Self-synchronous remote low input amplification system and method

Abstract

The invention discloses a self-synchronous remote low-input amplification system and method, comprising: a monitoring unit, a first optical fiber and a remote amplification unit, wherein the monitoring unit comprises: a first control module, an optical signal generating module, a first circulator and a first optical signal collecting module, and the remote amplification unit comprises: an optical splitter, a second circulator, a second optical signal collecting module, a second control module, a first SOA, a second SOA and a third circulator, the first SOA and the second SOA do not need to be turned on for a long time, the loss of the first SOA and the second SOA is reduced, the service life is extended, the first SOA and the second SOA do not need to be controlled to turn on and off the gain amplification function through an external communication mode, the monitoring frequency of a test pulse signal does not need to be reduced, and the monitoring efficiency is improved, the first SOA and the second SOA have a wider working wavelength range, and can perform gain amplification on weaker input optical signals, thereby realizing a remote monitoring function.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber communication technology, and in particular to a self-synchronous remote low-input amplification system and method. Background Art

[0002] The light intensity of the optical signal in the optical fiber network monitoring and management system cannot be increased indefinitely. Therefore, it is necessary to add an optical amplifier in the middle position to amplify the gain of the optical signal.

[0003] However, the optical amplifiers commonly used in the optical fiber network monitoring and management system have high requirements for input light intensity and a narrow working wavelength range. When the input optical signal in the optical fiber network monitoring and management system is weak and the wavelength is large, it cannot be amplified. In addition, the optical fiber network monitoring and management system needs to drive the optical amplifier through an external communication method, which has the problem of time synchronization. The optical signal in the optical fiber network monitoring and management system is at the ns level. In order to meet the speed requirements, the external communication method can only reduce the monitoring frequency of the optical signal, resulting in low efficiency, and the optical amplifier is turned on for a long time, resulting in large losses. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a self-synchronous remote low-input amplification system and method, which can solve the problems of being unable to amplify weaker optical signals with larger wavelengths, requiring external communication methods and having large losses.

[0005] According to a first aspect of the present invention, a self-synchronous remote low-input amplification system includes: a monitoring unit, the monitoring unit includes: a first control module, an optical signal generating module, a first circulator and a first optical signal acquisition module, the output end of the first control module is electrically connected to the control end of the optical signal generating module for controlling the optical signal generating module to send a start pulse signal and a test pulse signal, the output end of the optical signal generating module is connected to the first port of the first circulator, the third port of the first circulator is connected to the input end of the first optical signal acquisition module for collecting the returned test pulse signal, and the output end of the first optical signal acquisition module is electrically connected to the input end of the first control module; a first optical fiber, the second port of the first circulator is connected to one end of the first optical fiber; a remote amplification unit, the remote amplification unit includes: a splitter, a second circulator, a second optical signal acquisition module, a second control module, a first SOA, a second SOA and a third circulator The other end of the first optical fiber is connected to the input end of the optical splitter, the first optical splitter end of the optical splitter is connected to the first port of the second circulator, the second optical splitter end of the optical splitter is connected to the input end of the second optical signal acquisition module for detecting the start pulse signal and the test pulse signal in the first optical fiber, the output end of the second optical signal acquisition module is electrically connected to the input end of the second control module, the second port of the second circulator is connected to the input end of the first SOA, the output end of the second control module is electrically connected to the control ends of the first SOA and the second SOA respectively for controlling the first SOA and the second SOA to turn on and off the gain amplification function, the output end of the first SOA is connected to the first port of the third circulator, the second port of the third circulator is used to connect to the device under test, the third port of the third circulator is connected to the input end of the second SOA, and the output end of the second SOA is connected to the third port of the second circulator.

[0006] The self-synchronous remote low-input amplification system according to the first aspect of the present invention has at least the following beneficial effects:

[0007] The optical signal generating module sends a start pulse signal, and the optical signal generating module sends a test pulse signal after a delay time t1, t1 is greater than the time taken by the start pulse signal to pass through the first optical fiber. After the second control module receives the start pulse signal through the second optical signal acquisition module, the delay time t2 (t1>t2) simultaneously controls the first SOA and the second SOA to turn on the gain amplification function, and the test pulse signal enters the device under test after forward gain amplification by the first SOA, and the device under test reflects the test pulse signal, and the reflected test pulse signal is reversely gained by the second SOA. The first control module receives the test pulse signal through the first optical signal acquisition module, and can detect the test pulse signal after reflection. The wavelength, light intensity, distance and other information of the pulse signal are acquired. When the second optical signal acquisition module detects that the test pulse signal in the first optical fiber disappears, the second control module turns off the gain amplification function of the first SOA and the second SOA, and there is no need to turn on the first SOA and the second SOA for a long time, thereby reducing the loss of the first SOA and the second SOA and extending the service life. There is no need to control the first SOA and the second SOA to turn on and off the gain amplification function through an external communication method, and there is no need to reduce the monitoring frequency of the test pulse signal, thereby improving the monitoring efficiency. The first SOA and the second SOA have a wider working wavelength range, and can perform gain amplification on weaker input optical signals, thereby realizing a remote monitoring function.

[0008] According to some embodiments of the present invention, the optical signal generating module includes a light source and a third SOA, and an output end of the light source is connected to an input end of the third SOA.

[0009] According to some embodiments of the present invention, the light splitting ratio between the first light splitting end and the second light splitting end of the light splitter is 99:1.

[0010] According to some embodiments of the present invention, the second optical signal acquisition module includes a photoelectric converter and an AD converter, and an output end of the photoelectric converter is electrically connected to an input end of the AD converter.

[0011] According to some embodiments of the present invention, the monitoring unit also includes a fourth SOA, the third port of the first circulator is connected to the input end of the fourth SOA, the output end of the fourth SOA is connected to the input end of the first optical signal acquisition module, and the output end of the first control module is electrically connected to the control end of the fourth SOA.

[0012] According to some embodiments of the present invention, the first optical signal acquisition module is a photodetector.

[0013] The self-synchronous remote low input amplification method according to the second aspect of the present invention comprises the following steps:

[0014] S100, the optical signal generating module sends a start pulse signal, and the optical signal generating module sends a test pulse signal after a delay time t1, where t1 is greater than the time taken by the start pulse signal to pass through the first optical fiber;

[0015] S200, after the second control module receives the start pulse signal through the second optical signal acquisition module, the delay time t2 simultaneously controls the first SOA and the second SOA to turn on the gain amplification function, t1-t2=Δt, Δt>0;

[0016] S300, the test pulse signal enters the device under test after being amplified by the first SOA gain, the device under test reflects the test pulse signal, the reflected test pulse signal is amplified by the second SOA gain, and the first control module receives the test pulse signal through the first optical signal acquisition module;

[0017] S400: When the second optical signal acquisition module detects that the test pulse signal in the first optical fiber disappears, the second control module turns off the gain amplification functions of the first SOA and the second SOA.

[0018] The self-synchronous remote low input amplification method according to the second aspect of the present invention has at least the following beneficial effects:

[0019] The optical signal generating module sends a start pulse signal, and the optical signal generating module sends a test pulse signal after a delay time t1, t1 being greater than the time taken by the start pulse signal to pass through the first optical fiber. After the second control module receives the start pulse signal through the second optical signal acquisition module, the delay time t2 (t1>t2) simultaneously controls the first SOA and the second SOA to turn on the gain amplification function, and the test pulse signal enters the device under test after forward gain amplification by the first SOA, and the device under test reflects the test pulse signal, and the reflected test pulse signal is reversely gained by the second SOA. The first control module receives the test pulse signal through the first optical signal acquisition module, and can acquire the test pulse signal after reflection. The wavelength, light intensity, distance and other information of the pulse signal are acquired. When the second optical signal acquisition module detects that the test pulse signal in the first optical fiber disappears, the second control module turns off the gain amplification function of the first SOA and the second SOA, and there is no need to turn on the first SOA and the second SOA for a long time, thereby reducing the loss of the first SOA and the second SOA and extending the service life. There is no need to control the first SOA and the second SOA to turn on and off the gain amplification function through an external communication method, and there is no need to reduce the monitoring frequency of the test pulse signal, thereby improving the monitoring efficiency. The first SOA and the second SOA have a wider working wavelength range, and can perform gain amplification on weaker input optical signals, thereby realizing a remote monitoring function.

[0020] According to some embodiments of the present invention, in step S100, the start pulse signal is two continuously sent optical pulse signals of length R, and the test pulse signal is an optical pulse signal of length X, where X=NR, N=2, 3, 4...

[0021] According to some embodiments of the present invention, in step 200, the method in which the second control module simultaneously controls the first SOA and the second SOA to turn on the gain amplification function is as follows:

[0022] A first amplified pulse signal with a length of M is sent to the first SOA and a second amplified pulse signal with a length of L is sent to the second SOA at the same time, wherein M>2X, L>2X+t1.

[0023] According to some embodiments of the present invention, in step S400, when the second optical signal acquisition module detects that the test pulse signal in the first optical fiber disappears, the second control module turns off the gain amplification function of the first SOA and the second SOA after a delay time t3.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0026] Figure 1 It is the principle diagram of the self-synchronous remote low-input amplification system of the present invention;

[0027] Figure 2 It is a timing diagram of the start pulse signal, the test pulse signal, the first amplified pulse signal and the second amplified pulse signal of the present invention.

[0028] Figure Number:

[0029] Monitoring unit 100; first control module 110; light source 120; third SOA 130; first circulator 140; first optical signal acquisition module 150; fourth SOA 160;

[0030] A first optical fiber 200;

[0031] Remote amplifier unit 300; optical splitter 310; second circulator 320; second control module 330; first SOA 340; second SOA 350; third circulator 360; photoelectric converter 370; AD converter 380;

[0032] The second optical fiber 400 . DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0034] In the description of the present invention, it should be understood that descriptions involving orientation, such as orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0035] In the description of the present invention, "a plurality" means more than two. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0036] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0037] Reference Figure 1As shown, the self-synchronous remote low-input amplification system of the first aspect of the present invention comprises: a monitoring unit 100, a first optical fiber 200 and a remote amplification unit 300, the monitoring unit 100 comprises: a first control module 110, an optical signal generating module, a first circulator 140 and a first optical signal acquisition module 150, the output end of the first control module 110 is electrically connected to the control end of the optical signal generating module, the output end of the optical signal generating module is connected to the first port of the first circulator 140, the third port of the first circulator 140 is connected to the input end of the first optical signal acquisition module 150, the output end of the first optical signal acquisition module 150 is electrically connected to the input end of the first control module 110, the second port of the first circulator 140 is connected to one end of the first optical fiber 200, and the remote amplification unit 300 comprises: a splitter 310, a second circulator 320, a second optical signal acquisition module, a second control module 330, a first SOA 340 , a second SOA 350 and a third circulator 360, the other end of the first optical fiber 200 is connected to the input end of the optical splitter 310, the first optical splitting end of the optical splitter 310 is connected to the first port of the second circulator 320, the second optical splitting end of the optical splitter 310 is connected to the input end of the second optical signal acquisition module, the output end of the second optical signal acquisition module is electrically connected to the input end of the second control module 330, the second port of the second circulator 320 is connected to the input end of the first SOA 340, the output end of the second control module 330 is electrically connected to the control ends of the first SOA 340 and the second SOA 350 respectively, the output end of the first SOA 340 is connected to the first port of the third circulator 360, the second port of the third circulator 360 is connected to the device under test through the second optical fiber 400, the third port of the third circulator 360 is connected to the input end of the second SOA 350, and the output end of the second SOA 350 is connected to the third port of the second circulator 320. The first SOA 340 and the second SOA 350 are semiconductor optical amplifiers.

[0038] The optical signal generating module sends a start pulse signal, and the optical signal generating module sends a test pulse signal after a delay time t1, t1 being greater than the time taken by the start pulse signal to pass through the first optical fiber 200. After the second control module 330 receives the start pulse signal through the second optical signal acquisition module, the delay time t2 (t1>t2) simultaneously controls the first SOA340 and the second SOA350 to turn on the gain amplification function, and the test pulse signal enters the device under test after forward gain amplification by the first SOA340, and the device under test reflects the test pulse signal, and the reflected test pulse signal is reversely gain amplified by the second SOA350, and the first control module 110 receives the test pulse signal through the first optical signal acquisition module 150, and can collect the wave of the reflected test pulse signal. When the second optical signal acquisition module detects that the test pulse signal in the first optical fiber 200 disappears, the second control module 330 turns off the gain amplification function of the first SOA 340 and the second SOA 350, and there is no need to turn on the first SOA 340 and the second SOA 350 for a long time, thereby reducing the loss of the first SOA 340 and the second SOA 350 and extending the service life. There is no need to control the first SOA 340 and the second SOA 350 to turn on and off the gain amplification function through an external communication method, and there is no need to reduce the monitoring frequency of the test pulse signal, thereby improving the monitoring efficiency. The first SOA 340 and the second SOA 350 have a wider working wavelength range, and can perform gain amplification on weaker input optical signals, thereby realizing a remote monitoring function.

[0039] Reference Figure 1 As shown, the optical signal generating module includes a light source 120 and a third SOA 130, the output end of the first control module 110 is electrically connected to the light source 120 and the control end of the third SOA 130 respectively, the output end of the light source 120 is connected to the input end of the third SOA 130, the output end of the third SOA 130 is connected to the first port of the first circulator 140, the light source 120 generates an optical signal, the third SOA 130 functions as an optical switch, and the light source 120 and the third SOA 130 work together to accurately send a start pulse signal and a test pulse signal.

[0040] Reference Figure 1 As shown, the second optical signal acquisition module includes a photoelectric converter 370 and an AD converter 380, the second splitting end of the optical splitter 310 is connected to the input end of the photoelectric converter 370, the output end of the photoelectric converter 370 is electrically connected to the input end of the AD converter 380, and the output end of the AD converter 380 is connected to the second control module 330. The photoelectric converter 370 is a PIN, which has a lower dark current noise and a lower price, and the photoelectric converter 370 can also use an APD.

[0041] Reference Figure 1As shown, the splitting ratio of the first splitting end and the second splitting end of the splitter 310 is 99:1. The splitter 310 realizes the energy distribution of the start pulse signal and the test pulse signal. Considering the need to retain a large enough light intensity to achieve long-distance monitoring, 99% of the light intensity is output to the first SOA340 through the second circulator 320, and 1% of the light intensity is output to the second optical signal acquisition module. The splitter 310 can also adopt other splitting ratios.

[0042] Reference Figure 1 As shown, the monitoring unit 100 also includes a fourth SOA 160, the third port of the first circulator 140 is connected to the input end of the fourth SOA 160, the output end of the fourth SOA 160 is connected to the input end of the first optical signal acquisition module 150, the output end of the first control module 110 is connected to the control end of the fourth SOA 160, and the fourth SOA 160 acts as an optical switch.

[0043] The first optical signal acquisition module 150 is a photoelectric detector, which collects information such as wavelength, light intensity, and distance of the reflected test pulse signal.

[0044] Reference Figure 1 to Figure 2 As shown, the self-synchronous remote low input amplification method of the second aspect of the present invention comprises the following steps:

[0045] S100, the optical signal generating module sends a start pulse signal, and the optical signal generating module sends a test pulse signal after a delay time t1, the start pulse signal is two continuously sent optical pulse signals of length R, and the test pulse signal is an optical pulse signal of length X, wherein X=NR, N=2, 3, 4, ..., N can be taken within a range according to actual needs, t1 is greater than the time taken by the start pulse signal to pass through the first optical fiber 200, which can ensure that the test pulse signal is sent after the start pulse signal is transmitted;

[0046] S200, after the second control module 330 receives the start pulse signal through the second optical signal acquisition module, it delays the time t2 and simultaneously sends the first amplified pulse signal with a length of M to the first SOA340 and the second amplified pulse signal with a length of L to the second SOA350, wherein M>2X, L>2X+t1, t1-t2=Δt, Δt>0; the first amplified pulse signal and the second amplified pulse signal can take values ​​within a range according to actual needs, the length of M can ensure that the opening time of the first SOA340 can cover the test pulse signal through the forward gain amplification of the first SOA340, and the length of L can ensure that the opening time of the second SOA350 can cover the reflected test pulse signal through the reverse gain amplification of the second SOA350;

[0047] S300, the test pulse signal enters the device under test after being amplified by the forward gain of the first SOA340, the device under test reflects the test pulse signal, the reflected test pulse signal is amplified by the reverse gain of the second SOA350, and the first control module 110 receives the test pulse signal through the first optical signal acquisition module 150;

[0048] S400, when the second optical signal acquisition module detects that the test pulse signal in the first optical fiber 200 disappears, the second control module 330 turns off the gain amplification function of the first SOA 340 and the second SOA 350 after a delay time t3, and t3 can be set according to actual needs.

[0049] The optical signal generating module sends a start pulse signal, and the optical signal generating module sends a test pulse signal after a delay time t1. After the second control module 330 receives the start pulse signal through the second optical signal acquisition module, the delay time t2 simultaneously controls the first SOA340 and the second SOA350 to turn on the gain amplification function. The test pulse signal enters the device under test after forward gain amplification by the first SOA340. The device under test reflects the test pulse signal, and the reflected test pulse signal is reversely gain amplified by the second SOA350. The first control module 110 receives the test pulse signal through the first optical signal acquisition module 150, and can collect information such as the wavelength, light intensity, and distance of the reflected test pulse signal. When the second optical signal acquisition module After detecting that the test pulse signal in the first optical fiber 200 disappears, the second control module 330 turns off the gain amplification function of the first SOA 340 and the second SOA 350 after a delay time t3, and the first SOA 340 and the second SOA 350 do not need to be turned on for a long time, thereby reducing the loss of the first SOA 340 and the second SOA 350 and extending the service life. There is no need to control the first SOA 340 and the second SOA 350 to turn on and off the gain amplification function through an external communication method, and there is no need to reduce the monitoring frequency of the test pulse signal, thereby improving the monitoring efficiency. The first SOA 340 and the second SOA 350 have a wider operating wavelength range and can perform gain amplification on weaker input optical signals, thereby realizing a remote monitoring function.

[0050] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A self-synchronizing remote low input amplifier system, characterized in that, include: A monitoring unit (100), the monitoring unit (100) comprising: a first control module (110), an optical signal generating module, a first circulator (140) and a first optical signal collecting module (150), the output end of the first control module (110) being electrically connected to the control end of the optical signal generating module for controlling the optical signal generating module to send a start pulse signal and send a test pulse signal after a delay time t1, the output end of the optical signal generating module being connected to a first port of the first circulator (140), the third port of the first circulator (140) being connected to the input end of the first optical signal collecting module (150) for collecting a returned test pulse signal, and the output end of the first optical signal collecting module (150) being electrically connected to the input end of the first control module (110); a first optical fiber (200), wherein the second port of the first circulator (140) is connected to one end of the first optical fiber (200); A remote amplifier unit (300), the remote amplifier unit (300) comprising: an optical splitter (310), a second circulator (320), a second optical signal acquisition module, a second control module (330), a first SOA (340), a second SOA (350) and a third circulator (360), the other end of the first optical fiber (200) being connected to the input end of the optical splitter (310), the first optical splitting end of the optical splitter (310) being connected to the first port of the second circulator (320), the second optical splitting end of the optical splitter (310) being connected to the input end of the second optical signal acquisition module for detecting a start pulse signal and a test pulse signal in the first optical fiber (200), the output end of the second optical signal acquisition module being electrically connected to the input end of the second control module (330), the second port of the second circulator (320) being connected to the input end of the first SOA (340), and the output ends of the second control module (330) being electrically connected to the first SOA (3 40) and the control end of the second SOA (350), the output end of the first SOA (340) is connected to the first port of the third circulator (360), the second port of the third circulator (360) is used to connect to the device under test, the third port of the third circulator (360) is connected to the input end of the second SOA (350), and the output end of the second SOA (350) is connected to the third port of the second circulator (320), after the second control module (330) receives the start pulse signal through the second optical signal acquisition module, the delay time t2 simultaneously controls the first SOA (340) and the second SOA (350) to turn on the gain amplification function, t1-t2=Δt, Δt>0, when the second optical signal acquisition module detects that the test pulse signal in the first optical fiber (200) disappears, the second control module (330) turns off the gain amplification function of the first SOA (340) and the second SOA (350).

2. The self-synchronous remote low input amplifier system according to claim 1, characterized in that: The optical signal generating module comprises a light source (120) and a third SOA (130), wherein the output end of the light source (120) is connected to the input end of the third SOA (130).

3. The self-synchronous remote low input amplifier system according to claim 1, characterized in that: The light splitting ratio between the first light splitting end and the second light splitting end of the light splitter (310) is 99:

1.

4. The self-synchronous remote low input amplifier system according to claim 1, characterized in that: The second optical signal acquisition module comprises a photoelectric converter (370) and an AD converter (380), and the output end of the photoelectric converter (370) is electrically connected to the input end of the AD converter (380).

5. The self-synchronous remote low input amplifier system according to claim 1, characterized in that: The monitoring unit (100) further comprises a fourth SOA (160), the third port of the first circulator (140) is connected to an input end of the fourth SOA (160), an output end of the fourth SOA (160) is connected to an input end of the first optical signal acquisition module (150), and an output end of the first control module (110) is electrically connected to a control end of the fourth SOA (160).

6. The self-synchronous remote low input amplifier system according to claim 1, characterized in that: The first optical signal acquisition module (150) is a photoelectric detector.

7. A self-synchronous remote low input amplification method, characterized in that: The method applied to the self-synchronous remote low-input amplification system as claimed in any one of claims 1 to 6 comprises the following steps: S100, the optical signal generating module sends a start pulse signal, and the optical signal generating module sends a test pulse signal after a delay time t1, where t1 is greater than the time taken by the start pulse signal to pass through the first optical fiber (200); S200, after the second control module (330) receives the start pulse signal through the second optical signal acquisition module, the delay time t2 simultaneously controls the first SOA (340) and the second SOA (350) to turn on the gain amplification function, t1-t2=Δt, Δt>0; S300, the test pulse signal enters the device under test after being gain-amplified by the first SOA (340), the device under test reflects the test pulse signal, the reflected test pulse signal is gain-amplified by the second SOA (350), and the first control module (110) receives the test pulse signal through the first optical signal acquisition module (150); S400: When the second optical signal acquisition module detects that the test pulse signal in the first optical fiber (200) disappears, the second control module (330) turns off the gain amplification functions of the first SOA (340) and the second SOA (350).

8. The self-synchronous remote low input amplification method according to claim 7, characterized in that: In the step S100, the start pulse signal is two continuously transmitted optical pulse signals of length R, and the test pulse signal is an optical pulse signal of length X, wherein X=NR, N=2, 3, 4, . . . .

9. The self-synchronous remote low input amplification method according to claim 8, characterized in that: In step 200, the method in which the second control module (330) simultaneously controls the first SOA (340) and the second SOA (350) to turn on the gain amplification function is as follows: A first amplified pulse signal with a length of M is sent to the first SOA (340) and a second amplified pulse signal with a length of L is sent to the second SOA (350) at the same time, wherein M>2X, L>2X+t1.

10. The self-synchronous remote low input amplification method according to claim 7, characterized in that: In step S400, when the second optical signal acquisition module detects that the test pulse signal in the first optical fiber (200) disappears, the second control module (330) turns off the gain amplification functions of the first SOA (340) and the second SOA (350) after a delay time t3.

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