JP3385260B2 - Tunable filter device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength division multiplexing transmission system in optical communication and a wavelength tunable filter device used in the system.

[0002]

2. Description of the Related Art In optical communication, a wavelength division multiplexing optical transmission system for transmitting multi-channel signals through one optical fiber is known. The wavelength division multiplexing optical transmission system is that the signals of each channel are wavelength-multiplexed by the optical multiplexer with the light having different wavelengths, transmitted from the transmitting side to the receiving side by one fiber, and the receiving side multiplexes by the wavelength filter. The light is separated for each wavelength and regenerated. Therefore, a tunable filter that can tune the received wavelength is used.

In this way, it is possible to freely extract the light of the desired wavelength from the light in which many wavelengths are multiplexed. Therefore, a wavelength tunable filter device in which a wavelength tuning function for correctly selecting a reception wavelength is added to the wavelength tunable filter is being studied.

FIG. 10 shows the configuration of a conventional wavelength tunable filter device and the flow of data signals at each part.
In FIG. 10, 101 is a wavelength tunable filter, 102 is an optical / electrical conversion unit, 103 is a received light intensity detection unit, 104 is a wavelength / intensity storage unit, 105 is a peak position detection unit, and 106 is a wavelength scanning (changing) unit. A wavelength tunable filter device is configured by these units. Further, 107 is an electric signal processing unit.

Next, the operation of the conventional device having such a configuration will be described. The optical signal from the wavelength tunable filter 101 is converted into a photoelectric conversion signal by the optical / electrical conversion unit 102. This photoelectric conversion signal is sent to the electric signal processing unit 107, and a part of the received light intensity detection unit 103 detects the average value of the photoelectric conversion signal, that is, the average received light intensity. Both the average received light intensity and the wavelength position data from the wavelength scanning unit 106 are stored in the wavelength / intensity storage unit 104.

While changing the wavelength of the wavelength tunable filter 101 by the wavelength scanning unit 106, the wavelength / intensity storage unit 104
The wavelength can be set by specifying the wavelength at which the average received light intensity is the maximum in the peak position detection unit 105 based on the information stored in step 1 and sending the wavelength position to the wavelength scanning unit 106.

On the other hand, a method has also been proposed in which wavelength-multiplexed light is input to a wavelength tunable filter and the received light intensities of two wavelengths close to the selected wavelength are monitored to optimize the intensity difference (eg, Patent 2655479).

[0008]

However, in the above conventional wavelength tunable filter device, the wavelength tunable filter 10 is used.
When the received light intensity of No. 1 is decreased, whether the set wavelength of the wavelength filter 101 is shifted to the short wavelength side or the long wavelength side with respect to the oscillation wavelength of the light source to be transmitted depends on the set wavelength of the wavelength tunable filter. Can be understood only by shifting to the short-wave side and the long-wave side to detect the received light intensity and examining the direction in which the received light intensity increases.

In this case, in the above process, the wavelength tunable operation is performed at least twice, and when the wavelength is tuned in the direction in which the received light intensity decreases, the signal quality temporarily deteriorates due to the decrease in the received light intensity. there's a possibility that.

Further, in the method of monitoring the average received light intensity of light of adjacent wavelengths, there is a possibility that correct wavelength setting may not be possible if the wavelength intervals to be multiplexed are different or the original intensity level of light of adjacent wavelengths fluctuates. There is.

In consideration of the problems of the conventional wavelength tunable filter device, the present invention enables accurate resetting by simply changing the wavelength when the received light intensity is lowered by using only the wavelength light to be selected. An object of the present invention is to provide a variable wavelength filter device that can be used.

[0012]

[Means for Solving the Problems] The first invention (Claim 1)
Is a wavelength tunable filter whose selectable wavelength for the input optical signal can be changed, an optical-electrical converter that converts the light passing through the wavelength tunable filter into a received light intensity signal, and the intensity of the converted received light intensity signal. A received light intensity detection unit for detecting
A signal component detection unit that detects a signal component from the received light intensity signal, a signal intensity detection unit that detects the intensity of the detected signal component, a fluctuation of the received light intensity detected by the received light intensity detection unit, and the signal intensity An intensity fluctuation detecting unit that detects the strength fluctuation of each of the signal components detected by the detecting unit, and based on both of the detected fluctuations, the selected wavelength of the wavelength tunable filter is changed to change the optical-electrical conversion unit. A wavelength tunable filter device, comprising: wavelength setting means for appropriately setting a wavelength so that an output satisfies a predetermined condition.

According to a second aspect of the present invention (corresponding to claim 2), the direction of changing the selection wavelength of the wavelength tunable filter is determined based on both the fluctuations. It is a variable filter device.

A third aspect of the present invention (corresponding to claim 3) is the wavelength tunable filter device according to the first aspect of the present invention, wherein the selection wavelength of the wavelength tunable filter is changed by a feedback method. .

In a fourth aspect of the present invention (corresponding to claim 4), the wavelength setting means preliminarily changes the intensity of the received light intensity signal in the wavelength changing direction of the wavelength tunable filter and / or the signal component. A wavelength / intensity storage unit for storing reference data describing the state of intensity fluctuation, wherein the selection wavelength of the wavelength tunable filter is changed by changing the reference data and the detected at least one of the fluctuations. The wavelength tunable filter device according to the first aspect of the present invention is characterized in that it is changed by comparing

In a fifth aspect of the present invention (corresponding to claim 5), the wavelength setting means sets the set wavelength to a wavelength at which the intensity of the received light intensity signal has a maximum value. It is a wavelength tunable filter device of the present invention.

According to a sixth aspect of the present invention (corresponding to claim 6), the wavelength setting means sets the set wavelength to a wavelength at which the intensity of the signal component has a maximum value. It is a wavelength tunable filter device of the invention.

In a seventh aspect of the present invention (corresponding to claim 7), the wavelength setting means sets the set wavelength to a wavelength at which the intensity of the received light intensity signal has a maximum value and an intensity of the signal component to a maximum value. The wavelength tunable filter device according to the first aspect of the present invention is characterized in that the wavelength is set to a predetermined wavelength.

The eighth aspect of the present invention (corresponding to claim 8) is characterized in that the difference between the fluctuations of the both is further detected, and the appropriate wavelength is set based on the difference.
Is a wavelength tunable filter device of the present invention.

In a ninth aspect of the present invention (corresponding to claim 9), the wavelength setting means sends a signal notifying an abnormality when the relationship between the two fluctuations is a relationship indicating a predetermined abnormality. And / or the wavelength tunable filter device of the present invention is characterized in that the wavelength scanning is stopped.

The tenth aspect of the present invention (corresponding to claim 10) is
The electric signal detected by the signal component detection unit is a signal in which several modulated subcarrier frequency component signals are multiplexed, and one of the subcarrier signals is selectively extracted and extracted. The tunable filter device according to any one of the first to ninth aspects of the present invention, wherein the intensity of the signal component is guided to the signal intensity detector.

The eleventh invention (corresponding to claim 11) is
The electric signal detected by the signal component detection unit is a signal in which several modulated sub-carrier frequency component signals and non-modulated sub-carrier frequency component signals are multiplexed. The tunable filter device according to any one of the first to ninth aspects of the present invention, wherein the carrier wave signal is selectively extracted, and the intensity of the extracted signal component is guided to the signal intensity detection unit.

The twelfth aspect of the present invention (corresponding to claim 12) is
As the wavelength tunable filter, any one of a filter using a diffraction grating, a fiber diffraction grating, an interference film filter, a Fabry-Perot etalon filter, an acousto-optic filter, a Mach-Zehnder filter, or a combination thereof is used. The tunable filter device according to any one of the first to eleventh aspects of the present invention.

The thirteenth invention (corresponding to claim 13) is
A signal output that receives at least one or more wavelengths of light and outputs an electric signal component from the wavelength tunable filter device according to any one of the first to eleventh aspects of the present invention and the signal component detector included in the wavelength tunable filter. And an optical receiver.

The fourteenth invention (corresponding to claim 14) is
One electrical / optical conversion unit that inputs an electrical signal and performs electrical / optical conversion into an optical signal of a predetermined wavelength, or an optical signal that receives an electrical signal, performs electrical / optical conversion, and has different wavelengths. And an optical transmitter having a plurality of electric / optical converters and an optical combiner for multiplexing optical signals output from the electric / optical converters, and an optical signal output by the optical transmitter directly. Alternatively, the optical transmission device according to the thirteenth aspect of the present invention, which inputs indirectly, is provided.

The fifteenth invention (corresponding to claim 15) is
One electrical / optical conversion unit that inputs an electrical signal and performs electrical / optical conversion into an optical signal of a predetermined wavelength, or an optical signal that receives an electrical signal, performs electrical / optical conversion, and has different wavelengths. And an optical transmitter having a plurality of electric / optical converters and an optical combiner for multiplexing optical signals output from the electric / optical converters, and transmitting the optical signal output by the optical transmitter. And an optical receiving device according to a thirteenth aspect of the present invention for inputting the optical signal output from the optical transmission line.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing the embodiments thereof. (First Embodiment) A wavelength tunable filter device according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a block diagram of a wavelength tunable filter device according to a first embodiment of the present invention. In FIG. 1, 1 is a wavelength tunable filter, 2 is an optical / electrical converter,
3 is a received light intensity detection unit, 4 is an intensity fluctuation detection unit, 5 is a peak position detection unit, 6 is a wavelength scanning unit, 8 is a signal component detection unit, and 9 is a signal component detection unit.
Is a signal strength detector. Here, the peak position detector 5
The wavelength scanning unit 6 is an example of the wavelength setting means of the present invention.

Further, FIG. 2 is a conceptual diagram for explaining the operation of the wavelength tunable filter device of the first embodiment. Here, it is assumed that the received light is wavelength-multiplexed light, and some kind of modulation signal is applied to the wavelength light selected by the wavelength tunable filter device among the wavelength lights.

In FIG. 2, reference numeral 30 denotes an instantaneous photoelectric conversion signal intensity in which the photoelectric conversion signal intensity detected by the received light intensity detecting section 3 is represented with the time axis as the horizontal axis, and the modulation signal waveform is centered on the average received light intensity Iopt. Are superimposed. Reference numeral 31 denotes an instantaneous signal strength obtained by removing the Iopt component in the signal component detection unit 8 and extracting only the modulated signal component, and Ielc represents the average signal strength thereof.

Reference numeral 20 is a curve representing the behavior of the average received light intensity Iopt when the wavelength variable filter 1 receives the light input to the wavelength variable filter 1 and the filter wavelength is varied.
Is a curve representing the behavior of the average signal intensity Ielc.

FIG. 3 is a conceptual diagram showing the wavelength setting operation in the present embodiment, 22 is the wavelength position λ o at which the average received light intensity Iopt has a maximum value (peak),
Reference numeral 23 is a wavelength position λe at which the average signal intensity Ielc has a maximum value (peak), and 24 is a wavelength position λc set between λo and wavelength λe. The positional relationship is not limited as long as it is between the two wavelengths. Although λo and λe are arranged on the short wavelength side here, λo and λe may have the opposite wavelength positional relationship.

FIG. 4 is a flow chart showing the operation when the selected wavelength in this embodiment is set at the wavelength position where the average received light intensity has a maximum value. In FIG. 4, step 41 is an initial setting operation, step 42 is a decision to increase / decrease the average received light intensity, step 43 is a decision to increase / decrease the average signal intensity, and step 44 is a minute shift of the filter center wavelength to the long wavelength side. Regarding the operation, step 45 represents an operation for slightly moving the filter center wavelength to the short wavelength side, and step 46 and step 47 represent a peak judgment part of the average received light intensity.

Next, the operation of this embodiment will be described. The wavelength-multiplexed light incident on the wavelength tunable filter 1 is wavelength-selected according to the transmission characteristics of the wavelength tunable filter 1, and the output light is converted into a photoelectric conversion signal by the optical / electrical conversion unit 2. As for the instantaneous time variation of the photoelectric conversion signal, the modulation signal waveform is superimposed around the average received light intensity Iopt averaged by the received light intensity detector 3 as shown by the curve 30 in FIG.

The average received light intensity averaged by the received light intensity detector 3 is input to the intensity fluctuation detector 4. On the other hand, as for the photoelectric conversion signal, only the modulated signal component superimposed by the signal component detection unit 8 is extracted. The modulation signal component is Iopt as shown by the curve 31 in FIG.
It is centered on the average signal intensity Ielc obtained by removing the component and averaging by the signal intensity detection unit 9. This average signal strength is input to the strength fluctuation detection unit 4.

The intensity fluctuation detecting section 4 monitors the increase / decrease behavior of the average received light intensity and the average signal strength, and the peak position detecting section 5 monitors the average received light intensity or the average signal based on the level increase / decrease information from the intensity fluctuation detecting section 4. The peak wavelength position of one of the intensities is detected and set by the wavelength scanning unit 6 while the filter wavelength of the wavelength tunable filter 1 is slightly changed. In the operation of FIG. 4, the operation is performed so that the received light intensity has a peak.

More specifically, by partially repeating the description, the behaviors of the average received light intensity and the average signal intensity with respect to the change of the filter wavelength become the curves 20 and 21, respectively, which are different with respect to the wavelength axis. As shown in, the wavelengths λo and λe at which the respective average intensities peak are present at positions separated by Δλ. This is a phenomenon that appears prominently when the semiconductor laser is directly modulated, and the cause is that the oscillation spectrum of the semiconductor laser broadens (chirps) due to the direct modulation.
It is based on that.

Even if external modulation is performed, the transmission spectrum is wider than in the case where no modulation is performed, so the present invention can be applied to any modulation method in principle.

The operation when the wavelength shift occurs when the wavelength position λ o at which the average received light intensity peaks is set as the set wavelength will be described with reference to FIGS. 3 and 4. After the initial setting operation process step 41, if the relative wavelength of the laser wavelength and the filter wavelength shifts, Iopt decreases, so that it is detected by the average received light intensity variation detection process step 42, and by the average signal intensity detection process step 43. Determine the increase or decrease in strength. For example, if the filter wavelength is shifted to the short wavelength side, the average received light intensity decreases and the average signal intensity also decreases as shown in FIG. On the contrary, if the filter wavelength is shifted to the long wavelength side, the average signal strength will increase. Based on this tendency, the setting wavelength is readjusted in the process step 44 of shifting the filter wavelength to the long wavelength side in the former case, and readjusted in the process step 45 of shifting the filter wavelength to the short wavelength side in the latter case. After each process, the received light intensity peak detection process step 46,
When the average received light intensity peaks at 47, that is, the wavelength λ
Stop the adjustment work with o.

When the wavelength position λe at which the average signal intensity has a peak is set as the set wavelength, the setting can be made in the same way.

With the above configuration, the relative fluctuation of the filter wavelength and its fluctuation direction can be detected with high accuracy only by the wavelength light to be selected from among the wavelength-multiplexed lights, and the resetting to the set wavelength is easy. It has the effect that

(Second Embodiment) Next, the second embodiment of the present invention will be described.
Of the tunable filter device according to the embodiment of FIG.
This will be described with reference to FIGS. 5 and 6.

5 is different from the first embodiment in that the intensity fluctuation detecting section 4 and the peak position detecting section 5 in FIG. 1 are different.
Is a difference detection unit 10 as an intensity fluctuation detection unit that detects a difference value between the average received light intensity and the average signal intensity for each wavelength scan.
Then, the optimum wavelength position is detected based on the detected difference value,
Wavelength optimization detection unit 1 that outputs a signal off the optical axis when necessary
It is a point that it has been changed to 1, and those given the other same numbers have the same function. Here, the wavelength optimization detection unit 11 and the wavelength scanning unit 6 constitute wavelength setting means.

Further, FIG. 6 shows the setting wavelength of the wavelength tunable filter 1 at the wavelength position (λ) where the average received light intensity has a peak in FIG.
o) 22 and the wavelength position where the average signal strength reaches its peak (λe)
23 is a flowchart showing an operation when setting the wavelength position when the wavelength position (λc) 24 between 23 and 23 is set. In FIG. 6, step 51 is an initial setting operation, step 52 is a change detection of average received light intensity, step 421 is a determination of increase / decrease of average received light intensity, step 431 and step 432 is a determination of increase / decrease of average signal intensity, 44 is an operation for slightly moving the filter center wavelength to the short wavelength side,
Step 45 is an operation of slightly moving the filter center wavelength to the long wavelength side, Steps 53 and 54 are the determination of the optimum wavelength position based on the difference value, Step 55 is an optical axis deviation signal transmission process, and Step 56 is wavelength scanning. It represents the process of stopping.

As for the operation, similarly to the first embodiment, the received light intensity detector 3 detects the average received light intensity from the wavelength tunable filter 1, and the signal intensity detector 9 detects the average signal intensity. Is received by the wavelength scanning unit 6 and input to the difference detection unit 10. The difference detection unit 10 detects the difference value of the average received light intensity and the difference value of the average signal intensity at the previous wavelength scanning. It is determined in step 52 that the received light intensity variation is detected whether the difference value is within a desired allowable variation value. When the average received light intensity fluctuation is equal to or more than the allowable range, the difference value is calculated in the received light intensity increase / decrease detection process step 421.
Whether the strength is increased or decreased is judged by judging whether the sign is positive or negative. Then, in step 431 or 432, it is determined whether the average signal strength is increased or decreased. The setting wavelength of the tunable filter 1 is the wavelength λc in FIG.
If the filter wavelength is shifted to the long-wave side after the initial setting process step 51 is performed so as to be the position 24 of
As shown in FIG. 3, the average received light intensity increases and the average signal intensity decreases. This is judged in steps 421 and 431, and the filter wavelength is slightly moved to the short wave side in the short wave side wavelength scanning process step 44, and becomes a difference value near the optimum wavelength position stored in advance in the wavelength / intensity storage unit (not shown). The wavelength scanning is performed through the determination process step 53. on the other hand,
When the filter wavelength is shifted to the short wave side, the average received light intensity decreases and at the same time the average signal intensity increases. This is judged in steps 421 and 432, and the filter wavelength is slightly moved to the long-wave side in the long-wavelength side wavelength scanning step 45, and is passed through the judgment step 54 until the difference value near the optimum wavelength position stored in advance is reached. Perform wavelength scanning.

If the optical axis deviation, the level fluctuation of the input light, or the very large wavelength deviation occurs, the average received light intensity and the average signal intensity both decrease and increase.
This is judged in steps 421, 431 and 432, and a process step 55 of transmitting an abnormality occurrence signal such as deviation of the optical axis is carried out.
Then, the notification operation ends (step 56).

With such a configuration, in addition to the effect of the first embodiment, it is possible to determine an abnormal phenomenon such as a wavelength variation and a level variation of the input light to the wavelength tunable filter 1 and a deviation of the optical axis.

In this embodiment, the difference between the average received light intensities and the difference between the average signal intensities are used, but the present invention is not limited to this. For example, the difference between the average received light intensity and the average signal intensity is used. It is possible to specify the direction of shift.

(Third Embodiment) Next, the third embodiment of the present invention will be described.
The tunable filter device according to the embodiment will be described with reference to FIGS. 7 and 8.

In FIG. 7, the point different from the second embodiment is that instead of the signal component detection unit 8 of FIG. 5, only the pilot signal is extracted from the modulated signal that is sub-carrier multiplexed on the frequency axis, for example. The point is that it has a pilot signal detection unit 12 as a signal component detection unit for detection. FIG. 8 shows a modulation signal spectrum in which subcarriers are multiplexed, where 40 is a modulation signal group and 41 is a pilot signal arranged at a frequency away from the modulation signal group.

The operation of this embodiment is the same as the above-mentioned second operation except that the pilot signal 41 is separated by the pilot signal extraction unit 12 and the average signal strength is obtained by the signal strength detection unit 9.
The operation is the same as that of the above embodiment. Therefore, in the present embodiment, the average signal strength is not all the modulated signal strengths, but the average strength of the pilot signal is used for the wavelength position resetting operation.

With such a configuration, the wavelength tunable filter can independently construct the wavelength adjusting electric circuit by using the pilot signal arranged independently of the modulation signal group, irrespective of the frequency range of the modulation signal to be transmitted. It becomes a device. In particular, if the pilot signal is set to the low frequency side, the pilot signal extraction unit 12 can be composed of a simple low-pass filter, and the signal strength detection unit 9 does not need to have a high frequency response.

In the above embodiments, the type of the wavelength tunable filter is not specified, but as the wavelength tunable filter, for example, a filter using a diffraction grating, a fiber diffraction grating, an interference film filter, a Fabry-Perot etalon is used. A wavelength tunable filter composed of any one of a filter, an acousto-optic filter, a Mach-Zehnder filter, etc., or a combination thereof can be used.

Further, in the third embodiment, an example in which a pilot signal is separately used has been shown, but at least one of the subcarrier-multiplexed modulated signal groups may be selected and used as the average signal strength. . In this case, no pilot signal is needed. This is effective when handling a modulated signal in which subcarrier multiplexing is biased to some frequency bands.

FIG. 9 is a block diagram showing an embodiment of the optical transmission system of the present invention. Here, 24 is the wavelength tunable filter device described above, and 26 is a signal output unit for outputting the output of the signal component detection unit 8 in the device 24. The optical receiver 25 has a wavelength tunable filter device 24 and a signal output unit 26. Further, 20 is an optical transmitter, and an electric / optical converter 21 for converting an electric signal into light,
It has a photosynthesis unit 22. A plurality of electric / optical converters 21 are provided and can convert lights having different wavelengths. It should be noted that the number of the electric / optical converters 21 may be one.

The optical signal output from the optical combiner 22 is input to the optical receiver 25 through the optical fiber 23 which is an optical transmission line.

The optical fiber 23 may be omitted, and the light may be directly input from the optical transmitter 20 to the optical receiver 26.

[0058]

As is apparent from the above description, the wavelength tunable filter device of the present invention can easily and highly accurately adjust the wavelength using only the selected wavelength light regardless of the wavelength interval or the number of multiplexed lights. It has advantages.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a wavelength tunable filter device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing behaviors of fluctuations in received light intensity and fluctuations in signal intensity received by the wavelength tunable filter according to the first embodiment.

FIG. 3 is a diagram showing a positional relationship between peak wavelengths of average received light intensity and average signal intensity according to the first embodiment.

FIG. 4 is a flowchart showing a wavelength setting operation in the first embodiment.

FIG. 5 is a configuration diagram of a wavelength tunable filter device according to a second embodiment of the present invention.

FIG. 6 is a flowchart showing a wavelength setting operation in the second embodiment.

FIG. 7 is a configuration diagram of a wavelength tunable filter device according to a third embodiment of the present invention.

FIG. 8 is a diagram showing a signal spectrum of subcarrier-multiplexed signals including pilot signals in the third embodiment.

FIG. 9 is a configuration diagram showing an embodiment of an optical transmission system according to the present invention.

FIG. 10 is a configuration diagram of a conventional wavelength tunable filter device.

[Explanation of symbols]

1, 101 Wavelength tunable filter 2,102 Optical / electrical converter 3, 103 Received light intensity detector 4 Strength fluctuation detector 5, 105 Peak position detector 6, 106 Wavelength scanning unit 8 Signal component detector 9 Signal strength detector 10 Difference detector 11 Wavelength optimization detector 12 Pilot signal extraction unit

Claims (15)

(57) [Claims] 1. A wavelength tunable filter capable of changing a selected wavelength with respect to an input optical signal, an optical / electrical converter for converting light passing through the wavelength tunable filter into a received light intensity signal, and the intensity of the converted received light intensity signal. Detected by the received light intensity detection unit, a signal component detection unit that detects a signal component from the received light intensity signal, a signal intensity detection unit that detects the intensity of the detected signal component, and a received light intensity detection unit. Intensity fluctuation detecting section for detecting fluctuations in received light intensity and fluctuations in the signal component detected by the signal strength detecting section, and changing the selected wavelength of the wavelength tunable filter based on both detected fluctuations. And a wavelength setting means for appropriately setting the wavelength so that the output of the optical / electrical conversion unit satisfies a predetermined condition. apparatus. 2. The wavelength tunable filter device according to claim 1, wherein a direction in which a selected wavelength of the wavelength tunable filter is changed is determined based on both the fluctuations. 3. The wavelength tunable filter device according to claim 1, wherein the selection wavelength of the wavelength tunable filter is changed by a feedback method. 4. The wavelength setting means stores, in advance, reference data describing a state of intensity variation of the received light intensity signal and / or a state of intensity variation of the signal component in the wavelength changing direction of the wavelength tunable filter. A wavelength / intensity storage unit is provided, and the change of the selected wavelength of the wavelength tunable filter is changed by comparing the reference data with the detected change state of at least one of the two. The tunable filter device according to claim 1, which is characterized in that. 5. The wavelength setting means sets the set wavelength to
2. The wavelength tunable filter device according to claim 1, wherein the wavelength of the intensity of the received light intensity signal is a maximum value. 6. The wavelength setting means sets the set wavelength to
2. The wavelength tunable filter device according to claim 1, wherein the wavelength of the intensity of the signal component is a maximum value. 7. The wavelength setting means sets the set wavelength to
2. The wavelength tunable filter device according to claim 1, wherein the wavelength is a predetermined wavelength between a wavelength at which the intensity of the received light intensity signal has a maximum value and a wavelength at which the intensity of the signal component has a maximum value. 8. The wavelength tunable filter device according to claim 1, wherein a difference between the fluctuations of the both is further detected, and the appropriate wavelength is set based on the difference. 9. The wavelength setting means, when the relationship between the two fluctuations is a relationship indicating a predetermined abnormality, sends a signal notifying the abnormality and / or stops wavelength scanning. The wavelength tunable filter device according to claim 4, which is characterized in that. 10. The electric signal detected by the signal component detector is a signal in which several modulated sub-carrier frequency component signals are multiplexed, and one of the sub-carrier signals is selectively extracted. Then, the intensity of the extracted signal component is guided to the signal intensity detection unit.
10. The wavelength tunable filter device according to any one of 1 to 9. 11. The electric signal detected by the signal component detecting unit is a signal in which several modulated subcarrier frequency component signals and non-modulated subcarrier frequency component signals are multiplexed. 10. The wavelength tunable filter device according to claim 1, wherein the unmodulated subcarrier signal is selectively extracted, and the intensity of the extracted signal component is guided to the signal intensity detection unit. . 12. The wavelength tunable filter comprising a filter using a diffraction grating, a fiber diffraction grating, an interference film filter, a Fabry-Perot etalon filter, an acousto-optic filter, a Mach-Zehnder filter, or a combination thereof as the wavelength tunable filter. The wavelength tunable filter device according to claim 1, wherein a filter is used. 13. A light having at least one wavelength is input, and an electric signal component is output from the wavelength tunable filter device according to any one of claims 1 to 11 and the signal component detector included in the wavelength tunable filter. An optical receiver including a signal output unit for 14. One electric / optical conversion unit for inputting an electric signal and converting the electric / optical to an optical signal of a predetermined wavelength, or inputting each electric signal, converting the electric / optical to each other. An optical transmitter having a plurality of electric / optical converters for converting optical signals having different wavelengths, and an optical combiner for combining optical signals output from the electric / optical converters, and the optical transmitter outputs An optical transmission device comprising: the optical receiving device according to claim 13 for directly or indirectly inputting the optical signal. 15. One electric / optical conversion unit for inputting an electric signal and converting the electric / optical into an optical signal of a predetermined wavelength, or inputting each electric signal and converting the electric / optical to each other. An optical transmitter having a plurality of electric / optical converters for converting optical signals having different wavelengths, and an optical combiner for combining optical signals output from the electric / optical converters, and the optical transmitter outputs An optical transmission system comprising: an optical transmission line that transmits the optical signal, and the optical receiving device according to claim 13, which receives the optical signal output from the optical transmission line.