CN105939172A - An optical structure for optical relay amplifying optical fiber link to transmit COTDR signal - Google Patents

Abstract

The invention relates to an optical structure for transmitting a COTDR signal by an optical relay amplifying optical fiber link, wherein n stages of relay amplifiers corresponding to each other are respectively arranged on an A → B optical fiber and an A ← B optical fiber, and a set of optical structures for transmitting the COTDR signal at the A end are respectively installed in a matching way. A. The two ends of B can be configured with COTDR equipment at the same time, and the relay amplifiers at each level on the two optical fibers are provided with optical structures which are mutually centrosymmetric and transmit the COTDR signals at A, B ends. The insertion loss of the communication signal is reduced by at least 2dB, and the optical signal-to-noise ratio is improved by 2 dB; the optical cable is suitable for long-distance communication optical cables, easy to realize and suitable for popularization and application.

Description

An optical structure for optical relay amplifying optical fiber link to transmit COTDR signal

technical field

The invention relates to the technical field of transmission optical cable health monitoring, in particular to an optical structure for optical relay amplifying optical fiber links to transmit COTDR signals.

Background technique

For optical cables for long-distance transmission, in order to compensate for the loss of optical signal transmission, there are generally multi-stage relay amplifiers, also known as optical relay amplifier links. In some optical relay amplification links that are not convenient for manual maintenance, such as submarine optical cables, long-distance optical cables across deserts, etc., in order to check the signal gain of each relay amplifier on the entire optical fiber link, whether the optical cable is broken, and locate the breakpoint etc. Currently, COTDR (Coherent Detecting Optical Time Domain Reflectometer) capable of passing through fiber amplifiers is used for detection.

The existing COTDR is used for the detection of a dual-fiber bidirectional optical fiber communication system. One end of the transmission optical fiber (hereinafter referred to as end A) and two optical fibers are respectively connected to the transmitting port and the receiving port of the COTDR device, and the COTDR optical pulse detection signal is in the downlink optical fiber of the A end Transmission: The uplink optical fiber at the A end transmits the back Rayleigh scattering signal of the COTDR. The other end of the transmission fiber is called the B end. The communication signal transmitted by terminal B is transmitted in the downlink optical fiber of terminal B and received by terminal A. The downlink optical fiber of terminal B is the uplink optical fiber of A terminal, and the downlink optical fiber of A terminal is the uplink optical fiber of B terminal.

The COTDR optical fiber link detection system includes an n-stage optical structure for transmitting COTDR signals matched with an n-stage optical relay amplifier, and each optical structure contains a circulator and a 3dB fiber coupler. The COTDR device at the A end of the transmission optical cable sends an optical pulse detection signal, which is transmitted in the downlink optical fiber at the A end and the optical relay amplifiers on it at all levels, and a circulator is connected after each optical relay amplifier of the downlink optical fiber, and the amplified optical pulse The back Rayleigh scattering signal in the detection signal is separated from the transmission fiber through a circulator, and connected to the 3dB fiber coupler in the uplink fiber at the corresponding A end, and the back Rayleigh scattering signal of this stage in the 3dB fiber coupler The signal is coupled with the communication signal transmitted in the upstream optical fiber and the subsequent Rayleigh scattering signal, and enters the upstream optical fiber at the A end together, and is transmitted to the A end of the transmission optical fiber together, and the backward Rayleigh signal is filtered by the terminal wavelength division multiplexer and output to the COTDR device Receiving end. The COTDR equipment receives n optical pulse sequences returned by the n-level optical structure, and judges the status of the optical fiber link accordingly.

The current optical structure for transmitting COTDR signals is installed in optical relay amplifying optical fiber links to realize the health detection of long-distance optical cables, especially submarine optical cables.

However, because the optical structure for transmitting COTDR signals uses a 3dB fiber coupler in the uplink fiber, the communication signal transmitted in the uplink fiber must pass through the fiber coupler, and the insertion loss of the transmitted communication signal is greater than 3dB, which affects the communication quality. .

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of excessive insertion loss introduced by the existing COTDR signal transmission optical structure, to provide an optical structure for optical relay amplification optical fiber link transmission of COTDR signals, adding a wavelength division multiplexer and a wavelength division multiplexer The device makes the communication signal in the uplink optical fiber bypass the fiber coupler and continue to transmit, while the back Rayleigh scattering signal of this stage and the back Rayleigh scattering signal of the subsequent stage pass through the demultiplexer, fiber coupler, wave The demultiplexer and the communication signal are coupled into the uplink optical fiber transmission; this optical structure prevents the communication signal from passing through the 3dB optical fiber coupler, reducing its insertion loss.

An optical structure for transmitting COTDR signals through an optical relay amplifying optical fiber link designed by the present invention, there are two transmission optical fibers between the A end and the B end of the optical relay amplifying optical fiber link, and there is one at each of the A and B ends Communication equipment; A terminal is also equipped with COTDR equipment.

A→B optical fiber and A←B optical fiber are used to transmit communication signals between A and B terminals. The A→B fiber is the downlink fiber of the A terminal, and the signal sent by the communication equipment of the A terminal is transmitted to the B terminal in the A→B fiber, and the A←B fiber is the uplink fiber of the A terminal, and the communication equipment of the A terminal receives and transmits in the A←B fiber B-side communication signal to A-side. It can be seen that the A→B optical fiber is the uplink optical fiber at the B-end, and the B-end communication device receives the A-end communication signal transmitted to the B-end in the A→B optical fiber, and the A←B optical fiber is the B-end downlink optical fiber, and the communication sent by the B-end device The signal is transmitted to the A end in the A←B optical fiber.

There are n-level relay amplifiers corresponding to each other on the A→B fiber and A←B fiber. The A-end of the A→B fiber is connected to the signal sending end of the A-end communication equipment and the A-end COTDR respectively through the A-end wavelength division multiplexer. At the sending end of the equipment, the A-end of the A←B optical fiber is connected to the receiving end of the COTDR equipment at the A-end and the signal receiving end of the A-end communication equipment through the A-end demultiplexer, and the A-end COTDR signal is sent to the A-end and B-end communication equipment The wavelengths of the communication signals are different; the B-end of the A→B optical fiber is connected to the receiving end of the B-end communication equipment, and the B-end of the A←B optical fiber is connected to the sending end of the B-end communication equipment.

The COTDR device is located at the A-end, and the optical structure for transmitting the COTDR signal is an optical structure for transmitting the A-end COTDR signal, including a circulator and a fiber coupler. Each stage of relay amplifier on the A→B optical fiber and A←B optical fiber is equipped with an optical structure for transmitting the COTDR signal at the A-end. The circulator in the optical structure for transmitting the A-end COTDR signal at each stage has three ports, and the fiber coupler has two input ports and one output port. The first port of the circulator is connected to the output end of the same-level relay amplifier on the A→B fiber, the second port of the circulator is connected to the A→B fiber of the next-stage relay amplifier leading to the fiber, and the circulator’s The third port is connected with an input end of the fiber coupler.

The optical structure for transmitting COTDR signals of the present invention also includes a wavelength division multiplexer and a wavelength division multiplexer, and the wavelength division multiplexer and the wavelength division multiplexer of the same level of optical structure are connected in the A←B optical fiber, located at The input end side of the relay amplifier of this stage of A←B optical fiber; the wavelength division multiplexer and the wavelength division multiplexer both have three ports, and the three ports are the common end, the transmission end and the reflection end respectively, and the wavelength division multiplexer The common end of the multiplexer is connected to the rear A←B optical fiber, the transmission end is connected to the other input end of the fiber coupler, and the reflection end is connected to the reflection end of the wavelength division multiplexer; the transmission end of the wavelength division multiplexer is connected to the fiber coupler The output end and the common end are connected to the input end of the relay amplifier of the current stage of the A←B optical fiber.

The demultiplexer of a certain optical structure separates the multi-level back Rayleigh scattering signal and the communication signal transmitted in the A←B optical fiber, and sends it to the fiber coupler, while the communication signal is directly Entering the wavelength division multiplexer, the fiber coupler separates the backward Rayleigh scattering signal of the relay amplifier of the A→B optical fiber of the current stage separated by the circulator and the multi-stage backward Rayleigh scattering signal sent into the demultiplexer The Rayleigh scattering signal is coupled and sent to the wavelength division multiplexer in front of the fiber coupler, and the multi-level backward Rayleigh scattering signal of this stage and its front is combined with the communication signal in the A←B optical fiber to combine and amplify. The B fiber continues to transmit to the A end.

The back Rayleigh scattering signal separated by the optical structure of n-stage transmission A-side COTDR signal and the B-side communication signal are transmitted to the A-side together, and then separated by the A-side demultiplexer and respectively enter the receiving end of the A-side COTDR device With the receiving end of the A-end communication signal device, the A-end COTDR device receives n A-end COTDR optical pulse sequences returned by the optical structure that transmits the A-end COTDR signal in n stages.

Both ends of A and B can be equipped with COTDR equipment at the same time, and the optical structure for transmitting the COTDR signal of A is as described above. The B-end is equipped with COTDR equipment at the same time. The B-end of the A←B optical fiber is respectively connected to the signal sending end of the B-end communication equipment and the sending end of the B-end COTDR equipment through the B-end wavelength division multiplexer, and the B-end COTDR signal is connected to the A and B ends. The wavelength of the communication signal sent by the communication equipment is different, and it is different from the wavelength of the A-end COTDR signal; the B-end of the A→B optical fiber is connected to the receiving end of the B-end COTDR device and the signal receiving end of the B-end communication equipment through the B-end demultiplexer end.

The B-end COTDR sends an optical pulse detection signal from the B-end of the optical fiber link, that is, the B-end COTDR signal, and transmits along the downlink optical fiber at the B-end of the optical fiber link, that is, the A←B optical fiber.

Each stage of relay amplifiers on the A→B optical fiber and A←B optical fiber is also equipped with a set of optical structures for transmitting COTDR signals at the B end. The main components of the optical structure for transmitting COTDR signals at the B-end are the same as those for transmitting the COTDR signals at the A-end. The first port of the optical structure circulator that transmits the B-side COTDR signal is connected to the output end of the same-level relay amplifier on the A←B fiber, and the second port of the circulator is connected to the A← of the next-stage relay amplifier leading to the fiber B optical fiber, the third port of the circulator is connected with an input end of the optical fiber coupler of this optical structure. The wavelength division multiplexer and the wavelength division multiplexer of this optical structure are connected in the A→B optical fiber, and are located at the input end side of the relay amplifier of this stage of the A→B optical fiber; the wavelength division multiplexer of this optical structure The common end of the converter is connected to the rear A→B optical fiber, the transmission end is connected to the other input end of the fiber coupler, and the reflection end is connected to the reflection end of the wavelength division multiplexer; the transmission end of the wavelength division multiplexer is connected to the output end of the fiber coupler , and the common end is connected to the input end of the relay amplifier of the A→B optical fiber.

When passing through a stage of relay amplifier, the B-end COTDR signal is amplified, and then enters the optical structure for transmitting the B-end COTDR signal. The Rayleigh scattering signal and the communication signal are demultiplexed and sent to an input end of the fiber coupler, while the communication signal directly enters the wavelength division multiplexer, and the fiber coupler separates the A ←The back Rayleigh scattering signal of the relay amplifier of the B fiber is coupled with the multi-stage back Rayleigh scattering signal sent by the demultiplexer, sent to the wavelength division multiplexer, and multiplexed with the communication signal again Enter the A→B fiber.

The back Rayleigh scattering signal separated by the optical structure of n-stage transmission B-side COTDR signal is transmitted to the B-side together with the A-side communication signal, and then separated by the B-side demultiplexer into the receiving end of the B-side COTDR device With the receiving end of the B-side communication signal device, the B-side COTDR device receives n B-side COTDR optical pulse sequences returned by the optical structure for n-stage transmission of the B-side COTDR signal.

The operating wavelength of the circulator includes C-band and L-band.

The working wavelength of the fiber coupler includes C-band and L-band, and the best solution is a fiber coupler with a splitting ratio of 1:1, or a 3dB coupler.

The transmitted wave of the wavelength division multiplexer and the wavelength division multiplexer is a narrow-spectrum signal wave whose central wavelength is consistent with the working wavelength of the COTDR signal matched by the optical structure, and the reflected wave is a communication signal whose wavelength range includes the transmission of the optical fiber Wide-spectrum signal waves with wavelengths, and the common port carries two signals at the same time. When both ends of optical fiber link A and B are equipped with COTDR equipment, the optical structure for transmitting COTDR signals at end B is different from the optical structure for transmitting COTDR signals at end A. The wavelength division multiplexer and demultiplexer transmit wavelengths differently. It is consistent with the working wavelength of the matched COTDR detection pulse signal.

Compared with the prior art, the beneficial effect of the optical structure of a kind of optical relay amplification optical fiber link transmission COTDR signal of the present invention is: 1, reduce the insertion loss of communication signal, the optical structure of the present invention is inserted before and after the optical fiber coupler to understand For wavelength division multiplexer and wavelength division multiplexer, the communication signal does not pass through the optical fiber coupler when passing through the optical structure, so the insertion loss is only about 1dB, while the existing optical structure for transmitting COTDR signals passes through the optical fiber coupler. When the insertion loss is up to 3dB, the insertion loss is reduced by at least 2dB, so the present invention can improve the optical signal-to-noise ratio of the optical relay amplifying fiber link by 2dB; 2. Because the present invention can reduce the insertion loss, it is suitable for long-distance communication Optical cables, especially submarine communication optical cables; 3. The optical structure of the present invention is only equipped with a wavelength division multiplexer and a wavelength division multiplexer, which is easy to implement and suitable for popularization and application.

Description of drawings

Fig. 1 is the schematic diagram of the optical structure embodiment of this optical relay amplifying optical fiber link transmission COTDR signal;

Fig. 2 is the schematic diagram that this embodiment is installed in the application embodiment 1 of optical relay amplifying optical fiber link, COTDR equipment is in this optical fiber link A end;

Fig. 3 is a schematic diagram of this embodiment installed in the application embodiment 2 of the optical relay amplifying the optical fiber link, and two COTDR devices are respectively located at the A end and the B end of the optical fiber link.

1. Relay amplifier on A→B fiber, 2. Circulator, 3. A→B fiber, 4. A←B fiber, 5. Demultiplexer, 6. Fiber coupler, 7. WDM Multiplexer, 8, relay amplifier on A←B fiber, 1-1～1-16, 16-stage relay amplifier on A→B fiber, 8-1～8-16, A←B on fiber 16-stage relay amplifier, M1～M16, 16-stage optical structure for transmitting COTDR signal at A-end, N1-N16, 16-stage optical structure for transmitting COTDR signal at B-end, A9, A-side demultiplexer, A10, A Terminal wavelength division multiplexer, B9, B terminal demultiplexer, B10, B terminal wavelength division multiplexer,

detailed description

Optical structure embodiment of optical relay amplifying optical fiber link to transmit COTDR signal

The embodiment of the optical structure of this optical relay amplifying optical fiber link transmission COTDR signal is shown in Figure 1, there are two transmission optical fibers between the A end and the B end of the optical relay amplifying optical fiber link of this example, A→B optical fiber 3( The optical fiber with the arrow pointing to the left in Figure 1) and A←B optical fiber 4 (the optical fiber with the arrow pointing to the right in Figure 1), which are used to transmit communication signals between the A and B terminals. In this example, the communication signals sent by the communication equipment at the A and B terminals same wavelength.

A→B optical fiber 3 and A←B optical fiber 4 respectively have n-stage relay amplifiers 1 and 8 corresponding to each other. In this example, the COTDR equipment is located at A-side, and the optical structure for transmitting COTDR signals in this example is the optical structure for transmitting COTDR signals at A-side, including circulator 2, fiber coupler 6, demultiplexer 5 and wavelength division multiplexer 7 . Each stage of relay amplifiers 1 and 8 on the A→B optical fiber 3 and A←B optical fiber 4 is equipped with a set of optical structures for transmitting COTDR signals at the A-end. The circulator 2 in the optical structure in which each stage transmits the A-end COTDR signal has three ports, and the fiber coupler 6 has two input ports and one output port. The first port of the circulator 2 is connected to the output end of the same-stage relay amplifier 1 on the A→B fiber 3, and the second port of the circulator 2 is connected to the A→B fiber of the next-stage relay amplifier leading to the fiber 3. The third port of the circulator 2 is connected to an input end of the fiber coupler 6 . The wavelength division multiplexer 5 and the wavelength division multiplexer 7 of this optical structure are connected in the A←B optical fiber 4, and are positioned at the input end side of the stage relay amplifier 8 of the A←B optical fiber 4; Both the user 5 and the wavelength division multiplexer 7 have three ports, and the three ports are respectively a common end, a transmission end and a reflection end, and the common end of the wavelength division multiplexer 5 is connected to the rear A←B optical fiber 4, and the transmission The end is connected to the other input end of the fiber coupler 6, and the reflection end is connected to the reflection end of the wavelength division multiplexer 7; the transmission end of the wavelength division multiplexer 7 is connected to the output end of the fiber coupler 6, and the common end is connected to the A←B fiber 4 The 8 input terminals of the relay amplifier of this stage.

In this example, the working wavelength of circulator 2 includes C-band and L-band.

The fiber coupler 6 in this example is a 3dB fiber coupler, and its working wavelength includes C-band and L-band.

In this example, the transmitted wave of the wavelength division multiplexer 7 and the wavelength division multiplexer 5 is a narrow-spectrum signal wave whose central wavelength is consistent with the working wavelength of the COTDR signal matched with this optical structure, and the reflected wave is the wavelength range including the optical fiber transmission. The wide-spectrum signal wave of the communication signal wavelength, the common end carries two signals at the same time.

The demultiplexer of a certain optical structure separates the multi-level back Rayleigh scattering signal and the communication signal transmitted in the A←B optical fiber, and sends it to the fiber coupler, while the communication signal is directly Entering the wavelength division multiplexer, the fiber coupler separates the backward Rayleigh scattering signal of the relay amplifier of the A→B optical fiber of the current stage separated by the circulator and the multi-stage backward Rayleigh scattering signal sent into the demultiplexer The Rayleigh scattering signal is coupled and sent to the wavelength division multiplexer in front of the fiber coupler, and the multi-level backward Rayleigh scattering signal of this stage and its front is combined with the communication signal in the A←B optical fiber to combine and amplify. The B fiber continues to transmit to the A end.

The back Rayleigh scattering signal separated by the optical structure of n-stage transmission A-side COTDR signal and the B-side communication signal are transmitted to the A-side together, and then separated by the A-side demultiplexer and respectively enter the receiving end of the A-side COTDR device With the receiving end of the A-end communication signal device, the A-end COTDR device receives n A-end COTDR optical pulse sequences returned by the optical structure that transmits the A-end COTDR signal in n stages.

Application Example 1 of Optical Structure for Transmission of COTDR Signals

Fig. 2 shows the embodiment 1 in which the optical structure embodiment of the above-mentioned optical relay amplifying optical fiber link for transmitting COTDR signals is installed in the optical relay amplifying optical fiber link. The "optical structure for transmitting COTDR signals" is simply referred to as an optical structure hereinafter.

In this example, there is a communication device at the A and B ends of the optical relay amplifying fiber link to transmit 40-wave dense wavelength division signals from CH21 (1560.61nm) to CH60 (1529.19nm), and the COTDR equipment is installed in the optical relay amplifying fiber link A side of the road. The A end is generally the shore end of the submarine optical cable transmission. The COTDR device includes an optical pulse sending end and a receiving end. Send a downlink optical pulse detection signal with a wavelength of 1561.42nm (CH20). There are 16 levels of relay amplifiers corresponding to each other on the A→B fiber 3 and A←B fiber 4 of the optical relay amplification fiber link, that is, the A→B fiber 3 is installed in the first level A→B fiber in sequence at a certain distance Relay amplifier 1-1 to 16th stage A→B fiber optic relay amplifier 1-16, and corresponding 1st stage A←B fiber optic relay amplifier 8-1 to 16th stage A←B fiber optic relay amplifier 8-16, each stage of relay amplifier is equipped with a set of above-mentioned optical structures, that is, M1 to M16 in the figure.

The A end of A→B optical fiber 3 is respectively connected to the signal sending end of the A-end communication equipment and the sending end of the A-end COTDR device through the A-end wavelength division multiplexer A10, and the A-end of the A←B optical fiber 4 is demultiplexed through the A-end The multiplexer A9 is connected to the receiving end of the COTDR equipment at the A end and the signal receiving end of the communication equipment at the A end. The transmission center wavelength of the wavelength division multiplexer and the demultiplexer are both CH20, which is consistent with the signal wavelength of the COTDR equipment, and the wavelength of the communication equipment. The transmitted communication signals have different wavelengths CH21-CH60; the B end of the A→B optical fiber 3 is connected to the receiving end of the B-end communication equipment, and the B end of the A←B optical fiber 4 is connected to the sending end of the B-end communication equipment.

The A-end COTDR equipment includes a sending end and a receiving end. The COTDR downlink optical pulse detection signal sent by it passes through the first-stage A→B optical fiber relay amplifier 1-1, and then outputs an amplified optical pulse detection signal, and then enters the first-stage optical structure M1 The circulator 2 in the circulator, the Rayleigh scattering signal of the optical pulse detection signal is separated from the A→B optical fiber 3 through the circulator 2, and enters the 3dB optical fiber coupler 6 in M1; it is sent from the communication equipment at the B end of the optical fiber link When the communication signal transmitted in the A←B optical fiber 4 reaches the first-level optical structure M1, the demultiplexer will generate the second-level A←B optical fiber relay amplifier 8-2 in the A←B optical fiber 4 and the previous Rayleigh scattering signal demultiplexing, sent to the 3dB fiber coupler 6 of M1, and the B-side communication signal directly passes through the demultiplexer 5; the 3dB fiber coupler 6 converts A←B and The back Rayleigh scattering signal of the A→B optical fiber is sent to the wavelength division multiplexer 7 of the first-level optical structure M1, multiplexed with the B-end communication signal, and then enters the first-level optical relay amplifier 8 of the A←B optical fiber 4 -1, and then enter the A-side demultiplexer A9, the B-side communication signal is received by the A-side communication device, and the Rayleigh scattering signal enters the receiving end of the COTDR device to form the first COTDR receiving pulse. The COTDR optical pulse detection signal continues to be transmitted to the second-stage A→B optical fiber relay amplifier 1-2 through the A→B optical fiber 3, and the amplified optical pulse detection signal is output, and enters the circulator in the second-stage optical structure M2, and the optical pulse The back Rayleigh scattering signal of the detection signal is separated from the A→B fiber 3 through the circulator in M2, and sent to the 3dB fiber coupler in M2; the B-end communication signal transmitted upstream in the A←B fiber 4 reaches the second stage When the optical structure is M2, the demultiplexer in M2 demultiplexes all the backward Rayleigh scattering signals in the A←B fiber 4, and sends them to the 3dB fiber coupler of M2, while the communication signal at the B end directly passes through the dewave Division multiplexer; the 3dB fiber coupler sends the Rayleigh scattering signals of A→B and A←B fibers together into the wavelength division multiplexer and the B-side communication signal multiplexed into the second-level light of A←B fiber The relay amplifier 8-1 then enters the receiving end of the COTDR device to form the second COTDR receiving pulse. This is done in sequence to form the 1st to 16th COTDR receiving pulses, based on which the status of the optical fiber link can be judged.

Application example 2 of an optical structure for transmitting COTDR signals

This application embodiment 2 is shown in FIG. 3 , where COTDR equipment and communication equipment are installed at both ends of optical fiber links A and B, and operate independently of each other. There are 16 stages of relay amplifiers corresponding to each other on the A→B fiber 3 and A←B fiber 4 of the optical relay amplification fiber link, that is, the first stage A→B fiber optic relay amplifier 1-1 to the 16th stage A→ B fiber optic relay amplifier 1-16, and the corresponding first stage A←B fiber optic relay amplifier 8-1 to the 16th stage A←B fiber optic relay amplifier 8-16, each stage of relay amplifier is equipped with a Set of A-end optical structures that match with A-end COTDR equipment, that is, M1 to M16 in the figure. The wavelength of the COTDR optical pulse detection signal sent by the A-side COTDR equipment is CH20, and the transmission wavelength of the wavelength division multiplexers corresponding to M1 to M16 is also CH20; each stage of relay amplifier is equipped with a set behind the B-side COTDR equipment The optical structure, that is, N1 to N16 in the figure, the wavelength of the COTDR optical pulse detection signal sent by the B-side COTDR device is CH19, and the transmission wavelength of the wavelength division multiplexer corresponding to N1 to N16 is also CH19. N1 to N16 are the B-end optical structures that match the B-end COTDR equipment, with the B-end as the end and the A-end as the start. The structures of N1 to N16 in Figure 3 are the same as M1 to M16, and the installation of the A and B-end optical structures at all levels Symmetrical to each other. The upper part of Figure 3 shows the COTDR equipment and communication equipment at A-side and the first stage A→B fiber relay amplifier 1-1 to the third stage A→B fiber relay amplifier 1-3, and the first stage A←B fiber Relay amplifier 8-1 to third stage A←B fiber relay amplifier 8-3, and optical structures M1 to M3 and optical structures N1 to N3. The lower part of Figure 3 shows the COTDR equipment and communication equipment at the B end and the 14th stage A→B fiber relay amplifier 1-14 to the 16th stage A→B fiber relay amplifier 1-16, and the 14th stage A←B fiber Relay amplifiers 8-14 to 16th stage A←B fiber optic relay amplifiers 8-16, and optical structures M14 to M16 and optical structures N14 to N16. The p and q at the right end of the upper half are respectively connected with the p and q at the left end of the lower half. Other relay amplifiers and optical structures are not shown in FIG. 3 .

The COTDR optical pulse detection signal with a wavelength of CH20 sent by the COTDR equipment at the A-end passes through the 16-stage A→B fiber optical relay amplifiers 1-1 to 1-16 in turn through the A→B fiber 3, and the optical structures M1 to M16, and then passes through the A ←The 16-stage A←B fiber optical relay amplifiers 8-1 to 8-16 of the B fiber 4 return 16 receiving pulses of the COTDR equipment at the A end. Because the transmission wavelength of the wavelength division multiplexer in the optical structure N1 to N16 does not match the wavelength of the COTDR optical pulse detection signal at the A end, the COTDR optical pulse detection signal at the A end directly passes through the wavelength division multiplexer and demultiplexer in the optical structure N1 to N16 Multiplexer.

The COTDR optical pulse detection signal of the wavelength CH19 sent by the similar B-end COTDR equipment passes through the 16-stage A←B fiber optical relay amplifier 8-16 to 8-1 in sequence in the A←B optical fiber 4, and the optical structure N16 to N1, and then Through the 16-stage A→B fiber optic relay amplifiers 1-1 to 1-16 of the A→B fiber 3, 16 received pulses are returned to the B-side COTDR device.

Both A-end and B-end are equipped with COTDR equipment, so that both ends of the optical relay amplified optical fiber link can monitor the health status of the optical cable. When there are two breakpoints in the optical cable at the same time, the COTDR at one end can only detect and locate the distance close to the local end. The breakpoint of the other end cannot be detected, and the other end can only detect the breakpoint close to it. Configuring COTDR equipment at both ends can detect the status of the optical cable more comprehensively.

The above-mentioned embodiments are only specific examples for further specifying the purpose, technical solutions and beneficial effects of the present invention, and the present invention is not limited thereto. Any modifications, equivalent replacements, improvements, etc. made within the disclosed scope of the present invention are included in the protection scope of the present invention.

Claims (6)

1. An optical structure for optical relay amplifying optical fiber link transmission COTDR signal, there are two transmission optical fibers between A end and B end of described optical relay amplifying optical fiber link, A → B optical fiber (3) and A ←B optical fiber (4); A and B ends each have a communication device; A end is also equipped with COTDR equipment; The A→B optical fiber (3) and the A←B optical fiber (4) have n-stage relay amplifiers corresponding to each other, and the A ends of the A→B optical fiber (3) are respectively connected through the A-end wavelength division multiplexer (A10). The signal sending end of the A-end communication equipment and the sending end of the A-end COTDR equipment, the A-end of the A←B optical fiber (4) is connected to the A-end COTDR equipment receiving end and the A-end communication through the A-end demultiplexer (A9) At the signal receiving end of the equipment, the wavelengths of the A-end COTDR signal and the communication signals sent by the A- and B-end communication equipment are different; the B-end of the A→B optical fiber (3) is connected to the receiving end of the B-end communication equipment, and the A←B optical fiber ( 4) The B-end is connected to the sending end of the B-end communication device; The COTDR device is located at the A end, and the optical structure for transmitting the COTDR signal is an optical structure for transmitting the A end COTDR signal, including a circulator (2) and a fiber coupler (6), and the A→B optical fiber (3) and Each stage of relay amplifier on the A←B(4) optical fiber is equipped with a set of optical structure for transmitting COTDR signals; the circulator (2) in the optical structure for transmitting COTDR signals of each stage has three ports, and the fiber coupler ( 6) There are 2 input ends and an output end; the first port of the circulator (2) is connected with the output end of the relay amplifier of the same level on the A→B optical fiber (3), and the second port of the circulator (2) Connect the A→B optical fiber (3) leading to the next-stage relay amplifier of the optical fiber, the third port of the circulator (2) is connected with an input end of the fiber coupler (6); it is characterized in that: The optical structure of the transmission COTDR signal also includes a wavelength division multiplexer (5) and a wavelength division multiplexer (7), and a wavelength division multiplexer (5) and a wavelength division multiplexer ( 7) connected in the A←B optical fiber (4), at the input end side of the stage relay amplifier of the A←B optical fiber (4); the wavelength division multiplexer (5) and the wavelength division multiplexer (7) ) are three ports, and the three ports are respectively the common end, the transmission end and the reflection end, the common end of the demultiplexer (5) is connected to the A←B optical fiber (4) at the rear, and the transmission end is connected to the fiber coupler (6) The other input end, the reflection end is connected to the reflection end of the wavelength division multiplexer (7); the transmission end of the wavelength division multiplexer (7) is connected to the output end of the fiber coupler (6), and the common end is connected to A← The input end of the relay amplifier of the present stage of the B optical fiber (4). 2. the optical structure of optical relay amplifying optical fiber link transmission COTDR signal according to claim 1, is characterized in that: The B end of the optical relay amplifies the optical fiber link and configures the B end COTDR equipment simultaneously, and the B end of A←B optical fiber (4) is respectively connected to the signal transmitting end and the B end communication equipment of the B end wavelength division multiplexer (B10) At the sending end of the B-side COTDR device, the wavelength of the B-side COTDR signal is different from that of the communication signals sent by the A and B-side communication equipment, and is also different from the wavelength of the A-side COTDR signal; the B-side of the A→B optical fiber (4) is decomposed by the B-side The wavelength division multiplexer (B9) is connected to the signal receiving end of the B-end COTDR equipment receiving end and the B-end communication equipment; The B-end COTDR device sends an optical pulse detection signal from the B-end of the optical fiber link, that is, the B-end COTDR signal, and transmits along the downlink optical fiber at the B-end of the optical fiber link, that is, the A←B optical fiber (4); Each stage of relay amplifiers on the A→B optical fiber (3) and A←B optical fiber (4) is also equipped with a set of optical structure for transmitting COTDR signals at the B end; The main components of the optical structure of the COTDR signal are the same. The optical structure installed on the optical fiber link to transmit the B-end COTDR signal and the optical structure to transmit the A-end COTDR signal are symmetrical to each other; the optical structure circulator (2 ) is connected to the output end of the same-stage relay amplifier on the A←B optical fiber (4), and the second port of the circulator (2) is connected to A←B of the next-stage relay amplifier leading to the optical fiber The optical fiber (4), the third port of the circulator (2) is connected to an input end of the optical fiber coupler (6) of the optical structure; the demultiplexer (5) and the wavelength division multiplexer (7) of the optical structure ) is connected in the A→B optical fiber (3), at the input end side of the stage relay amplifier of the A→B optical fiber (3); The A→B optical fiber (3) is connected, the transmission end is connected to the other input end of the fiber coupler (6), and the reflection end is connected to the reflection end of the wavelength division multiplexer (7); the transmission end of the wavelength division multiplexer (7) is connected to The output end of the optical fiber coupler (6), and the common end are connected to the input end of the relay amplifier of the present stage of the A→B optical fiber (3). 3. according to claim 1 and 2 described optical structure of optical relay amplifying optical fiber link transmission COTDR signal, it is characterized in that: The working wavelength of the circulator (2) includes C-band and L-band. 4. according to claim 1 and 2 described optical structure of amplifying optical fiber link transmission COTDR signal, it is characterized in that: The working wavelength of the optical fiber coupler (6) includes C-band and L-band. 5. the optical structure of optical relay amplifying optical fiber link transmission COTDR signal according to claim 4, is characterized in that: The fiber coupler (6) is a 3dB fiber coupler with a splitting ratio of 1:1. 6. the optical structure of optical relay amplifying optical fiber link transmission COTDR signal according to claim 4, is characterized in that: The transmitted wave of the wavelength division multiplexer (7) and the wavelength division multiplexer (5) is a narrow spectrum signal wave whose central wavelength is consistent with the working wavelength of the COTDR signal matched by the optical structure, and the reflected wave is a wavelength range including all It is a wide-spectrum signal wave at the wavelength of the communication signal transmitted by the optical fiber, and the common end carries two signals at the same time.