JPH04326218A - Submarine optical repeater - Google Patents

Abstract

PURPOSE:To recognize a distance from an optical repeater to a broken point. CONSTITUTION:A cable is equipped with an optical fiber for measurement separately from a fiber for optical signal. A branching filter 2 branches the exciting beams of an exciting light source 1, one exciting beam is applied to a synthesizer 3 and the other exciting beam is applied to a branching filter 9. The branching filter 9 outputs this exciting beam to the optical fiber for measurement, inputs the exciting beam returned from a broken point P and applies it to a photodetector 12. Based on a reset signal outputted from a pulse current supply circuit 7 simultaneously with a pulse current for excitation and the electric pulse signal of the photodetector 12, a delay time calculation circuit 8 calculates the delay time of the returning exciting beam. Based on this delay time, a computing element 13 computes a distance to the broken point.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of Industrial Application The present invention is applied to a failure point searching device for a submarine optical repeater. In particular, the present invention relates to a failure point search device for an optical direct amplification submarine optical repeater.

0002

2. Description of the Related Art FIG. 2 is a block diagram of a conventional submarine optical repeater.

Conventionally, submarine optical repeaters have been configured to use loopback as a means of fault point evaluation, as shown in FIG. As shown in Figure 2, this method takes the faulty transmission line offline and sends out a unique pulse pattern assigned to each uplink and downlink transmission system repeater 15 and 16 from the terminal station 14, and Connect output a of the uplink optical repeater and input b of the downlink optical repeater. As a result, the uplink signal is looped back to the downlink and returned to the terminal station 1.
Return to 4. And at the terminal station 14, the optical repeater 1
Perform loopback sequentially from 7 and compare the transmitted and received signals,
It is designed to search for faulty sections. Note that 18 in Figure 2
1 shows signal lines of uplink and downlink transmission systems 15 and 16.

0004

[Problem to be Solved by the Invention] However, in such conventional submarine optical repeater systems, it is not possible to determine where the fault is between optical repeaters because the loopback method is used to search for faults. There wasn't. therefore,
When making repairs, it is necessary to pull the cables from the optical repeater in the faulty section and search for the point of failure. However, recently the relay intervals have become longer, especially in optical submarine relays, which are about to reach 100km.
The conventional loopback method also had the problem of being inefficient when searching for failure points.

[0005] The present invention solves the above problems.
An object of the present invention is to provide a submarine optical repeater that can determine the distance from an optical repeater to a breaking point.

[0006]

[Means for Solving the Problems] The present invention includes a plurality of optical repeaters and a cable composed of signal optical fibers that cascade connects the plurality of optical repeaters. a multiplexer that multiplexes the optical signal and input pump light;
A submarine optical fiber that includes a doped fiber that directly amplifies the output optical signal of this multiplexer, a pulse current supply circuit that supplies a pulsed pumping current, and a pumping light source that inputs this pulsed pumping current and outputs the pumping light. In the repeater, the cable includes a measurement optical fiber in addition to the signal optical fiber, the pulse current supply circuit includes means for supplying the excitation pulse current and at the same time outputs a reset signal, and the optical repeater , a first demultiplexer inserted between the excitation light source and the multiplexer, which demultiplexes the output excitation light of the excitation light source and supplies one of the excitation lights to the multiplexer; a second splitter which inputs the pump light from the other branch of the splitter into one output and outputs it to the measurement optical fiber, inputs the pump light returned from the break point and outputs it from the other output; A photodetector that converts the output return excitation light of the second branching filter into electric pulses, and a delay time of the return excitation light calculated based on the output electric pulses of this photodetector and the reset signal of the pulse current supply circuit. The present invention is characterized in that it includes a delay time calculation circuit that calculates the delay time, and an arithmetic unit that calculates the distance to the breaking point based on the calculated delay time.

Further, in the present invention, the measurement cable may have a length up to just before the input of the next-stage optical repeater.

[0008]

[Operation] The cable includes an optical fiber for measurement in addition to the optical fiber for signal, and the pulse current supply circuit supplies a pulse current for excitation and outputs a reset signal at the same time. The first branching filter is inserted between the pumping light source and the multiplexer, and splits the output pumping light of the pumping light source and supplies one of the pumping lights to the multiplexer. The second splitter inputs the pumping light from the other side of the first splitter into one output, outputs it to the measurement optical fiber, inputs the pumping light returned from the break point, and outputs it from the other output. . A photodetector converts the output return excitation light of the second splitter into electrical pulses. The delay time calculation circuit calculates the delay time of the return excitation light based on the output electric pulse of the photodetector and the reset signal of the pulse current supply circuit. The calculator calculates the distance to the breaking point based on the calculated delay time.

As described above, the distance from the optical repeater to the breaking point can be known.

0010

Embodiments Examples of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a submarine optical repeater according to an embodiment of the present invention.

In FIG. 1, the submarine optical repeater includes a plurality of optical repeaters 5 and a cable 6 composed of signal optical fibers 10 that connect the plurality of optical repeaters 5 in cascade. A multiplexer 3 that combines an input optical signal and an input pumping light, a doped fiber 4 that directly amplifies the output optical signal of the multiplexer 3, and a pulse current supply circuit 7 that supplies a pulsed current for excitation. and an excitation light source 1 which inputs this excitation pulse current and outputs the excitation light.

The features of the present invention are that the cable 6 includes a measurement optical fiber 11 in addition to the signal optical fiber 10, and the pulse current supply circuit 7 supplies the excitation pulse current and at the same time outputs a reset signal. Each optical repeater 5 is inserted between the pump light source 1 and the multiplexer 3, and splits the output pump light of the pump light source 1 and sends one of the pump lights to the multiplexer 3. Demultiplexer 2 serves as the first demultiplexer to give
and a second demultiplexer which inputs the pumping light from the other side of the demultiplexer 2 into one output and outputs it to the measurement optical fiber 11, and inputs the return pumping light from the break point P and outputs it from the other output. A demultiplexer 9, a photodetector 12 that converts the output return excitation light of the demultiplexer 9 into electric pulses, and a return excitation light based on the output electric pulses of the photodetector 12 and the reset signal of the pulse current supply circuit 7. a delay time calculation circuit 8 for calculating the delay time of
It also includes a calculator 13 that calculates the distance to the breaking point P based on the calculated delay time.

Furthermore, the measurement cable 11 has a length up to just before the input of the optical repeater 5 at the next stage.

[0014] The operation of the submarine optical repeater having such a configuration will be explained.

In FIG. 1, pump light output from a pump light source 1 is injected into a doped fiber 4 through a first optical demultiplexer 2 and an optical multiplexer 3, and an optical repeater 5 receives light input from an input A. Amplify the transmission signal and output it from output B.

Now, suppose that a cable break occurs at a certain point (referred to as a break point P) on the cable 6 beyond the optical repeater 5. At this time, the pulse current supply circuit 7
A pulse current is passed through the excitation light source 1, and at the same time, a reset signal is sent to the delay time calculation circuit 8.

The first optical demultiplexer 2 branches the optical pulses output from the excitation light source 1 and supplies one of them to the second optical demultiplexer 9 . The optical pulse inputted from the output port of the second optical demultiplexer 9 passes through a measurement optical fiber 11 that is separate from the signal optical fiber 10 provided in the cable 6, and passes through a measurement optical fiber 11 provided at a breaking point P.
reach up to.

The optical pulse is reflected back from the breaking point P, passes through the second optical demultiplexer 9 again, and is branched. The branched optical pulse (return light) is input to the photodetector 12.

The photodetector 12 converts the optical pulse into electricity and outputs the electrical pulse signal to the delay time calculation circuit 8. The delay time calculating circuit 8 calculates the time difference t between the reset signal when a pulse current is applied to the excitation light source 1 and the electric pulse signal from the photodetector 12, and sends this information to the calculator 13.

The computing unit 13 performs the following calculation based on the time difference t, and can determine the distance L from the optical repeater 5 to the breaking point P.

L=C・t/2・n Here, L: Distance from the optical repeater 5 to the breaking point P C: Speed of light t: Reset signal and light when a pulse signal is sent to the excitation light source 1 Time difference n with the electric pulse signal from the detector 12:
refractive index of optical fiber

[0022]

As explained above, the present invention has an excellent effect of being able to determine the distance from the optical repeater to the breaking point.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a submarine optical repeater according to an embodiment of the present invention.

FIG. 2 is a block configuration diagram of a conventional submarine optical repeater.

[Explanation of symbols]

1 Excitation light source 2, 9 splitter 3 Multiplexer 4 Doped fiber 5, 17 Optical repeater 6 Cable 7 Pulse current supply circuit 8 Delay time calculation circuit 10 Signal optical fiber 11 Optical fiber for measurement 12 Photodetector 13 Arithmetic unit 14 Terminal 15 Upstream transmission system 16 Downward transmission system 18 Signal line

Claims (2)

[Claims] Claim 1: Each optical repeater comprises a plurality of optical repeaters and a cable made up of signal optical fibers that connects the plurality of optical repeaters in cascade, and each of the optical repeaters receives an input optical signal and an input pumping light. a doped fiber that directly amplifies the output optical signal of this multiplexer, a pulse current supply circuit that supplies a pulsed excitation current, and a pulsed current supply circuit that inputs this pulsed excitation current and outputs the above excitation light. In the submarine optical repeater including an excitation light source for output, the cable includes a measurement optical fiber in addition to the signal optical fiber, and the pulse current supply circuit supplies the excitation pulse current and outputs a reset signal at the same time. Each of the optical repeaters includes means for splitting the output pumping light of the pumping light source and providing one of the pumping lights to the multiplexer, the optical repeater being inserted between the pumping light source and the multiplexer. Input the excitation light from the first demultiplexer and the other from the first demultiplexer into one output and output it to the above-mentioned measurement optical fiber, input the return excitation light from the break point, and output from the other output. a second branching filter that converts the output return excitation light of the second branching filter into an electric pulse; A submarine optical repeater comprising: a delay time calculation circuit that calculates the delay time of the return pumping light based on the calculated delay time; and an arithmetic unit that calculates the distance to the break point based on the calculated delay time. 2. The submarine optical repeater according to claim 1, wherein the measurement cable has a length up to just before the input of the next-stage optical repeater.