CN105577269B - A kind of light path detection method and device - Google Patents

Abstract

The invention discloses an optical path detection method and device, which are used to solve the problems of low accuracy and poor precision of optical path detection in the prior art. The method includes: receiving detection optical signals of different wavelengths; determining a plurality of detection optical signal combinations according to the received detection optical signals of different wavelengths, wherein each combination of detection optical signals contains at least one detection optical signal; The optical splitting ratio set by each detection optical signal sends a detection optical signal combination to each optical network unit ONU branch in the passive optical network PON; receives the combination of the detection optical signal fed back by each ONU branch and the detection optical signal received by itself The backscattered light signal corresponding to the included detection light signal; realizes the detection of each ONU branch according to the received backscattered light signal fed back by each ONU branch.

Description

An optical path detection method and device

technical field

The invention relates to the technical field of optical communication, in particular to an optical path detection method and device.

Background technique

Optical Time Domain Reflectometer (OTDR) is a sophisticated photoelectric integrated instrument made by using Rayleigh scattering and backscattering produced by Fresnel reflection when light is transmitted in optical fiber. It is widely used in the maintenance and construction of optical cable lines, and can measure the length of optical fiber, transmission attenuation of optical fiber, joint attenuation and fault location.

In a traditional passive optical network (Passive Optical Network, PON), the OTDR uses a signal of a specified wavelength to detect the optical cable lines in the network. The specific system structure is shown in Figure 1.

In the system shown in Fig. 1, OTDR uses the signal that the wavelength is λ ₁ to carry on the detection of the optical cable line. After passing through an optical splitter, the power of the signal is evenly distributed to each optical network unit (Optical Network Unit, ONU) branch according to the splitting ratio of the optical splitter. After the backscattered optical signals of each ONU branch are converged at the optical splitter, they are received and analyzed by the OTDR.

This scheme mainly has the following disadvantages:

1. The signal used by OTDR is a single-wavelength signal, which is coupled to all ONU branches in the PON network after passing through the optical splitter. When performing optical cable line detection, each ONU branch feeds backscattered light at the same time, and OTDR cannot distinguish the source of backscattered light, so it cannot locate the detection result to the accurate ONU branch.

2. After the signal used by OTDR passes through the optical splitter, the power is evenly distributed to each ONU branch. Normally, the optical power in each ONU branch is only 1/128-1/32 of the main power. The optical power in each ONU branch directly affects the power of backscattered light, resulting in low detection accuracy of the optical path of each ONU branch.

Contents of the invention

Embodiments of the present invention provide an optical path detection method and device to solve the problems of low accuracy and poor precision of optical path detection in the prior art.

Embodiments of the present invention adopt the following technical solutions:

An embodiment of the present invention provides an optical path detection method, including:

Receive detection optical signals of different wavelengths;

Determine a plurality of detection optical signal combinations according to the received detection optical signals of different wavelengths, wherein each detection optical signal combination includes at least one detection optical signal;

According to the light splitting ratio set for each detection optical signal, send a detection optical signal combination to each optical network unit ONU branch in the passive optical fiber network PON;

Receiving the backscattered optical signal fed back by each ONU branch and corresponding to the detected optical signal contained in the combination of detected optical signals received by itself;

The detection of each ONU branch is realized according to the received backscattered light signal fed back by each ONU branch.

Optionally, the combinations of detection optical signals sent to each ONU branch in the PON are different; then

According to the received backscattered light signal fed back by each ONU branch, the detection of each ONU branch is realized, including:

When there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light signal combination corresponding to the backscattered light signal representing the fault in the optical cable line ;

The ONU branch corresponding to the determined combination of detected optical signals is determined as the faulty branch.

Optionally, the detection optical signal combination sent to each ONU branch in the PON is not exactly the same; then

According to the received backscattered light signal fed back by each ONU branch, the detection of each ONU branch is realized, including:

When there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light signal combination corresponding to the backscattered light signal representing the fault in the optical cable line ;

When the ONU branch corresponding to the determined combination of detected optical signals is one, the ONU branch is determined as a faulty branch;

When there are at least two ONU branches corresponding to the determined combination of detected optical signals, a faulty branch is determined from the ONU branches corresponding to the determined detected optical signals.

Optionally, when there are at least two ONU branches corresponding to the determined combination of detected optical signals, the faulty branch is determined from the ONU branches corresponding to the determined detected optical signal, specifically including:

Judging whether the difference in the physical length of the ONU branch corresponding to the determined detected optical signal is less than a preset threshold;

When the judgment result is yes, according to the backscattered optical signal corresponding to the determined combination of detected optical signals, and the pre-acquired system analysis information, determine the faulty branch from the ONU branch corresponding to the determined detected optical signal;

When the judgment result is no, combine the corresponding backscattered light signal according to the determined detection light signal, and combine the determined detection light signal with the reflected light signal generated based on the reflective plate in the corresponding ONU branch, from the determined A faulty branch is determined in the ONU branch corresponding to the optical signal.

An embodiment of the present invention provides an optical path detection device, including:

A detection optical signal receiving unit, configured to receive detection optical signals of different wavelengths;

A detection optical signal combination determining unit, configured to determine a plurality of detection optical signal combinations according to received detection optical signals of different wavelengths, wherein each detection optical signal combination includes at least one detection optical signal;

The detection optical signal combination sending unit is used to send a detection optical signal combination to each optical network unit ONU branch in the passive optical fiber network PON according to the splitting ratio set for each detection optical signal;

The backscattered light signal receiving unit is used to receive the backscattered light signal fed back by each ONU branch and corresponding to the detection light signal contained in the detection light signal combination received by itself;

The detection unit is configured to detect each ONU branch according to the received backscattered light signal fed back by each ONU branch.

Optionally, the combination of detection optical signals sent by the detection optical signal combination sending unit to each ONU branch in the PON is different; then

The detection unit is specifically used for:

When there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light signal combination corresponding to the backscattered light signal representing the fault in the optical cable line ; Determining the ONU branch corresponding to the determined combination of detected optical signals as the faulty branch.

Optionally, the detection optical signal combination sent by the detection optical signal combination sending unit to each ONU branch in the PON is not exactly the same; then

The detection unit is specifically used for:

When there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light signal combination corresponding to the backscattered light signal representing the fault in the optical cable line ; When the ONU branch corresponding to the determined combination of detected optical signals is one, determine the ONU branch as a faulty branch; when the determined combination of detected optical signals corresponds to at least two ONU branches, from the determined A faulty branch is determined in the ONU branch corresponding to the detected optical signal.

Optionally, the detection unit is specifically used for:

Judging whether the difference in the physical length of the ONU branch corresponding to the determined detected optical signal is less than a preset threshold;

When the judgment result is yes, according to the backscattered optical signal corresponding to the determined combination of detected optical signals, and the pre-acquired system analysis information, determine the faulty branch from the ONU branch corresponding to the determined detected optical signal;

When the judgment result is no, combine the corresponding backscattered light signal according to the determined detection light signal, and combine the determined detection light signal with the reflected light signal generated based on the reflective plate in the corresponding ONU branch, from the determined A faulty branch is determined in the ONU branch corresponding to the optical signal.

The beneficial effects of the embodiments of the present invention are as follows:

Compared with the prior art, the embodiment of the present invention generates a plurality of detection optical signals of different wavelengths, and then combines the detection optical signals of different wavelengths to obtain different combinations of detection optical signals, and sends a branch to each ONU in the PON. The path sends a combination of detection light signals, wherein at least one detection light signal is included in the combination of detection light signals, so that when performing optical path detection, on the one hand, the source of the received backscattered light signal can be identified, so that the detection result can be located at Accurate ONU branches, on the other hand, can also increase the transmission power of each detected optical signal in the corresponding ONU branches, thereby ensuring the accuracy of optical path detection.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute improper limitations to the present invention. In the attached picture:

FIG. 1 is a schematic structural diagram of an optical path detection system in the prior art;

Fig. 2 is a schematic flow chart of the principle of the optical path detection method in the embodiment of the present invention;

FIG. 3 is a schematic diagram of a system architecture for implementing an optical path detection method in practical applications in an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of an optical path detection device in an embodiment of the present invention.

Detailed ways

In order to solve the problems of low accuracy and poor precision of optical path detection existing in the prior art, embodiments of the present invention provide an optical path detection method and device. Compared with the prior art, this technical solution generates a plurality of detection optical signals of different wavelengths, and then combines the detection optical signals of different wavelengths to obtain different combinations of detection optical signals, and sends them to each ONU branch in the PON. Send a detection light signal combination, wherein at least one detection light signal is included in the detection light signal combination, so that when performing optical path detection, on the one hand, the source of the received backscattered light signal can be identified, so that the detection result can be located accurately On the other hand, the transmission power of each detected optical signal in the corresponding ONU branch can be increased, thereby ensuring the accuracy of optical path detection.

The embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention. And in the case of no conflict, the embodiments and the features of the embodiments in the present invention can be combined with each other.

The embodiment of the present invention provides an optical path detection method, as shown in Figure 2, which is a principle flowchart of the method, specifically including the following steps:

Step 21, generating detection optical signals of different wavelengths.

During specific implementation, the wavelengths of the generated detection optical signals should all be non-service wavelengths, so as to ensure that the wavelengths of the detection optical signals can be relatively independent from the service wavelengths.

Step 22, according to the received detection light signals of different wavelengths, determine a plurality of detection light signal combinations; wherein, each detection light signal combination includes at least one detection light signal.

Step 23: Send a combination of detected optical signals to each ONU branch in the passive optical fiber network PON according to the optical splitting ratio set for each detected optical signal.

Wherein, when the detection optical signal combination is sent to the ONU branch in the PON, it can be allocated according to the principle that one detection optical signal combination is only used by one ONU branch. However, in some specific cases, for example, the number of received detection optical signals is relatively limited, resulting in a relatively limited number of detection optical signal combinations determined, so one detection optical signal combination can also be used by multiple ONU branches.

Step 24, receiving the backscattered optical signal fed back by each ONU branch and corresponding to the detected optical signal included in the combination of detected optical signals received by itself.

Step 25, realize the detection of each ONU branch according to the received backscattered light signal fed back by each ONU branch.

In the case that the combinations of detection optical signals sent to each ONU branch in the PON are different, step 25 can be implemented, but not limited to, in the following manner:

When there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light signal combination corresponding to the backscattered light signal representing the fault in the optical cable line ;

The ONU branch corresponding to the determined combination of detected optical signals is determined as the faulty branch.

In the case where the combinations of detected optical signals sent to each ONU branch in the PON are not exactly the same, step 25 can be, but not limited to, implemented in the following manner:

When there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light signal combination corresponding to the backscattered light signal representing the fault in the optical cable line ;

When the ONU branch corresponding to the determined combination of detected optical signals is one, the ONU branch is determined as a faulty branch;

When there are at least two ONU branches corresponding to the determined combination of detected optical signals, a faulty branch is determined from the ONU branches corresponding to the determined detected optical signals.

Typically, the physical lengths of the ONU branches using the same detection optical signal combination should not be the same, so that the reflection sheet added to the ONU branch can be used to locate the fault of the optical cable line; but if the same detection optical signal combination is used If the physical lengths of the ONU branches are the same or very close, it is necessary to use system analysis tools, such as fault logs, to locate the fault of the optical cable line.

Therefore, when there are at least two ONU branches corresponding to the determined combination of detected optical signals, determining the faulty branch from the ONU branches corresponding to the determined detected optical signal can be implemented in the following manner, but not limited to:

Judging whether the difference in the physical length of the ONU branch corresponding to the determined detected optical signal is less than a preset threshold;

When the judgment result is yes, according to the backscattered optical signal corresponding to the determined combination of detected optical signals, and the pre-acquired system analysis information, determine the faulty branch from the ONU branch corresponding to the determined detected optical signal;

When the judgment result is no, combine the corresponding backscattered light signal according to the determined detection light signal, and combine the determined detection light signal with the reflected light signal generated based on the reflective plate in the corresponding ONU branch, from the determined A faulty branch is determined in the ONU branch corresponding to the optical signal.

In order to better understand the embodiments of the present invention, the specific implementation process of the embodiments of the present invention will be described below in combination with specific implementations.

As shown in FIG. 3 , it is a schematic diagram of a system architecture for implementing an optical path detection method in practical applications, mainly including an OTDR, an optical splitter, and a PON network.

Among them, the OTDR needs to be equipped with an adjustable wavelength laser, which is used to generate detection optical signals of different wavelengths and send them to the optical splitter; and receive the backscattered light signal fed back by the optical splitter, and realize optical path detection according to the backscattered optical signal;

The optical splitter needs to have the function of setting the splitting ratio for different detection light signals. After receiving the detection light signal sent by the OTDR, first determine a plurality of detection light signal combinations, wherein each detection light signal combination contains at least one detection light signal signal, and then send a combination of detection optical signals to each ONU branch in the PON according to the splitting ratio set for each detection optical signal; and receive backscattered light signals fed back by each ONU branch. And feed back to OTDR.

During specific implementation, the wavelengths of the multiple detection optical signals generated by the OTDR using the tunable wavelength laser should all be non-service wavelengths, so as to ensure that the wavelengths of the detection optical signals can be relatively independent from the service wavelengths.

Among them, when the combination of detection optical signals sent by the optical splitter to each ONU branch in the PON is different, the OTDR is specifically used for:

When there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light signal combination corresponding to the backscattered light signal representing the fault in the optical cable line ;

The ONU branch corresponding to the determined combination of detected optical signals is determined as the faulty branch.

When the detection optical signal combination sent by the optical splitter to each ONU branch in the PON is not exactly the same, the OTDR is specifically used for:

When there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light signal combination corresponding to the backscattered light signal representing the fault in the optical cable line ;

When the ONU branch corresponding to the determined combination of detected optical signals is one, the ONU branch is determined as a faulty branch;

When there are at least two ONU branches corresponding to the determined combination of detected optical signals, it is determined whether the difference in physical length of the ONU branches corresponding to the determined detected optical signal is less than a preset threshold;

When the judgment result is yes, according to the backscattered optical signal corresponding to the determined combination of detected optical signals, and the pre-acquired system analysis information, determine the faulty branch from the ONU branch corresponding to the determined detected optical signal;

When the judgment result is no, combine the corresponding backscattered light signal according to the determined detection light signal, and combine the determined detection light signal with the reflected light signal generated based on the reflective plate in the corresponding ONU branch, from the determined A faulty branch is determined in the ONU branch corresponding to the optical signal.

The optical path detection method provided by the embodiment of the present invention will be described in detail below in conjunction with the above system architecture diagram.

Assume that the PON network includes 8 ONU branches.

OTDR uses tunable wavelength lasers to generate four detection optical signals of different wavelengths, which are λ ₁ , λ ₂ , λ ₃ and λ ₄ , and send them to the optical splitter.

The splitter sets the splitting ratio of λ ₁ , λ ₂ , λ ₃ and λ ₄ , the splitting ratio of λ ₁ is 1:4, the splitting ratio of λ ₂ and λ ₃ is 1:3, and the splitting ratio of λ ₄ is 1 :2;

Different detection optical signal combinations are determined, and a detection optical signal combination is sent to each ONU branch in the PON. As shown in Table 1 below, it is the corresponding relationship between the detection optical signal combination and the ONU branch in the embodiment of the present invention.

Table 1:

ONU branch 1 2 3 4 5 6 7 8

Detect light signal combinations lambda ₁ lambda ₂ lambda ₃ lambda ₄ λ ₁ λ ₂ λ ₁ λ ₃ λ ₁ λ ₄ λ ₂ λ ₃

Referring to Table 1, the detection optical signal combinations assigned to ONU branches 1-4 respectively include only one detection optical signal, and the detection optical signal combinations assigned to ONU branches 5-8 respectively include two detection optical signals.

It should be noted that, in practical applications, the determination method and distribution method of the detection optical signal combination are not limited to the above example, and can be customized according to the specific needs of the system.

In this embodiment, since the combination of detection optical signals assigned to each ONU branch is unique, the OTDR can receive and compare backscattered light signals of different wavelengths to realize optical cable line detection of the ONU branch. Analysis and positioning.

For example, in actual operation, if the backscattered optical signal corresponding to _λ1 represents a fault in an optical cable line, the fault can be preliminarily located in ONU branches 1, 5, 6 and 7. At this point, it is only necessary to continue to judge the backscattered light signals of _λ2 , _λ3 , and _λ4 . If the backscattered light signal corresponding to _λ2 indicates that an optical cable line fault occurs at the same position, the fault can be located in the ONU branch. Road 5; if the backscattered light signal corresponding to λ ₃ represents a cable line fault at the same position, the fault can be located in the ONU branch 6; and so on, the algorithm extracts the same Fault information, the system can locate the fault branch.

In the above application scenarios, the setting of the splitting ratio of the service signal carrying the service by the optical splitter should be independent of the splitting ratio of the detection optical signal, so as to ensure that the service signal and the detection optical signal can be relatively independent. In addition, the splitting ratio of the detection optical signal should not be too large, so as to provide greater power and ensure the detection accuracy of the ONU branch.

When using this system for optical path detection, if you need to detect several specific ONU branches, you can adjust the wavelength-tunable laser in the OTDR to a specific wavelength for targeted detection. In addition, the system can also provide a full scan of the health of the optical path of the ONU branch, that is, the tunable wavelength laser in the OTDR is sequentially adjusted to different wavelengths and allocated to the ONU branch.

Based on the same inventive concept, an optical path detection device is also provided in the embodiment of the present invention. Since the problem-solving principle of the above-mentioned device is similar to the method of optical path detection, the implementation of the above-mentioned device can refer to the implementation of the method, and the repetition is no longer repeat.

As shown in Figure 4, it is a schematic structural diagram of the optical path detection device provided by the embodiment of the present invention, including:

A detection optical signal receiving unit 41, configured to receive detection optical signals of different wavelengths;

The detection optical signal combination determining unit 42 is configured to determine a plurality of detection optical signal combinations according to the received detection optical signals of different wavelengths, wherein each detection optical signal combination includes at least one detection optical signal;

The detection optical signal combination sending unit 43 is used to send a detection optical signal combination to each optical network unit ONU branch in the passive optical fiber network PON according to the splitting ratio set for each detection optical signal;

The backscattered light signal receiving unit 44 is configured to receive the backscattered light signal fed back by each ONU branch and corresponding to the detection light signal contained in the detection light signal combination received by itself;

The detection unit 45 is configured to detect each ONU branch according to the received backscattered light signal fed back by each ONU branch.

Optionally, the detection optical signal combination sent by the detection optical signal combination sending unit 42 to each ONU branch in the PON is different; then

The detection unit 45 is specifically used for:

When there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light signal combination corresponding to the backscattered light signal representing the fault in the optical cable line ; Determining the ONU branch corresponding to the determined combination of detected optical signals as the faulty branch.

Optionally, the detection optical signal combination sent by the detection optical signal combination sending unit 42 to each ONU branch in the PON is not exactly the same; then

The detection unit 45 is specifically used for:

When there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light signal combination corresponding to the backscattered light signal representing the fault in the optical cable line ; When the ONU branch corresponding to the determined combination of detected optical signals is one, determine the ONU branch as a faulty branch; when the determined combination of detected optical signals corresponds to at least two ONU branches, from the determined A faulty branch is determined in the ONU branch corresponding to the detected optical signal.

Further, the detection unit 45 is specifically used for:

Judging whether the difference in the physical length of the ONU branch corresponding to the determined detected optical signal is less than a preset threshold;

When the judgment result is yes, according to the backscattered optical signal corresponding to the determined combination of detected optical signals, and the pre-acquired system analysis information, determine the faulty branch from the ONU branch corresponding to the determined detected optical signal;

When the judgment result is no, combine the corresponding backscattered light signal according to the determined detection light signal, and combine the determined detection light signal with the reflected light signal generated based on the reflective plate in the corresponding ONU branch, from the determined A faulty branch is determined in the ONU branch corresponding to the optical signal.

Those skilled in the art should understand that the embodiments of the present invention may be provided as methods, systems, or computer program products. Accordingly, the present invention can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

While preferred embodiments of the invention have been described, additional changes and modifications to these embodiments can be made by those skilled in the art once the basic inventive concept is appreciated. Therefore, it is intended that the appended claims be construed to cover the preferred embodiment as well as all changes and modifications which fall within the scope of the invention.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (6)

1. A light path detection method, characterized in that, comprising: Receive detection optical signals of different wavelengths; Determine a plurality of detection optical signal combinations according to the received detection optical signals of different wavelengths, wherein each detection optical signal combination includes at least one detection optical signal; According to the light splitting ratio set for each detection optical signal, send a detection optical signal combination to each optical network unit ONU branch in the passive optical fiber network PON; Receiving the backscattered optical signal fed back by each ONU branch and corresponding to the detected optical signal contained in the combination of detected optical signals received by itself; According to the received backscattered light signal fed back by each ONU branch, the detection of each ONU branch is realized; Among them, the detection optical signal combination sent to each ONU branch in the PON is not exactly the same; then, according to the received backscattered light signal fed back by each ONU branch, the detection of each ONU branch is realized, specifically Including: when there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light corresponding to the backscattered light signal representing a fault in the optical cable line Signal combination; when the determined ONU branch corresponding to the detected optical signal combination is one, determine the ONU branch as the fault branch; when the determined detected optical signal combination corresponds to at least two ONU branches, from A faulty branch is determined in the ONU branch corresponding to the determined detected optical signal. 2. The method according to claim 1, characterized in that, the detection optical signal combination sent to each ONU branch in the PON is different; According to the received backscattered light signal fed back by each ONU branch, the detection of each ONU branch is realized, including: When there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light signal combination corresponding to the backscattered light signal representing the fault in the optical cable line ; The ONU branch corresponding to the determined combination of detected optical signals is determined as the faulty branch. 3. The method according to claim 1, wherein when there are at least two ONU branches corresponding to the determined combination of detected optical signals, the faulty branch is determined from the ONU branches corresponding to the determined detected optical signals , including: Judging whether the difference in the physical length of the ONU branch corresponding to the determined detected optical signal is less than a preset threshold; When the judgment result is yes, according to the backscattered optical signal corresponding to the determined combination of detected optical signals, and the pre-acquired system analysis information, determine the faulty branch from the ONU branch corresponding to the determined detected optical signal; When the judgment result is no, combine the corresponding backscattered light signal according to the determined detection light signal, and combine the determined detection light signal with the reflected light signal generated based on the reflective plate in the corresponding ONU branch, from the determined A faulty branch is determined in the ONU branch corresponding to the optical signal. 4. An optical path detection device, characterized in that, comprising: A detection optical signal receiving unit, configured to receive detection optical signals of different wavelengths; A detection optical signal combination determining unit, configured to determine a plurality of detection optical signal combinations according to received detection optical signals of different wavelengths, wherein each detection optical signal combination includes at least one detection optical signal; The detection optical signal combination sending unit is used to send a detection optical signal combination to each optical network unit ONU branch in the passive optical fiber network PON according to the splitting ratio set for each detection optical signal; The backscattered light signal receiving unit is used to receive the backscattered light signal fed back by each ONU branch and corresponding to the detection light signal contained in the detection light signal combination received by itself; The detection unit is used to realize the detection of each ONU branch according to the received backscattered light signal fed back by each ONU branch; Among them, the detection optical signal combination sent to each ONU branch in the PON is not exactly the same; then, according to the received backscattered light signal fed back by each ONU branch, the detection of each ONU branch is realized, specifically Including: when there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light corresponding to the backscattered light signal representing a fault in the optical cable line Signal combination; when the determined ONU branch corresponding to the detected optical signal combination is one, determine the ONU branch as the fault branch; when the determined detected optical signal combination corresponds to at least two ONU branches, from A faulty branch is determined in the ONU branch corresponding to the determined detected optical signal. 5. The device according to claim 4, characterized in that, the detection optical signal combination sent by the detection optical signal combination sending unit to each ONU branch in the PON is different; The detection unit is specifically used for: When there is a backscattered light signal representing a fault in the optical cable line among the received backscattered light signals fed back by each ONU branch, determine the detection light signal combination corresponding to the backscattered light signal representing the fault in the optical cable line ; Determining the ONU branch corresponding to the determined combination of detected optical signals as the faulty branch. 6. The device according to claim 4, wherein the detection unit is specifically used for: Judging whether the difference in the physical length of the ONU branch corresponding to the determined detected optical signal is less than a preset threshold; When the judgment result is yes, according to the backscattered optical signal corresponding to the determined combination of detected optical signals, and the pre-acquired system analysis information, determine the faulty branch from the ONU branch corresponding to the determined detected optical signal; When the judgment result is no, combine the corresponding backscattered light signal according to the determined detection light signal, and combine the determined detection light signal with the reflected light signal generated based on the reflective plate in the corresponding ONU branch, from the determined A faulty branch is determined in the ONU branch corresponding to the optical signal.