WO2010040297A1

WO2010040297A1 - Method, device and system for optical transmission

Info

Publication number: WO2010040297A1
Application number: PCT/CN2009/073703
Authority: WO
Inventors: 王国忠
Original assignee: 华为海洋网络有限公司
Priority date: 2008-10-10
Filing date: 2009-09-02
Publication date: 2010-04-15
Also published as: CN101729151A; CN101729151B

Abstract

A method, device and system for optical transmission, related to communications field, are provided by the embodiment of the present invention. The method includes: amplifying the probe optical signal received from the first fiber, and isolating the optical signal that has the opposite direction to the probe optical signal; coupling the amplified and isolated probe optical into the second fiber; amplifying the back scattered optical signal of the probe optical signal coupled into the second fiber, and isolating the optical signal that has the opposite direction to the back scattered optical signal, and outputting the amplified and isolated back scattered optical signal. The device includes: the first amplifying and isolating module, the coupling module and the second amplifying and isolating module. The system includes: the land terminal station, the optical transmission device, the first and second fiber. By changing the flow direction of probe optical signal, the method, device and system of the present invention make the land terminal station utilize the optical time domain reflectometer (OTDR) technology to detect the fiber from the received direction.

Description

Optical transmission method, device and system

Technical field

The present invention relates to the field of communications, and in particular, to an optical transmission method, apparatus, and system. Background art

With the rapid development of information technology, the submarine cable network covers all the sea areas of the world. The submarine cable optical communication system generally uses dense wavelength division multiplexing technology, and the traffic generally exceeds Tbit/s, which has become an important international communication service. Important communication network. Submarine cables, especially in offshore shallow water areas, in addition to normal corrosion and aging, are also subject to damage by seabed geological activities, human fishing exploration behavior, and sea creature bites. If the line is degraded or faulty, the economic loss is very large. Therefore, in order to ensure the smooth progress of the communication service, the seabed part of the submarine cable optical communication system is monitored and the location and damage degree of the submarine cable damage are timely and accurately located. Significance.

One of the methods for monitoring optical fibers is to use the basic principle of an OTDR (Optical Time Domain Reflectometer) to transmit a probe optical pulse signal to the optical fiber. When the optical transmission is in the optical fiber, along the length of the optical fiber. Every point on it causes scattering, and reflection occurs at the connector, mechanical connection, break, or fiber termination. Part of the scattered and reflected light is transmitted back to the OTDR along the fiber, and is received by the detector of the OTDR meter. From the strength of the received light, the performance of the fiber mentioned above can be judged.

The submarine portion of a submarine cable optical communication system generally consists of a submarine cable and an optical repeater. Usually, the optical signal is amplified in the optical repeater after every tens of kilometers of submarine cable transmission. In this way, the submarine cable optical communication system can cross the Pacific Ocean and reach the transmission distance of tens of thousands of kilometers. .

Due to its particularity, the submarine fiber optic communication system can only be measured as a whole at the land end station, rather than independently measured in each span as in the terrestrial fiber optic communication system. Usually, the fibers in the submarine cable exist in pairs. For the land end station of each submarine cable communication system, one of the pair of fibers is used to transmit optical signals to the terrestrial end station. Another optical fiber is used to receive the optical signal transmitted by the terrestrial end station of the opposite end. Similarly, each submarine optical repeater typically also includes a pair of optical signal amplifiers.

The two optical signal amplifiers respectively amplify the optical signals transmitted in the respective optical fibers, and the two optical signals are transmitted in opposite directions. Due to the principle limitation of the optical amplifier, in general, the optical amplifier needs to be used in combination with an isolator, and the characteristic of the isolator is that the optical signal passing through one direction of the attenuation is small, and the optical signal passing through it in the opposite direction is greatly attenuated. Guaranteed optical letter The number is unidirectionally amplified, and the optical signal transmitted in the reverse direction is blocked.

In this case, when the terrestrial station uses the OTDR instrument to monitor the fiber in the submarine cable, the OTDR probe light pulse of the input fiber along the forward transmission direction can be transmitted normally, and can also be amplified in each optical repeater. . However, the backscattered or reflected optical signal of the probe optical pulse signal is blocked at the isolator of each optical repeater and cannot be reversely transmitted back to the terrestrial end station, so that the OTDR meter cannot receive the reflected optical signal. Therefore, in order to be able to monitor optical fibers using OTDR technology in a submarine cable system, the problem of reverse transmission of backscattered light must be addressed.

In the prior art, in order to solve the problem of reverse transmission of backscattered light of the probe light when detecting the fiber using the OTDR technique, a coupler is added to the optical repeater, see Fig. 1. For example, when monitoring the downstream fiber, the terrestrial station transmits a probe optical signal to the downstream fiber, and the probe optical signal is forwardly transmitted in the downstream fiber, which can be amplified by the optical repeater and passed through the isolator. The forward-transmitted probe light signal in the downstream fiber is not affected by the coupler, and the back-scattered light of the probe light signal is split into two parts when it reaches the coupler, and a part is reversely transmitted along the port connected to the isolator. After reaching the isolator, it is attenuated and cannot be reversely transmitted through the isolator; another part of the reverse transmitted optical signal is coupled to another port, which is connected to the coupler on the upstream fiber and coupled into the upstream fiber for transmission. Thus, the terrestrial end station transmitting the sounding signal can receive the backscattered light of the sounding signal in the upstream fiber.

In the above solution, the terrestrial end station transmits the probe optical signal to the downlink optical fiber, and receives the backscattered optical signal of the probe optical signal in the uplink optical fiber, and the optical signal reflects the information of the downlink optical fiber. Therefore, this technical solution can only allow each land end station to monitor the fiber in the transmission direction, but not the fiber in the receiving direction. Summary of the invention

In order to enable a terrestrial end station to monitor an optical fiber in a receiving direction, an embodiment of the present invention provides an optical transmission method, apparatus, and system. The technical solution is as follows:

An optical transmission method, the method comprising:

Amplifying the probe optical signal received by the first optical fiber and isolating the optical signal opposite to the direction of the probe optical signal; coupling the amplified and isolated probe optical signal into the second optical fiber;

Amplifying the backscattered light signal coupled to the probe light signal in the second optical fiber, and isolating the optical signal in a direction opposite to the backscattered light signal, and then performing the amplified and isolated backscattering Optical signal output.

An optical transmission device, the device includes: a first amplification isolation module, a coupling module, and a second amplification isolation module; the first amplification isolation module is configured to amplify the detection optical signal received by the first optical fiber, and Isolating an optical signal opposite to the direction of the probe light signal;

The coupling module is configured to couple the probe optical signal after the first amplifying isolation module into the second optical fiber; The second amplifying isolation module is configured to amplify a backscattered optical signal coupled to the probe optical signal in the second optical fiber by the coupling module, and isolate the optical signal in a direction opposite to the backscattered optical signal, and then The isolated backscattered light signal is output.

An optical transmission system, the system comprising: a land end station, an optical transmission device, a first optical fiber, and a second optical fiber; the terrestrial end station, configured to transmit a probe optical signal to the first optical fiber, and further configured to receive And monitoring a backscattered light signal in the second optical fiber;

The optical transmission device is configured to amplify and isolate the probe optical signal in the first optical fiber and couple into the second optical fiber; and is further configured to couple the probe optical signal into the second optical fiber The backscattered light signal is amplified and isolated.

The technical solution provided by the embodiment of the present invention has the beneficial effects of: changing the flow direction of the probe optical signal by the coupler, so that the land end station can monitor the optical fiber in the receiving direction by using the OTDR technology. DRAWINGS

1 is a schematic diagram of a reverse transmission of a back astigmatism signal in the prior art;

2 is a flowchart of an optical transmission method according to Embodiment 1 of the present invention;

Figure 3 is a schematic view of a coupler provided in Embodiment 1 of the present invention;

4 is a schematic diagram of a coupling process of a probe optical signal according to Embodiment 1 of the present invention;

FIG. 5 is a schematic structural diagram of an optical transmission apparatus according to Embodiment 2 of the present invention; FIG.

6 is a schematic structural diagram of an optical transmission apparatus according to Embodiment 2 of the present invention;

7 is a schematic structural diagram of another optical transmission device according to Embodiment 2 of the present invention;

FIG. 8 is a schematic structural diagram of an optical transmission system according to Embodiment 3 of the present invention.

detailed description

The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

Example 1

Referring to FIG. 2, an embodiment of the present invention provides an optical transmission method, in which a flow direction of a probe optical signal is changed by a coupler, so that a terrestrial end station can monitor an optical fiber in a receiving direction by using an OTDR technology. In this embodiment, the first optical fiber is used as the optical fiber in the transmitting direction, and the second optical fiber is used as the optical fiber in the receiving direction. The method specifically includes:

101: amplifying the probe optical signal received by the first optical fiber, and isolating the optical signal opposite to the direction of the detected optical signal number.

The received probe optical signal may be transmitted by the terrestrial end station, and may be amplified by the optical amplifier on the first optical fiber, and the optical signal opposite to the detected optical signal is isolated by the isolator.

102: Coupling the amplified and isolated probe optical signal into the second optical fiber.

Among them, the coupler is used for coupling, see Figure 3, which is a schematic diagram of the coupler. The probe optical signal is input from port 2 and coupled into port 1 and port 3 in a certain ratio.

Among them, the coupler has directionality. The directionality of the coupler means that the ports on the same side cannot communicate with each other, and the ports on the two sides can couple optical signals to each other. For example, port 1 and port 3 in Figure 3 cannot communicate with each other. Port 1 and port 2 The optical signals can be coupled to each other between port 3 and port 2. For example, the optical signal input from port 1 can only be coupled into port 2 output at a certain ratio (for example, 9/10), cannot be coupled into port 3 output, or the optical signal coupled into port 3 is so weak that it is completely exhausted in the application. Can be ignored; the optical signal input from port 3 can only be coupled into port 2 output in a certain ratio (for example, 1/10), can not be coupled into port 1 output, or the optical signal coupled into port 1 is very weak, so that in application It can be completely ignored; the optical signal input from port 2 is coupled into port 1 and port 3 output according to a certain ratio. For example, a 9/10 ratio optical signal is coupled into port 1 output, and 1/10 of the optical signal is coupled into port 3. Output. In the three input scenarios, the ratio of optical power distribution has a certain relationship and the relationship is constant.

In the embodiment of the present invention, referring to FIG. 4, the couplers are present in pairs, that is, there are couplers in the first optical fiber and the second optical fiber, respectively being a first coupler and a second coupler, wherein the first coupling The second coupler is connected by a common port 3. The probe optical signal transmitted into the first optical fiber is coupled into the second optical fiber through the first coupler and the second coupler, and the specific process is as follows:

The probe optical signal transmitted into the first optical fiber enters from the port 2 of the first coupler, and is coupled into the first coupler port 1 and port 3 according to a certain ratio;

a probe optical signal coupled to port 1 of the first coupler is transmitted along the first optical fiber;

The probe optical signal coupled to port 3 of the first coupler is output from port 2 of the second coupler, i.e., the probe optical signal is coupled into the second fiber from the first fiber.

103: amplifying the backscattered optical signal coupled to the probe optical signal in the second optical fiber, and isolating the optical signal opposite to the backscattered optical signal, and then outputting the amplified and isolated backscattered optical signal .

After receiving the backscattered light signal, the land end station can monitor the second optical fiber according to the backscattered light signal. Wherein, the optical amplifier can amplify the backscattered optical signal of the detected optical signal, and the isolator is used to isolate the optical signal in the opposite direction to the backscattered optical signal.

Since the optical signal is attenuated after every tens of kilometers of submarine cable transmission, after every tens of kilometers of submarine cable transmission To zoom in, repeat in this way, so that the submarine cable fiber communication system can cross the Pacific Ocean and reach a transmission distance of tens of thousands of kilometers. At the same time, due to the principle limitation of the optical amplifier, in general, the optical amplifier needs to be combined with the isolator. The characteristic of the isolator is that the optical signal passing through one direction of its attenuation is small, and the optical signal passing through it in the opposite direction is greatly attenuated, thereby ensuring that the optical signal is unidirectionally amplified, and the optical signal transmitted in the reverse direction is attenuated. , that is blocked.

Continuing with the above example, still referring to FIG. 4, the probe optical signal is output from the port 2 of the second coupler, that is, the probe optical signal is coupled into the second optical fiber from the first optical fiber, and then the optical signal is detected along the second optical fiber. To the transmission. Since the probe optical signal is transmitted in the second optical fiber at this time, the backscattered optical signal of the partially detected optical signal carries the information of the second optical fiber. At the same time, the backscattered optical signal carrying the second optical fiber information is transmitted in the forward direction along the second optical fiber, that is, the direction in which the backscattered optical signal is transmitted is the same as the direction of the second optical fiber. After the backscattered light signal enters from the port 2 of the second coupler, it is coupled into port 1 and port 3 of the second coupler in a certain ratio;

The backscattered light signal coupled to port 3 of the second coupler is output from port 2 of the first coupler and is attenuated. The backscattered light signal coupled to port 1 of the second coupler is forwardly transmitted along the second fiber, amplified and isolated, and output to the land end station.

Wherein, before the amplified and isolated probe optical signal is coupled into the second optical fiber, the method includes:

The received optical signal is divided into a probe optical signal and a service optical signal.

Specifically, the optical signal can be differentiated by using a signal processor, such as filtering, attenuation, and the like. When the discrimination is performed by filtering, only the optical signal of a certain frequency is allowed to pass, and the optical signals of other frequencies are blocked. In this way, only the probe optical signal is allowed to pass between the uplink and downlink fibers, and the service optical signal is not allowed to pass, so that the optical cable monitoring function can be realized, and the mutual interference between the service optical signals in the uplink and downlink optical fibers can be avoided. When the discrimination is performed by the attenuation, both the probe optical signal and the service optical signal are attenuated to ensure that the traffic optical signal in the first optical fiber does not affect the traffic optical signal in the second optical fiber.

The optical transmission method provided by the embodiment of the present invention can change the flow direction of the probe optical signal, so that the land end station can monitor the optical fiber in the receiving direction by using the OTDR technology. Example 2

Referring to FIG. 5, an embodiment of the present invention provides an optical transmission apparatus. The coupler is used to change the flow direction of the probe optical signal, so that the land end station can monitor the optical fiber in the receiving direction by using the OTDR technology. In this embodiment, the first optical fiber is used as the optical fiber in the transmitting direction, and the second optical fiber is used as the optical fiber in the receiving direction. The device comprises: a first amplification isolation module 51, a coupling module 52 and a second amplification isolation module 53;

The first amplification isolation module 51 is configured to amplify the probe optical signal transmitted by the terrestrial end station into the first optical fiber, And isolating the optical signal opposite to the direction of the probe optical signal;

a coupling module 52, configured to couple the probe optical signal after passing through the first amplifying isolation module 51 into the second optical fiber; and a second amplification isolation module 53 for coupling the probe optical signal into the second optical fiber through the coupling module 52. The backscattered light signal is amplified and isolated from the optical signal in the opposite direction of the backscattered light signal, and the amplified and isolated backscattered light signal is output to the terrestrial end station.

After receiving the backscattered light signal, the land end station can monitor the second optical fiber according to the backscattered light signal. As shown in FIG. 6, the first amplifying isolation module 51 includes: a first optical amplifier 501 and a first isolator 502; wherein the first optical amplifier 501 is located in the first optical fiber, and is used to transmit the terrestrial end station to the first A probe optical signal in an optical fiber is amplified;

The first isolator 502 is located in the first optical fiber for isolating the optical signal opposite to the direction of the amplified optical signal of the first optical amplifier 501;

The coupling module 52 includes: a first coupler 503 and a second coupler 504; the first coupler 503 and the second coupler 504 are connected by a common port 3;

The first coupler 503 is located in the first optical fiber for transmitting the probe optical signal after passing through the first amplifying isolation module 51 to the second coupler 504;

The second coupler 504 is located in the second optical fiber for receiving the probe optical signal transmitted by the first coupler 503 such that the probe optical signal is coupled into the second optical fiber.

See Figure 3 in Embodiment 1 for a schematic diagram of the coupler. The probe light is input from port 2 of the coupler and coupled into port 1 and port 3 at a certain ratio.

Among them, the coupler has directionality. The directionality of the coupler means that the ports on the same side cannot communicate with each other, and the ports on the two sides can couple optical signals to each other. For example, port 1 and port 3 in Figure 3 cannot communicate with each other. Port 1 and port 2 The optical signals can be coupled to each other between port 3 and port 2. For example, an optical signal input from port 1 can only be coupled into port 2 at a certain ratio (for example, 9/10), cannot be coupled into port 3 output, or the optical signal coupled into port 3 is so weak that it is completely exhausted in the application. Can be ignored; the optical signal input from port 3 can only be coupled into port 2 output in a certain ratio (for example, 1/10), can not be coupled into port 1 output, or the optical signal coupled into port 1 is very weak, so that it is applied It can be completely ignored; the optical signal input from port 2 is coupled into port 1 and port 3 output according to a certain ratio. For example, a 9/10 ratio optical signal is coupled into port 1 output, and 1/10 of the optical signal is coupled into port 3. Output. In the three input scenarios, the ratio of optical power distribution has a certain relationship and the relationship is constant.

The second amplification isolation module 53 includes: a second optical amplifier 505, a second isolator 506;

Wherein the second optical amplifier 505 is located in the second optical fiber for coupling into the second optical fiber through the coupling module 52. A backscattered light signal of the detected optical signal is amplified;

The second isolator 506 is located in the second optical fiber for isolating the optical signal opposite to the direction of the backscattered light signal amplified by the second optical amplifier 505, and outputting the backscattered optical signal through the second isolator 506 Land end station.

Referring to FIG. 6, the probe optical signal separated by the first isolator 502 enters from the port 2 of the first coupler 503, and is coupled into the first coupler 503 port 1 and port 3 according to a certain ratio;

A probe optical signal coupled to port 1 of the first coupler 503 is transmitted along the first optical fiber;

The probe light signal coupled to port 3 of the first coupler 503 is output from port 2 of the second coupler 504, that is, the probe optical signal is coupled into the second fiber, and then the probe light signal is transmitted in the reverse direction along the second fiber. Since the probe light signal is transmitted in the second fiber at this time, the backscattered light signal of the portion of the probe light signal carries the information of the second fiber. At the same time, the backscattered light signal carrying the second fiber information is transmitted in the forward direction along the second fiber. The backscattered optical signal carrying the second optical fiber information enters port 2 of the second coupler 504 and is coupled to port 1 and port 3 of the second coupler 504 in a certain ratio;

The backscattered light signal coupled to port 3 of second coupler 504 is output from port 2 of first coupler 503, and is attenuated by first isolator 502 when it reaches first isolator 502;

The backscattered light signal coupled to port 1 of the second coupler 504 is forwardly transmitted along the second fiber, the second optical amplifier 505 amplifies the backscattered light signal, and the second isolator 506 is isolated and second. The optical amplifier 505 amplifies the optical signal having the opposite direction of the backscattered light signal, and then outputs the backscattered optical signal passing through the amplifier and the isolator to the land end station.

Among them, due to the principle limitation of the optical amplifier, in general, the optical amplifier needs to be combined with the isolator. The characteristic of the isolator is that the optical signal passing through one direction of its attenuation is small, and the optical signal passing through it in the opposite direction is greatly attenuated, thereby ensuring that the optical signal is unidirectionally amplified, and the optical signal transmitted in the reverse direction is blocked. .

For example, the probe light signal in the first fiber is transmitted along the forward direction of the first fiber, substantially no attenuation when passing through the first isolator 502, and the backscattered light signal coupled to port 3 of the second coupler 504 is from The port 2 output of a coupler 503, when reaching the first isolator 502, is largely attenuated due to the reverse transmission and is substantially blocked.

Among them, see Figure 7, the device also includes:

The signal processor 507 is located at a junction of the first coupler 503 and the second coupler 504, and is configured to distinguish the optical signal received by the first coupler 503 into a probe optical signal and a service optical signal, and send the probe optical signal to Second coupler 504.

Among them, the signal processor 507 can be an optical filter, an optical attenuator or other device that can process the signal. For example, when an optical filter is selected, only an optical signal whose frequency is a certain frequency is allowed to pass, and optical signals of other frequencies are blocked; the connection between the upper and lower optical fibers only allows the detection of the optical signal to pass, and the service optical signal is not allowed to pass. , this can be achieved For the cable monitoring function, the mutual interference between the service optical signals in the uplink and downlink fibers is avoided.

For example, when an optical attenuator is selected, both the probe optical signal and the service optical signal are attenuated to ensure that the service optical signal in the first optical fiber does not affect the service optical signal in the second optical fiber when passing through the coupler.

In the embodiment of the present invention, the first optical fiber is used as the optical fiber in the transmitting direction. In practical applications, the second optical fiber may also be used as the optical fiber for transmitting the square wire. The specific changes are obvious and will not be described here.

The optical transmission device provided by the embodiment of the invention changes the flow direction of the probe optical signal through the coupler, so that the land end station can monitor the optical fiber in the receiving direction by using the OTDR technology.

Example 3

Referring to FIG. 8, an embodiment of the present invention provides an optical transmission system. The optical transmission device is used to change the flow direction of the probe optical signal, so that the terrestrial end station can monitor the optical fiber in the receiving direction by using the OTDR technology. In this embodiment, the first optical fiber is used as the optical fiber in the transmitting direction, and the second optical fiber is used as the optical fiber in the receiving direction. The system includes: a land end station 701, an optical transmission device 702, a first optical fiber 703, and a second optical fiber 704;

The land end station 701 is configured to transmit a probe optical signal to the first optical fiber 703, and is further configured to receive and monitor a backscattered optical signal in the second optical fiber 704;

The optical transmission device 702 is configured to amplify the probe optical signal transmitted into the first optical fiber 703, and isolate the optical signal opposite to the direction of the probe optical signal, and couple the amplified and isolated probe optical signal into the second optical fiber. 704; is further for amplifying the backscattered light signal coupled to the probe light signal in the second optical fiber 704 and isolating the optical signal in a direction opposite to the backscattered light signal.

The optical transmission device 702 includes: a first amplification isolation module, a coupling module, and a second amplification isolation module; and a first amplification isolation module, configured to amplify and isolate the probe optical signal transmitted by the terrestrial end station into the first optical fiber. An optical signal opposite to the direction of the probe optical signal;

a coupling module, configured to couple the probe optical signal after passing through the first amplifying isolation module into the second optical fiber;

a second amplification isolation module for amplifying the backscattered light signal coupled to the probe light signal in the second optical fiber by the coupling module, and isolating the optical signal opposite to the backscattered light signal, and then passing the The backscattered light signal of the second amplification isolation module is output to the terrestrial end station.

The first amplification isolation module specifically includes: a first optical amplifier and a first isolator;

a first optical amplifier, configured to amplify the probe optical signal transmitted by the terrestrial end station into the first optical fiber;

a first isolator for isolating an optical signal opposite to the direction of the probe optical signal amplified by the first optical amplifier; the coupling module specifically includes: a first coupler and a second coupler;

The first coupler is located in the first optical fiber, and is configured to send the probe optical signal after passing the first amplification isolation module to the second Rate matching 3⁄4S;

The second coupler is located in the second optical fiber for receiving the probe light signal sent by the first coupler.

The second amplification isolation module specifically includes: a second optical amplifier and a second isolator;

a second optical amplifier for amplifying the backscattered optical signal coupled to the probe optical signal in the second optical fiber by the coupling module;

And a second isolator for isolating the optical signal opposite to the direction of the backscattered light signal amplified by the second optical amplifier, and then outputting the backscattered optical signal through the second isolator to the terrestrial end station.

The optical transmission device further includes:

a signal processor, located at the first coupler and the second coupler connection, for distinguishing the optical signal received from the first coupler into a probe optical signal and a service optical signal, and transmitting the probe optical signal to the second coupling Device.

The specific structure of the optical transmission device is the same as that of the optical transmission device in Embodiment 2, and details are not described herein again.

The optical transmission system provided by the embodiment of the present invention changes the flow direction of the probe optical signal by the optical transmission device, so that the land end station can monitor the optical fiber in the receiving direction by using the OTDR technology.

Embodiments of the invention may be implemented in software, and the corresponding software program may be stored in a readable storage medium, such as a hard disk, a cache, or an optical disk of a computer.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., which are within the spirit and scope of the present invention, should be included in the protection of the present invention. Within the scope.

Claims

What is claimed is: 1 . An optical transmission method, comprising:

Amplifying the backscattered light signal coupled to the probe light signal in the second fiber weight, and isolating the light signal in a direction opposite to the backscattered light signal, and then omitting the amplified and isolated back Scattered light signal output.

The method according to claim 1, wherein before the amplifying and isolating the probe optical signal is coupled into the second optical fiber, the method further includes:

An optical transmission device, comprising: a first amplification isolation module 51, a coupling module 52, and a second amplification isolation module 53;

The first amplifying and separating module 51 is configured to amplify the probe optical signal received by the first optical fiber and isolate the optical signal in a direction opposite to the detected optical signal;

The coupling module 52 is configured to couple the probe optical signal amplified and isolated by the first amplifying isolation module 51 into the second optical fiber;

The second amplification isolation module 53 is configured to amplify a backscattered optical signal coupled to the probe optical signal in the second optical fiber by the coupling module 52, and isolate the opposite direction from the backscattered optical signal. The optical signal then outputs the isolated backscattered light signal.

The optical transmission device according to claim 3, wherein the coupling module 52 comprises: a first coupler 503 and a second coupler 504;

The first coupler 503 is located in the first optical fiber, and is configured to send the probe light signal after the first amplifying isolation module 51 to the second coupler 504;

The second coupler 504 is located in the second optical fiber and is configured to receive the probe optical signal sent by the first coupler 503.

The optical transmission device according to claim 4, wherein the device further comprises:

a signal processor 507, located at the junction of the first coupler 503 and the second coupler 504, for distinguishing the optical signal received by the first coupler 503 into a probe optical signal and a service optical signal, a probe optical signal is sent to the

~ · Rate fit 3⁄4F.

6. An optical transmission system, characterized in that: the system comprises: a land end station 701, an optical transmission device 702, a An optical fiber 703 and a second optical fiber 704;

The terrestrial end station 701 is configured to transmit a probe optical signal to the first optical fiber 703, and is further configured to receive and monitor a backscattered optical signal in the second optical fiber 704;

The optical transmission device 702 is configured to amplify and isolate the probe optical signal in the first optical fiber 703 and couple into the second optical fiber 704; and is further configured to be coupled into the second optical fiber 704. The backscattered light signal that detects the optical signal is amplified and isolated.

The optical transmission system of claim 6, wherein the optical transmission device 702 comprises: a first amplification isolation module, a coupling module, and a second amplification isolation module;

The first amplifying and separating module is configured to amplify the probe optical signal transmitted by the terrestrial end station into the first optical fiber, and isolate the optical signal in a direction opposite to the detecting optical signal;

The coupling module is configured to couple the probe optical signal amplified and isolated by the first amplification isolation module into the second optical fiber;

The second amplifying isolation module is configured to amplify a backscattered optical signal coupled to the probe optical signal in the second optical fiber by the coupling module, and isolate the optical signal in a direction opposite to the backscattered optical signal, and then The isolated backscattered light signal is output to the terrestrial end station.

The optical transmission system according to claim 7, wherein the coupling module specifically includes: a first coupler and a second coupler;

The first coupler is located in the first optical fiber, and is configured to send the probe optical signal after the first amplifying isolation module to the second coupler;

The second coupler is located in the second optical fiber, and is configured to receive the probe optical signal sent by the first coupler.

9. The optical transmission system of claim 8, wherein the optical transmission device 702 further comprises: a signal processor located at the first coupler and the second coupler connection, The optical signal received by the first coupler is divided into a probe optical signal and a traffic optical signal, and the probe optical signal is transmitted to the second coupler.