JP2658607B2 - Optical regeneration repeater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical regenerative repeater in a high-speed optical transmission system using an optical fiber.

[0002]

2. Description of the Related Art With the advance of optical transmission technology, large capacity /
Ultra-high-speed optical transmission technology using long-wavelength optical devices / single-mode fiber has been studied as a potential for long-distance transmission systems, and especially broadband information communication networks that provide a wide variety of services for images, data, and voice. In order to realize this, high speed and stable practical use of optical transmission equipment are expected. The transmission capacity of the backbone transmission system in such a broadband information communication network reaches several gigabits / second in a division multiplex transmission system, and the optical transmission / reception apparatus is also required to have a wide band / high speed.

Usually, the basic functions of an optical regenerator are:
(1) shaping by equalization amplification (reshaping),
These are roughly classified into three "R" of (2) retiming, and (3) re-registration. The general configuration is 3 as shown in FIG.
It typically has a circuit that performs two basic functions (see: "Optical Fiber Communications" Telecommunications Technology News).

As means for further enhancing the function of a communication network, optical signals are processed as they are, ie, the amplifier 61, the timing circuit 62, and the identification circuit 63 in FIG. (Eg, 1989 IEICE Autumn National Convention Papers;
“Optical regenerative repeater using 1.5 μm band multi-electrode DFB-LD” by Jinno et al.)).

[0005]

However, in such an all-optical regenerative repeater which aims at increasing the speed and function of the conventional optical regenerator, the characteristics and repeatability of the optical regenerative repeater are considered. Since even the timing extraction circuit, which greatly affects the multi-stage characteristics of the optical device, is made optical, the electrical components such as the realization characteristics of the optical device, the instability of the timing signal due to stability, the increase in timing jitter, the accumulation of timing jitter, etc. However, there is a disadvantage that the characteristics are deteriorated as compared with the optical regenerative repeater configured by using.

Further, since the optical semiconductor amplifier in the all-optical regenerative repeater is configured to secure a fixed gain, the gain cannot be varied according to the level fluctuation of the optical input signal to the optical regenerative repeater. There was a disadvantage.

When the input signal from the transmission line is in a non-input state, the optical signal output from the optical semiconductor amplifier, the optical discriminating circuit, and the optical timing circuit is dominated by noise, resulting in optical regeneration. Unnecessary noise is generated from the repeater, and there is a disadvantage that an abnormal state is caused in the optical communication system.

[0008] An object of the present invention is to provide an optical regenerative repeater in which such disadvantages are eliminated.

[0009]

According to a first aspect of the present invention, there is provided an optical regenerative repeater for regenerating and relaying a transmission signal on an optical fiber transmission line. An optical semiconductor amplifier for amplifying, an injection current supply circuit for supplying a drive current to the optical semiconductor amplifier, an optical splitter for splitting output light of the optical semiconductor amplifier into two via an optical isolator, and the optical splitter An optical latch that receives one of the two branched optical signals and performs data latch as it is, a photodiode that converts the other optical signal that is branched in the optical branching device into an electric signal, A broadband amplifier that amplifies the output signal,
A differentiating circuit for detecting a change point with respect to the output signal of the broadband amplifier; a full-wave rectifier circuit for generating a bright line spectrum component using the output signal of the differentiator circuit; and a timing signal based on the output signal of the full-wave rectifier circuit. A timing tank for extracting the timing signal, a narrow band amplifier for amplifying an output signal of the timing tank, an optical latch drive current circuit for outputting a drive timing current to the optical latch using an output signal of the narrow band amplifier, A peak value detection circuit that branches and outputs an output signal of the wave rectification circuit and detects a peak value of the input signal; and a DC amplifier that generates a control voltage of the injection current supply circuit from an output signal of the peak value detection circuit. Wherein the gain of the optical semiconductor amplifier is made variable by the output current of the injection current supply circuit.

According to a second aspect of the present invention, there is provided an optical regenerative repeater for regenerating and relaying a transmission signal on an optical fiber transmission line, comprising: an optical semiconductor amplifier for inputting an optical signal input to the optical regenerative repeater and amplifying the signal as light An injection current supply circuit for supplying a drive current to the optical semiconductor amplifier, an optical splitter for splitting output light of the optical semiconductor amplifier into two via an optical isolator, and a light split in the optical splitter. An optical latch that receives one of the signals and performs data latch as it is, an optical signal, a photodiode that converts the other optical signal branched by the optical splitter into an electric signal, and a wideband that amplifies an output signal of the photodiode An amplifier, a differentiating circuit for detecting a change point with respect to the output signal of the wideband amplifier, and a full-wave rectifying circuit for generating a bright line spectrum component using the output signal of the differentiating circuit. A timing tank for extracting a timing signal from an output signal of the full-wave rectifier circuit; a narrow-band amplifier for amplifying the output signal of the timing tank; and a first detecting a peak value of the output signal of the narrow-band amplifier. A peak value detection circuit, a first DC amplifier that amplifies an output signal of the first peak value detection circuit to an appropriate level, compares the amplified signal with a set reference voltage, and generates an abnormal state display signal if the values match. An optical latch drive current circuit that inputs an output signal of the narrow band amplifier and an output signal of the first DC amplifier and supplies a drive timing current to the optical latch; and branches an output signal of the full-wave rectifier circuit. A second peak value detection circuit for inputting and detecting a peak value of the input signal; and generating a control voltage for the injection current supply circuit from an output signal of the second peak value detection circuit. A second DC amplifier, wherein the gain of the optical semiconductor amplifier is made variable by the output current of the injection current supply circuit, and the output current of the optical latch drive current circuit is stopped by the output signal of the first DC amplifier. It is characterized by doing.

According to a third aspect of the present invention, there is provided an optical regenerative repeater for regenerating and repeating a transmission signal on an optical fiber transmission line, wherein the first optical splitter splits an optical signal input to the optical regenerative repeater into two, An optical semiconductor amplifier that inputs one of the optical signals branched into two in the first optical splitter and amplifies the optical signal as light; an injection current supply circuit that supplies a drive current to the optical semiconductor amplifier; A second optical splitter for splitting the output light of the amplifier into two via an optical isolator; and an optical latch for receiving one of the optical signals split by the second optical splitter and performing data latch as it is. A first photodiode for converting the other optical signal split by the second optical splitter into an electric signal, a wideband amplifier for amplifying an output signal of the first photodiode, and a wideband amplifier. output A differentiating circuit for detecting a change point with respect to a signal, a full-wave rectifier circuit for generating a bright line spectrum component using an output signal of the differentiating circuit, and a timing tank for extracting a timing signal from the output signal of the full-wave rectifier circuit A narrow band amplifier for amplifying an output signal of the timing tank; a first peak value detection circuit for detecting a peak value of the output signal of the narrow band amplifier; and an output signal of the first peak value detection circuit. A first DC amplifier that amplifies the signal to an appropriate level and compares it with a first set reference voltage, and if they match, generates an abnormal state indication signal; and outputs the output signal of the first DC amplifier to one input signal. An AND circuit, an optical latch drive current circuit that receives the output signal of the narrow band amplifier and the output signal of the AND circuit, and supplies a drive timing current to the optical latch. A second peak value detection circuit for branching and inputting an output signal of the full-wave rectifier circuit and detecting a peak value of the input signal, and controlling the injection current supply circuit from an output signal of the second peak value detection circuit A second DC amplifier for generating a voltage, a second photodiode for receiving the other output light of the first optical splitter, and a voltage signal corresponding to an average photocurrent received by the second photodiode And a third DC amplifier that outputs an abnormal state display signal to the AND circuit when the values match with each other and outputs a signal indicating an abnormal state to the AND circuit. It is characterized in that the gain of the optical semiconductor amplifier is made variable and the output current of the optical latch drive current circuit is stopped by performing an AND operation on the output signal of the first DC amplifier and the output signal of the third DC amplifier. Sign.

According to a fourth aspect of the present invention, there is provided an optical regenerative repeater for regenerating and repeating a transmission signal on an optical fiber transmission line, wherein the first optical splitter bifurcates the optical signal input to the optical regenerative repeater; An optical semiconductor amplifier that inputs one of the optical signals branched into two in the first optical splitter and amplifies the optical signal as light; an injection current supply circuit that supplies a drive current to the optical semiconductor amplifier; A second optical splitter for splitting the output light of the amplifier into two via an optical isolator; and an optical latch for receiving one of the optical signals split by the second optical splitter and performing data latch as it is. A first photodiode for converting the other optical signal split by the second optical splitter into an electric signal, a wideband amplifier for amplifying an output signal of the first photodiode, and a wideband amplifier. output A differentiating circuit for detecting a change point with respect to a signal, a full-wave rectifier circuit for generating a bright line spectrum component using an output signal of the differentiating circuit, and a timing tank for extracting a timing signal from the output signal of the full-wave rectifier circuit A narrow band amplifier for amplifying an output signal of the timing tank; a first peak value detection circuit for detecting a peak value of the output signal of the narrow band amplifier; and an output signal of the first peak value detection circuit. A first DC amplifier that amplifies the signal to an appropriate level and compares it with a first set reference voltage, and if they match, generates an abnormal state indication signal; and outputs the output signal of the first DC amplifier to one input signal. An AND circuit, an optical latch drive current circuit that receives the output signal of the narrow band amplifier and the output signal of the AND circuit, and supplies a drive timing current to the optical latch. A second peak value detection circuit for branching and inputting an output signal of the full-wave rectifier circuit and detecting a peak value of the input signal, and controlling the injection current supply circuit from an output signal of the second peak value detection circuit A second DC amplifier for generating a voltage, a second photodiode for receiving the other output light of the first optical splitter, and a voltage signal corresponding to an average photocurrent received by the second photodiode And compares it with a second set reference voltage. If the two match, an abnormal state display signal is output from the AND circuit and the third DC amplifier that outputs the signal to the injection current supply circuit. The gain of the optical semiconductor amplifier is made variable by the output current of the supply circuit.
The output current of the injection current supply circuit is determined by the output signal of the DC amplifier and the output of the optical latch drive current circuit is calculated by performing a logical product operation on the output signal of the first DC amplifier and the output signal of the third DC amplifier. The current is stopped.

According to a fifth aspect of the present invention, there is provided an optical regenerative repeater for regenerating and relaying a transmission signal of an optical fiber transmission line, wherein the first optical splitter splits an optical signal input to the optical regenerative repeater into two, An optical semiconductor amplifier that inputs one of the optical signals branched into two in the first optical splitter and amplifies the optical signal as light; an injection current supply circuit that supplies a drive current to the optical semiconductor amplifier; A second optical splitter for splitting the output light of the amplifier into two via an optical isolator; and an optical latch for receiving one of the optical signals split by the second optical splitter and performing data latch as it is. A first photodiode for converting the other optical signal split by the second optical splitter into an electric signal, a wideband amplifier for amplifying an output signal of the first photodiode, and a wideband amplifier. output A differentiating circuit for detecting a change point with respect to a signal, a full-wave rectifier circuit for generating a bright line spectrum component using an output signal of the differentiating circuit, and a timing tank for extracting a timing signal from the output signal of the full-wave rectifier circuit A narrow band amplifier for amplifying an output signal of the timing tank; a first peak value detection circuit for detecting a peak value of the output signal of the narrow band amplifier; and an output signal of the first peak value detection circuit. A first DC amplifier that amplifies the signal to an appropriate level and compares it with a first set reference voltage, and if they match, generates an abnormal state indication signal; and outputs the output signal of the first DC amplifier to one input signal. An AND circuit, an optical latch drive current circuit that receives the output signal of the narrow band amplifier and the output signal of the AND circuit, and supplies a drive timing current to the optical latch. A second peak value detection circuit for branching and inputting an output signal of the full-wave rectifier circuit and detecting a peak value of the input signal, and controlling the injection current supply circuit from an output signal of the second peak value detection circuit A second DC amplifier for generating a voltage, a second photodiode for receiving the other output light of the first optical splitter, and a voltage signal corresponding to an average photocurrent received by the second photodiode And compares it with a second set reference voltage, and if they match, a third DC amplifier that outputs an abnormal state display signal to the AND circuit, the injection current supply circuit, and the second peak. An output signal of the value detection circuit is used as an input signal, a comparison is made with a third set reference voltage, and if they match, a fourth DC amplifier that generates an abnormal state display signal, and an output signal of the third DC amplifier are output. First arra as input A second alarm display circuit to which an output signal of the first display circuit and an output signal of the fourth DC amplifier are input, and an output signal of the second alarm display circuit and the second alarm display circuit. A third alarm display circuit that receives an output signal of the first DC amplifier as an input, wherein the gain of the optical semiconductor amplifier is made variable by an output current of the injection current supply circuit, and an output of the third DC amplifier is further changed. The output current of the injection current supply circuit is stopped by the signal, and the output current of the optical latch drive current circuit is stopped by AND processing of the output signal of the second DC amplifier and the output signal of the third DC amplifier. It is characterized in that a fault display is performed by an alarm display circuit.

[0014]

According to the first aspect of the present invention, an optical signal transmitted through an optical fiber is amplified by an optical semiconductor amplifier and then branched into two.
One is input to an optical latch, and the other of the two branched optical signals is subjected to optical / electrical conversion, and then a timing signal is extracted in an electric circuit and input to the optical latch as timing information for optical latch processing. As a result, it is possible to secure a highly stable timing signal with very little timing jitter as a timing signal and to perform optical latch processing using the timing signal, so that there is almost no accumulation of jitter and the like, and the characteristics as an optical regenerator are improved. Can be. Also,
An AGC amplifier can be configured by performing peak value detection using the output signal of the full-wave rectifier circuit of the electric timing extraction circuit and inputting it to the injection current supply circuit of the optical semiconductor amplifier. It is possible to sufficiently cope with fluctuations in the input optical signal level.

Further, according to the second invention, the timing signal extracted in the timing tank is amplified to a sufficient amplitude value in the narrow-band amplifier, and the output signal of the narrow-band amplifier is branched into two to split one of the timing signals. A peak value is detected and compared with a preset reference voltage value corresponding to a non-input state of an optical signal, and when they match, an abnormality occurrence display signal is output to a drive timing current supply circuit that drives an optical latch. By stopping the drive current to the optical latch, it is possible to prevent unnecessary noise generated when no optical signal is input from being output from the optical regenerator.

According to the third aspect of the present invention, the optical input signal to the optical semiconductor amplifier is split into two and optical / electrical conversion is performed, and the state of the optical signal input to the optical regenerator is monitored and set in advance. Performs a comparison with a reference voltage value corresponding to a non-input state of a certain optical signal, and generates an abnormal state occurrence display signal when they match,
An AND operation of this signal and an abnormal state occurrence display signal from the timing system is performed, and the resulting signal is used to control the drive timing current supply circuit that drives the optical latch, so that the non-input state of the optical signal is obtained. Is detected from the timing signal and the optical data signal, and unnecessary noise generated when no signal is input can be prevented from being output from the optical regenerator.

According to the fourth aspect of the present invention, the optical input signal to the optical semiconductor amplifier is divided into two and optical / electrical conversion is performed, and the state of the optical signal input to the optical regenerator is monitored and set in advance. Performs a comparison with a reference voltage value corresponding to a non-input state of a certain optical signal, and generates an abnormal state occurrence display signal when they match,
With this signal, the injection current of the optical semiconductor amplifier is stopped, and a logical AND operation with the abnormal state occurrence display signal from the timing system is performed, and the drive timing current supply circuit that drives the optical latch using the resulting signal is provided. By controlling, it is possible to detect the non-input state of the optical signal from the timing signal and the optical data signal, to prevent unnecessary noise generated when the signal is not input from being output from the optical regenerator and to control the optical semiconductor. It is possible to prevent supply of an excessively large injection current to the amplifier, and it is possible to avoid shortening the life of the optical semiconductor amplifier.

Further, according to the fifth aspect of the present invention, by using the timing system when the optical signal is in the non-input state, the abnormal state display signal of the input monitor system, and the peak value level monitor signal of the AGC control system, Failure monitoring of the regenerative repeater can be performed, and the reliability of the entire optical communication system can be improved.

[0019]

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

FIG. 1 is a block diagram of an optical regenerator according to an embodiment of the first invention. This optical regenerative repeater is provided with an optical semiconductor amplifier 12 for inputting an input optical signal and amplifying it as light.
An injection current supply circuit 13 that supplies a drive current to the optical semiconductor amplifier; and an optical splitter 15 that splits output light of the optical semiconductor amplifier 12 into two via an optical isolator 14.
And an optical latch 17 which receives one of the two optical signals branched by the optical splitter and performs data latch as it is.
And a photodiode (photodetector) for converting the other optical signal split by the optical splitter 15 into an electric signal
16, a broadband amplifier 18 for amplifying the output signal of the photodiode, a differentiating circuit 19 for detecting a change point with respect to the output signal of the broadband amplifier, and generating a bright line spectrum component using the output signal of the differentiating circuit. Rectifying circuit 20, a timing tank 21 for extracting a timing signal from an output signal of the full-wave rectifying circuit, and a narrow band amplifier 22 for amplifying an output signal of the timing tank.
And an optical latch 17 using the output signal of the narrow band amplifier.
And a peak value detecting circuit 2 for branching and inputting the output signal of the full-wave rectifier circuit 20 and detecting the peak value of the input signal.
4 and a DC amplifier 25 that generates a control voltage for the injection current supply circuit 13 from an output signal of the peak value detection circuit.

The optical signal transmitted through the optical fiber 11 is input to the optical semiconductor amplifier 12. Optical semiconductor amplifier 12
Is amplified as an optical signal by the gain amount set by the amount of the injection current supplied from the injection current supply circuit 15 and output as an optical signal from the optical semiconductor amplifier 12. The bandwidth for the optical signal in the optical semiconductor amplifier 12 is ９9 THz or more, which is a band that cannot be realized by the optical receiving circuit using the APD.
Accordingly, it can be said that there is substantially no band limitation in the optical semiconductor amplifier 12. The principle of this optical semiconductor amplifier is described in “Semiconductor Laser Optical Amplifier”
See Communications Research Institute Technical Report, CS82-24.

An optical signal output from the optical semiconductor amplifier 12 is input to an optical splitter 15 via an isolator 14 for removing the influence of reflection, and is split into two. The split optical signal is input to the photodetector 16 and the optical latch 17.
Although not shown in the figure, the optical semiconductor amplifier 1
It is an effective means to provide an optical narrow band filter between the optical semiconductor amplifier 12 and the isolator 14 for avoiding S / N degradation due to the influence of spontaneous emission noise from the optical amplifier 2.
The bandwidth of this filter is about 1 nm. The optical signal input to the photodetector 16 undergoes optical / electrical conversion, and is input to the broadband amplifier 18.
It is amplified to an appropriate signal level. Here, when the transmission path code is, for example, an NRZ (non-return-to-zero) code, the output signal of the broadband amplifier 18 does not have a timing emission line spectrum. Therefore, the differentiation circuit 1
9. A timing bright line spectrum component is generated in the full-wave rectifier circuit 20 and input to the timing tank 21. It is desirable to use a stable tank such as a surface acoustic wave filter (SAW) as the timing tank 21. In addition, it is desirable that the ratio bandwidth Q of the filter is as large as possible from the viewpoint of timing characteristics.
Considering the feasibility and the influence of temperature fluctuation, for example, 100
It is considered sufficient to have about 0. The timing signal extracted in the timing tank 21 has a frequency synchronized with the data transmission speed of the transmission path. In the narrow-band amplifier 22, only this frequency component is tuned and amplified, and a timing signal having a sufficient signal level is output to the drive current circuit 23 for driving the optical latch 17. In the optical latch 17, the optical data signal input from the optical branching device 15 is subjected to the identification processing of the optical data signal by the timing current supplied from the optical latch drive current circuit 23, and is output to the transmission line. Research has been conducted on, for example, a bistable LD or the like as the optical latch 17, and the principle of the details is described in, for example, Suzuki et al., IEICE Technical Report SE84.
-62, "Study of time division optical switch using bistable LD"
See October 1987. The output signal of the full-wave rectifier circuit 20 is branched and input to the peak value detection circuit 24. The detection result of the peak value detection circuit 24 is input to the DC amplifier 25. Here, in the DC amplifier 25, the input optical signal level to the optical latch 17 is always kept constant.
It has a reference voltage corresponding to the signal level, compares it with the input signal from the photodetector 16, and changes the amplification gain. Therefore, the current value from the injection current supply circuit 135 that supplies the injection current to the optical semiconductor amplifier 12 changes according to the output voltage of the DC amplifier 25. That is, the gain of the optical semiconductor amplifier 12 changes.
Therefore, an optical AGC amplifier is configured.

As described above, the timing signal supplied to the optical latch is extracted by the electrical timing extraction circuit, and the optical latch process is performed using the extracted timing signal. As a signal, a signal having good characteristics with little jitter can be output. Also, the optical semiconductor amplifier 12 performs variable gain amplification following the fluctuation of the optical input level to the optical regenerator.

FIG. 2 is a block diagram of an optical regenerative repeater according to an embodiment of the second invention. This optical regenerative repeater is provided with an optical semiconductor amplifier 12 for inputting an input optical signal and amplifying it as light.
An injection current supply circuit 13 that supplies a drive current to the optical semiconductor amplifier; and an optical splitter 15 that splits output light of the optical semiconductor amplifier 12 into two via an optical isolator 14.
And an optical latch 17 which receives one of the two optical signals branched by the optical splitter and performs data latch as it is.
And a photodiode (photodetector) for converting the other optical signal split by the optical splitter 15 into an electric signal
16, a broadband amplifier 18 for amplifying the output signal of the photodiode, a differentiating circuit 19 for detecting a change point with respect to the output signal of the broadband amplifier, and generating a bright line spectrum component using the output signal of the differentiating circuit. Rectifying circuit 20, a timing tank 21 for extracting a timing signal from an output signal of the full-wave rectifying circuit, and a narrow band amplifier 22 for amplifying an output signal of the timing tank.
And a first peak value detection circuit 232 for detecting the peak value of the output signal of the narrow band amplifier, and comparing the output signal of the first peak value detection circuit to an appropriate level and comparing with a set reference voltage. And a first DC amplifier 233 for generating an abnormal state display signal if they match, and a narrow band amplifier 2
2 and an output signal of the first DC amplifier 233 to input an optical latch drive current circuit 231 for supplying a drive timing current to the optical latch 17; It comprises a second peak value detection circuit 24 for detecting a peak value of an input signal, and a second DC amplifier 13 for generating a control voltage for the injection current supply circuit 13 from an output signal of the second peak value detection circuit. Have been.

This optical regenerative repeater basically performs the same operation as that of the optical regenerative repeater shown in FIG. 1, but in this embodiment, the optical regenerator responds to no input of an optical signal.

That is, the extraction timing signal amplified by the narrow band amplifier 22 is branched into two, one of which is input to the optical latch drive current circuit 231 and the other is the peak value detection circuit 2.
32, and the peak value is detected. In the timing signal output from the narrow band amplifier 22, only the timing frequency component is selectively amplified. Therefore, the signal level difference between the signal transmission and the signal interruption is sufficiently large. The output signal of the peak value detection circuit 232 is supplied to the first DC amplifier 233
, A comparison is made with a set voltage corresponding to the output voltage of the peak value detection circuit 232 when the optical signal to the optical regenerator is in the non-input state as a comparison reference voltage, and as an abnormal state occurrence display signal, for example, the TTL level Is input to the optical latch drive current circuit 231, and as a result, the timing drive current to the optical latch 17 is completely stopped when the no light input state is detected.

Therefore, the optical signal input becomes non-input,
The AGC control works so that the gain of the optical semiconductor amplifier 12 is maximized. Even if the optical signal input to the optical latch 17 is mainly noise, the operation of the optical latch 17 is eventually stopped. Therefore, unnecessary noise is not generated from the optical regenerative repeater, and the reliability of the optical communication system is improved. Also, in the electrical system timing extraction circuit,
In a no-signal input state, unnecessary noise may be generated due to a large gain of the amplifier. However, according to the second aspect of the present invention, even if noise from the timing extraction circuit is input to the optical latch 17, the current itself for operating the optical latch 17 is cut off, so that no noise is output to the transmission line. .

FIG. 3 shows an embodiment of the third invention. This optical regenerative repeater includes a first optical splitter 31 that splits an input optical signal into two, and a light that receives one of the optical signals split into two in the first optical splitter and amplifies the optical signal as it is. A semiconductor amplifier 12, an injection current supply circuit 13 for supplying a drive current to the optical semiconductor amplifier, a second optical splitter 15 for splitting output light of the optical semiconductor amplifier 12 via an optical isolator 14, An optical latch 17 that receives one of the optical signals branched into two in the second optical splitter and performs data latch as it is, and converts the other optical signal split in the second optical splitter 15 into electrical signals. A first photodiode (photodetector) 16 for converting a signal into a signal, and a wideband amplifier 1 for amplifying an output signal of the first photodiode
8, a differentiating circuit 19 for detecting a change point with respect to the output signal of the broadband amplifier, and a full-wave rectifying circuit 20 for generating a bright line spectrum component using the output signal of the differentiating circuit.
A timing tank 21 for extracting a timing signal from an output signal of the full-wave rectifier circuit, a narrow-band amplifier 22 for amplifying the output signal of the timing tank, and a second detection unit for detecting a peak value of the output signal of the narrow-band amplifier. The first peak value detection circuit 232 and the output signal of the first peak value detection circuit are amplified to an appropriate level and compared with a first set reference voltage. If they match, an abnormal state display signal is generated. A first DC amplifier 233, an AND circuit 34 using the output signal of the first DC amplifier as one input signal,
An output signal of the narrow-band amplifier 22 and an output signal of the AND circuit 34 are input, and an optical latch drive current circuit 35 for supplying a drive timing current to the optical latch, and an output signal of the full-wave rectifier circuit 20 are branched and input. A second peak value detection circuit 24 for detecting a peak value of the input signal, a second DC amplifier 25 for generating a control voltage for the injection current supply circuit 13 from an output signal of the second peak value detection circuit, A second photodiode (photodetector) 32 for receiving the other output light of the first optical splitter 31 and a voltage signal corresponding to an average photocurrent received by the second photodiode are input to a second photodiode. A third DC amplifier that compares the voltage with the set reference voltage and outputs an abnormal state display signal to the AND circuit 34 if the voltage is equal to the reference voltage.

The basic operation of this optical regenerative repeater is almost the same as that of the optical regenerative repeater shown in FIG. 2, but the stop control of the optical latch 17 is controlled not only by the detection result from the timing system but also by the optical semiconductor amplifier. The monitoring is also performed using the input signal, that is, the monitoring result of the optical signal input to the optical regenerator.

That is, the optical input signal to the optical regenerative repeater is split into two in the first optical splitter 31, and one is input to the second photodetector 32. As the output of the photodetector 32, the voltage corresponding to the average value of the optical signal current is the third voltage.
Is output to the DC amplifier 33. Third DC amplifier 33
Then, the input voltage value corresponds to a non-input state, and is compared with a preset second set reference voltage (Vref2). The "H" signal is output as an abnormal state occurrence display signal. At this time, it is necessary to consider the mark rate of the optical data signal and to set a voltage value smaller than the minimum reference rate so as not to make an error, in consideration of the mark rate of the optical data signal. The AND circuit 34 performs an AND operation on the abnormal state occurrence display signal from the timing circuit system and the detection result of the third DC amplifier 33, and when both are at the “H” level, for example, the timing to the optical latch 17 is output. A signal for completely stopping the drive current is output to the optical latch drive current circuit 35 to perform control.

Therefore, even when the optical input signal to the optical regenerative repeater becomes non-input, unnecessary noise can be prevented from being generated from the repeater. Further, the first photodetector 16
Even if the input to the input becomes a non-input state, the transmission path 26 is not affected. Further, since the control system detects the peak values of the input signal and the timing signal of the optical semiconductor amplifier, the data optical signal is not lost due to malfunction.

FIG. 4 shows an embodiment of the fourth invention. This optical regenerative repeater includes a first optical splitter 31 that splits an input optical signal into two, and a light that receives one of the optical signals split into two in the first optical splitter and amplifies the optical signal as it is. A semiconductor amplifier 12, an injection current supply circuit 43 for supplying a drive current to the optical semiconductor amplifier, a second optical splitter 15 for splitting output light of the optical semiconductor amplifier 12 into two via an optical isolator 14, An optical latch 17 that receives one of the optical signals branched into two in the second optical splitter and performs data latch as it is, and converts the other optical signal split in the second optical splitter 15 into electrical signals. A first photodiode (photodetector) 16 for converting a signal into a signal, and a wideband amplifier 1 for amplifying an output signal of the first photodiode
8, a differentiating circuit 19 for detecting a change point with respect to the output signal of the broadband amplifier, and a full-wave rectifying circuit 20 for generating a bright line spectrum component using the output signal of the differentiating circuit.
A timing tank 21 for extracting a timing signal from the output signal of the full-wave rectifier circuit, a narrow-band amplifier 22 for amplifying the output signal of the timing tank, and a peak value of the output signal of the narrow-band amplifier circuit. The first peak value detection circuit 232 amplifies the output signal of the first peak value detection circuit to an appropriate level, compares it with a first set reference voltage, and if they match, generates an abnormal state display signal. A first DC amplifier 233, an AND circuit 34 using the output signal of the first DC amplifier as one input signal,
An output signal of the narrow-band amplifier 22 and an output signal of the AND circuit 34 are input, and an optical latch drive current circuit 35 for supplying a drive timing current to the optical latch, and an output signal of the full-wave rectifier circuit 20 are branched and input. A second peak value detection circuit 24 for detecting the peak value of the input signal, a second DC amplifier 25 for generating a control voltage for the injection current supply circuit 43 from an output signal of the second peak value detection circuit, A second photodiode (photodetector) 32 for receiving the other output light of the first optical splitter 31 and a voltage signal corresponding to an average photocurrent received by the second photodiode are input to a second photodiode. A comparison is made with the set reference voltage, and if they match, an abnormal state display signal is output to the AND circuit 34 and the injection current supply circuit 4.
3 and a third DC amplifier for outputting to the third DC amplifier.

The basic operation of this optical regenerator is almost the same as that of the optical regenerator of FIG.
Not only the detection result from the timing system but also the monitoring result of the optical input signal to the optical semiconductor amplifier, that is, the monitoring result of the optical signal input to the optical regenerator, is used. ing.

That is, the optical input signal to the optical regenerator is split into two in the first optical splitter 31, and one of the split signals is input to the second photodetector 32. As the output of the photodetector 32, the voltage corresponding to the average value of the optical signal current is the third voltage.
Is output to the DC amplifier 33. Third DC amplifier 33
Then, the input voltage value corresponds to the non-input state, and is compared with a preset second set reference voltage (Vref2). For example, a TTL level “H” signal is output as an abnormal state occurrence display signal. At this time, as the set reference voltage, the mark ratio of the optical data signal is considered,
It is necessary to set a voltage value smaller than the mark ratio when the mark ratio is minimum so as not to make an error. AND circuit 34
Now, an abnormal condition occurrence display signal from the timing circuit system,
An AND operation with the detection result of the third DC amplifier 33 is performed, and when both are at the “H” level, for example, a signal for completely stopping the timing driving current to the optical latch 17 is output to the optical latch driving current circuit 35. And control. In addition, in the injection current supply circuit 43, the optical amplifier 1 also receives the abnormal state occurrence display signal input from the third DC amplifier 33.
The supply of the injection current to 2 is stopped.

Therefore, even when the optical input signal to the optical regenerative repeater becomes non-input, unnecessary noise can be prevented from being generated from the repeater. Further, the first photodetector 16
Even if the input to the input becomes a non-input state, the transmission path 26 is not affected. Further, since the control system detects the peak values of the input signal and the timing signal of the optical semiconductor amplifier, the data optical signal is not lost due to malfunction. On the other hand, when the optical input to the optical regenerative repeater enters the non-input state, the AGC control system, that is, the second DC amplifier 25 outputs a control voltage to the injection current supply circuit 43 in a direction to increase the gain of the optical amplifier 12. I do. In the operation in this state, an excessive injection current may be supplied to the optical amplifier 12, and as a result, the optical amplifier 12 may be damaged. However, in FIG.
When the optical signal to the optical regenerative repeater becomes non-input by the control signal from the optical amplifier 12, the injection current to the optical amplifier 12 is cut off.
2 can be avoided.

FIG. 5 shows a fifth embodiment of the present invention. This optical regenerative repeater comprises a first optical splitter for splitting an input optical signal into two.
, An optical semiconductor amplifier 12 that receives one of the optical signals branched into two in the first optical splitter and amplifies the optical signal as it is, and an injection that supplies a drive current to the optical semiconductor amplifier. Current supply circuit 43 and optical semiconductor amplifier 12
Output light is split into two via the optical isolator 14.
, An optical latch 17 that receives one of the optical signals branched into two in the second optical splitter and performs data latch as it is, and splits in the second optical splitter 15 A first photodiode (photodetector) 16 for converting the other optical signal into an electric signal, and a broadband amplifier 18 for amplifying an output signal of the first photodiode
A differentiating circuit 19 for detecting a change point with respect to the output signal of the broadband amplifier, a full-wave rectifying circuit 20 for generating a bright line spectrum component using the output signal of the differentiating circuit,
A timing tank 21 for extracting a timing signal from an output signal of the full-wave rectifier circuit, a narrow band amplifier 22 for amplifying the output signal of the timing tank, and a first band detecting a peak value of the output signal of the narrow band amplifier. A peak value detection circuit 232 and an output signal of the first peak value detection circuit are amplified to an appropriate level and compared with a first set reference voltage. , An AND circuit 34 using the output signal of the first DC amplifier as one input signal, an output signal of the narrow band amplifier 22 and an output signal of the AND circuit 34, and input to the optical latch 17. An optical latch drive current circuit 35 for supplying a drive timing current; and a second peak value detection circuit for branching and inputting the output signal of the full-wave rectifier circuit 20 and detecting the peak value of the input signal. A circuit 24, and the second DC amplifier 25 which generates a control voltage for injection current supply circuit 43 from the output signal of the second peak value detecting circuit, a first optical splitter 3
1 and a second photodiode (photodetector) 32 for receiving the other output light, and a voltage signal corresponding to an average photocurrent received by the second photodiode is input and compared with a second set reference voltage. And if they match, an abnormal state display signal is output to the AND circuit 34 and the injection current supply circuit 43.
The output signal of the third DC amplifier 33 and the output signal of the second peak value detection circuit 24 are used as an input signal, and a comparison is made with a third set reference voltage. 4 and the third DC amplifier 3
The first alarm display circuit 55 to which the output signal of the third is input.
A second alarm display circuit 56 to which the output signal of the first alarm display circuit and the output signal of the fourth DC amplifier 54 are input, and the output signal of the second alarm display circuit and the first DC A third inputting the output signal of the amplifier 233
And an alarm display circuit 57.

This optical regenerative repeater basically performs the same operation and function as the optical regenerative repeater shown in FIG. 4, except that an abnormal state occurrence display signal 51 detected from the optical input signal of the optical semiconductor amplifier 12 and , The abnormal state occurrence display signal 52 detected from the extraction timing signal, and the second peak value detection circuit 24
Output signal and a third reference voltage (Vre
f3) is used to perform a fault occurrence display (fault management) of the optical regenerator using the output signal 53 of the fourth DC amplifier 54, which is the result of comparison with f3). That is, the first alarm display circuit 55 outputs an alarm signal to the external monitoring system when the output signal of the third DC amplifier 33 is at "H" level, for example. The second and third alarm display circuits 56 and 57 perform the same operation according to the input state. For example, when there is an abnormal display in the output of all the display circuits by these display circuits, it means that the input of the optical regenerator is in a non-input state. When the second and third display circuits 56 and 57 display an abnormality, it indicates that an optical signal has arrived at the repeater, but an abnormality has occurred in the system after the optical amplifier 12. When only the third display circuit 57 indicates the abnormality, it is possible to indicate the state of the timing signal interruption due to the abnormality of the timing extraction circuit. As described above, according to the fifth aspect, fault management of the optical regenerator can be performed, and the reliability of the entire optical communication system can be improved.

[0038]

According to the first aspect of the invention, an optical signal transmitted through an optical fiber is amplified by an optical semiconductor amplifier and then branched into two, one of which is input to an optical latch, and the other of the two branched optical signals. After the signal is subjected to optical / electrical conversion, a timing signal is extracted in an electric circuit and input to the optical latch as timing information for the optical latch process. Since the signal is secured and the optical latch process is performed using the timing signal, there is almost no accumulation of jitter and the like, and the characteristics as the optical regenerator can be improved. Also, by detecting the peak value using the output signal of the full-wave rectifier circuit of the electric timing extraction circuit and inputting the peak value to the injection current supply circuit of the optical semiconductor amplifier, an AGC amplifier can be configured. Can sufficiently cope with fluctuations in the input optical signal level.

Further, according to the second invention, the timing signal extracted in the timing tank is amplified to a sufficient amplitude value in the narrow band amplifier, and the output signal of the narrow band amplifier is divided into two to split the output signal of one of the timing signals. A peak value is detected and compared with a preset reference voltage value corresponding to a non-input state of an optical signal, and when they match, an abnormality occurrence display signal is output to a drive timing current supply circuit that drives an optical latch. By stopping the drive current to the optical latch, it is possible to prevent unnecessary noise generated when no optical signal is input from being output from the optical regenerator.

According to the third aspect of the present invention, the optical input signal to the optical semiconductor amplifier is divided into two and optical / electrical conversion is performed, and the state of the optical signal input to the optical regenerator is monitored and set in advance. Performs a comparison with a reference voltage value corresponding to a non-input state of a certain optical signal, and generates an abnormal state occurrence display signal when they match,
An AND operation of this signal and an abnormal state occurrence display signal from the timing system is performed, and the resulting signal is used to control the drive timing current supply circuit that drives the optical latch, so that the non-input state of the optical signal is obtained. Is detected from the timing signal and the optical data signal, and unnecessary noise generated when no signal is input can be prevented from being output from the optical regenerator.

According to the fourth aspect of the present invention, the optical input signal to the optical semiconductor amplifier is divided into two and optical / electrical conversion is performed, and the state of the optical signal input to the optical regenerator is monitored and set in advance. Performs a comparison with a reference voltage value corresponding to a non-input state of a certain optical signal, and generates an abnormal state occurrence display signal when they match,
With this signal, the injection current of the optical semiconductor amplifier is stopped, and a logical AND operation with the abnormal state occurrence display signal from the timing system is performed, and the drive timing current supply circuit that drives the optical latch using the resulting signal is provided. By controlling, it is possible to detect the non-input state of the optical signal from the timing signal and the optical data signal, to prevent unnecessary noise generated when the signal is not input from being output from the optical regenerator and to control the optical semiconductor. It is possible to prevent supply of an excessively large injection current to the amplifier, and it is possible to avoid shortening the life of the optical semiconductor amplifier.

Further, according to the fifth aspect of the present invention, by using the timing system when the optical signal is in the non-input state, the abnormal state display signal of the input monitor system, and the peak value level monitor signal of the AGC control system, the optical reproduction is performed. Fault monitoring of the repeater can be performed, and the reliability of the entire optical communication system can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the first invention.

FIG. 2 is a diagram showing an embodiment of the second invention.

FIG. 3 is a diagram showing an embodiment of the third invention.

FIG. 4 is a diagram showing an embodiment of the fourth invention.

FIG. 5 is a diagram showing an embodiment of the fifth invention.

FIG. 6 is a diagram for explaining a conventional technique.

[Explanation of symbols]

 11, 26 Optical fiber 13, 43 Injection current supply circuit 14 Optical isolator 15, 31 Optical splitter 16, 32 Photodetector 17 Optical latch 18 Broadband amplifier 19 Differentiation circuit 20 Full-wave rectifier circuit 21 Timing tank 22 Narrow band amplifier 23, 35 , 231 Drive current circuit 24, 232 Peak value detection circuit 25, 33, 54, 233 DC amplifier 34 Logical product circuit 51, 52, 53 Signal line 55, 56, 57 Alarm display circuit 58, 59, 60 Terminal

Claims (5)

(57) [Claims] 1. An optical regenerative repeater for regenerating and repeating a transmission signal on an optical fiber transmission line, comprising: an optical semiconductor amplifier for inputting an optical signal input to the optical regenerative repeater and amplifying the optical signal as light; An injection current supply circuit for supplying a drive current to the amplifier, an optical splitter that splits the output light of the optical semiconductor amplifier into two via an optical isolator, and one of the optical signals split in the optical splitter. An optical latch that receives and performs data latching as an optical signal, a photodiode that converts the other optical signal branched by the optical splitter into an electric signal, a broadband amplifier that amplifies an output signal of the photodiode, and A differentiating circuit for detecting a change point with respect to an output signal of the broadband amplifier; a full-wave rectifier circuit for generating an emission line spectrum component using the output signal of the differentiating circuit; A timing tank for extracting a timing signal from an output signal of a flow circuit, a narrow band amplifier for amplifying the output signal of the timing tank, and a light for outputting a drive timing current to the optical latch using the output signal of the narrow band amplifier. A latch drive current circuit, a peak value detection circuit for branching and inputting an output signal of the full-wave rectification circuit and detecting a peak value of the input signal, and a peak value detection circuit of the injection current supply circuit based on an output signal of the peak value detection circuit. An optical regenerative repeater, comprising: a DC amplifier that generates a control voltage, wherein the gain of the optical semiconductor amplifier is made variable by an output current of the injection current supply circuit. 2. An optical regenerative repeater for regenerating and relaying a transmission signal on an optical fiber transmission line, comprising: an optical semiconductor amplifier for inputting an optical signal input to the optical regenerative repeater and amplifying the optical signal as light; An injection current supply circuit for supplying a drive current to the amplifier, an optical splitter that splits the output light of the optical semiconductor amplifier into two via an optical isolator, and one of the optical signals split in the optical splitter. An optical latch that receives and performs data latching as an optical signal, a photodiode that converts the other optical signal branched by the optical splitter into an electric signal, a broadband amplifier that amplifies an output signal of the photodiode, and A differentiating circuit for detecting a change point with respect to an output signal of the broadband amplifier; a full-wave rectifier circuit for generating an emission line spectrum component using the output signal of the differentiating circuit; A timing tank for extracting a timing signal from an output signal of the flow circuit, a narrow band amplifier for amplifying the output signal of the timing tank, and a first peak value detection circuit for detecting a peak value of the output signal of the narrow band amplifier. Amplifying the output signal of the first peak value detection circuit to an appropriate level and comparing it with a set reference voltage;
A first DC amplifier for generating an abnormal state indication signal if they match, an optical latch for inputting an output signal of the narrow band amplifier and an output signal of the first DC amplifier and supplying a drive timing current to the optical latch; A drive current circuit, a second peak value detection circuit for branching and inputting an output signal of the full-wave rectifier circuit, and detecting a peak value of the input signal;
And a second DC amplifier for generating a control voltage of the injection current supply circuit from an output signal of the peak value detection circuit, wherein the gain of the optical semiconductor amplifier is made variable by an output current of the injection current supply circuit. An optical regenerative repeater, wherein an output current of the optical latch drive current circuit is stopped by an output signal of a first DC amplifier. 3. An optical regenerative repeater for regenerating and relaying a transmission signal on an optical fiber transmission line, comprising: a first optical splitter for bifurcating an optical signal input to the optical regenerative repeater; An optical semiconductor amplifier for inputting one of the optical signals branched into two in the optical splitter and amplifying the optical signal as it is, an injection current supply circuit for supplying a drive current to the optical semiconductor amplifier, and an output light of the optical semiconductor amplifier A second optical splitter that splits the optical signal into two via an optical isolator, an optical latch that receives one of the optical signals split by the second optical splitter and performs data latch as it is, and A first photodiode for converting the other optical signal split by the two optical splitters into an electric signal, a wideband amplifier for amplifying an output signal of the first photodiode, and a Strange A differentiating circuit for performing point detection, a full-wave rectifier circuit for generating a bright line spectrum component using an output signal of the differentiator circuit, a timing tank for extracting a timing signal from an output signal of the full-wave rectifier circuit, and the timing tank , A first peak value detection circuit for detecting a peak value of an output signal of the narrow band amplifier, and an output signal of the first peak value detection circuit to an appropriate level. A first DC amplifier that compares the first DC voltage with a first set reference voltage and generates an abnormal state display signal if they match, and an AND circuit that uses the output signal of the first DC amplifier as one input signal An optical latch drive current circuit that inputs an output signal of the narrow band amplifier and an output signal of the AND circuit and supplies a drive timing current to the optical latch; and the full-wave rectifier circuit. A second peak value detection circuit for branching and inputting the output signal and detecting a peak value of the input signal; and a second peak value generation circuit for generating a control voltage for the injection current supply circuit from an output signal of the second peak value detection circuit. 2
A second photodiode for receiving the other output light of the first optical splitter; and a second signal receiving a voltage signal corresponding to an average photocurrent received by the second photodiode. A third step of comparing with a set reference voltage and outputting an abnormal state display signal to the AND circuit when they match.
Wherein the gain of the optical semiconductor amplifier is made variable by the output current of the injection current supply circuit, and the logical product of the output signal of the first DC amplifier and the output signal of the third DC amplifier An optical regenerative repeater, wherein the output current of the optical latch drive current circuit is stopped by processing. 4. An optical regenerative repeater for regeneratively relaying a transmission signal on an optical fiber transmission line, comprising: a first optical splitter for bifurcating an optical signal input to the optical regenerative repeater; An optical semiconductor amplifier for inputting one of the optical signals branched into two in the optical splitter and amplifying the optical signal as it is, an injection current supply circuit for supplying a drive current to the optical semiconductor amplifier, and an output light of the optical semiconductor amplifier A second optical splitter that splits the optical signal into two via an optical isolator, an optical latch that receives one of the optical signals split by the second optical splitter and performs data latch as it is, and A first photodiode for converting the other optical signal split by the two optical splitters into an electric signal, a wideband amplifier for amplifying an output signal of the first photodiode, and a Strange A differentiating circuit for performing point detection, a full-wave rectifier circuit for generating a bright line spectrum component using an output signal of the differentiator circuit, a timing tank for extracting a timing signal from an output signal of the full-wave rectifier circuit, and the timing tank , A first peak value detection circuit for detecting a peak value of an output signal of the narrow band amplifier, and an output signal of the first peak value detection circuit to an appropriate level. A first DC amplifier that compares the first DC voltage with a first set reference voltage and generates an abnormal state display signal if they match, and an AND circuit that uses the output signal of the first DC amplifier as one input signal An optical latch drive current circuit that inputs an output signal of the narrow band amplifier and an output signal of the AND circuit and supplies a drive timing current to the optical latch; and the full-wave rectifier circuit. A second peak value detection circuit for branching and inputting the output signal and detecting a peak value of the input signal; and a second peak value generation circuit for generating a control voltage for the injection current supply circuit from an output signal of the second peak value detection circuit. 2
A second photodiode for receiving the other output light of the first optical splitter; and a second signal receiving a voltage signal corresponding to an average photocurrent received by the second photodiode. A comparison is made with a set reference voltage, and if they match, an abnormal state display signal is constituted by the AND circuit and a third DC amplifier that outputs the signal to the injection current supply circuit,
The gain of the optical semiconductor amplifier is made variable by the output current of the injection current supply circuit, and the output current of the injection current supply circuit is further changed by the output signal of the third DC amplifier. An optical regenerative repeater, wherein an output current of the optical latch drive current circuit is stopped by performing an AND operation with an output signal of the third DC amplifier. 5. An optical regenerative repeater for regenerating and relaying a transmission signal on an optical fiber transmission line, comprising: a first optical splitter for bifurcating an optical signal input to the optical regenerative repeater; An optical semiconductor amplifier for inputting one of the optical signals branched into two in the optical splitter and amplifying the optical signal as it is, an injection current supply circuit for supplying a drive current to the optical semiconductor amplifier, and an output light of the optical semiconductor amplifier A second optical splitter that splits the optical signal into two via an optical isolator, an optical latch that receives one of the optical signals split by the second optical splitter and performs data latch as it is, and A first photodiode for converting the other optical signal split by the two optical splitters into an electric signal, a wideband amplifier for amplifying an output signal of the first photodiode, and a Strange A differentiating circuit for performing point detection, a full-wave rectifier circuit for generating a bright line spectrum component using an output signal of the differentiator circuit, a timing tank for extracting a timing signal from an output signal of the full-wave rectifier circuit, and the timing tank , A first peak value detection circuit for detecting a peak value of an output signal of the narrow band amplifier, and an output signal of the first peak value detection circuit to an appropriate level. A first DC amplifier that compares the first DC voltage with a first set reference voltage and generates an abnormal state display signal if they match, and an AND circuit that uses the output signal of the first DC amplifier as one input signal An optical latch drive current circuit that inputs an output signal of the narrow band amplifier and an output signal of the AND circuit and supplies a drive timing current to the optical latch; and the full-wave rectifier circuit. A second peak value detection circuit for branching and inputting the output signal and detecting a peak value of the input signal; and a second peak value generation circuit for generating a control voltage for the injection current supply circuit from an output signal of the second peak value detection circuit. 2
A second photodiode for receiving the other output light of the first optical splitter; and a second signal receiving a voltage signal corresponding to an average photocurrent received by the second photodiode. A comparison is made with a set reference voltage, and if they match, a third DC amplifier that outputs an abnormal state display signal to the AND circuit, the injection current supply circuit, and an output signal of the second peak value detection circuit Is used as an input signal to compare with a third set reference voltage, and when they match, a fourth DC amplifier that generates an abnormal state display signal, and a first DC amplifier that receives an output signal of the third DC amplifier as an input. An alarm display circuit, a second alarm display circuit that receives an output signal of the first display circuit and an output signal of the fourth DC amplifier, and an output signal of the second alarm display circuit,
And a third alarm display circuit that receives an output signal of the DC amplifier as an input, the gain of the optical semiconductor amplifier is made variable by an output current of the injection current supply circuit, and an output signal of the third DC amplifier is further changed. The output current of the optical latch drive current circuit is stopped by the AND operation of the output current of the injection current supply circuit and the output signal of the second DC amplifier and the output signal of the third DC amplifier, and the alarm is issued. An optical regenerative repeater characterized by performing a fault display by a display circuit.