Optical fiber sensing system based on BOTDR

Abstract

The utility model relates to the field of optical cable monitoring, in particular to an optical fiber sensing system based on a BOTDR (Brillouin Optical Time Domain Reflectometer), which comprises an optical path acquisition module, an optical path conversion module, a power distribution assembly, a frequency spectrum splicing assembly and a plurality of microwave frequency spectrum measuring circuits, each microwave frequency spectrum measurement circuit comprises an ADC analog-to-digital conversion assembly; the light path acquisition module is respectively connected with to-be-measured optical fiber light and the input end of the light path conversion module; the output end of the optical path conversion module is connected with the input end of the power distribution assembly; each output end of the power distribution assembly is connected with the input end of one microwave frequency spectrum measuring circuit, and each input end of the frequency spectrum splicing assembly is connected with the output end of one microwave frequency spectrum measuring circuit. Compared with the prior art, large-bandwidth microwave electric signals are equally divided by using the power distribution assembly, and then can be processed by the low-speed small-bandwidth ADC analog-to-digital conversion assemblies on the plurality of microwave frequency spectrum measurement lines, so that the application cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of optical cable monitoring, more particularly to a BOTDR-based optical fiber sensing system. BACKGROUND

[0002] With the continuous development of optical fiber technology, optical fiber sensing technology has begun to popularize, among them, BOTDR (Brillouin Optical Time Domain Reflectometer) is a kind of optical fiber sensing technology based on Brillouin scattering, mainly used for distributed temperature and strain measurement. In the prior art, the measurement range of BOTDR strain and temperature can be improved by using high-speed large-bandwidth ADC analog-digital converter to measure temperature and strain, but the cost of high-speed large-bandwidth ADC analog-digital converter is extremely high, which will lead to the decline of the popularity of BOTDR. SUMMARY

[0003] The utility model aims at overcoming at least one of the above prior art defects, providing a BOTDR-based optical fiber sensing system for effectively reducing the application cost of BOTDR strain and temperature measurement.

[0004] The technical scheme adopted by the utility model is:

[0005] The utility model provides a BOTDR-based optical fiber sensing system, the sensing system includes optical path acquisition module, optical path conversion module, power distribution component, spectrum splicing component and several microwave spectrum measurement lines;

[0006] The optical path acquisition module is used to be connected with the optical fiber to be measured, and the optical information to be measured is acquired;

[0007] The output end of the optical path acquisition module is connected with the input end of the optical path conversion module;

[0008] The optical path conversion module is used to convert the optical signal to be measured transmitted by the optical path acquisition module into microwave electrical signal; The output end of the optical path conversion module is connected with the input end of the power distribution component;

[0009] The power distribution component is used to distribute the microwave electrical signal output by the optical path conversion module into several paths of microwave measurement signal; The power distribution component is provided with several output ports; Each output port is connected with the input end of each microwave spectrum measurement line one by one;

[0010] Each input end of the spectrum splicing component is connected with the output end of one microwave spectrum measurement line respectively.

[0011] By converting the collected to-be-measured optical signal into a large-bandwidth microwave electrical signal, the large-bandwidth microwave electrical signal is divided into several small-bandwidth microwave measurement signals by using a power distribution component, and the microwave measurement signals are processed by corresponding microwave spectrum measurement lines, so that, compared with a conventional high-speed large-bandwidth ADC analog-to-digital converter, each microwave spectrum measurement line can use a low-speed small-bandwidth ADC analog-to-digital converter with lower cost and lower power consumption to process the small-bandwidth microwave measurement signal after division, thereby effectively reducing the application cost of BOTDR strain and temperature measurement.

[0012] Further, each microwave spectrum measurement line includes a mixing component, an ADC analog-to-digital conversion component, and a local oscillator signal component.

[0013] The mixing component is provided with a first input end, a second input end, and an output end.

[0014] The first input end of the mixing component serves as the input end of the microwave spectrum measurement line and is connected to the output end of the power distribution component, the output end of the mixing component is connected to the input end of the ADC analog-to-digital conversion component, and the output end of the ADC analog-to-digital conversion component serves as the output end of the microwave spectrum measurement line and is connected to one input end of the spectrum splicing component.

[0015] One output end of the spectrum splicing component is connected to the second input end of the corresponding mixing component through the local oscillator signal component.

[0016] The local oscillator signal component receives the electrical signal sent by the spectrum splicing component, generates a corresponding local oscillator signal according to the electrical signal, and sends the local oscillator signal to the mixing component to mix with the microwave measurement signal converted from the to-be-measured optical signal and divided, so that the coherent detection of the to-be-measured optical signal can be better realized, and the phase and polarization information of the to-be-measured optical signal can be recovered, thereby better realizing the detection of temperature and stress.

[0017] Further, the mixing component includes a first microwave low-noise amplifier and a mixer.

[0018] The input end of the first microwave low-noise amplifier serves as the first input end of the mixing component and is connected to the output end of the power distribution component, and the output end of the first microwave low-noise amplifier is connected to the first input end of the mixer.

[0019] The output end of the mixer is connected with the input end of the ADC module conversion component as the output end of the mixing component.

[0020] The microwave low noise amplifier amplifies the microwave measurement signal with small bandwidth after being divided by the power distribution component, which can reduce the influence caused by the power distribution component, and make the mixer better utilize the microwave measurement signal with small bandwidth for mixing.

[0021] Further, the ADC module conversion component comprises an intermediate frequency amplifier and an ADC module converter.

[0022] The input end of the intermediate frequency amplifier is connected with the output end of the mixing component as the input end of the ADC module conversion component, and the output end of the intermediate frequency amplifier is connected with the input end of the ADC module converter.

[0023] The output end of the ADC module converter is connected with one input end of the spectrum splicing component as the output end of the ADC module conversion component.

[0024] After the microwave measurement signal with small bandwidth obtained by the power distribution component is mixed with the local oscillator signal by the mixing component, an intermediate frequency signal is usually obtained, so an intermediate frequency amplifier is needed to amplify the intermediate frequency signal, so that the intermediate frequency signal can be better converted into a digital signal by the ADC module converter.

[0025] Further, the local oscillator signal component comprises a local oscillator.

[0026] The input end of the local oscillator is connected with the corresponding output end of the spectrum splicing component, and the output end of the local oscillator is connected with the second input end of the mixing component.

[0027] Further, the optical path acquisition module comprises a laser emission component, a first laser amplification component, a second laser amplification component and a ring laser.

[0028] The laser emission component is provided with a first output end, a second output end and an input end.

[0029] The first output end of the laser emission component is connected with the input end of the first laser amplification component, the second output end of the laser emission component is connected with the input end of the optical path conversion module, and the input end of the laser emission component is connected with the output end of the second laser amplification component.

[0030] The output end of the first laser amplification component is connected with the input end of the circulator, the first output end of the circulator is connected with the to-be-tested optical fiber, and the second output end of the circulator is connected with the input end of the second laser amplification component.

[0031] Further, the laser emission component comprises a laser emitter, a first coupler and a second coupler.

[0032] The output end of the laser emitter is connected with the input end of the first coupler; the first output end of the first coupler serves as the first output end of the laser emission component and is connected with the input end of the first laser amplification component; and the second output end of the first coupler is connected with the first input end of the second coupler.

[0033] The second input end of the second coupler serves as the input end of the laser emission component and is connected with the output end of the second laser amplification component.

[0034] The output end of the second coupler serves as the second output end of the laser emission component and is connected with the input end of the optical path conversion module.

[0035] Further, the first laser amplification component comprises a semiconductor optical amplifier and a first erbium-doped fiber amplifier.

[0036] The input end of the semiconductor optical amplifier serves as the input end of the first laser amplification component and is connected with the first output end of the first coupler, and the output end of the semiconductor optical amplifier is connected with the input end of the first erbium-doped fiber amplifier.

[0037] The output end of the first erbium-doped fiber amplifier serves as the output end of the first laser amplification component and is connected with the input end of the circulator.

[0038] Further, the second laser amplification component comprises a second erbium-doped fiber amplifier and an optical filter.

[0039] The input end of the second erbium-doped fiber amplifier serves as the input end of the second laser amplification component and is connected with the second output end of the circulator.

[0040] The output end of the second erbium-doped fiber amplifier is connected with the input end of the optical filter, and the output end of the optical filter serves as the output end of the second laser amplification component and is connected with the second input end of the second coupler.

[0041] Further, the optical path conversion module comprises a photodetector and a second microwave low-noise amplifier.

[0042] The input end of the photoelectric detector is connected with the output end of the optical path acquisition module as the input end of the optical path conversion module.

[0043] The output end of the photoelectric detector is connected with the input end of the second microwave low-noise amplifier.

[0044] The output end of the second microwave low-noise amplifier is connected with the power distribution component as the output end of the optical path acquisition module.

[0045] Compared with the prior art, the utility model has the advantages that:

[0046] In the embodiment, the collected optical signal is converted into a microwave signal with a large bandwidth, the microwave signal with the large bandwidth is divided into a plurality of microwave measurement signals with small bandwidths by the power distribution component, the microwave measurement signals with the small bandwidths are processed by corresponding microwave spectrum measurement lines, the ADC analog-digital conversion component with low speed and small bandwidth is used on each microwave spectrum measurement line to reduce the cost and power consumption of the BOTDR strain and temperature measurement application. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 It is the circuit structure diagram of the utility model as a whole.

[0048] Figure 2 It is the circuit structure diagram of the optical path acquisition module of the utility model.

[0049] Figure 3 It is the circuit structure diagram of the optical path conversion module of the utility model.

[0050] BRIEF DESCRIPTION OF DRAWINGS Optical path acquisition module 100, optical path conversion module 200, power distribution component 310, spectrum splicing component 320, mixing component 331, ADC analog-digital conversion component 332, first microwave low-noise amplifier 3311, mixer 3312, intermediate frequency amplifier 3321, ADC analog-digital converter 3322, local oscillator 333, laser emission component 110, first laser amplification component 120, second laser amplification component 130, circulator 140, laser emitter 111, first coupler 112, second coupler 113, semiconductor optical amplifier 121, first erbium-doped fiber amplifier 122, second erbium-doped fiber amplifier 131, optical filter 132, photoelectric detector 210, second microwave low-noise amplifier 220, optical fiber to be measured 400. DETAILED DESCRIPTION

[0051] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this invention. To better illustrate the following embodiments, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0052] Example 1

[0053] As an emerging sensing technology, fiber optic sensing technology has been widely applied in recent years with the continuous development of fiber optic technology. Among them, Brillouin Optical Time Domain Reflectometer (BOTDR) technology based on Brillouin scattering has become a research hotspot due to its ability to achieve distributed temperature and strain measurements.

[0054] The basic principle of BOTDR technology is to utilize the spontaneous Purlyan scattering effect in optical fibers to obtain temperature and strain information at various points along the fiber by analyzing the frequency shift of the scattered light. Compared with traditional point sensors, BOTDR technology has advantages such as long measurement distance, high spatial resolution, and strong resistance to electromagnetic interference, showing great application potential in fields such as bridge health monitoring, pipeline leak detection, and perimeter security.

[0055] However, the practical application of BOTDR technology still faces some challenges. One key issue is how to improve the measurement range of strain and temperature. Existing technologies typically employ high-speed, high-bandwidth ADCs (Analog-to-Digital Converters) like the 3322 to enhance the measurement range. This is because the frequency shift of the Brillouin scattering signal is proportional to the changes in temperature and strain, and a high-speed, high-bandwidth ADC can more accurately capture these minute frequency changes, thereby expanding the measurement range.

[0056] However, the high-speed, high-bandwidth ADC analog-to-digital converter 3322 is extremely expensive and consumes more power, which directly increases the overall cost of the BOTDR system and limits its widespread adoption in practical applications. Therefore, reducing the cost of the BOTDR system while ensuring measurement accuracy has become the key to promoting the further development of this technology.

[0057] In order to solve the technical problems in the prior art, such as Figure 1 As shown, this embodiment provides a BOTDR-based fiber optic sensing system, which may specifically include an optical path acquisition module 100, an optical path conversion module 200, a power distribution component 310, a spectrum splicing component 320, and several microwave spectrum measurement lines.

[0058] The optical path acquisition module 100 is connected with the optical fiber to be measured 400, and is configured to emit laser into the optical fiber to be measured 400 and collect the measured optical signal returned from the optical fiber to be measured 400; the input end of the optical path conversion module 200 is connected with the optical path acquisition module 100, and is configured to convert the measured optical signal collected and transmitted by the optical path acquisition module 100 into a microwave electrical signal;

[0059] The power distribution assembly is configured to distribute the microwave electrical signal output by the optical path conversion module into several microwave measurement signals; specifically, the power distribution assembly 310 is provided with one input end and several output ports, the input end of the power distribution assembly 310 is connected with the output end of the optical path conversion module 200, and each output port of the power distribution assembly 310 is connected with the input end of each microwave spectrum measurement line in one-to-one correspondence.

[0060] The spectrum splicing assembly 320 is provided with several input ends, and each input end of the spectrum splicing assembly 320 is connected with the output end of one microwave spectrum measurement line.

[0061] It can be understood that, in the embodiment, after the optical path acquisition module 100 emits laser to the optical fiber to be measured 400 and collects the measured optical signal returned from the optical fiber to be measured, the power distribution assembly 310 is used to divide the large-bandwidth microwave electrical signal into several small-bandwidth microwave measurement signals, so that each small-bandwidth microwave measurement signal can be sent to each microwave spectrum measurement line through each output port of the power distribution assembly 310, the microwave measurement signal is processed through the microwave spectrum measurement line, and then the digital signal obtained by processing each microwave spectrum measurement line is concentrated in the spectrum splicing assembly 320 for splicing and restoration, so that the stress and temperature spectrum information in the optical fiber to be measured 400 can be obtained; wherein, after being divided by the power distribution assembly 310, the bandwidth of the microwave measurement signal to be processed in each microwave spectrum measurement line is small, and a low-speed small-bandwidth ADC analog-digital converter 3321 can be used in each microwave spectrum measurement line, so that the application cost of the BOTDR stress and temperature measurement is greatly reduced compared with the prior art which directly uses a high-speed large-bandwidth ADC analog-digital converter 3321 for processing.

[0062] In a specific example, it is assumed that the sensing system includes four microwave spectrum measurement lines, the bandwidth of the microwave electrical signal converted by the optical path conversion module 200 is 10.7-11.1 GHz, the microwave electrical signal is divided into four microwave measurement signals by the power distribution assembly 310, the bandwidth of each microwave measurement signal is 10.7-10.8 GHz, 10.8-10.9 GHz, 10.9-11 GHz and 11-11.1 GHz respectively, and the four microwave measurement signals are sent to the four microwave spectrum measurement lines for processing respectively, realizing the division of the microwave electrical signal with a larger bandwidth, so as to be processed by the ADC analog-to-digital converter 3321 with lower cost and power consumption, and achieving the effect of reducing the application cost of the whole sensing system.

[0063] It should be noted that in the present embodiment, the output ports of the power distribution assembly 310 and the input ends of the spectrum splicing assembly 320 refer to the ports actually connected with the microwave spectrum measurement lines on the power distribution assembly 310 and the spectrum splicing assembly 320; in actual application, the actual number of ports on the power distribution assembly 310 and the spectrum splicing assembly 320 is greater than the number of microwave spectrum measurement lines, so as to better realize the distribution of the microwave spectrum measurement lines, therefore, in the present embodiment, the actually connected ports on the power distribution assembly 310 and the spectrum splicing assembly 320 are taken as the corresponding output ports and input ends.

[0064] Specifically, in the present embodiment, each microwave spectrum measurement line can include a mixing assembly 331, an ADC analog-to-digital conversion assembly 332 and a local oscillator signal assembly; wherein the local oscillator signal assembly is used to generate a corresponding local oscillator signal according to the electrical signal sent by the spectrum splicing assembly 320 and send it to the mixing assembly 331, so as to realize the frequency modulation of the microwave measurement signal.

[0065] Specifically, the mixing assembly 331 is provided with a first input end, a second input end and an output end; the mixing assembly 331 is used to mix the microwave measurement signal output by the power distribution assembly 310 with the local oscillator signal generated by the local oscillator signal assembly to obtain an intermediate frequency microwave signal; the ADC analog-to-digital conversion assembly 332 is used to convert the intermediate frequency microwave signal obtained by the mixing assembly 331 into a corresponding digital signal.

[0066] The first input end of the mixing component 331 is connected with the output end of the power distribution component 310 as an input end of the microwave spectrum measurement line, and the output end of the mixing component 331 is connected with the input end of the ADC analog-digital conversion component 332; the output end of the ADC analog-digital conversion component 332 is connected with one input end of the spectrum splicing component 320 as an output end of the microwave spectrum measurement line.

[0067] In a specific embodiment of the present embodiment, the mixing component 331 can include a first microwave low-noise amplifier 3311 and a mixer 3312; the ADC analog-digital conversion component 332 can include an intermediate frequency amplifier 3321 and an ADC analog-digital converter 3322; the local oscillation signal component can include a local oscillator 333.

[0068] Specifically, the input end of the first microwave low-noise amplifier 3311 is connected with the output end of the power distribution component 310 as the first input end of the mixing component 331, and the output end of the first microwave low-noise amplifier 3311 is connected with the first input end of the mixer 3312.

[0069] The output end of the mixer 3312 is connected with the input end of the ADC analog-digital conversion component 332 as the output end of the mixing component 331; the second input end of the mixer 3312 is connected with the corresponding output end of the spectrum splicing component 320 through the local oscillation signal component as the second input end of the mixing component 331.

[0070] The input end of the intermediate frequency amplifier 3321 is connected with the output end of the mixing component 331 as the input end of the ADC analog-digital conversion component 332, and the output end of the intermediate frequency amplifier 3321 is connected with the input end of the ADC analog-digital converter 3322.

[0071] The output end of the ADC analog-digital converter 3322 is connected with one input end of the spectrum splicing component 320 as the output end of the ADC analog-digital conversion component 332.

[0072] The input end of the local oscillator 333 is connected with the corresponding output end of the spectrum splicing component 320, and the output end of the local oscillator 333 is connected with the second input end of the mixing component 331.

[0073] The first microwave low-noise amplifier 3311 is configured to amplify the microwave measurement signal output by the power distribution component 310; the frequency mixer 3312 is configured to mix the microwave measurement signal amplified by the first microwave low-noise amplifier 3311 with the local oscillator signal generated by the local oscillator signal component to obtain the intermediate frequency microwave signal; the intermediate frequency amplifier 3321 is configured to amplify the intermediate frequency microwave signal output by the frequency mixer; and the ADC (analog-to-digital converter) 3322 is configured to convert the intermediate frequency microwave signal amplified by the intermediate frequency amplifier 3321 into a corresponding digital signal.

[0074] The local oscillator 333 is configured to receive a specific electrical signal sent by the spectrum splicing component 320, generate a specific, stable and high-frequency local oscillator signal, and send the local oscillator signal to the frequency mixer 3312 to mix with the low-frequency microwave measurement signal; the specific electrical signal is pre-configured in the spectrum splicing component 320 to enable the frequency mixer 3312 to obtain a specific frequency intermediate frequency microwave signal through mixing.

[0075] Because the large-bandwidth microwave electrical signal converted from the optical signal to be measured by the power distribution component 310 is divided into several small-bandwidth microwave measurement signals, the power of the microwave measurement signal is reduced during the division, so the first microwave low-noise amplifier 3311 is used to amplify the microwave measurement signal before mixing to enable the microwave measurement signal to be better mixed with the local oscillator signal.

[0076] Meanwhile, as described above, the intermediate frequency microwave signal passing through the frequency mixer 3312 is obtained by mixing and adjusting the microwave measurement signal and the local oscillator signal, the microwave measurement signal is a low-frequency signal, and the local oscillator signal is usually a high-frequency signal, and the intermediate frequency microwave signal is obtained after the adjustment of the frequency mixer 3312; therefore, a corresponding intermediate frequency amplifier 3321 needs to be set to amplify the intermediate frequency microwave signal output by the frequency mixer 3312, and then the low-speed small-bandwidth ADC (analog-to-digital converter) 3322 can be better used to collect and convert the intermediate frequency microwave signal.

[0077] Preferably, in the embodiment, the spectrum splicing component 320 can adopt an FPGA (Field-Programmable Gate Array), the FPGA supports high-speed parallel computing, can effectively receive and compute the digital signals input on the multiple microwave spectrum measurement lines, and realizes the computation and splicing of the spectrum.

[0078] In some embodiments, as Figure 2As shown, the light path acquisition module 100 can include a laser emission assembly 110, a first laser amplification assembly 120, a second laser amplification assembly 130, and an optical circulator 140;

[0079] The laser emission assembly 110 is provided with a first output end, a second output end, and an input end;

[0080] The first output end of the laser emission assembly 110 is connected with the input end of the first laser amplification assembly 120, the second output end of the laser emission assembly 110 is connected with the input end of the light path conversion module 200, and the input end of the laser emission assembly 110 is connected with the output end of the second laser amplification assembly 130;

[0081] The output end of the first laser amplification assembly 120 is connected with the input end of the optical circulator 140, the first output end of the optical circulator 140 is connected with the to-be-measured optical fiber 400, and the second output end of the optical circulator 140 is connected with the input end of the second laser amplification assembly 130.

[0082] The laser emission assembly 110 emits laser through the first output end to the first laser amplification assembly 120, the first laser amplification assembly 120 amplifies the laser and emits the laser into the optical circulator 140, the optical circulator 140 emits the laser into the to-be-measured optical fiber 400 through the second output end thereon and receives the to-be-measured optical signal returned by the to-be-measured optical fiber 400, the optical circulator 140 sends the received to-be-measured optical signal to the second laser amplification assembly 130 through the second output end thereon, the second laser amplification assembly 130 amplifies and processes the to-be-measured optical signal, and the laser emission assembly 110 receives the amplified to-be-measured optical signal through the input end thereon and sends the to-be-measured optical signal to the light path conversion module 200 after coupling the to-be-measured optical signal with part of the local laser emitted by the laser emission assembly 110.

[0083] The laser emission assembly 110 includes a laser emitter 111, a first coupler 112, and a second coupler 113, the first laser amplification assembly 120 includes a semiconductor optical amplifier 121 and a first erbium-doped fiber amplifier 122, and the second laser amplification assembly 130 includes a second erbium-doped fiber amplifier 131 and an optical filter 132.

[0084] Specifically, the output end of the laser emitter 111 is connected with the input end of the first coupler 112, the first output end of the first coupler 112 serves as the first output end of the laser emission assembly 110 and is connected with the input end of the first laser amplification assembly 120, and the second output end of the first coupler 112 is connected with the first input end of the second coupler 113.

[0085] The second input end of the second coupler 113 is connected with the output end of the second laser amplification component 130 as the input end of the laser emission component 110;

[0086] The output end of the second coupler 113 is connected with the input end of the optical path conversion module 200 as the second output end of the laser emission component 110.

[0087] The part of the local laser emitted by the laser emitter 111 is distributed through the first coupler 112, and the part of the local laser is coupled with the to-be-measured optical signal returned by the to-be-measured optical fiber 400 through the second coupler 113, so that the to-be-measured optical signal obtained by the coupling has the reference information of the local laser for subsequent spectrum calculation.

[0088] The input end of the semiconductor optical amplifier 121 is connected with the first output end of the first coupler 112 as the input end of the first laser amplification component 120, and the output end of the semiconductor optical amplifier 121 is connected with the input end of the first erbium-doped fiber amplifier 122.

[0089] The output end of the first erbium-doped fiber amplifier 122 is connected with the input end of the circulator 140 as the output end of the first laser amplification component 120.

[0090] The input end of the second erbium-doped fiber amplifier 131 is connected with the second output end of the circulator 140 as the input end of the second laser amplification component 130.

[0091] The output end of the second erbium-doped fiber amplifier is connected with the input end of the optical filter 132, and the output end of the optical filter 132 is connected with the second input end of the second coupler 113 as the output end of the second laser amplification component 130.

[0092] As shown in Figure 3 The optical path conversion module 200 includes a photodetector 210 and a second microwave low-noise amplifier 220.

[0093] The photodetector 210 is used for photoelectric conversion of the to-be-measured optical signal sent by the optical path acquisition module 200 into a corresponding microwave electrical signal, and the second microwave low-noise amplifier 220 is used for amplification of the microwave electrical signal output by the photodetector 210. Preferably, the photodetector 210 can adopt a high-speed photodetector.

[0094] The input end of the photoelectric detector 210 is connected with the output end of the second coupler 113 in the optical path collecting module 100 as the input end of the optical path conversion module 200.

[0095] Specifically, the output end of the photoelectric detector 210 is connected with the input end of the second microwave low-noise amplifier 220.

[0096] The output end of the second microwave low-noise amplifier 220 is connected with the power distribution assembly 310 as the output end of the optical path collecting module 100.

[0097] Obviously, the above embodiments of the utility model are only examples for clearly illustrating the technical scheme of the utility model, and are not a limitation on the specific embodiments of the utility model. Any modification, equivalent replacement and improvement within the spirit and principle of the utility model claim should be included in the protection scope of the utility model claim.

Claims

1. A BOTDR-based optical fiber sensing system, characterized by, The sensing system comprises an optical path acquisition module, an optical path conversion module, a power distribution assembly, a spectrum splicing assembly and a plurality of microwave spectrum measurement lines; The optical path acquisition module is used to be connected with a fiber to be measured to acquire a to-be-measured optical signal; an output end of the optical path acquisition module is connected with an input end of the optical path conversion module; The optical path conversion module is used to convert the to-be-measured optical signal transmitted by the optical path acquisition module into a microwave electrical signal; An output end of the optical path conversion module is connected with an input end of the power distribution assembly; The power distribution assembly is used to distribute the microwave electrical signal output by the optical path conversion module into a plurality of microwave measurement signals; the power distribution assembly is provided with a plurality of output ports; each output port is connected with an input end of each microwave spectrum measurement line in one-to-one correspondence; Each input end of the spectrum splicing assembly is connected with an output end of one microwave spectrum measurement line.

2. The BOTDR-based optical fiber sensing system of claim 1, wherein, Each microwave spectrum measurement line comprises a mixing component, an ADC analog-digital conversion component and a local oscillator signal component; The mixing component is provided with a first input end, a second input end and an output end; The first input end of the mixing component serves as an input end of the microwave spectrum measurement line and is connected with an output end of the power distribution assembly; an output end of the mixing component is connected with an input end of the ADC analog-digital conversion component; an output end of the ADC analog-digital conversion component serves as an output end of the microwave spectrum measurement line and is connected with one input end of the spectrum splicing assembly; One output end of the spectrum splicing assembly is connected with the second input end of the corresponding mixing component through the local oscillator signal component.

3. The BOTDR-based optical fiber sensing system of claim 2, wherein, The mixing component comprises a first microwave low-noise amplifier and a mixer; An input end of the first microwave low-noise amplifier serves as the first input end of the mixing component and is connected with an output end of the power distribution assembly; an output end of the first microwave low-noise amplifier is connected with a first input end of the mixer; An output end of the mixer serves as an output end of the mixing component and is connected with an input end of the ADC analog-digital conversion component; a second input end of the mixer serves as the second input end of the mixing component and is connected with the corresponding output end of the spectrum splicing assembly through the local oscillator signal component.

4. The BOTDR-based optical fiber sensing system of claim 2, wherein, The ADC analog-digital conversion component comprises an intermediate frequency amplifier and an ADC analog-digital converter; An input end of the intermediate frequency amplifier serves as an input end of the ADC analog-digital conversion component and is connected with an output end of the mixing component; an output end of the intermediate frequency amplifier is connected with an input end of the ADC analog-digital converter; An output end of the ADC analog-digital converter serves as an output end of the ADC analog-digital conversion component and is connected with one input end of the spectrum splicing assembly.

5. The BOTDR-based optical fiber sensing system of claim 2, wherein, The local oscillator signal component comprises a local oscillator; An input end of the local oscillator is connected with the corresponding output end of the spectrum splicing assembly; an output end of the local oscillator is connected with the second input end of the mixing component.

6. A BOTDR-based optical fiber sensing system according to any one of claims 1-5, characterized in that, The optical path acquisition module comprises a laser emission component, a first laser amplification component, a second laser amplification component and a circulator; The laser emission assembly is provided with a first output end, a second output end and an input end; The first output end of the laser emission assembly is connected with the input end of the first laser amplification assembly, the second output end of the laser emission assembly is connected with the input end of the optical path conversion module, and the input end of the laser emission assembly is connected with the output end of the second laser amplification assembly; The output end of the first laser amplification assembly is connected with the input end of the circulator, the first output end of the circulator is connected with the optical fiber to be measured, and the second output end of the circulator is connected with the input end of the second laser amplification assembly.

7. A BOTDR-based optical fiber sensing system according to claim 6, wherein, The laser emission assembly comprises a laser emitter, a first coupler and a second coupler; The output end of the laser emitter is connected with the input end of the first coupler; the first output end of the first coupler serves as the first output end of the laser emission assembly and is connected with the input end of the first laser amplification assembly; and the second output end of the first coupler is connected with the first input end of the second coupler; The second input end of the second coupler serves as the input end of the laser emission assembly and is connected with the output end of the second laser amplification assembly; The output end of the second coupler serves as the second output end of the laser emission assembly and is connected with the input end of the optical path conversion module.

8. The BOTDR-based optical fiber sensing system of claim 7, wherein, The first laser amplification assembly comprises a semiconductor optical amplifier and a first erbium-doped fiber amplifier; The input end of the semiconductor optical amplifier serves as the input end of the first laser amplification assembly and is connected with the first output end of the first coupler, and the output end of the semiconductor optical amplifier is connected with the input end of the first erbium-doped fiber amplifier; The output end of the first erbium-doped fiber amplifier serves as the output end of the first laser amplification assembly and is connected with the input end of the circulator.

9. The BOTDR-based optical fiber sensing system of claim 8, wherein, The second laser amplification assembly comprises a second erbium-doped fiber amplifier and an optical filter; The input end of the second erbium-doped fiber amplifier serves as the input end of the second laser amplification assembly and is connected with the second output end of the circulator; The output end of the second erbium-doped fiber amplifier is connected with the input end of the optical filter; The output end of the optical filter serves as the output end of the second laser amplification assembly and is connected with the second input end of the second coupler.

10. A BOTDR-based optical fiber sensing system according to any one of claims 1-5, characterized in that, The optical path conversion module comprises a photodetector and a second microwave low-noise amplifier; The input end of the photodetector serves as the input end of the optical path conversion module and is connected with the output end of the optical path acquisition module; The output end of the photodetector is connected with the input end of the second microwave low-noise amplifier; The output end of the second microwave low-noise amplifier serves as the output end of the optical path acquisition module and is connected with the power distribution assembly.

Images