JPH04371030A - Monitor system for optical amplifying repeater - Google Patents

Abstract

PURPOSE:To gather monitor information in plural optical amplifying repeaters without degrading a principal signal. CONSTITUTION:An optical transmitter 102 selects optical amplifying repeaters 101 one by one and superposes an operation command on the principal signal to output it. When reveiving the operation command destined for each optical amplifying repeater 101 itself, this optical amplifying repeater 101 superpose monitor information in the repeater itself on input signal light by modulating pumping light and outputs this light to an optical receiver 103. The optical receiver 103 demodulates monitor information sent from optical amplifying repeaters 101 by one demodulator and outputs the result.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repeater monitoring system using an optical amplifier in an optical transmission system.

0002

2. Description of the Related Art FIG. 5 is a block diagram showing an example of an optical repeater using a conventional Er (erbium) doped fiber optical amplifier. In FIG. 5, 200 is an Er-doped fiber optical amplifier, a wavelength multiplexing coupler 202, and an Er-doped fiber optical amplifier.
Doped fiber 203, isolator 204, pump LD (laser diode) 209, monitor PD
(Photodiode) 210, which directly amplifies the signal light propagated through the transmission fiber 201 and sends it to the transmission fiber 205.

Next, a method for monitoring this optical repeater will be explained. Current, temperature of LD209 for pump of optical repeater,
Information within the optical repeater that requires monitoring of the amplified output power, amplification degree, etc. of the Er-doped fiber optical amplifier 200 is converted into a digital electrical signal by the electrical signal converting circuit 206, and the FS
K (Frequency Shift Keying)
A modulation circuit 207 modulates the subcarrier, and an amplitude modulation circuit 208 modulates the drive current to the pump LD 209 to modulate the pump light output from the pump LD 209. This pump light is input to the Er-doped fiber 203 through the wavelength multiplexing coupler 202, and the amplification degree of the Er-doped fiber optical amplifier 200 is modulated. therefore,
The amplified main signal from the Er-doped fiber optical amplifier 200 is combined with the sub-signal Fi from the FSK modulation circuit 207.
The signal light in the form of superimposed
5 is input. Note that the frequency of the sub-signal from the FSK modulation circuit 207 is assigned a different frequency to each optical repeater, and the degree of amplitude modulation of the signal light by the sub-signal from the FSK modulation circuit 207 is the amplitude of the main signal. It is set so that it is sufficiently low compared to .

[0004] The signal light that has passed through each optical repeater reaches an optical receiver. FIG. 6 is a block diagram showing an example of a conventional optical receiver. Here, 217, 219, 221 are band filters for extracting the sub-signals of each optical repeater, 218, 220,
222 is an FSK demodulator that demodulates this sub-signal.

The optical signal from the transmission fiber 213 is converted into an electrical signal by an optical-to-electrical conversion element 214, and the optical signal is converted to an electrical signal by an amplifier 215.
After being amplified by the main signal demodulator 216, the bandpass filter 2
17, 219, and 221. band filter 21
The sub signals from each optical repeater are selected by FSK demodulators 7, 219, and 221, and demodulated by FSK demodulators 218, 220, and 222, and the internal information of each optical repeater is extracted. Thereby, the operation of each optical repeater can be monitored.

[0006]

[Problems to be Solved by the Invention] However, in the optical repeater monitoring method described above, as the number of stages of optical repeaters increases, the number of subcarriers for subsignals increases, and the transmission characteristics of the main signal by the subsignals deteriorate. There was a problem in that the degree of deterioration was increasing. Another problem is that the optical receiver requires as many bandpass filters and FSK demodulators as there are optical repeaters.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to prevent the deterioration of the transmission characteristics of the main signal due to the sub-signal from increasing even if the number of stages of optical repeaters increases, and to improve optical reception. An object of the present invention is to provide a monitoring method for an optical amplification repeater that can be configured with a single sub-signal demodulation circuit regardless of the number of optical repeaters in the machine.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for monitoring an optical amplifying repeater in an optical transmission system consisting of an optical transmitter, a plurality of optical amplifying repeaters, and an optical receiver. The optical transmitter includes means for generating a first sub-signal modulated with an operation command for a specific optical amplification repeater, and means for superimposing the first sub-signal on the main signal and converting it into light, means for demodulating the first sub-signal to the optical amplification repeater; means for generating a second sub-signal modulated with monitoring information within the own station when the demodulated operation command is addressed to the own station;
means for modulating the driving current of a pump laser diode that supplies pump light to the Er-doped fiber with the sub-signal of the second sub-signal, and means for demodulating the second sub-signal in the optical receiver. .

[0009]

[Operation] The optical transmitter selects the optical amplifying repeaters one by one and outputs the operation command superimposed on the main signal. When each optical amplifying repeater receives an operation command addressed to its own station, it modulates the pump light to superimpose monitoring information within its own station onto the input signal light, and outputs the superimposed information to the optical receiver. The optical receiver demodulates the monitoring information sent from each optical amplification repeater using one demodulator and outputs it.

[0010] Here, the transmission of monitoring information by each optical amplifying repeater ends before the optical transmitter outputs the next operation command.

[0011]

Embodiment FIG. 1 is a system configuration diagram showing an embodiment of the present invention. In the figure, 101 is an optical amplification repeater, 102
103 is an optical transmitter, 103 is an optical receiver, 104 is a transmission fiber, and the optical amplification repeater 101 amplifies the optical signal attenuated by the transmission fiber 104 and outputs the amplified signal. The monitoring method for this optical amplification repeater 101 will be explained below.

[0012] The optical transmitter 102 sends a main signal for information transmission,
A sub-signal with a low speed and small amplitude is superimposed on this main signal,
It is converted into an optical signal and sent to the transmission fiber 104. This sub-signal is operation command information for each optical amplifier repeater 101, and its signal shape has a digitally coded intensity modulation format. In other words, this corresponds to a change in the envelope of the main signal. Further, the content of the operation command is to sequentially send out a predetermined address code unique to each optical amplification repeater 101 and cause each optical amplification repeater 101 to send out monitoring information.

Next, each optical amplifying repeater 101 extracts a part of the incoming optical signal on its input side, and further detects and demodulates only the sub-signal. At this time, when the demodulated signal matches the address code given in advance to the own station, that is, when the own station call identification is performed, the temperature information, amplification information, optical output information, etc. inside the optical amplification repeater are encoded. If necessary, add the own relay station code to this and convert it into an optical signal,
It is coupled to the output side of the optical amplification repeater and sent to the downstream transmission system. At this time, the sub-signal from the optical transmitter 102 has not been sent yet.

[0014] After all such monitoring information is sent out, the sub-signal from the optical amplification repeater 101 is not sent out. Naturally, the optical amplifying repeater 101 that is not called does not send out the sub-signal.

Next, the optical transmitter 102 is connected to another optical amplifying repeater 1.
A similar operation command signal is sent to the optical amplifier 01, and monitoring information from the optical amplification repeater 101 is sent downstream.

As described above, the optical transmitter 102 has the function of causing each optical amplification repeater 101 to sequentially transmit monitoring information at regular intervals.

The optical receiver 103 not only detects the main signal for information transmission, but also extracts and demodulates the sub-signal for monitoring information to identify each optical amplifier repeater 101 and obtain monitoring information. Detect.

In this system, the transmission speed of the sub signal is extremely slow compared to the main signal. This is because as the transmission speed becomes slower, the reception level sensitivity of the optical receiver generally improves, so it is possible to detect a signal even if the sub signal has a much smaller amplitude than the main signal. This is what I did.

Next, embodiments of the optical transmitter 102, optical amplification repeater 101, and optical receiver 103 shown in FIG. 1 will be described in sequence.

FIG. 3 is a block diagram showing an embodiment of the optical transmitter 102. The sub-signal circuit 106 generates a sub-signal having a small amplitude and low speed in response to the main signal from the main signal circuit 105, the content of which is a call to the optical amplifying repeater that is instructed to operate,
The modulator 107 sends a signal waveform obtained by superimposing the sub-signal onto the main signal to the drive circuit 108, and modulates and drives the semiconductor laser 109. The output light from the semiconductor laser 109 has an optical waveform in which the main signal is modulated and a sub signal is superimposed at a low speed with a small modulation degree. After sending the operation command sub-signal to the optical amplifying repeater, the sub-signal of the specified optical amplifying repeater is sent, so the next optical amplifying repeater is sent at an appropriate time interval to avoid overlapping. Sends sub-signals for operation commands to.

FIG. 2 is a block diagram showing an embodiment of the optical amplification repeater 101 shown in FIG. The isolator 119, the multiplexing filter 120, the Er-doped fiber 121, the isolator 122, and the pump laser diode 133 are
An r-doped fiber optical amplifier 137 is configured.

Input fiber 117 and isolator 119
A coupler 118 is inserted between the optical and electrical converters 12
5 converts a part of the input signal light into an electrical signal, which is amplified by an amplifier 126 , and a sub-signal is taken out by a low-pass filter 127 .
It is determined whether or not the station has issued an operation command to its own station, and the result is sent to the control circuit 129.

Isolator 122 and output fiber 124
A coupler 123 is inserted between them, and a part of the output power from the Er-doped fiber optical amplifier 137 is guided from the optical-to-electrical converter 135 and the amplifier 136 to an output power measurement circuit (not shown), and then an optical amplification relay. The output power of the device is measured. Also in the input section, the output of the amplifier 126 is guided to an input power measurement circuit (not shown), and the input power of the optical amplification repeater is measured.

The temperature of the pump laser diode 133 is controlled by a temperature control circuit 134, and the temperature of the pump laser diode 133 is measured.

Input signal light power to the optical amplification repeater 101, output signal light power of the optical amplification repeater 101, amplification degree of the Er-doped fiber optical amplifier 137, drive current to the pump laser diode 133, temperature, etc. The information in the repeater is encoded by the encoding circuit 130, passes through the modulator 131, and enters the pump laser diode drive circuit 132.
It is sent to the pump laser diode 133. The power of the pump light from the pump laser diode 133 is modulated, and therefore the power of the pump light from the pump laser diode 133 is
The amplification degree of 7 is modulated, and the amplified output power is also modulated. However, the information within the repeater does not always continue to enter the pump laser diode drive circuit 132.

Unless the own station call identification circuit 128 recognizes that there is an operation command for the own station, the control circuit 129
The encoding circuit 130 and modulator 131 are not operated, and the pump laser diode 133 is driven without modulation.

When the own station call identification circuit 128 recognizes that there is an operation command for the own station, the control circuit 129
The encoder circuit 130 and the modulator 131 are operated, and the drive current from the pump laser diode drive circuit 132 is modulated by the sub-signal, and the drive current from the pump laser diode drive circuit 132 is modulated by the sub-signal.
The output light from the main signal is in the form of a sub signal superimposed on the main signal.

FIG. 4 is a block diagram showing an embodiment of the optical receiver 103 shown in FIG. An input optical signal from the transmission fiber 111 is converted into an electrical signal by an optical-to-electrical converter 112 and amplified by an amplifier 113. The amplified electrical signal enters the main signal demodulator 114, but a portion passes through the low-pass filter 11.
5 and is taken out as only the sub signal, which is sent to the sub signal demodulation circuit 11.
6, an operation command from the optical transmitter 102 to the optical amplification repeater;
The repeater information from each optical amplification repeater 101 is demodulated. Based on this repeater internal information, etc., the operating state of each optical amplification repeater can be monitored.

[0029]

As described above in detail, according to the present invention, only the optical amplifying repeater that has been instructed by the optical transmitter transmits information within the repeater as a sub signal, and other optical amplifying repeaters does not output a sub-signal, so regardless of the number of optical amplification repeaters, the deterioration of the main signal is limited to the amount when one sub-signal is superimposed. Furthermore, the optical receiver only needs to include one low-pass filter and a sub-signal demodulator.

[Brief explanation of drawings]

FIG. 1 is a system configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an embodiment of the optical amplification repeater in FIG. 1;

FIG. 3 is a configuration diagram showing an embodiment of the optical transmitter in FIG. 1;

FIG. 4 is a configuration diagram showing an embodiment of the optical receiver in FIG. 1;

FIG. 5 is a configuration diagram of a conventional optical repeater.

FIG. 6 is a configuration diagram of a conventional optical receiver.

[Explanation of symbols]

101 Optical amplification repeater 102 Optical transmitter 103 Optical receiver 104 Transmission fiber

Claims (1)

[Claims] 1. A monitoring method for an optical amplifying repeater in an optical transmission system comprising an optical transmitter, a plurality of optical amplifying repeaters, and an optical receiver, wherein the optical transmitter is modulated with an operation command for a specific optical amplifying repeater. means for generating a first sub-signal, and means for superimposing the first sub-signal on a main signal and converting it into light, and means for demodulating the first sub-signal into the optical amplification repeater. a means for generating a second sub-signal modulated with monitoring information within the own station when the demodulated operation command is addressed to the own station; and a pump for supplying pump light to the Er-doped fiber with the second sub-signal. 1. A monitoring system for an optical amplification repeater, comprising means for modulating a drive current of a laser diode, and means for demodulating said second sub-signal in said optical receiver.