JP2000349717A - Device and method for amplifying light - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control output power without raising cost and without being affected by the maximum number of the channels of signal light and the arrangement of signal light wavelength by monitoring the power of monitor wavelength light, outputting the result as an output monitor signal, inputting a first input monitor signal and an output monitor signal and controlling the gain of an optical amplification part so that the ratio of the two signals becomes a prescribed constant value. SOLUTION: Wavelength multiplex signal light having a spectrum is inputted from an input port 1. Part of wavelength multiplex signal light is branched by an optical branch unit 2 and a WDM coupler 3 separates the light into a plurality of main signal light beams and SV light. Multiplex main signal light is converted into an electric signal by an optic/electric conversion circuit 7 and the power of the signal light from the input part of the optical amplification device is monitored. An SV light component is outputted to the optical branch unit 4, is further branched by the optical branch unit 4, and the resultant components are inputted to an SV reception circuit 5 and an electric/optic conversion circuit 6. A gain constant control circuit 16 calculates the ratio of the input SV light power monitored by the conversion circuit 6 and the output SV light power monitored by a conversion circuit 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical amplifying apparatus and an optical amplifying method, and more particularly, to an optical amplifying apparatus and an optical amplifying method for amplifying a wavelength multiplexed optical signal.

[0002]

2. Description of the Related Art As a promising system for expanding the transmission capacity of an optical communication system, a wavelength division multiplexing optical communication system is being actively developed. In order to transmit wavelength-division multiplexed signal light over a long distance in an optical fiber transmission line, it is necessary to appropriately insert an optical amplifying device in the transmission line and to transmit while securing an optical power level required for transmission. . In order to set the wavelength multiplexed signal light to a predetermined power level at the output unit of each optical amplifier, it is necessary to introduce gain control of the optical amplifier.

At this time, a method of monitoring the power of the output light of the optical amplifying device collectively, that is, monitoring the optical power of the entire WDM signal light, and controlling the gain of the optical amplifying device so that the total power becomes constant. Is also conceivable. However, when such a method is adopted, when the number of signal lights included in the wavelength-division multiplexed signal light input to the optical amplifier changes, the control target is not changed unless the control target is appropriately changed according to the change in the number of wavelengths. Of each signal light changes. In order to ensure good transmission characteristics, it is necessary that the signal light power in the transmission path be maintained at a predetermined value, so the above control method is not preferable.

As a method for solving such a problem, an optical amplifying device having a configuration shown in FIG. 10 has been conventionally proposed. The optical amplifying device shown in FIG.
4, 107 and 1014, optical amplification unit 106, excitation light source 1
05 and 108, optical demultiplexer 1010, optical / electrical conversion circuit 1011, output control circuit 1012, excitation light source drive circuit 1
013, SV light receiving circuit 103, SV light transmitting circuit 101
5 is comprised.

[0005] The wavelength multiplexed signal light input from the input port 101 is amplified by the optical amplifying medium 106. The optical amplification medium 106 is driven by two excitation light sources 105 and 108. The amplified wavelength multiplexed signal light is supplied to the optical splitter 10.
At 9, a part thereof is branched and input to the optical demultiplexer 1010. The wavelength multiplexed signal light is separated into each wavelength component by the optical demultiplexer 1010, and is converted into an electric signal by the optical / electrical conversion circuit 1011. The output control circuit 1012 detects a wavelength component having the maximum optical power level from these electric signals, and controls the excitation light sources 105 and 1 so that the maximum value is constant.
08 is adjusted. By using such a control method, it is possible to control the output power of each signal light to be constant even if the number of signal lights included in the wavelength multiplexed signal light changes.

[0006]

However, in the above-mentioned prior art, it is necessary to mount an expensive optical demultiplexer on each optical amplifying device, which increases the cost of the wavelength multiplexing optical amplifying device. I have. Furthermore, if the optical demultiplexer mounted on the optical amplifying device changes the maximum number of signal lights included in the wavelength multiplexed signal light or the signal light wavelength arrangement, the light according to the number of signal lights or the signal light wavelength arrangement is changed. Since it is necessary to change to a duplexer, it is difficult to change the system configuration flexibly.

The present invention provides an optical amplifying apparatus which does not increase the cost and which can control the output power without being affected even if the maximum number of signal light channels or the wavelength arrangement of the signal light changes. The purpose is to do.

[0008]

According to a first aspect of the present invention, there is provided an optical amplifying apparatus for amplifying and outputting a wavelength multiplexed light including a monitoring wavelength light and at least one signal light. A first input light monitoring unit that monitors the power of the monitoring wavelength light at an input unit of the optical amplification device and outputs the result as a first input monitoring signal; An optical amplifier that amplifies light and outputs amplified wavelength multiplexed light, and an output light monitor that monitors the power of the monitoring wavelength light included in the amplified wavelength multiplexed light and outputs the result as an output monitoring signal, A first control circuit that receives the first input monitor signal and the output monitor signal and outputs a control signal for controlling a gain of the optical amplifier unit such that a ratio between the first input monitor signal and the output monitor signal is a predetermined constant value; And

The optical amplifier further monitors a power of the at least one signal light, and outputs a result as a second input monitoring signal, and a second input monitoring unit. When the signal indicates that the power of the at least one signal light is lower than a predetermined value, a shutdown circuit that turns off the optical amplification unit may be provided.

An optical amplifying device according to a second configuration of the present invention is an optical amplifying device for amplifying and outputting a wavelength multiplexed light including a monitoring wavelength light and at least one signal light. An optical amplifier that amplifies and outputs amplified wavelength multiplexed light, an output light monitor that monitors the power of the monitoring wavelength light included in the amplified wavelength multiplexed light, and outputs the result as an output monitoring signal; A control circuit for receiving a monitoring signal and outputting a control signal for controlling the gain of the optical amplifier so that the value becomes a predetermined constant value.

[0011] The optical amplifier of the second configuration further includes:
A second input light monitoring unit that monitors the power of the at least one signal light and outputs the result as a second input monitoring signal; and wherein the second input monitoring signal is
A shut-down circuit for turning off the optical amplifier when the power of the two signal lights is lower than a predetermined value.

Further, an optical amplifying apparatus according to a third configuration of the present invention is an optical amplifying apparatus for amplifying and outputting wavelength multiplexed light including monitoring wavelength light and at least one signal light, wherein the wavelength multiplexed light is used. An optical variable attenuator that receives and changes the amount of attenuation based on an attenuation setting signal, and a first input light that monitors the power of the input wavelength-division multiplexed light and outputs the result as a first input monitoring signal A monitoring unit, an optical amplification unit that amplifies the wavelength division multiplexed light and outputs amplified wavelength division multiplexed light, and a first unit that monitors the power of the amplified wavelength division multiplexed light and outputs the result as a first output monitoring signal. Output light monitoring unit, monitors the power of the monitoring wavelength light included in the amplified wavelength multiplexed light,
A first output light monitoring unit that outputs the result as a second output monitoring signal, the first input monitoring signal and the first output monitoring signal are input, and a ratio between the two becomes a predetermined constant value. As described above, the first control circuit that outputs a control signal for controlling the gain of the optical amplification unit, and the second output monitoring signal is input, and the value is a predetermined constant value, A second control circuit for adjusting the attenuation setting signal.

[0013] The optical amplifier of the first configuration further includes:
An optical variable attenuator to which the wavelength multiplexed light is inputted, the amount of attenuation of which is changed based on the amount of attenuation setting signal; and the output monitoring signal is inputted, and the attenuation amount setting signal is inputted so that the value becomes a predetermined constant value. And a second control circuit for adjusting.

The optical amplifier of the fourth configuration according to the present invention has a first
And a second optical amplifying unit cascaded, wherein the first optical amplifying unit includes the optical amplifying device having the first configuration, and the second optical amplifying unit includes An optical amplification device having a third configuration is provided.

The optical amplifying device of the fourth configuration further includes:
A second input light monitoring unit that monitors the power of the at least one signal light and outputs the result as a second input monitoring signal; and wherein the second input monitoring signal is
And a shutdown circuit for turning off the second optical amplifier when the power of the two signal lights is lower than a predetermined value.

The optical amplifier, the first optical amplifier, or the second optical amplifier included in the optical amplifier of each of the above structures includes an optical fiber amplifier or a semiconductor optical amplifier.

An optical amplification method according to the present invention is an optical amplification method for amplifying a wavelength multiplexed light including a supervisory signal light and at least one signal light, wherein the first power for measuring the power of the supervisory signal light is provided. A measuring step, an optical amplification step of amplifying the wavelength multiplexed light, a second power measuring step of measuring the power of the monitor signal light amplified in the optical amplification step, and the first and second power measurement Controlling the gain of the optical amplification step so that the ratio of the values obtained in the step becomes a predetermined constant value.

Another optical amplification method according to the present invention is an optical amplification method for amplifying wavelength-division multiplexed light including supervisory signal light and at least one signal light, wherein the optical amplification step for amplifying the wavelength-division multiplexed light includes: A power measurement step of measuring the power of the monitoring signal light amplified in the optical amplification step, and a control step of controlling the gain of the optical amplification step so that the value obtained in the power measurement step is a predetermined constant value. Contains.

The above-described optical amplification method may further include a signal light power measuring step of measuring the power of the at least one signal light, and a case where a result obtained in the signal light power measuring step is less than a predetermined value. May include a shutdown step for terminating the optical amplification step.

As described above, in the present invention, in controlling the gain and the output of the optical amplifying device, instead of the signal light, the power of the monitoring signal light at the input section and the output section of the optical amplifying apparatus is monitored. The control is performed by this. Therefore, even when the number of signal lights included in the wavelength multiplexed light, the maximum number of multiplexed lights, the arrangement of signal light wavelengths, and the like change, the gain and output of the optical amplifier can be controlled without being affected by the change. In addition, since the monitoring signal light is also used in the existing transmission system, it is necessary to newly provide a dummy light source used as a probe light, an optical demultiplexer for wavelength monitoring, and the like in order to realize the control of the present invention. However, a simple configuration can be realized at low cost.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration and operation of an optical amplifier according to the present invention will be described with reference to FIGS. In each of the following embodiments, the signal light input to the optical amplifier is:
Multiplexed main signal light composed of a plurality of main signal lights having different wavelengths and S
Suppose wavelength multiplexed signal light including V light. FIG. 2 shows the spectrum of the wavelength multiplexed signal light.

(First Embodiment) FIG. 1 shows the configuration of an optical amplifier according to a first embodiment of the present invention. The optical amplifying device of the present invention includes an input port 1, an optical splitter 2, a WDM coupler 3, an optical splitter 4, an SV receiving circuit 5, an optical / electrical converting circuit 6,
Optical / electrical conversion circuit 7, forward excitation light source 9, WDM coupler 8, optical amplifier 10, backward excitation light source 12, WDM coupler 11, WDM coupler 13, optical / electrical conversion circuit 15, constant gain control circuit 16, WDM It comprises a coupler 25 and an SV light transmission circuit 26.

The optical splitter 2 splits the optical signal from the input port 1 and outputs it to the optical amplifier 10 and the WDM coupler 3.
The WDM coupler 3 splits the signal light split by the optical splitter 2, outputs the SV light to the optical splitter 4, and outputs the signal light to the optical / electrical conversion circuit 7. The optical splitter 4 is a WDM coupler 3
The SV light separated in step (1) is output to the SV receiving circuit 5 and the optical / electrical conversion circuit 6. The SV receiving circuit 5 receives the SV light output from the optical splitter 4. The optical / electrical conversion circuit 6
The SV light output from the optical splitter 4 is received and converted into an electric signal. The optical / electrical conversion circuit 7 receives the signal light output from the optical splitter 4 and converts it into an electric signal. The WDM coupler 8 multiplexes the output light of the forward pumping light source 9 and the wavelength multiplexed signal light, and inputs the multiplexed light to the optical amplifier 10. The optical amplifier 10 collectively amplifies the wavelength multiplexed signal light with an amplification medium such as an erbium-doped fiber (EDF). The WDM coupler 11
The output light from the backward pumping light source 12 and the wavelength multiplexed signal light are multiplexed, and the backward pumping light is input to the optical amplifier 10. WD
The M coupler 13 separates the wavelength multiplexed signal light output from the optical amplifying unit 10 into signal light and SV light, outputs the signal light to the output port 17, and outputs the SV light to the optical / electrical conversion circuit 15. The optical / electrical conversion circuit 15 receives the SV light separated by the WDM coupler 13 and converts it into an electric signal. The constant gain control circuit 16 controls the power of the SV light at the input section of the optical amplifier detected by the optical / electrical conversion circuit 6 and the power of the optical / electrical conversion circuit 15.
Then, the power of the output SV light of the optical amplifying device detected by the above is compared, and the excitation currents of the front excitation light source 9 and the rear excitation light source 12 are controlled so that the ratio becomes constant.

Next, the operation of the optical amplifying device of this embodiment will be described. A wavelength multiplexed signal light having the spectrum shown in FIG. 2 is input from the input port 1 in FIG. As shown in FIG. 2, the wavelength multiplexed signal light includes a multiplexed main signal light composed of a plurality of main signal lights and an SV light. A part of the wavelength multiplexed signal light is split by the optical splitter 2 and the WDM coupler 3
Is separated into a plurality of main signal lights and SV lights. The multiplexed main signal light is converted into an electric signal by the optical / electrical conversion circuit 7, and the power of the signal light at the input section of the optical amplifier is monitored. The SV light component is output to the optical branch 4, further branched at the optical branch 4, and input to the SV receiving circuit 5 and the optical / electrical conversion circuit 6.
The optical / electrical conversion circuit 6 converts the input SV light into an electric signal and monitors the power of the SV light at the input section of the optical amplifier. On the other hand, the wavelength division multiplexed signal light input to the optical amplifier 10 is amplified and output. The wavelength-division multiplexed signal light amplified by the optical amplifier 10 is wavelength-separated by the WDM coupler 13 into a multiplexed main signal light and an SV light, of which the multiplexed main signal light is output to the output port 17 and the SV light is an optical signal. / Output to the electric conversion circuit 15. The optical / electrical conversion circuit 15 monitors the power of the SV light at the output section of the optical amplifier. In addition,
In the output section of the optical amplifying device, the SV light transmitting circuit 26 generates SV light to be transmitted downstream of the transmission path. The newly generated SV light is combined with the multiplexed main signal light via the WDM coupler 25 and transmitted to the transmission path.

In this embodiment, the SV light is used as a probe light for monitoring the gain of the optical amplifier.
For this purpose, the outputs of the optical / electrical conversion circuits 6 and 15 are supplied to a gain control circuit 16. In the gain control circuit 16, the light /
The input SV light power monitored by the electric conversion circuit 6;
The ratio with the output SV light power monitored by the optical / electrical conversion circuit 15 is calculated. This ratio is the gain of the optical amplifier. The obtained gain value is compared with a predetermined constant value in the gain control circuit 16, and a control signal for reducing this error to zero is generated. The control signal output from the gain control circuit 16 is supplied to the forward pumping light source 9 and the backward pumping light source 12, and controls the pumping current which is the output. For example, when the gain is smaller than a predetermined value, the control is performed so as to increase the excitation current.

The power of the SV light input to the optical amplifier is:
Since the power is smaller than the multiplexed input signal light power, S
V light hardly affects the gain characteristics of the optical amplifier. For this reason, the optical amplifying device of the present embodiment makes it possible to perform constant gain control of the optical amplifying device irrespective of the number of multiplexed signal lights.

(Second Embodiment) FIG. 3 shows the configuration of an optical amplifier according to a second embodiment of the present invention. The optical amplifying device of the present embodiment has a configuration in which a shutdown circuit 18 is added to the configuration of the first embodiment.

In the optical amplifier of FIG. 3, the output of the optical / electrical conversion circuit 7 is supplied to a shutdown circuit 18. The shutdown circuit 18 detects the power of the multiplexed main signal light from the supplied signal and compares it with a predetermined threshold. As a result, when it is determined that the input signal has fallen below the threshold value, it is determined that the input signal to the optical amplifying device has been interrupted, and the optical amplifying device is shut down. Specifically, the forward pumping light source 9 and the backward pumping light source 12 of the optical amplifier are turned off.
The electric signal to be caused is output to the front excitation light source 9 and the rear excitation light source 12.

(Third Embodiment) FIG. 4 shows the configuration of an optical amplifier according to a third embodiment of the present invention. In this embodiment, output light power stabilization control is employed in place of the gain stabilization control employed in the first embodiment. Therefore, FIG.
In this configuration, the optical splitter 4 and the optical / electrical conversion circuit 6 are eliminated, and the constant output control circuit 21 is used instead of the constant gain control circuit 16.

In the optical amplifier shown in FIG. 4, the SV light separated by the WDM coupler 13 is converted into an electric signal by an optical / electrical conversion circuit 15. This electric signal is output constant control circuit 2
1 is supplied. The output constant control circuit 21 detects the power of the SV light from the magnitude of the input electric signal, and performs control to make the power of the SV light a predetermined constant value. More specifically, a control signal is generated such that an error signal obtained by comparing the electric signal with a predetermined value becomes zero, and outputs the control signal to the front excitation light source 9 and the rear excitation light source 12. For example, when the electric signal is larger than a predetermined value, the injection current to the front excitation light source 9 and the rear excitation light source 12 is decreased so as to reduce the excitation current output from them.

(Fourth Embodiment) FIG. 5 shows a configuration of an optical amplifying device according to a fourth embodiment of the present invention. The optical amplifying device of this embodiment has a configuration in which a shutdown circuit 18 is added to the configuration of the third embodiment.

In the optical amplifier shown in FIG. 5, the output of the optical / electrical conversion circuit 7 is supplied to a shutdown circuit 18. The shutdown circuit 18 detects the power of the multiplexed main signal light from the supplied signal and compares it with a predetermined threshold. As a result, when it is determined that the input signal has fallen below the threshold value, it is determined that the input signal to the optical amplifying device has been interrupted, and the optical amplifying device is shut down. Specifically, the forward pumping light source 9 and the backward pumping light source 12 of the optical amplifier are turned off.
The electric signal to be caused is output to the front excitation light source 9 and the rear excitation light source 12.

(Fifth Embodiment) FIG. 6 shows the configuration of an optical amplifier according to a fifth embodiment of the present invention. This embodiment includes a cascade-connected front-stage amplifier and rear-stage amplifier.

Here, the preamplifier includes the optical splitter 32 and the W
DM coupler 33, SV receiving circuit 34, optical / electrical conversion circuit 35, pre-stage forward pumping light source 37, WDM coupler 36, pre-stage optical amplifier 38, pre-stage backward pumping light source 40, WDM coupler 39, optical splitter 41, light Bandpass filter 80, light /
It comprises an electric conversion circuit 42 and a constant gain control circuit 43.

The post-amplifying unit includes an optical variable attenuator 44,
Optical splitter 45, optical / electrical conversion circuit 46, rear forward pumping light source 48, WDM coupler 47, rear optical amplifier 49, rear rear pumping light source 51, WDM coupler 50, optical splitter 5
2, optical / electrical conversion circuit 53, constant gain control circuit 54, W
It comprises a DM coupler 55, an optical / electrical conversion circuit 58, a constant output control circuit 59, a WDM coupler 25, and an SV light transmission circuit 26.

Here, the optical splitter 32 is connected to the input port 31.
The optical signal is branched to the optical amplifier 38 and output to the WDM coupler 33. The WDM coupler 33 includes the optical splitter 32
Splits the signal light split into a multiplexed main signal light and an SV light,
Among them, the SV light is output to the SV receiving circuit 34, and the multiplexed main signal light is output to the optical / electrical conversion circuit 35. The SV receiving circuit 34 receives the SV light output from the WDM coupler 33. The optical / electrical conversion circuit 35 receives the multiplexed main signal light output from the optical splitter 33 and converts it into an electric signal.
The WDM coupler 36 multiplexes the pre-stage forward pumping light and the wavelength multiplexed signal light, and inputs the multiplexed light to the pre-stage optical amplifier 38.

The pre-stage optical amplifier 38 collectively amplifies the wavelength multiplexed signal light with an amplification medium such as an erbium-doped fiber (EDF). The WDM coupler 39 multiplexes the pre-stage backward pumping light and the wavelength multiplexed signal light, and inputs the pre-stage backward pumping light to the pre-stage optical amplifier 38. The optical splitter 41 splits the wavelength multiplexed signal light output from the pre-stage optical amplifier 38 and outputs the split light to the variable optical attenuator 44 and the optical bandpass filter 80. The optical band-pass filter 80 removes the SV light from the output light split by the optical splitter 41 and outputs only the multiplexed signal light.
Output to the electric conversion circuit 42. Optical / electrical conversion circuit 42
Receives the output light of the optical bandpass filter 80 and converts it into an electric signal. The constant gain control circuit 43 compares the power of the pre-stage input SV light with the power of the pre-stage output SV light from the output signals of the optical / electrical conversion circuit 35 and the optical / electrical conversion circuit 42,
The excitation currents of the front-stage front pumping light source 37 and the front-stage rear pumping light source 40 are controlled so that the ratio becomes constant.

The variable optical attenuator 44 applies a predetermined amount of attenuation to an input optical signal based on a control signal input from the outside. The optical splitter 45 splits the optical signal from the optical variable attenuator 44, and outputs the optical signal to the downstream optical amplifier 49 and the optical / electrical conversion circuit 46.
Output to The optical / electrical conversion circuit 46 receives the wavelength multiplexed signal light output from the optical splitter 45 and converts it into an electric signal. The WDM coupler 47 multiplexes the rear-stage forward pump light and the wavelength multiplexed signal light, and inputs the multiplexed light to the rear-stage optical amplifier 49. The post-amplifier 49 is an erbium-doped fiber (ED
The wavelength multiplexed signal light is collectively amplified by an amplification medium such as F).

The WDM coupler 50 multiplexes the rear-stage pumping light and the wavelength-multiplexed signal light, and inputs the rear-stage rearward pumping light to the rear-stage optical amplifier 49. The optical splitter 52 splits the optical multiplex signal output from the post-stage optical amplifier 49 and outputs the split signal to the WDM coupler 55 and the optical / electrical conversion circuit 53. The optical / electrical conversion circuit 53 receives the output signal light of the optical branch 52 and converts it into an electric signal. The constant gain control circuit 54 calculates the ratio between the post-stage input signal light power and the post-stage output signal light power from the output signals of the optical / electrical conversion circuit 48 and the optical / electrical conversion circuit 53 so that the ratio becomes a predetermined value. Next, the excitation current of the rear-stage front pumping light source 48 and the rear-stage rear pumping light source 51 is controlled.

The WDM coupler 55 splits the optical signal output from the optical splitter 52, outputs the multiplexed main signal light to the output port 57 of the optical amplifier, and converts the SV light into the optical / electrical conversion circuit 5
8 is output. The optical / electrical conversion circuit 58 receives the SV light branched by the WDM coupler 55 and converts it into an electric signal.
The constant output control circuit 59 outputs to the optical variable attenuator 44 a control signal for controlling the amount of attenuation of the optical variable attenuator 44 so that the output power of the optical amplifier becomes constant from the output signal of the optical / electrical conversion circuit 58. I do. In the output section of the optical amplifier,
The SV light transmission circuit 26 generates SV light to be transmitted downstream of the transmission path. The newly generated SV light is combined with the multiplexed main signal light via the WDM coupler 25 and transmitted to the transmission path.

Next, the operation of the optical amplifier of FIG. 6 will be described.
In the optical amplifying device of FIG. 6, first, gain stabilization control is performed on each of the pre-amplifier and the post-amplifier with a gain that optimizes the gain flatness. With respect to the fluctuation of the input power to the post-amplifier, the SV detected by the optical / electrical conversion circuit 58
The attenuation of the variable optical attenuator 44 at the input of the post-amplifier is adjusted so that the optical output power is constant. Such control makes it possible to perform output constant control in which the input power dependence of the flatness of the optical amplifier is reduced. Note that a double control loop is configured in the post-amplifier of the present embodiment. At this time, in order to prevent interference between the two, the response speeds of the two control loops are set to differ by about one digit or more.
(Sixth Embodiment) FIG. 7 shows the configuration of an optical amplifier according to a sixth embodiment of the present invention. The optical amplifying device according to the present embodiment includes:
The configuration of the optical amplifying device of the fifth embodiment is such that a shutdown circuit 60 is added.

In the optical amplifier shown in FIG. 7, the output of the optical / electrical conversion circuit 35 is supplied to a shutdown circuit 60. The shutdown circuit 60 detects the power of the multiplexed main signal light from the supplied signal and compares it with a predetermined threshold. As a result, when it is determined that the input signal has fallen below the threshold value, it is determined that the input signal to the optical amplifying device has been interrupted, and the optical amplifying device is shut down. Specifically, the front-stage forward pumping light source 3 that supplies pump light to the front-stage optical amplifier 38
7 and an electric signal for turning off the rear-stage front pumping light source 48 and the rear-stage rear pumping light source 51 for supplying the pumping light source to the rear-stage pumping light source 40 and the rear-stage optical amplifier 49 are output to the respective pumping light sources.

(Seventh Embodiment) FIG. 8 shows the configuration of an optical amplifier according to a seventh embodiment of the present invention. The optical amplifying device of this embodiment is different from the optical amplifying device of the fifth embodiment shown in FIG. 6 in that the optical splitter 52, the optical / electrical conversion circuit 53, and the optical bandpass filter 80 are removed, while the optical splitter 71 is removed. , Optical / electrical conversion circuit 72, optical splitter 74, optical / electrical conversion circuit 7
5. The configuration is such that an optical / electrical conversion circuit 77 and an optical bandpass filter 81 are added.

The optical splitter 71 is connected to the WDM coupler 33.
The output SV light on the side of the SV light receiving circuit 34 of FIG.
It outputs to the SV light receiving circuit 34 and the optical / electrical conversion circuit 72. The optical / electrical conversion circuit 72 outputs the output SV of the optical splitter 71.
The light is converted into an electric signal, and S
The monitor value of the V light power is output to the gain control circuit 43.
From the output signals of the optical / electrical conversion circuit 72 and the optical / electrical conversion circuit 42, the ratio of the previous-stage input SV light power and the previous-stage output SV light power is calculated, and the front-stage forward excitation light source 37 is set so that the ratio becomes a predetermined value. The excitation current of the front-stage backward excitation light source 40 is controlled. The optical splitter 74 splits the output light on the optical / electrical conversion circuit 46 side of the optical splitter 45 and converts the signal light into the optical / electrical conversion circuit 4.
6 outputs the SV light to the optical / electrical conversion circuit 75. The optical / electrical conversion circuit 75 converts the SV light output from the optical splitter 74 into an electric signal. The optical / electrical conversion circuit 77
It receives the SV light output from the WDM coupler 55, converts it into an electric signal, and outputs a monitor value of the output power at the output section of the optical amplifier to the gain control circuit 54 and the output control circuit 59.

(Eighth Embodiment) FIG. 9 shows the configuration of an optical amplifier according to an eighth embodiment of the present invention. The optical amplifying device according to the present embodiment has a configuration in which a shutdown circuit 76 is added to the optical amplifying device according to the seventh embodiment.

In the optical amplifier shown in FIG. 9, the output of the optical / electrical conversion circuit 35 is supplied to a shutdown circuit 76. The shutdown circuit 76 detects the power of the multiplexed main signal light from the supplied signal and compares it with a predetermined threshold value. As a result, when it is determined that the input signal has fallen below the threshold value, it is determined that the input signal to the optical amplifying device has been interrupted, and the optical amplifying device is shut down. Specifically, the front-stage forward pumping light source 3 that supplies pump light to the front-stage optical amplifier 38
7 and an electric signal for turning off the rear-stage front pumping light source 48 and the rear-stage rear pumping light source 51 for supplying the pumping light source to the rear-stage pumping light source 40 and the rear-stage optical amplifier 49 are output to the respective pumping light sources.

In each of the above embodiments, an example has been described in which a bidirectional pumping system is used as a pumping system for an EDF which is an amplification medium used as an optical amplifier. However, the present invention is not limited to this, and a unidirectional excitation method such as forward excitation or backward excitation may be used.
Also in this case, the gain of the optical amplifier can be adjusted by the injection current to the pump light source. Further, an optical fiber amplifier is assumed as an optical amplifier used in the optical amplifying device. However, the present invention is not limited to this. For example, a semiconductor optical amplifier may be used. In this case, the adjustment of the gain of the optical amplifier may be performed by changing the magnitude of the current injected into the semiconductor optical amplifier.

[0048]

As described above, in the optical amplifying apparatus and optical amplifying method according to the present invention, in controlling the gain and output of the optical amplifying apparatus, the SV light is regarded as the probe light instead of the multiplexed main signal light. The control is performed by monitoring the power of the input section and the output section of the optical amplifier of the SV light. For this reason, even when the number of signal lights included in the multiplexed main signal light, the maximum multiplexing number, the signal light wavelength arrangement, and the like are changed, the gain and output of the optical amplifier can be controlled without being affected by the changes. . In addition, since SV light is also used in existing transmission systems, it is not necessary to newly provide a dummy light source used as probe light, an optical demultiplexer for wavelength monitoring, and the like in order to realize the control of the present invention. Therefore, a simple configuration can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an optical amplifying device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a spectrum of a wavelength multiplexed signal light input to the optical amplifying device of the present invention.

FIG. 3 is a diagram illustrating a configuration of an optical amplifying device according to a second embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration of an optical amplifying device according to a third embodiment of the present invention.

FIG. 5 is a diagram illustrating a configuration of an optical amplifier according to a fourth embodiment of the present invention.

FIG. 6 is a diagram illustrating a configuration of an optical amplifier according to a fifth embodiment of the present invention.

FIG. 7 is a diagram illustrating a configuration of an optical amplifying device according to a sixth embodiment of the present invention.

FIG. 8 is a diagram illustrating a configuration of an optical amplifying device according to a seventh embodiment of the present invention.

FIG. 9 is a diagram illustrating a configuration of an optical amplifying device according to an eighth embodiment of the present invention.

FIG. 10 is a diagram illustrating a configuration of an optical amplifying device according to a conventional technique.

[Explanation of symbols]

1: input port 2: optical branching device 3, 8, 11, 13, 25: WDM coupler 4: optical branching device 5: SV receiving circuit circuit 6, 7, 15: optical / electrical conversion circuit 9: forward excitation light source 10 : Optical amplifier 12: backward pumping light source 16: constant gain control circuit 17: output port 18: shutdown circuit 21: constant output control circuit 26: SV light transmission circuit 32, 41, 45, 52, 71, 74: optical branching 33, 36, 39, 47, 50, 55: WDM coupler 34: SV receiving circuit 35, 42, 46, 53, 58, 72, 75, 77: optical / electrical conversion circuit 37: front-stage forward pumping light source 38: Pre-stage optical amplifier 40: pre-stage backward pumping light source 43, 54: constant gain control circuit 44: variable optical attenuator 48: rear-stage forward pumping light source 49: rear-stage optical amplifier 51: rear-stage backward pumping light source 59: constant output Control circuit 60, 76: Shutdown circuit 80: Optical bandpass filter 81: Optical bandpass filter 102, 104, 107, 1014: WDM coupler 103: SV light receiving circuit 105, 108: Excitation light source 106: Optical amplifier 1010: Light Demultiplexer 1011: Optical / electrical conversion circuit 1012: Output control circuit 1013: Excitation light source drive circuit 1015: SV light transmission circuit

Claims (15)

[Claims] 1. An optical amplifying device for amplifying and outputting a wavelength multiplexed light including a monitoring wavelength light and at least one signal light, wherein the optical amplifying device includes a monitoring wavelength light at an input unit of the optical amplifying device. A first input light monitoring unit that monitors the power of the input signal and outputs the result as a first input monitoring signal; an optical amplification unit that amplifies the wavelength multiplexed light and outputs amplified wavelength multiplexed light; An output light monitoring unit that monitors the power of the monitoring wavelength light included in the multiplexed light and outputs the result as an output monitoring signal; and the first input monitoring signal and the output monitoring signal are input; A first control circuit that outputs a control signal for controlling a gain of the optical amplifying unit so as to have a predetermined constant value. 2. The optical amplifying device according to claim 1, wherein said optical amplifying device further monitors the power of said at least one signal light, and outputs the result as a second input monitoring signal. And a shutdown circuit for turning off the optical amplifier when the second input monitoring signal indicates that the power of the at least one signal light is lower than a predetermined value. An optical amplifying device comprising: 3. An optical amplifying device for amplifying and outputting wavelength multiplexed light including a monitoring wavelength light and at least one signal light, wherein the optical amplifying device amplifies the wavelength multiplexed light and outputs amplified wavelength multiplexed light. An optical amplifier that outputs the output monitoring signal, an output light monitoring unit that monitors the power of the monitoring wavelength light included in the amplified wavelength multiplexed light, and outputs the result as an output monitoring signal, A control circuit for outputting a control signal for controlling a gain of the optical amplifying unit so that the value becomes a predetermined constant value. 4. The optical amplifying device according to claim 3, wherein said optical amplifying device further monitors the power of said at least one signal light, and outputs the result as a second input monitoring signal. And a shutdown circuit for turning off the optical amplifier when the second input monitoring signal indicates that the power of the at least one signal light is lower than a predetermined value. An optical amplifying device comprising: 5. An optical amplifying device for amplifying and outputting a wavelength multiplexed light including a monitoring wavelength light and at least one signal light, wherein the optical amplifying device receives the wavelength multiplexed light and an attenuation setting signal. An optical variable attenuator whose attenuation changes based on: a first input light monitoring unit that monitors the power of the input wavelength multiplexed light and outputs the result as a first input monitoring signal; An optical amplifier for amplifying light and outputting amplified wavelength multiplexed light; monitoring the power of the amplified wavelength multiplexed light;
A first output light monitoring section that outputs the output wavelength as the output monitoring signal, and a first output that monitors the power of the monitoring wavelength light included in the amplified wavelength multiplexed light and outputs the result as a second output monitoring signal. An optical monitoring unit, a control signal for controlling the gain of the optical amplifying unit such that the first input monitoring signal and the first output monitoring signal are input and a ratio of the two becomes a predetermined constant value. Output the first
And the second output monitoring signal is inputted, and the second output monitoring signal is adjusted so that the value becomes a predetermined constant value.
An optical amplifying device comprising: 6. The optical amplifying device according to claim 1, wherein the optical amplifying device further comprises: a variable optical attenuator to which the wavelength-division multiplexed light is input and whose attenuation changes based on an attenuation setting signal. An optical amplifier, comprising: a second control circuit that receives the output monitoring signal and adjusts the attenuation setting signal so that the value becomes a predetermined constant value. 7. An optical amplifying device in which first and second optical amplifying units are cascaded, wherein the first optical amplifying unit includes the optical amplifying device according to claim 1, and An optical amplifying device, comprising: the optical amplifying device according to claim 5. 8. The optical amplifying device according to claim 7, wherein said optical amplifying device further monitors the power of said at least one signal light, and outputs the result as a second input monitoring signal. A second input light monitoring unit, and turning off the second optical amplification unit when the second input monitoring signal indicates that the power of the at least one signal light is lower than a predetermined value. And a shutdown circuit that performs the operation. 9. The optical amplifying device according to claim 1, wherein the optical amplifying unit includes an optical fiber amplifier. . 10. The optical amplifying device according to claim 7, wherein the first and second optical amplifying units include an optical fiber amplifier. Characteristic optical amplifier. 11. The optical amplifying device according to claim 1, wherein the optical amplifying unit includes a semiconductor optical amplifier. . 12. The optical amplifying device according to claim 7, wherein the first and second optical amplifying units include a semiconductor optical amplifier. Characteristic optical amplifier. 13. An optical amplification method for amplifying a wavelength multiplexed light including a supervisory signal light and at least one signal light, wherein the optical amplification method comprises: a first power measuring step of measuring a power of the supervisory signal light. An optical amplification step of amplifying the wavelength multiplexed light; a second power measurement step of measuring the power of the monitor signal light amplified in the optical amplification step; and a first and second power measurement step. Controlling the gain of the optical amplification step so that the ratio of the obtained values becomes a predetermined constant value. 14. An optical amplification method for amplifying a wavelength multiplexed light including a supervisory signal light and at least one signal light, wherein the optical amplification method comprises: an optical amplification step of amplifying the wavelength multiplexed light; A power measuring step of measuring the power of the monitor signal light amplified in the step, and a controlling step of controlling a gain of the optical amplifying step so that a value obtained in the power measuring step becomes a predetermined constant value. An optical amplification method, comprising: 15. The optical amplifying method according to claim 13, wherein said optical amplifying method further comprises: a signal light for measuring a power of said at least one signal light. An optical amplification method, comprising: a power measurement step; and a shutdown step of terminating the optical amplification step when a result obtained in the signal light power measurement step is below a predetermined value.