CN114526809A - Ultra-long distance distributed optical fiber vibration sensing detection method and device - Google Patents
Ultra-long distance distributed optical fiber vibration sensing detection method and device Download PDFInfo
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Abstract
The invention relates to the technical field of optical fiber communication, and provides a method and a device for detecting ultra-long distance distributed optical fiber vibration sensing, wherein the method comprises the following steps: n optical repeaters are arranged in the sensing optical fiber link at a certain interval, and the interval between the adjacent optical repeaters is determined by the attenuation coefficient of the sensing optical fiber link section between the N optical repeaters and the attenuation coefficient of the next-stage optical repeater; inputting detection light to a sensing optical fiber, wherein the detection light is transmitted in a downlink optical transmission link; when the sensing optical fiber is influenced by vibration, backward Rayleigh scattered light generated by the vibration is transmitted backward in the uplink direction, and enters an uplink optical transmission link through a loopback link in an optical repeater closest to the backward Rayleigh scattered light; the backward Rayleigh scattering light returns to the optical fiber vibration sensing detection system after being subjected to optical power amplification through an amplifier of an optical repeater in the uplink optical transmission link, and the optical fiber vibration sensing detection system analyzes the backward Rayleigh scattering light to obtain a vibration position.
Description
Technical Field
The invention relates to the technical field of optical fiber communication, in particular to a method and a device for detecting ultra-long distance distributed optical fiber vibration sensing.
Background
Distributed fiber optic vibration sensors include interferometric sensors and backscatter type sensors. The formation of rayleigh scattering in optical fibers arises primarily from material density and refractive index non-uniformities created during the fabrication of the optical fiber for various reasons. The optical fiber distributed sensor based on the interference technology is mainly based on the phase modulation characteristic of an external disturbance signal on optical wave transmission in an optical fiber, and sensing and detection of the external disturbance signal are achieved through phase information change of a demodulation return optical wave signal. The conventional Optical Time-Domain reflectometer (OTDR) obtains the intensity distribution of a scattering signal on an Optical fiber by measuring a backward rayleigh scattering signal, thereby effectively positioning and measuring fault information such as abnormal loss, bending, and breaking of an Optical cable in a communication system. A distributed optical fiber sensing system based on a Phase-sensitive optical time domain reflectometer (Phase-sensitive OTDR) has the high sensitivity of an interference type vibration sensor and the distributed sensing and networking capabilities of an OTDR technology, so that the distributed optical fiber sensing system becomes an optical fiber distributed sensing solution most suitable for dynamic vibration measurement at present.
In long-haul optical communications, the optical communication cables are typically used in pairs, divided into uplinks and downlinks. However, in long-distance optical communication, the strength of a backward rayleigh scattering signal generated when light is transmitted through an optical fiber is weak, so that the detection distance is generally less than 40 km. Even if the disturbance of the outside to the optical fiber is strong, when the length of the disturbance source from the distributed sensing system exceeds more than 40km, the backward Rayleigh scattering signal is attenuated when being transmitted in the optical fiber, so that the signal is greatly weakened, even cannot be detected by the sensing system, and therefore the detection distance of the existing distributed sensing system has certain limitation.
Disclosure of Invention
The invention provides an ultra-long distance distributed optical fiber vibration sensing detection method and an ultra-long distance distributed optical fiber vibration sensing detection device, aiming at overcoming the defect that the detection distance of a distributed sensing system in the prior art has certain limitation.
In order to solve the technical problems, the technical scheme of the invention is as follows:
an ultra-long distance distributed optical fiber vibration sensing detection method comprises the following steps: n Optical Repeaters (RPT) are arranged in the sensing Optical fiber link at a certain interval, and the interval between the adjacent Optical repeaters is determined by the attenuation coefficient of the sensing Optical fiber link section between the N Optical repeaters and the amplification gain coefficient of the next-stage Optical Repeater;
inputting detection light Ls to a sensing optical fiber, wherein the detection light Ls is transmitted in a downlink optical transmission link; when the sensing optical fiber is influenced by vibration, backward Rayleigh scattering light Lb generated by the vibration is transmitted backward in the uplink direction, and enters an uplink optical transmission link through a loopback link in an optical repeater closest to the backward Rayleigh scattering light Lb; the backward rayleigh scattering light Lb is subjected to optical power amplification by an amplifier of an optical repeater in the uplink optical transmission link and then returns to the optical fiber vibration sensing detection system, and the optical fiber vibration sensing detection system analyzes the backward rayleigh scattering light Lb to obtain a vibration position.
In the technical scheme, a sensing optical fiber is used as a communication optical cable, and the detection light Ls is input to the sensing optical fiber. When external vibration causes the detection light Ls to generate backward Rayleigh reflection light Lb in the transmission process of the down optical link of the sensing optical fiber, the backward Rayleigh reflection light Lb enters the up optical link through the loop optical link of the optical repeater, is amplified by the optical amplifier of the optical repeater at each level of the up optical link, and then enters the distributed sensing system. The amplifier of the optical repeater amplifies the intensity of the backward Rayleigh reflected light, solves the problem that the backward Rayleigh reflected light is weak and cannot be transmitted in a long distance, and greatly prolongs the sensing detection distance of the optical fiber vibration sensing detection system.
Preferably, the optical repeater disposed in the sensing optical fiber link satisfies the following conditions: the attenuation coefficient of the sensing optical fiber link section between the adjacent optical repeaters is smaller than the amplification gain coefficient of the next-stage optical repeater.
Preferably, N optical repeaters arranged in the sensing optical fiber link satisfy a condition (N-1) × a > B; where a represents the optical gain of the optical repeater and B represents the sensing attenuation of the sensing fiber link.
The invention also provides an ultra-long distance distributed optical fiber vibration sensing detection device and an ultra-long distance distributed optical fiber vibration sensing detection method provided by applying any technical scheme. The device comprises N optical repeaters and an optical fiber vibration sensing detection system; the optical repeaters are arranged in the sensing optical fiber link to be detected at a certain interval, and the interval between the adjacent optical repeaters is determined by the attenuation coefficient of the sensing optical fiber link section between the optical repeaters and the attenuation coefficient of the next-stage optical repeater; the optical repeater is provided with a loopback link and an optical amplifier, the loopback link is used for enabling backward Rayleigh scattering light Lb generated by external vibration to enter an uplink optical transmission link, and the optical amplifier is used for carrying out optical power amplification on passing detection light Ls or the backward Rayleigh scattering light Lb; the optical fiber vibration sensing detection system is connected with one end of the sensing optical fiber link and used for inputting the detection light Ls to the sensing optical fiber link and analyzing the backward Rayleigh scattering light Lb which is generated by external vibration and returned by the optical repeater to obtain a vibration position.
Preferably, the optical fiber vibration sensing detection system comprises a light source, an optical beam splitter, a circulator, an optical combiner and a detection module; wherein, the optical signal output by the light source is divided into a detecting light Ls and a reference light Lc after passing through the optical beam splitter; the detection light Ls enters the sensing optical fiber link through the circulator; and after backward Rayleigh scattering light Lb which is generated by external vibration and returned by the optical repeater passes through the optical combiner, heterodyne interference is carried out on the backward Rayleigh scattering light Lc output by the optical beam splitter, and then the backward Rayleigh scattering light Lb enters the detection module, and the detection module analyzes an input signal and outputs a vibration position.
Preferably, the light source comprises a narrow linewidth light source.
Preferably, the loop-back link provided in the optical repeater includes a narrow band pass optical link.
Preferably, the optical fiber vibration sensing and detecting system further comprises a pulse width optical modulator and a signal generator; the detection light Ls output by the optical beam splitter passes through the pulse width optical modulator, the pulse width optical modulator adjusts the pulse width of the detection light Ls through the signal generator, and then the detection light Ls enters the sensing optical fiber link through the circulator.
Preferably, the optical fiber vibration sensing and detecting system further comprises a first optical amplifier; the detection light Ls modulated by the pulse width light modulator passes through the first optical amplifier to adjust the output power, and then enters the sensing optical fiber link through the circulator.
Preferably, the detection module includes a second optical amplifier, an optical filter, a photodetector and a signal processing unit, wherein the backward rayleigh scattered light Lb generated by external vibration and returned by the optical repeater sequentially passes through the optical combiner, the second optical amplifier and the optical filter, then performs heterodyne interference with the reference light Lc output by the optical splitter, and then sequentially enters the photodetector and the signal processing unit, and the signal processing unit analyzes an input signal and outputs a vibration position.
Compared with the prior art, the technical scheme of the invention has the beneficial effects that: the optical repeater is arranged in the sensing optical fiber link serving as the long-distance communication optical cable, and the loopback and amplification functions of the optical repeater are utilized, so that the problem that backward Rayleigh reflected light is weak and long-distance transmission cannot be realized is solved, and the sensing detection distance of the optical fiber vibration sensing detection system is greatly prolonged.
Drawings
Fig. 1 is a flowchart of an ultra-long distance distributed optical fiber vibration sensing detection method according to embodiment 1.
Fig. 2 is a schematic diagram showing a change in optical power of the probe light Ls according to embodiment 1.
Fig. 3 is an enlarged schematic view of each stage of the optical link of the back rayleigh scattered light Lb of embodiment 1.
Fig. 4 is a schematic structural diagram of an ultra-long-distance distributed optical fiber vibration sensing and detecting device in embodiment 2.
Fig. 5 is a schematic structural view of an optical repeater according to embodiment 2.
Fig. 6 is a schematic structural diagram of an ultra-long-distance distributed optical fiber vibration sensing and detecting device according to embodiment 3.
Fig. 7 is a schematic structural diagram of an ultra-long-distance distributed optical fiber vibration sensing and detecting apparatus according to embodiment 4.
The optical fiber vibration detection system comprises a 1-optical repeater, a 101-loopback link, a 102-optical amplifier, a 2-optical fiber vibration sensing detection system, a 201-light source, a 202-optical beam splitter, a 203-circulator, a 204-optical combiner, a 205-pulse width optical modulator, a 206-signal generator, a 207-first optical amplifier, a 3-detection module, a 301-second optical amplifier, a 302-optical filter, a 303-photoelectric detector and a 304-signal processing unit.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the patent;
for the purpose of better illustrating the present embodiments, certain elements of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product;
it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.
Example 1
The present embodiment provides an ultra-long distance distributed optical fiber vibration sensing detection method, which is a flowchart of the ultra-long distance distributed optical fiber vibration sensing detection method of the present embodiment, as shown in fig. 1.
The method for detecting the vibration of the ultra-long distance distributed optical fiber provided by the embodiment comprises the following steps:
s1, N optical repeaters 1 are arranged in the sensing optical fiber link at a certain interval.
In this embodiment, the distance between the optical repeaters 1 disposed adjacent to each other is determined by the attenuation coefficient of the sensing optical fiber link section therebetween and the amplification gain coefficient of the next-stage optical repeater 1.
And S2, inputting the detection light Ls to the sensing optical fiber, and transmitting the detection light Ls in the downlink optical transmission link.
The detection light Ls input in this step is transmitted in a sensing optical fiber link serving as a communication optical cable and passes through a section of sensing optical fiber link L(n-1)After being attenuated, the signal is amplified by the nth optical repeater 1 and then enters the next section of sensing optical fiber L(n). In the present embodiment, N optical repeaters 1 are arranged on the sensing optical fiber link, and each time the detection light Ls passes through one optical repeater 1, the optical power of the detection light pulse Ls is amplified once, and a schematic diagram of the optical power change is shown in fig. 2.
When the sensing optical fiber is affected by vibration, the backward rayleigh scattered light Lb generated by the vibration is transmitted backward in the upstream direction, and enters the upstream optical transmission link through the loopback link 101 in the optical repeater 1 nearest thereto. The backward rayleigh scattering light Lb is subjected to optical power amplification by an amplifier in the optical repeater 1 in the uplink optical transmission link, and then returns to the optical fiber vibration sensing detection system 2 for vibration sensing detection.
As shown in fig. 3, it is an enlarged schematic diagram of each stage of the optical link of the back rayleigh scattered light Lb of the present embodiment.
S3, the optical fiber vibration sensing and detecting system 2 analyzes the back rayleigh scattered light Lb to obtain a vibration position.
In one embodiment, the optical repeater 1 disposed in the sensing fiber link satisfies the following condition: the attenuation coefficient of the sensing optical fiber link section between the adjacent optical repeaters 1 is smaller than the amplification gain coefficient of the next-stage optical repeater 1, so that the long-distance stable transmission of light in the communication optical cable can be effectively ensured.
In another embodiment, N optical repeaters 1 disposed in the sensing fiber link satisfy the condition:
(N-1)×A>B
wherein, a represents the optical gain of the optical repeater 1, and B represents the sensing attenuation of the sensing optical fiber link; at this time, the back rayleigh scattering light Lb signal can be accurately collected by the optical fiber vibration sensing detection system 2.
In the embodiment, the optical repeater 1 is arranged in the sensing optical fiber link serving as the long-distance communication optical cable, and the loopback and amplification functions of the optical repeater 1 are utilized, so that the difficulty that the traditional distributed optical fiber system cannot realize long-distance sensing is overcome, and the problem that communication service and vibration sensing information cannot be carried out simultaneously is also solved. The method can quickly acquire the position and the related information of the vibration source in the optical fiber sensing, is simple and flexible, and can be applied to a large area in a common communication optical cable application scene.
Example 2
The embodiment provides an ultra-long distance distributed optical fiber vibration sensing detection device, and the ultra-long distance distributed optical fiber vibration sensing detection method provided by the embodiment 1 is applied. Fig. 4 is a schematic structural diagram of the ultra-long distance distributed optical fiber vibration sensing and detecting device according to this embodiment.
The ultra-long distance distributed optical fiber vibration sensing detection device provided by the embodiment comprises N optical repeaters 1 and an optical fiber vibration sensing detection system 2.
The N optical repeaters 1 are arranged in the sensing optical fiber link to be detected at a certain interval, and the interval between the adjacent optical repeaters 1 is determined by the attenuation coefficient of the sensing optical fiber link section between the two optical repeaters and the amplification gain coefficient of the next-stage optical repeater 1.
Further, in an embodiment, the attenuation coefficient of the sensing fiber link section between the adjacently disposed optical repeaters 1 is smaller than the amplification gain coefficient of the next-stage optical repeater 1.
In another embodiment, N optical repeaters 1 disposed in the sensing fiber link satisfy the following condition:
(N-1)×A>B
where a represents the optical gain of the optical repeater 1 and B represents the sensing attenuation of the sensing fiber link.
In this embodiment, the optical fiber vibration sensing and detecting system 2 is connected to one end of the sensing optical fiber link, and is configured to input the probe light Ls to the sensing optical fiber link, and analyze the backward rayleigh scattering light Lb that is generated by the external vibration and returned through the optical repeater 1 to obtain the vibration position.
In a specific implementation process, the optical fiber vibration sensing detection system 2 inputs the probe light Ls to the sensing optical fiber, and the probe light Ls is transmitted in a downlink optical transmission link in the sensing optical fiber link. When the sensing optical fiber is affected by vibration, the backward rayleigh scattered light Lb generated by the vibration is transmitted backward in the uplink direction, enters the uplink optical transmission link through the loopback link 101 in the optical repeater 1 closest to the backward rayleigh scattered light Lb, is amplified in optical power by the amplifier of the optical repeater 1 in the uplink optical transmission link, and is input into the optical fiber vibration sensing detection system 2 for detection, and the optical fiber vibration sensing detection system 2 analyzes the backward rayleigh scattered light Lb to obtain a vibration position.
Fig. 5 is a schematic structural diagram of the optical repeater according to the present embodiment.
The embodiment utilizes the loopback and amplification functions of the optical repeater 1, and solves the problems that the rayleigh scattered light signal generated by the optical fiber sensing after exceeding 40km in the distributed optical fiber sensing is too weak, the attenuation is too large, the signal-to-noise ratio is too low, and the rayleigh scattered light signal cannot be demodulated and used.
Example 3
The embodiment is an improvement on the ultra-long distance distributed optical fiber vibration sensing detection device provided in embodiment 2.
The optical fiber vibration sensing detection system 2 in the present embodiment includes a light source 201, an optical beam splitter 202, a circulator 203, an optical combiner 204, and a detection module 3.
Fig. 6 is a schematic structural diagram of the ultra-long distance distributed optical fiber vibration sensing and detecting device according to this embodiment.
Further, the light source 201 in this embodiment adopts a narrow linewidth light source, wherein the narrower the linewidth of the adopted light source 201 is, the better the coherence of the light source 201 is, the smaller the phase noise is, and the signal-to-noise ratio of the long-distance detection is effectively improved.
In addition, the wavelength of the narrow-linewidth light source 201 in this embodiment should meet the wavelength requirement of the detection light of the communication optical cable, so as to satisfy the requirement of not affecting the normal communication service of the communication optical cable, and also can use the whole optical cable as the usage requirement of the optical fiber sensing system.
Further, the loop-back link 101 arranged in the optical repeater 1 in this embodiment includes a narrow-band loop-back optical link, which satisfies the passing of the narrow-band light source adopted in this embodiment, and is beneficial to improving the signal-to-noise ratio of the long-distance detection.
In a specific implementation process, an optical signal output by the light source 201 in the optical fiber vibration sensing detection system 2 passes through the optical beam splitter 202 and is divided into probe light Ls and reference light Lc, wherein the probe light Ls enters the sensing optical fiber link through the circulator 203, and the reference light Lc is transmitted to the input side of the detection module 3 and used for heterodyne interference with the backward rayleigh scattered light Lb, so that vibration sensing signal demodulation is realized.
The backward rayleigh scattering light Lb generated by external vibration and returned through the optical repeater 1 passes through the optical combiner 204, then performs heterodyne interference with the reference light Lc output by the optical splitter 202, and then enters the detection module 3, and the detection module 3 analyzes an input signal and outputs a vibration position.
Further, the detection module 3 in this embodiment includes a second optical amplifier 301, an optical filter 302, a photodetector 303, and a signal processing unit 304, wherein the backward rayleigh scattering light Lb generated by external vibration and returned by the optical repeater 1 sequentially passes through the optical combiner 204, the second optical amplifier 301, and the optical filter 302, then performs heterodyne interference with the reference light Lc output by the optical beam splitter 202, and then sequentially enters the photodetector 303 and the signal processing unit 304, and the signal processing unit 304 analyzes an input signal and outputs a vibration position.
Further, the optical combiner 204 in this embodiment is provided with a compatible optical combiner 204 interface, and when the length of the sensing optical cable is not long and there is no optical repeater 1, the upstream optical reflection reception interface RX may not be used.
Example 4
This embodiment is an improvement on the ultra-long distance distributed optical fiber vibration sensing detection device proposed in embodiment 2 or 3.
The optical fiber vibration sensing detection system 2 in this embodiment further includes a pulse width optical modulator 205 and a signal generator 206 for performing pulse width adjustment on the probe light Ls output through the optical beam splitter 202.
The detection light Ls output by the optical beam splitter 202 passes through the pulse width optical modulator 205, and the pulse width optical modulator 205 adjusts the pulse width of the detection light Ls through the signal generator 206, and then enters the sensing optical fiber link through the circulator 203.
Fig. 7 is a schematic structural diagram of the ultra-long distance distributed optical fiber vibration sensing and detecting device according to this embodiment.
In this embodiment, the signal generator 206 and the pulse width modulator are used to adjust the pulse width of the narrow-linewidth light source 201, and the pulse widths of different light sources 201 are selected for optical fibers with different lengths, which is beneficial to improving the signal intensity of rayleigh reflection, and can effectively improve the signal-to-noise ratio of long-distance detection.
Further, the optical fiber vibration sensing detection system 2 further includes a first optical amplifier 207 for adjusting the optical power of the probe light Ls.
The detection light Ls modulated by the pulse width optical modulator 205 passes through the first optical amplifier 207 to adjust the output power, and then enters the sensing optical fiber link through the circulator 203.
In this embodiment, different powers of the light source 201 are selected for optical fibers with different lengths, which is beneficial to improving the signal intensity of the backward rayleigh scattered light and effectively improving the signal-to-noise ratio of long-distance detection.
The same or similar reference numerals correspond to the same or similar parts;
the terms describing positional relationships in the drawings are for illustrative purposes only and are not to be construed as limiting the patent;
it should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. This need not be, nor should it be exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (10)
1. A vibration sensing detection method for an ultra-long distance distributed optical fiber is characterized by comprising the following steps: n optical repeaters (1) are arranged in the sensing optical fiber link at a certain interval, and the interval between the adjacent optical repeaters (1) is determined by the attenuation coefficient of the sensing optical fiber link section between the N optical repeaters and the adjacent optical repeaters and the amplification gain coefficient of the next-stage optical repeater (1);
inputting detection light Ls to a sensing optical fiber, wherein the detection light Ls is transmitted in a downlink optical transmission link; when the sensing optical fiber is influenced by vibration, backward Rayleigh scattering light Lb generated by the vibration is transmitted backward in the upstream direction, and enters an upstream optical transmission link through a loopback link (101) in an optical repeater (1) nearest to the backward Rayleigh scattering light Lb;
the backward Rayleigh scattering light Lb returns to the optical fiber vibration sensing detection system (2) after being subjected to optical power amplification through an amplifier of an optical repeater (1) in the uplink optical transmission link, and the optical fiber vibration sensing detection system (2) analyzes the backward Rayleigh scattering light Lb to obtain a vibration position.
2. The method for sensing and detecting vibration of an ultra-long distance distributed optical fiber according to claim 1, wherein the optical repeater (1) arranged in the sensing optical fiber link satisfies the following conditions: the attenuation coefficient of the sensing optical fiber link section between the adjacently arranged optical repeaters (1) is smaller than the amplification gain coefficient of the next-stage optical repeater (1).
3. The method for detecting vibration of an ultra-long distance distributed optical fiber according to claim 1, wherein the N optical repeaters (1) arranged in the sensing optical fiber link satisfy the following conditions:
(N-1)×A>B
wherein A represents the optical gain of the optical repeater (1) and B represents the sensing attenuation of the sensing optical fiber link.
4. An ultra-long distance distributed optical fiber vibration sensing detection device is characterized by comprising N optical repeaters (1) and an optical fiber vibration sensing detection system (2); wherein:
the optical repeaters (1) are arranged in a sensing optical fiber link to be detected at a certain interval, and the interval between the adjacent optical repeaters (1) is determined by the attenuation coefficient of the sensing optical fiber link section between the optical repeaters and the adjacent optical repeater and the amplification gain coefficient of the next-stage optical repeater (1);
the optical repeater (1) is provided with a loopback link (101) and an optical amplifier (102), the loopback link (101) is used for allowing backward Rayleigh scattering light Lb generated by external vibration to enter an uplink optical transmission link, and the optical amplifier (102) is used for performing optical power amplification on passing detection light Ls or the backward Rayleigh scattering light Lb;
the optical fiber vibration sensing detection system (2) is connected with one end of the sensing optical fiber link and is used for inputting the detection light Ls to the sensing optical fiber link and analyzing the backward Rayleigh scattering light Lb which is generated by external vibration and returns through the optical repeater (1) to obtain a vibration position.
5. The ultra-long distance distributed optical fiber vibration sensing detection device according to claim 4, wherein the optical fiber vibration sensing detection system (2) comprises a light source (201), an optical beam splitter (202), a circulator (203), an optical combiner (204) and a detection module (3);
wherein, the optical signal output by the light source (201) is divided into a detection light Ls and a reference light Lc after passing through the optical beam splitter (202); the detection light Ls enters the sensing optical fiber link through a circulator (203);
the backward Rayleigh scattering light Lb which is generated by external vibration and returned by the optical repeater (1) passes through the optical combiner (204), then performs heterodyne interference with the reference light Lc output by the optical beam splitter (202), and then enters the detection module (3), and the detection module (3) analyzes the input signal and outputs the vibration position.
6. The ultra-long distance distributed optical fiber vibration sensing detection device according to claim 5, wherein said light source (201) comprises a narrow linewidth light source.
7. The ultra-long distance distributed optical fiber vibration sensing detection device according to claim 6, wherein the loop back link (101) provided in the optical repeater (1) comprises a narrow band pass optical link.
8. The ultra-long distance distributed optical fiber vibration sensing detection device according to claim 5, wherein the optical fiber vibration sensing detection system (2) further comprises a pulse width optical modulator (205) and a signal generator (206); the detection light Ls output by the optical beam splitter (202) passes through the pulse width optical modulator (205), and the pulse width optical modulator (205) adjusts the pulse width of the detection light Ls through a signal generator (206) and then enters the sensing optical fiber link through a circulator (203).
9. The ultra-long distance distributed optical fiber vibration sensing detection device according to claim 8, wherein said optical fiber vibration sensing detection system (2) further comprises a first optical amplifier (207); the detection light Ls modulated by the pulse width optical modulator (205) passes through the first optical amplifier (207) to adjust the output power, and then enters the sensing optical fiber link through the circulator (203).
10. The ultra-long distance distributed optical fiber vibration sensing detection device according to claim 5, wherein the detection module (3) includes a second optical amplifier (301), an optical filter (302), a photodetector (303), and a signal processing unit (304), wherein the backward rayleigh scattering light Lb generated by external vibration and returned through the optical repeater (1) passes through the optical combiner (204), the second optical amplifier (301), and the optical filter (302) in sequence, then interferes with the reference light Lc output by the optical beam splitter (202) for heterodyne, and then enters the photodetector (303) and the signal processing unit (304) in sequence, and the signal processing unit (304) analyzes the input signal and outputs the vibration position.
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