanese Patent Application Laid-Open No. 1-205486 as a conventional optical transmitting device and its wavelength maintenance device. In FIG. 11, 3 is a transmission light source that oscillates in a single longitudinal mode, 4 is an optical isolator, 110 is a coupler that branches a part of output light, 6 is a wavelength detector, 7 is an arithmetic circuit, 8 is an error amplifier, and 9 is A reference voltage input terminal, 12 is a low-pass filter for determining a control time constant of the feedback loop, and 13 is a drive circuit for finely adjusting the wavelength of the transmission light source.

As the wavelength detector 6, for example, a device utilizing the shoulder of the transmission characteristic of a bandpass filter constituted by a dielectric multilayer filter as shown in FIG. 12 is used. 12, reference numeral 120 denotes an input terminal, 121 denotes a dielectric multilayer filter, and 122 denotes a first photodiode (hereinafter, referred to as a first photodiode).
PD), 123 is the second PD, and 124 is the first P
D output, 125 is a second PD output.

Next, the operation will be described. Wavelength detector 6
Of the light input from the input terminal 120, a specific wavelength is reflected by the dielectric
D122 is received by the first PD output 12 as a signal a.
4 is generated. On the other hand, as the second PD output 125, a wavelength not reflected by the dielectric multilayer filter 121 is received and output as a signal b.

The wavelength characteristic of the signal a as the first PD output 124 has a band pass characteristic as shown in FIG. 13A, and the wavelength characteristic of the signal b as the second PD output 125 is shown in FIG. It has a band rejection characteristic complementary to the wavelength characteristic of the signal a as shown in FIG. First PD
Since a + b, which is the sum of the signal a of the output 124 and the signal b of the second PD output 125, represents the total input optical power, the difference (ab) shown in FIG. 13C is divided by (a + b). The result shows only the response to the wavelength irrespective of the fluctuation of the total optical power. FIG.
In (c), the point indicated by the black circle is the target wavelength to be controlled, and the output voltage at this point is Vref. From this point, the voltage output decreases when shifted to the long wavelength side, and increases when shifted to the short wavelength side. The error amplifier 8 outputs the difference from the reference voltage input terminal 9 as an error signal. The drive circuit 13 finely adjusts the wavelength of the transmission light source according to the obtained error signal.

[0008]

Since the conventional optical transmission apparatus and its wavelength maintenance apparatus are constructed as described above, the wavelength detector 6 is designed so that the wavelength detection characteristics do not change with temperature fluctuations or aging. Is required to have high reliability, but those currently in practical use cannot be said to have established long-term reliability, and if the wavelength detector 6 becomes abnormal, The wavelength of the controlled transmission light source deviates from a predetermined value, and in the worst case, interferes with an adjacent channel, significantly deteriorating the quality of not only its own channel but also the adjacent channel. There is a problem that the importance of maintenance / inspection of No. 6 has increased, especially maintenance / inspection in the in-service state.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an optical transmission apparatus and a wavelength maintenance apparatus that enable the state of a wavelength detector to be maintained in-service from outside. The purpose is to gain.

[0010]

An optical transmitter according to the present invention comprises a maintenance device for inputting maintenance reference wavelength light of a maintenance reference wavelength for detecting a change in the characteristics of a wavelength detector to the wavelength detector. Reference wavelength light input circuit, and a wavelength detector for taking out an output of the wavelength detector when the maintenance reference wavelength light is input to the wavelength detector by the maintenance reference wavelength light input circuit. An output extracting circuit is provided.

An optical transmitter according to the present invention uses a reference wavelength light for maintenance, which is intensity-modulated so as to be distinguishable from light output from a transmission light source.

In the optical transmitter according to the present invention, while the maintenance reference wavelength light is being input from the maintenance reference wavelength light input circuit to the wavelength detector, the wavelength of the light output from the transmission light source is kept constant by the control signal. And a control signal input circuit for supplying the control signal from the outside to the transmission light source output wavelength fixing means.

The optical transmitter according to the present invention includes a fiber coupler for inputting the maintenance reference wavelength light to the wavelength detector together with the split light of the light output from the transmission light source as a maintenance reference wavelength light input circuit. It was done.

The optical transmitter according to the present invention is provided with an optical switch for inputting the maintenance reference wavelength light to the wavelength detector together with the split light of the light output from the transmission light source as the maintenance reference wavelength light input circuit. It was done.

The optical transmitter according to the present invention uses a wavelength detector adjustment signal generated based on the output of the wavelength detector extracted outside by the wavelength detector output extraction circuit.
It is provided with a wavelength detector whose characteristics are automatically adjusted to return to the initial characteristics.

The optical transmission apparatus according to the present invention provides maintenance reference wavelength light having a different maintenance reference wavelength corresponding to each wavelength detector from each input side of the multiplexer to each of the wavelength detectors. The input fiber coupler is provided as a maintenance reference wavelength optical input circuit.

In the optical transmitter according to the present invention, the maintenance reference wavelength light having a different maintenance reference wavelength corresponding to each wavelength detector is input to each of the wavelength detectors from the output side of the multiplexer. A fiber coupler for maintenance is provided as a reference wavelength optical input circuit for maintenance.

A wavelength maintenance device according to the present invention is a maintenance light source for outputting a maintenance reference wavelength light of a maintenance reference wavelength for detecting a characteristic change of a wavelength detector of a transmission light source output wavelength adjusting means in an optical transmission device. A detection unit that detects the output of the wavelength detector, and the wavelength detector detected by the detection unit when the maintenance reference wavelength light output from the maintenance light source is input to the wavelength detector. Based on the output of the wavelength detector and the output of the wavelength detector for the maintenance reference wavelength light set in advance, a characteristic change of the wavelength detector is detected, and whether the wavelength detector is normal or abnormal is determined. And a signal processing unit.

A wavelength maintenance device according to the present invention outputs a control signal for maintaining a constant wavelength of light output from a transmission light source of an optical transmission device while a maintenance reference wavelength light is being input to a wavelength detector. A wavelength control unit is provided.

The wavelength maintenance device according to the present invention is characterized in that the transmission light source output of the wavelength detector when only the branch light of the light output from the transmission light source of the optical transmission device is input to the wavelength detector, and the optical transmission device A detection unit that detects the split light of the light output from the transmission light source of the device and the combined output of the wavelength detector when the maintenance reference wavelength light output from the maintenance light source is input to the wavelength detector. Based on the transmission light source output and the combined output, calculate the output of the wavelength detector when the maintenance reference wavelength light output from the maintenance light source is input to the wavelength detector, Based on the calculation result and a preset reference output of the wavelength detector with respect to the maintenance reference wavelength light, a characteristic change of the wavelength detector is detected to determine whether the wavelength detector is normal or abnormal. And a signal processing unit One in which the.

According to the wavelength maintenance apparatus of the present invention, the maintenance reference wavelength light is intensity-modulated so that it can be distinguished from the light output from the transmission light source of the optical transmission device, and the intensity-modulated maintenance reference light is used. A detection unit that detects an output of the wavelength detector for the maintenance reference wavelength light when the wavelength light is input to the wavelength detector, and an output of the wavelength detector detected by the detection unit, which is set in advance. A signal processing unit that detects a change in the characteristics of the wavelength detector based on a reference output for the maintenance reference wavelength light in the wavelength detector and determines whether the wavelength detector is normal or abnormal. It is like that.

The wavelength maintenance apparatus according to the present invention generates a wavelength detector adjustment signal for automatically adjusting the characteristics of the wavelength detector to return to the initial characteristics based on the detection result of the change in the characteristics of the wavelength detector. An automatic adjustment circuit for generating and outputting is provided.

According to the wavelength maintenance apparatus of the present invention, a maintenance reference wavelength different from the maintenance reference wavelength corresponding to each wavelength detector is provided to each wavelength detector of each transmission light source output wavelength adjusting means in the wavelength division multiplexing optical communication. A reference wavelength light, an optical splitter that inputs via a fiber coupler from each input side of a multiplexer that combines optical signals of different wavelengths output from each transmission light source, and the maintenance reference wavelength is input by the optical splitter. A selector for selecting and taking in the output of each wavelength detector when light is input to each of the wavelength detectors, and a maintenance for generating a maintenance reference wavelength light having a different maintenance reference wavelength for each of the wavelength detectors And a control unit for controlling the selector.

According to the wavelength maintenance apparatus of the present invention, a maintenance reference wavelength having a different maintenance reference wavelength corresponding to each wavelength detector is provided to each wavelength detector of each transmission light source output wavelength adjusting means in wavelength division multiplexed optical communication. A fiber coupler that inputs the reference wavelength light from the output side of the multiplexer that combines optical signals of different wavelengths output from each transmission light source, and the maintenance reference wavelength light is transmitted to each of the wavelength detectors by the fiber coupler. A selector for selecting and taking in the output of each wavelength detector when input, a maintenance light source for generating a maintenance reference wavelength light having a different maintenance reference wavelength for each wavelength detector, and controlling the selector. And a control unit.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a block diagram showing a configuration of the wavelength maintenance device and the optical transmission device according to the first embodiment. In FIG. 1, reference numeral 1 denotes an optical transmission device, and 2 denotes a wavelength maintenance device. 3 is a transmission light source, 4 is an optical isolator, 5 is an optical network, 6 is a wavelength detector, 7 is an arithmetic circuit (transmission light source output wavelength adjustment means), 8 is an error amplifier (transmission light source output wavelength adjustment means), 9 is Input terminal of reference voltage Vref, 10: front value holding circuit (transmission light source output wavelength fixing means), 11: switch (transmission light source output wavelength fixing means), 12: low-pass filter (transmission light source output wavelength adjusting means), 13 Is a drive circuit (transmission light source output wavelength adjusting means) for finely adjusting the wavelength of the transmission light source 3, and 100 is for inputting the maintenance reference wavelength light output from the maintenance light source 14 of the wavelength maintenance device 2 to the optical transmission device 1. Optical connector (maintenance reference wavelength optical input circuit), 101
Are connectors (wavelength detector output extraction circuit, control signal input circuit) for inputting the output of the wavelength detector 6 to the wavelength maintenance device 2 and for inputting the control signal 18 output from the wavelength maintenance device 2 to the optical transmitter 1. ). In the wavelength maintenance device 2, 14 is a maintenance light source, 15 is a detection unit, 16 is a signal processing unit, 17 is a control unit (wavelength control unit), 18 is the control signal for controlling the front value holding circuit 10 and the switch 11, 19
Is an output terminal of the transmission light source 3. The wavelength maintenance device 2 is, for example, a general type device, and is used by being periodically connected to the optical transmission device 1.

The maintenance light source 14 is a light source that outputs maintenance reference wavelength light, and can be a light source obtained by calibrating a wavelength tunable laser with a wavelength meter or a light source whose wavelength is locked to an absorption line of gas. The optical network 5 is an optical circuit having at least four terminals, and outputs light incident from each terminal to another terminal at a predetermined ratio. However, it is assumed that the light incident from the terminal D does not only exit to B.

Next, the operation will be described. Normally, a part of the output of the transmission light source 3 is connected from the terminal A of the optical network 5 to the terminal C.
And enters the wavelength detector 6. Then, based on an error signal obtained by comparing the output of the arithmetic circuit 7 with the reference voltage Vref by the error amplifier 8, the driving circuit 13
The feedback control is performed so as to adjust the wavelength to a desired value.

When performing maintenance, first, the wavelength maintenance device 2
A control signal 18 as shown in FIG. When the control signal 18 is “Hig”
The level changes from the “h” level to the “Low” level,
During the maintenance period in which the level is maintained, the previous value holding circuit 10 continues to hold the output of the error amplifier 8 when the control signal 18 changes from the “High” level to the “Low” level.
Similarly, during the maintenance period, the switch 11 is
, And the drive circuit 13 switches to the previous value holding circuit 1
The wavelength of the transmission light source 3 is maintained at a constant output from zero.
Thus, no matter what light is input to the wavelength detector 6, the wavelength of the transmission light source 3 corresponds to the output of the error amplifier 8 when the control signal 18 changes from 'High' level to 'Low' level during the maintenance period. Is kept at the specified value. The previous value holding circuit 10 can be easily constituted by an A / D converter and a memory.

While maintaining the wavelength of the transmission light source 3, the maintenance reference wavelength light output from the maintenance light source 14 is input from the terminal D of the optical network 5 to the wavelength detector 6 via the terminal C. I do. The detection unit 15 detects the output of the maintenance light source 14 generated by the wavelength detector 6 with respect to the maintenance reference wavelength light. The error amplifier 8 outputs the error signal at that time, but the feedback control is not performed because the switch 11 has been switched to the previous value holding circuit 10 side. The voltage obtained by the detector 15 is compared with the output voltage at the reference wavelength for maintenance of the wavelength detector 6 stored in the memory in advance in the signal processor 16. As a result of the comparison, if the difference is smaller than a predetermined value, it is determined that the wavelength detector 6 is normal. Due to factors such as aging, the characteristics of the wavelength detector 6 change,
If the difference is larger than a predetermined value, it is determined that the state is abnormal.

The deterioration of the wavelength detector 6 is caused by a change with the passage of time, and does not change remarkably in a few minutes to a few tens of minutes for maintenance. Therefore, after the maintenance, the switch 11
Is brought back to the error amplifier 8 side and feedback control is resumed, and the wavelength becomes the same value. Further, even if there is a slight change, the wavelength control does not malfunction because the low-pass filter 12 suppresses a sudden change.

As described above, according to the first embodiment, the wavelength detector 6 is connected to the optical transmitter 1 and, when necessary and in-service, detects the state of deterioration of the wavelength detector 6 and performs wavelength detection. There is an effect that a wavelength maintenance device of the optical transmission device that can maintain and check the device 6 can be obtained.

Embodiment 2 FIG. FIG. 3 shows the second embodiment.
FIG. 3 is a structural diagram showing an optical circuit network of the optical transmission device of FIG. The other configurations of the optical transmission device and the wavelength maintenance device of the second embodiment are the same as those of the optical transmission device 1 shown in FIG. In FIG. 3, reference numeral 5a denotes an optical network (maintenance reference wavelength optical input circuit) of the optical transmitter 1, and reference numerals 30 and 31 denote fiber couplers. For example, the branch ratio of the fiber coupler 30 is 90:10, and the branch ratio of the fiber coupler 31 is 50:50.
And

The transmission light from the terminal A is 90%
Is output from terminal B, but 10% is
1 and output to terminal C. The wavelength detector 6 is connected to the terminal C. On the other hand, terminal D has a maintenance light source 1
4 are connected. The maintenance reference wavelength light from the maintenance light source 14 incident from the terminal D is output to the terminal C via the fiber coupler 31. With this configuration, the light from the transmission light source 3 to be controlled and the maintenance reference wavelength light output from the maintenance light source 14 can simultaneously enter the wavelength detector 6.

As described above, according to the second embodiment, the light from the transmission light source 3 connected to the optical transmitter 1 via the fiber coupler 30 and the light from the maintenance light source 14 via the fiber coupler 31 are transmitted. Advantageous Effect of the Invention A wavelength maintenance device of an optical transmission device capable of detecting the state of deterioration of the wavelength detector 6 when necessary and in-service by the maintenance reference wavelength light and maintaining and inspecting the wavelength detector 6 is obtained. There is.

Embodiment 3 FIG. FIG. 4 shows the third embodiment.
FIG. 3 is a structural diagram showing an optical circuit network of the optical transmission device of FIG. The other configurations of the optical transmission device and the wavelength maintenance device of the third embodiment are the same as those of the optical transmission device 1 shown in FIG. In FIG. 4, the same or corresponding parts as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. FIG.
In the figure, 5b denotes an optical circuit network (maintenance reference wavelength optical input circuit) of the optical transmitter 1, and 40 and 41 denote fiber couplers. For example, the branch ratio of the fiber coupler 40 is 90:10,
The branch ratio of the fiber coupler 41 is set to 50:50.

90% of the light of the transmission light source 3 incident from the terminal A that has passed through the fiber coupler 30 is further converted to 90% by the fiber coupler 40 and output from the terminal B. The other 10% output of the fiber coupler 30 is output to the terminal C via the fiber coupler 41. The wavelength detector 6 is connected to the terminal C. On the other hand, the maintenance light source 14 is connected to the terminal D. 10% of the reference wavelength light for maintenance from the maintenance light source 14 incident from the terminal D is input to the fiber coupler 30 via the fiber coupler 40. Further, 10% of the signal is subjected to a 50% loss via the fiber coupler 41, and then output to the terminal C. Even with such a configuration, the light from the transmission light source 3 to be controlled also
The maintenance reference wavelength light from the maintenance light source 14 can also enter the wavelength detector 6 at the same time.

As described above, according to the third embodiment, connection to the optical transmitter 1 and the fiber couplers 30 and 41
And the fiber couplers 40 and 3
The maintenance reference wavelength light from the maintenance light source 14 via 0 and 41 detects the state of deterioration of the wavelength detector 6 when necessary and in the in-service state, and performs maintenance / inspection of the wavelength detector 6. There is an effect that a wavelength maintenance device for an optical transmission device that can be obtained is obtained.

Embodiment 4 FIG. FIG. 5 shows the fourth embodiment.
FIG. 3 is a structural diagram showing an optical circuit network of the optical transmission device of FIG. The other configurations of the optical transmission device and the wavelength maintenance device of the fourth embodiment are the same as those of the optical transmission device 1 shown in FIG. In FIG. 5, the same or corresponding parts as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. FIG.
In the figure, reference numeral 5c denotes an optical network (maintenance reference wavelength optical input circuit) of the optical transmitter 1, and 50 denotes an optical switch.

Next, the operation will be described. The light of the transmission light source 3 incident from the terminal A passes through the fiber coupler 30 and
0% is output from terminal B. The other 10% output of the fiber coupler 30 is output to the terminal C via the optical switch 50 (when the switch is in the bar state). The wavelength detector 6 is connected to the terminal C. On the other hand, the maintenance light source 14 is connected to the terminal D. Maintenance light source 14 incident from terminal D
Is discarded to the terminal port via the optical switch 50 (when the switch is in the bar state). On the other hand, when the optical switch 50 enters the cross state, the maintenance reference wavelength light from the maintenance light source 14 incident from the terminal D is output from the terminal C. In such a configuration, either the light from the transmission light source 3 to be controlled or the maintenance reference wavelength light from the maintenance light source 14 can be made incident on the wavelength detector 6 by switching the optical switch 50. .

As described above, according to the fourth embodiment, the light from the transmission light source 3 via the fiber coupler 30 and the optical switch 50 is changed by switching the optical switch 50 while connected to the optical transmitter 1. The maintenance reference wavelength light from the maintenance light source 14 via the optical switch 50 detects the state of deterioration of the wavelength detector 6 when necessary and in the in-service state, and performs maintenance / inspection of the wavelength detector 6 There is an effect that a wavelength maintenance device for an optical transmission device that can be obtained is obtained.

Embodiment 5 FIG. FIG. 6 shows the fifth embodiment.
FIG. 2 is a block diagram illustrating a configuration of a wavelength maintenance device and an optical transmission device. 6, the same or corresponding parts as those in FIGS. 1 and 3 are denoted by the same reference numerals, and description thereof is omitted.
In FIG. 6, 2a is a wavelength maintenance device, 15a is a detection unit,
Reference numeral 60 denotes an oscillator included in the detection unit 15a, and reference numerals 61 and 62 denote lock-in detectors. 16a is a signal processing unit, 63 is an arithmetic circuit included in the signal processing unit 16a, and 64 is an A / D converter.

Next, the operation will be described. In this embodiment, since both the light from the transmission light source 3 to be controlled and the maintenance reference wavelength light from the maintenance light source 14 enter the wavelength detector 6, the output voltage signal depends on which light is used. Distinction. The outputs of the wavelength detector 6 for the light of the transmission light source 3 are denoted by a and b. These outputs a and b have no correlation with the frequency of the oscillator 60. The maintenance light source 14 is minutely intensity-modulated with the low-frequency dither signal from the oscillator 60, and the dither signal component of the voltage output from the wavelength detector 6 is detected by the lock-in detectors 61 and 62. Since these have a correlation with the frequency of the oscillator 60, if the voltage detected by the lock-in detector 61 is a 'and the voltage detected by the lock-in detector 62 is b', the arithmetic circuit 63 calculates (a'-b ') /
(A ′ + b ′) is a response output of only the maintenance reference wavelength light from the maintenance light source 14. The result of this operation is converted into a digital signal by the A / D converter 64 and compared with the output voltage of the wavelength detector 6 at the reference wavelength for maintenance stored in the memory in advance. As a result of the comparison, if the difference is smaller than a predetermined value, it is determined that the wavelength detector 6 is normal. Further, the characteristics of the wavelength detector 6 change due to factors such as aging, and if the difference is larger than a predetermined value, it is determined that the wavelength detector 6 is abnormal.

The lock-in detectors 61 and 62 can be easily constituted by a quadrature detection circuit. When the light from the transmission light source 3 is input to the wavelength detector 6 after being intensity-modulated with data, noise due to the low-frequency component of the data signal is generated near the dither signal, but the lock-in detectors 61 and 62. Is limited in a sufficiently narrow band, only the output voltage from the maintenance light source 14 can be extracted with an excellent signal-to-noise ratio.

As described above, according to the fifth embodiment, by connecting to the optical transmitting apparatus and using the optical transmitting apparatus having the same configuration as the optical transmitting apparatus 1 of the first embodiment, necessary There is an effect that a wavelength maintenance device of an optical transmission device capable of maintaining and inspecting the wavelength detector 6 by detecting the state of deterioration of the wavelength detector 6 sometimes and in-service is obtained.

Embodiment 6 FIG. FIG. 7 shows Embodiment 6
FIG. 2 is a block diagram illustrating a configuration of a wavelength maintenance device and an optical transmission device. In FIG. 7, the same or corresponding parts as those in FIGS. 1 and 3 are denoted by the same reference numerals, and description thereof is omitted.
In FIG. 7, 2b is a wavelength maintenance device, 15b is a detection unit,
70 and 71 are A / D converters provided in the detection unit 15b;
16b is a signal processing unit, 72 is an arithmetic circuit, and 73 is a memory.

Next, the operation will be described. In the fifth embodiment, the light output from the transmission light source 3 and the light source for maintenance 1
Although the lock-in detection method using low-frequency dither is used to distinguish the maintenance reference wavelength light output from the fourth reference light, in the sixth embodiment, the distinction is made by calculating a DC signal. The response of the wavelength detector 6 to the transmission light source 3 is a, b (output voltage a, b), and the response of the wavelength detector 6 to the maintenance light source 14 is a ', b' (output voltage a ', b'). . First,
The output voltages a and b of the wavelength detector 6 with respect to the transmission light source 3 are A
The signals are detected by the / D converters 70 and 71 and stored in the memory 73.

Next, in the same manner as in the fifth embodiment, the previous value holding circuit 10 and the switch 11 are operated by the control signal 18 from the control unit 17, and the error signal output from the error amplifier 8 immediately before is sent to the drive circuit 13. Keep giving. Thus, the wavelength of the transmission light source 3 is maintained. Next, the maintenance light source 14 is caused to emit light by the control signal 74 from the control unit 17. The wavelength detector 6 detects a + a ′ and b + b ′, and the arithmetic circuit 72 subtracts the output voltage a and the output voltage b previously stored therefrom, and outputs the output which is the response of the wavelength detector 6 to the maintenance light source 14. A voltage a 'and an output voltage b' are obtained. Finally, the arithmetic circuit 72 calculates (a'-b ') / (a' + b '), whereby a response of only the maintenance reference wavelength light from the maintenance light source 14 can be obtained. As a result of comparison with the reference value of the output voltage of the wavelength detector 6 for maintenance reference wavelength light stored in the memory 73 in advance, if the difference is smaller than a predetermined value, it is determined that the wavelength detector 6 is normal. Lower. Further, the characteristics of the wavelength detector 6 change due to factors such as aging, and if the difference is larger than a predetermined value, it is determined that the wavelength detector 6 is abnormal.

As described above, according to the sixth embodiment, based on the output voltages a and b of the wavelength detector 6 with respect to the transmission light source 3 and connected to the optical transmission device and stored in the memory 73,
By using the optical transmission device having the same configuration as the optical transmission device 1 of the first embodiment, the deterioration state of the wavelength detector 6 is detected when necessary and in the in-service state, and the wavelength detector 6 is used. There is an effect that a wavelength maintenance device of the optical transmission device that can be maintained and inspected can be obtained.

Embodiment 7 FIG. FIG. 8 shows Embodiment 7
FIG. 2 is a block diagram illustrating a configuration of a wavelength maintenance device and an optical transmission device. 8, parts that are the same as or correspond to those in FIG. 6 are given the same reference numerals, and descriptions thereof will be omitted. In FIG. 8, reference numeral 1c denotes an optical transmitter, and 81 denotes a wavelength detector of the optical transmitter 1c. 2c is a wavelength maintenance device, 16c is a signal processing unit of the wavelength maintenance device 2c, 80 is an automatic adjustment circuit, and 82 is a control signal output from the automatic adjustment circuit 80. 101a
Captures the output of the wavelength detector 6 into the wavelength maintenance device 2c,
The control signals 18 and 8 output from the wavelength maintenance device 2c
2 is a connector for inputting 2 to the optical transmitter 1c.

Next, the operation will be described. The operation of the seventh embodiment is basically the same as that of the fifth embodiment. However, in each of the above-described embodiments, as a result of the maintenance,
If it is determined that the wavelength detector is abnormal, it is assumed that the wavelength detector is replaced. In this embodiment, the wavelength detector 81 determined to be abnormal is fed back to the wavelength detector 81 by a control signal 82 output from the automatic adjustment circuit 80 based on information obtained from the A / D converter 64. Is automatically controlled so that the characteristics of the wavelength detector 81 return to the initial characteristics. The adjustment of the wavelength detector 81 is performed, for example, by referring to FIG.
2, a method of changing the incident angle of light by providing an actuator to the dielectric multilayer film 121, a method of providing a temperature controller to the wavelength detector 81, and changing the characteristics by using the temperature dependence of the wavelength characteristics, or There is a method in which a correction circuit is provided for the output of the wavelength detector, and the obtained output is corrected by a predetermined value.

As described above, according to the seventh embodiment, it is possible to automatically adjust the characteristics of the wavelength detector 81 to the initial characteristics without replacing the wavelength detector 81 determined to be abnormal. There is an effect that a device and its wavelength maintenance device can be obtained.

Embodiment 8 FIG. FIG. 9 shows Embodiment 8
FIG. 2 is a block diagram illustrating a configuration of a wavelength maintenance device and an optical transmission device. In the eighth embodiment, one wavelength maintenance device is commonly applied to a plurality of optical transmission devices.
In FIG. 9, the same or corresponding parts as those in FIGS. 1 and 4 are denoted by the same reference numerals, and description thereof will be omitted. 9, reference numerals 51, 52, 53, and 54 denote four optical transmitters having the same configuration, 40a denotes a fiber coupler having a branch ratio of 90:10 of the optical transmitter 52, and 40b similarly denotes a fiber coupler of the optical transmitter 53. Reference numeral 40c denotes a fiber coupler of the optical transmitter 54, and reference numeral 43 denotes a wavelength monitor (wavelength detector). 9
0 is a multiplexer, 91 is an optical distributor, 92 is a maintenance light source having a wavelength variable function, 93 is a selector, 94 is a detector, 95
Denotes a signal processing unit, and 96 denotes a control unit. Reference numeral 101b denotes a connector for outputting the output of the wavelength monitor 43 to the selector 93.

Next, the operation will be described. Optical transmitter 5
1, 52, 53, and 54 have the same configuration as the optical transmitter described in the first embodiment. The optical network 5b has the same configuration as that described in FIG. 4 of the third embodiment.
Multiplex one. Then, the maintenance reference wavelength light output from the maintenance light source 92 is divided into four by the optical distributor 91, and is input to each optical transmission device via the fiber couplers 40, 40a, 40b, and 40c, respectively. The control unit 96 includes the maintenance light source 9.
2 is controlled to sequentially sweep the maintenance reference wavelength of each optical transmitter. Each optical transmission device 51, 52, 53, 54
The output voltage obtained by the wavelength detector provided in (in the optical transmitting device 51, indicated by reference numeral 6 in FIG. 1 and included in the wavelength monitor unit 43) is selected by the selector 93 that performs switching operation by the sequential sweep. Thereafter, the signal processing unit 95 compares the signal with a reference value to determine whether the signal is normal or abnormal.

As described above, according to the eighth embodiment, there is an effect that a wavelength maintenance device that can maintain and check the wavelength detectors of a plurality of optical transmission devices with one wavelength maintenance device is obtained.

Embodiment 9 FIG. FIG. 10 is a block diagram showing a configuration of the wavelength maintenance device and the optical transmission device according to the ninth embodiment. In FIG. 10, the same or corresponding parts as those in FIG. 9 are denoted by the same reference numerals, and description thereof will be omitted. The configuration of the ninth embodiment differs from the configuration of the eighth embodiment in that light from the maintenance light source 92 is incident on the output side of the multiplexer 90. In FIG. 9, reference numeral 40d denotes a fiber coupler for inputting light from the maintenance light source 92 from the output side of the multiplexer 90. With such a configuration, the light distributor 91 and the fiber couplers 40, 40a, 40b, and 40c required in FIG. 9 become unnecessary. The operation of the ninth embodiment is the same as the operation described in the eighth embodiment.

As described above, according to the ninth embodiment, the optical distributor 91 and the fiber couplers 40, 40a,
By eliminating the need for 40b and 40c, there is an effect that a wavelength maintenance device that can maintain and check the wavelength detectors of a plurality of optical transmission devices with one wavelength maintenance device is obtained.

[0057]

As described above, according to the present invention, when the maintenance reference wavelength light is inputted to the wavelength detector by the maintenance reference wavelength light input circuit, the output of the wavelength detector is taken out. Is provided with a wavelength detector output extraction circuit for the purpose of the present invention, so that there is an effect that it is possible to effectively cope with external monitoring and maintenance of the state of the wavelength detector in an in-service state.

According to the present invention, the maintenance reference wavelength light is configured to be intensity-modulated so that the maintenance reference wavelength light can be distinguished from the light output from the transmission light source.
There is an effect that it is possible to effectively cope with external monitoring and maintenance in the in-service state by the intensity-modulated maintenance reference wavelength light for the characteristic change of the wavelength detector.

According to the present invention, while the maintenance reference wavelength light is being input from the maintenance reference wavelength light input circuit to the wavelength detector, the wavelength of the light output from the transmission light source is kept constant by the control signal. A transmission light source output wavelength fixing means, and a control signal input circuit for supplying the control signal from the outside to the transmission light source output wavelength fixing means, so that the wavelength of light output from the transmission light source is fixed. In this state, it is possible to effectively cope with highly accurate external monitoring and maintenance of the characteristic change of the wavelength detector in the in-service state using the maintenance reference wavelength light.

According to the present invention, the fiber coupler for inputting the maintenance reference wavelength light to the wavelength detector together with the split light of the light output from the transmission light source is provided as the maintenance reference wavelength light input circuit. With respect to the characteristic change of the wavelength detector, it is possible to effectively cope with highly accurate external monitoring and maintenance in the in-service state by the maintenance reference wavelength light input from the fiber coupler.

According to the present invention, the optical switch for inputting the maintenance reference wavelength light to the wavelength detector together with the split light of the light output from the transmission light source is provided as the maintenance reference wavelength light input circuit. With respect to the characteristic change of the wavelength detector, it is possible to effectively cope with highly accurate external monitoring and maintenance in the in-service state by the maintenance reference wavelength light input from the optical switch.

According to the present invention, the characteristics are automatically returned to the initial characteristics by the wavelength detector adjustment signal generated based on the output of the wavelength detector extracted outside by the wavelength detector output extraction circuit. Since the wavelength detector is configured so as to be dynamically adjusted, there is an effect that it is possible to effectively cope with an automatic adjustment of the characteristics of the wavelength detector from the outside with respect to the characteristic change of the wavelength detector.

According to the present invention, the reference wavelength for maintenance is made different from each input side of the multiplexer that combines optical signals of different wavelengths output from each transmission light source, corresponding to each wavelength detector. Since the maintenance reference wavelength light input circuit is provided with a fiber coupler for inputting the maintenance reference wavelength light to each wavelength detector of each wavelength maintenance device, the transmission light source output wavelength adjustment means in the wavelength multiplexing optical communication is provided. With respect to the state of each wavelength detector, there is an effect that it is possible to effectively cope with external monitoring and maintenance in an in-service state.

According to the present invention, from the output side of the multiplexer that combines optical signals of different wavelengths output from the respective transmission light sources, a maintenance reference wavelength different from the output side of the multiplexer corresponding to each wavelength detector is used. Since the configuration is such that a fiber coupler for inputting the reference wavelength light to each wavelength detector of each optical transmission device is provided as a maintenance reference wavelength light input circuit, each wavelength of each transmission light source output wavelength adjustment means in wavelength division multiplexed optical communication is provided. As for the state of the detector, there is an effect that the increase in the number of fiber couplers can be suppressed and external monitoring and maintenance can be effectively performed in the in-service state.

According to the present invention, a maintenance light source for outputting a maintenance reference wavelength light of a maintenance reference wavelength for detecting a characteristic change of a wavelength detector of a transmission light source output wavelength adjusting means in an optical transmission device; A detection unit that detects the output of the wavelength detector, and the output of the wavelength detector detected by the detection unit when the maintenance reference wavelength light output from the maintenance light source is input to the wavelength detector. A signal processing unit that detects a change in characteristics of the wavelength detector based on an output of the wavelength detector with respect to the preset maintenance reference wavelength light and determines whether the wavelength detector is normal or abnormal. By connecting to the optical transmitter, the maintenance reference wavelength light is output to the wavelength detector of the optical transmitter and the output of the wavelength detector is detected, so that the Wavelength detector There is an effect that it becomes possible to monitor the state from the external in-service maintenance.

According to the present invention, the wavelength control for outputting the control signal for maintaining the wavelength of the light output from the transmission light source of the optical transmission device constant while the maintenance reference wavelength light is being input to the wavelength detector. Since the wavelength of the light output from the transmission light source of the optical transmission device is kept constant by the control signal, the state of the wavelength detector is externally monitored and maintained in an in-service state by the control signal. There is an effect that can be performed.

According to the present invention, when only the split light of the light output from the transmission light source of the optical transmission device is input to the wavelength detector, the transmission light source output of the wavelength detector and the transmission of the optical transmission device A detection unit that detects a split light of the light output from the light source and a combined output of the wavelength detector when the maintenance reference wavelength light output from the maintenance light source is input to the wavelength detector; and Based on the light source output and the combined output, calculate the output of the wavelength detector when the maintenance reference wavelength light output from the maintenance light source is input to the wavelength detector, and the calculation result Signal processing for detecting a characteristic change of the wavelength detector based on a preset reference output of the wavelength detector with respect to the maintenance reference wavelength light, and determining whether the wavelength detector is normal or abnormal. Was configured to have Without directly detecting the output of the wavelength detector when the maintenance reference wavelength light is input to the wavelength detector, it is possible to externally monitor and maintain the state of the wavelength detector in an in-service state. There is an effect that becomes possible.

According to the present invention, the maintenance reference wavelength light is intensity-modulated so that it can be distinguished from the light output from the transmission light source of the optical transmission device, and the intensity-modulated maintenance reference wavelength light is modulated. A detection unit for detecting an output of the wavelength detector for the maintenance reference wavelength light when input to the wavelength detector, an output of the wavelength detector detected by the detection unit, and the wavelength set in advance. Based on the reference output for the maintenance reference wavelength light in the detector, based on the characteristic change of the wavelength detector is detected, the normality of the wavelength detector,
And a signal processing unit for determining an abnormality, so that the output of the wavelength detector when the maintenance reference wavelength light is input to the wavelength detector is output from the transmission light source of the optical transmission device. Separated from the output of the wavelength detector for the separated light, based on the output of the wavelength detector for the separated maintenance reference wavelength light, the state of the wavelength detector from the outside in the in-service state This has the effect of enabling monitoring and maintenance.

According to the present invention, a wavelength detector adjustment signal for automatically adjusting the characteristic of the wavelength detector to return to the initial characteristic is generated and output based on the detection result of the characteristic change of the wavelength detector. Since the configuration is such that an automatic adjustment circuit is provided, there is an effect that the characteristics of the wavelength detector can be automatically adjusted to the initial characteristics.

According to the present invention, the reference wavelength light for maintenance in which the reference wavelength for maintenance is changed corresponding to each wavelength detector to each wavelength detector of each transmission light source output wavelength adjusting means in the wavelength division multiplexing optical communication. An optical splitter that inputs via a fiber coupler from each input side of a multiplexer that combines optical signals of different wavelengths output from each transmission light source, and the maintenance reference wavelength light is output by the optical splitter. A selector for selecting and capturing the output of each wavelength detector when input to each wavelength detector, a maintenance light source for generating a maintenance reference wavelength light having a different maintenance reference wavelength for each of the wavelength detectors, and And a control unit for controlling the selector,
There is an effect that the state of each wavelength detector of each transmission light source output wavelength adjusting unit in the wavelength multiplexing optical communication can be monitored and maintained from an external in-service state.

According to the present invention, the maintenance reference wavelength light having a different maintenance reference wavelength corresponding to each wavelength detector is supplied to each wavelength detector of each transmission light source output wavelength adjusting means in the wavelength division multiplexing optical communication. A fiber coupler input from the output side of a multiplexer that combines optical signals of different wavelengths output from each transmission light source, and the maintenance reference wavelength light is input to each of the wavelength detectors by the fiber coupler. A selector that selects and captures the output of each of the wavelength detectors, a maintenance light source that generates a maintenance reference wavelength light having a different maintenance reference wavelength for each of the wavelength detectors, and a control unit that controls the selector. In the wavelength division multiplexed optical communication, the state of each wavelength detector of each transmission light source output wavelength adjusting means is suppressed from increasing the number of fiber couplers, and the in-service state is controlled from the outside. There is an effect that it is possible to monitor and maintain.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a wavelength maintenance device and an optical transmission device according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram showing a control signal output from a control unit of the wavelength maintenance device according to the first embodiment of the present invention and an output of a front value holding circuit of the optical transmission device.

FIG. 3 is a structural diagram illustrating an optical circuit network of an optical transmission device according to a second embodiment of the present invention.

FIG. 4 is a structural diagram illustrating an optical circuit network of an optical transmission device according to a third embodiment of the present invention.

FIG. 5 is a structural diagram showing an optical circuit network of an optical transmitter according to a fourth embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of a wavelength maintenance device and an optical transmission device according to a fifth embodiment of the present invention.

FIG. 7 is a block diagram illustrating a configuration of a wavelength maintenance device and an optical transmission device according to a sixth embodiment of the present invention.

FIG. 8 is a block diagram illustrating a configuration of a wavelength maintenance device and an optical transmission device according to a seventh embodiment of the present invention.

FIG. 9 is a block diagram illustrating a configuration of a wavelength maintenance device and an optical transmission device according to an eighth embodiment of the present invention.

FIG. 10 is a block diagram illustrating a configuration of a wavelength maintenance device and an optical transmission device according to a ninth embodiment of the present invention.

FIG. 11 is a block diagram showing a schematic configuration of a wavelength stabilizing device for a semiconductor laser disclosed in Japanese Patent Application Laid-Open No. 1-205486 as a conventional optical transmitting device and its wavelength maintenance device.

FIG. 12 is an explanatory diagram illustrating a configuration of a wavelength detector of a conventional optical transmission device.

FIG. 13 is a characteristic diagram for explaining operations of a wavelength detector and an arithmetic circuit of a conventional optical transmission device.

[Explanation of symbols]

1, 1c, 51, 52, 53, 54 optical transmitter, 2,
2a, 2b, 2c Wavelength maintenance device, 3 transmission light source, 5
a, 5b, 5c optical network (maintenance reference wavelength optical input circuit), 7 arithmetic circuit (transmission light source output wavelength adjusting means), 8
Error amplifier (transmission light source output wavelength adjusting means), 10 previous value holding circuit (transmission light source output wavelength fixing means), 11 switch (transmission light source output wavelength fixing means), 12 low-pass filter (transmission light source output wavelength adjusting means), 13 drive circuit (transmission light source output wavelength adjusting means), 14, 92 maintenance light source, 15, 94 detection unit, 16, 95 signal processing unit, 1
7 control unit (wavelength control unit), 31, 40, 40a, 40
b, 40c, 40d, 41 Fiber coupler, 43 Wavelength monitor (wavelength detector), 50 optical switch, 80 automatic adjustment circuit, 90 multiplexer, 91 optical distributor, 93 selector, 96 controller, 100 optical connector ( Reference wavelength optical input circuit for maintenance), 101 connector (wavelength detector output extraction circuit, control signal input circuit).

Continuing on the front page (72) Inventor Hitoshi Matsushita 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (15)

[Claims] 1. A light output from a transmission light source in optical communication is branched, a wavelength of the branched light is detected by a wavelength detector, and a change amount of the detected wavelength with respect to a reference wavelength is determined. In an optical transmission device including a transmission light source output wavelength adjustment unit that adjusts and maintains a wavelength of light output from the transmission light source to the reference wavelength, a maintenance reference wavelength for detecting a characteristic change of the wavelength detector. A maintenance reference wavelength light input circuit for inputting maintenance reference wavelength light to the wavelength detector; anda maintenance reference wavelength light input to the wavelength detector by the maintenance reference wavelength light input circuit. A wavelength detector output extracting circuit for extracting the output of the wavelength detector to the outside. 2. The optical transmission apparatus according to claim 1, wherein the maintenance reference wavelength light is intensity-modulated so as to be distinguishable from the light output from the transmission light source. 3. A transmission light source output wavelength for maintaining a wavelength of light output from a transmission light source by a control signal during a period in which the maintenance reference wavelength light is input to the wavelength detector from the maintenance reference wavelength light input circuit. 3. The optical transmission apparatus according to claim 1, further comprising a fixing unit, and a control signal input circuit for supplying the control signal from the outside to the transmission light source output wavelength fixing unit. 4. The maintenance reference wavelength optical input circuit is a fiber coupler that inputs the maintenance reference wavelength light to the wavelength detector together with the split light of the light output from the transmission light source. The optical transmission device as described in the above. 5. The maintenance reference wavelength light input circuit is an optical switch for inputting the maintenance reference wavelength light to the wavelength detector together with the split light of the light output from the transmission light source. The optical transmission device as described in the above. 6. A wavelength detector according to claim 1, wherein the characteristic returns to an initial characteristic by a wavelength detector adjustment signal generated based on an output of the wavelength detector taken out from the wavelength detector output extraction circuit. The optical transmitter according to claim 1, wherein the optical transmission is adjusted automatically. 7. A maintenance reference wavelength optical input circuit, wherein a maintenance reference wavelength is made different for each wavelength detector of each transmission light source output wavelength adjustment means in wavelength division multiplexing optical communication in accordance with each wavelength detector. 2. The optical transmission device according to claim 1, wherein the maintenance reference wavelength light is a fiber coupler input from each input side of a multiplexer that combines optical signals of different wavelengths output from each transmission light source. 8. A maintenance reference wavelength optical input circuit, wherein a maintenance reference wavelength is made different for each wavelength detector of each transmission light source output wavelength adjusting means in wavelength division multiplexing optical communication in correspondence with each wavelength detector. 2. The optical transmission device according to claim 1, wherein the maintenance reference wavelength light is a fiber coupler input from an output side of a multiplexer that combines optical signals of different wavelengths output from each transmission light source. 9. A maintenance light source for outputting a maintenance reference wavelength light of a maintenance reference wavelength for detecting a characteristic change of a wavelength detector of a transmission light source output wavelength adjusting means in an optical transmission device; A detection unit that detects an output, the output of the wavelength detector detected by the detection unit when the maintenance reference wavelength light output from the maintenance light source is input to the wavelength detector, and is set in advance. A signal processing unit that detects a change in the characteristics of the wavelength detector based on the output of the wavelength detector with respect to the maintenance reference wavelength light and determines whether the wavelength detector is normal or abnormal. Wavelength maintenance device. 10. A wavelength control unit for outputting a control signal for maintaining a constant wavelength of light output from a transmission light source of an optical transmission device while a maintenance reference wavelength light is being input to a wavelength detector. 10. The wavelength maintenance device according to claim 9, wherein: 11. A detection unit comprising: a transmission light source output of a wavelength detector when only a split light beam of light output from a transmission light source of the optical transmission device is input to the wavelength detector; The signal processing unit detects the split light of the light output from the light source and the combined output of the wavelength detector when the maintenance reference wavelength light output from the maintenance light source is input to the wavelength detector. Based on the transmission light source output and the combined output, calculate the output of the wavelength detector when the maintenance reference wavelength light output from the maintenance light source is input to the wavelength detector,
Based on the calculation result and a preset reference output of the wavelength detector with respect to the maintenance reference wavelength light, a characteristic change of the wavelength detector is detected, and whether the wavelength detector is normal or abnormal is determined. The wavelength maintenance device according to claim 9 or 10, wherein the determination is performed. 12. A detecting unit, which modulates the intensity of the maintenance reference wavelength light so as to be distinguishable from the light output from the transmission light source of the optical transmitter, and outputs the intensity-modulated maintenance reference wavelength light. An output of the wavelength detector for the maintenance reference wavelength light when input to the wavelength detector is detected, and the signal processing unit is preset with the output of the wavelength detector detected by the detection unit. Based on a reference output for the maintenance reference wavelength light in the wavelength detector, a characteristic change of the wavelength detector is detected, and whether the wavelength detector is normal or abnormal is determined. The wavelength maintenance device according to claim 9 or 10. 13. An automatic adjustment circuit for generating and outputting a wavelength detector adjustment signal for automatically adjusting the characteristics of the wavelength detector to return to the initial characteristics based on the detection result of the characteristic change of the wavelength detector. 13. The wavelength maintenance device according to claim 12, comprising: 14. A maintenance reference wavelength light having a different maintenance reference wavelength corresponding to each wavelength detector is transmitted to each wavelength detector of each transmission light source output wavelength adjusting means in the wavelength division multiplexing optical communication. An optical splitter that inputs via a fiber coupler from each input side of a multiplexer that combines optical signals of different wavelengths output from the light source; and the optical splitter converts the maintenance reference wavelength light into each of the wavelength detectors. A selector for selecting and taking in the output of each wavelength detector when it is input to the control unit, a maintenance light source for generating a maintenance reference wavelength light having a different maintenance reference wavelength for each of the wavelength detectors, and controlling the selector. The wavelength maintenance device according to claim 1, further comprising a control unit configured to detect an output of each of the wavelength detectors selected by the selector. 15. A maintenance reference wavelength light having a different maintenance reference wavelength corresponding to each wavelength detector is transmitted to each wavelength detector of each transmission light source output wavelength adjusting means in the wavelength division multiplexing optical communication. A fiber coupler input from the output side of the multiplexer that combines optical signals of different wavelengths output from the light source, and each of the fiber couplers when the maintenance reference wavelength light is input to each of the wavelength detectors. A selector for selecting and capturing an output of the wavelength detector, a maintenance light source for generating a maintenance reference wavelength light having a different maintenance reference wavelength for each of the wavelength detectors, and a control unit for controlling the selector; The wavelength maintenance device according to claim 1, wherein the unit detects an output of each of the wavelength detectors selected by the selector.