TGD-OFDR / OCC-BOTDR fused multi-parameter sensing system and working method thereof

Abstract

The invention discloses a TGD-OFDR / OCC-BOTDR integrated multi-parameter sensing system and a working method thereof, and relates to the technical field of optical fiber sensors. The multi-parameter sensing system comprises a laser, an optical fiber coupler, an electro-optical modulator, an optical fiber circulator, an optical fiber Bragg grating, an acoustic optical modulator, an erbium-doped optical fiber amplifier, a random scrambler, a piezoelectric ceramic tube, a heating vessel, a delay optical fiber, a photoelectric balance detector, a filter and detector, a data acquisition card, a polarization controller, a direct-current power supply and a microwave source. An arbitrary waveform generator and the like. According to the invention, multiple parameters can be represented at the same time, the measuring speed is fast, and the sampling rate of the system can be effectively improved under the condition that sensing parameters are the same; the method has the advantage of high spatial resolution; the sensor has the advantages of high fusion and low cost, can realize simultaneous measurement of vibration and temperature / strain through single sensing, and is high in fusion and effective in cost control.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber sensors, and in particular to a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR and a working method thereof. Background Art

[0002] Distributed fiber optic sensors (DOFS) have broad application prospects due to their unique advantages of remote distributed measurements in industrial applications. However, no matter which DOFS is used, the changes in the measured parameters (usually temperature, strain or vibration) are limited. In industrial monitoring, coordinated multi-parameter measurements are urgently needed to accurately identify fault events. Hybrid DOFS technology combines Rayleigh, Brillouin and Raman scattering mechanisms to integrate multiple DOFS systems in a single configuration, which has attracted increasing attention and rapid development. Compared with a single DOFS system, multi-parameter measurements based on hybrid DOFS provide multi-dimensional valuable information to prevent misjudgments and false alarms. The highly integrated sensing structure makes engineering monitoring more efficient and economical. Summary of the invention

[0003] In view of the above problems, the present invention proposes a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR and a working method thereof.

[0004] According to one aspect of the present invention, a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR is proposed, and the multi-parameter sensing system comprises: a first laser 1, a first fiber coupler 2, a second fiber coupler 3, a first electro-optic modulator 4, a first fiber circulator 5, a fiber Bragg grating 6, a first acousto-optic modulator 7, a first erbium-doped fiber amplifier 8, a random polarization scrambler 9, a third fiber coupler 10, a second fiber circulator 11, a piezoelectric ceramic tube 12, a heating vessel 13, and a second electro-optic modulator 1 4. a third fiber circulator 15, a second laser 16, a fourth fiber coupler 17, a second acousto-optic modulator 18, a second erbium-doped fiber amplifier 19, a delay fiber 20, a third erbium-doped fiber amplifier 21, a fifth fiber coupler 22, a sixth fiber coupler 23, a first photoelectric balanced detector 24, a filter and detector 25, a data acquisition card 26, a polarization controller 27, a seventh fiber coupler 28, a second photoelectric balanced detector 29, a DC power supply 30, a microwave source 31, and an arbitrary waveform generator 32; wherein,

[0005] The optical signal output end of the first laser 1 is connected to the optical signal input end of the first optical fiber coupler 2, the first optical signal output end 2-1 of the first optical fiber coupler 2 is connected to the optical signal input end of the second optical fiber coupler 3, and the second optical signal output end 2-2 of the first optical fiber coupler 2 is connected to the optical signal input end of the polarization controller 27;

[0006] The first optical signal output end 3-1 of the second optical fiber coupler 3 is connected to the optical signal input end of the first electro-optic modulator 4, the optical signal output end of the first electro-optic modulator 4 is connected to the first port 5-1 of the first optical fiber circulator 5, the second port 5-2 of the first optical fiber circulator 5 is connected to the fiber Bragg grating 6, the third port 5-3 of the first optical fiber circulator 5 is connected to the optical signal input end of the first acousto-optic modulator 7, the optical signal output end of the first acousto-optic modulator 7 is connected to the optical signal input end of the first erbium-doped fiber amplifier 8, The optical signal output end of the first erbium-doped fiber amplifier 8 is connected to the optical signal input end of the random polarization scrambler 9, the optical signal output end of the random polarization scrambler 9 is connected to the first optical signal input end 10-1 of the third optical fiber coupler 10, the optical signal output end of the third optical fiber coupler 10 is connected to the first port 11-1 of the second optical fiber circulator 11, the second port 11-2 of the second optical fiber circulator 11 is connected to one end of the sensing optical fiber, the other end of the sensing optical fiber is connected to the piezoelectric ceramic tube 12, and the piezoelectric ceramic tube 12 is connected to the heating vessel 13;

[0007] The second optical signal output end 3-2 of the second optical fiber coupler 3 is connected to the optical signal input end of the second electro-optic modulator 14, the optical signal output end of the second electro-optic modulator 14 is connected to the first port 15-1 of the third optical fiber circulator 15, the second port 15-2 of the third optical fiber circulator 15 is connected to the optical signal output end of the second laser 16, the third port 15-3 of the third optical fiber circulator 15 is connected to the optical signal input end of the fourth optical fiber coupler 17, the first optical signal output end 17-1 of the fourth optical fiber coupler 17 is connected to the optical signal input end of the second acousto-optic modulator 18, the optical signal output end of the second acousto-optic modulator 18 is connected to the optical signal input end of the second erbium-doped fiber amplifier 19, the optical signal output end of the second erbium-doped fiber amplifier 19 is connected to one end of the delay optical fiber 20, and the other end of the delay optical fiber 20 is connected to the second optical signal input end 10-2 of the third optical fiber coupler 10;

[0008] The third port 11-3 of the second optical fiber circulator 11 is connected to the optical signal input end of the third erbium-doped fiber amplifier 21, the optical signal output end of the third erbium-doped fiber amplifier 21 is connected to the optical signal input end of the fifth optical fiber coupler 22, the second optical signal output end 17-2 of the fourth optical fiber coupler 17 and the first optical signal output end 22-1 of the fifth optical fiber coupler 22 are respectively connected to the first optical signal input end 23-1 and the second optical signal input end 23-2 of the sixth optical fiber coupler 23, the optical signal output end of the sixth optical fiber coupler 23 is connected to the optical signal input end of the first photoelectric balanced detector 24, the electrical signal output end of the first photoelectric balanced detector 24 is connected to the electrical signal input end of the filter and detector 25, and the electrical signal output end of the filter and detector 25 is connected to the electrical signal input end of the data acquisition card 26;

[0009] The second optical signal output end 22-2 of the fifth optical fiber coupler 22 and the optical signal output end of the polarization controller 27 are respectively connected to the first optical signal input end 28-1 and the second optical signal input end 28-2 of the seventh optical fiber coupler 28, the optical signal output end of the seventh optical fiber coupler 28 is connected to the optical signal input end of the second photoelectric balance detector 29, and the electrical signal output end of the second photoelectric balance detector 29 is connected to the electrical signal input end of the data acquisition card 26;

[0010] The output end of the DC power supply 30 is respectively connected to the bias voltage input end of the first electro-optic modulator 4 and the bias voltage input end of the second electro-optic modulator 14; the microwave signal output end of the microwave source 31 is connected to the radio frequency signal input end of the first electro-optic modulator 4; the radio frequency output end of the arbitrary waveform generator 32 is respectively connected to the radio frequency signal input end of the first acousto-optic modulator 7, the radio frequency signal input end of the second electro-optic modulator 14, the radio frequency signal input end of the second acousto-optic modulator 18 and the trigger signal input end of the data acquisition card 26.

[0011] Furthermore, the first laser 1 is a polarization-maintaining output with a power of 30 mW and a wavelength of 1550.16 nm; the second laser 17 is a polarization-maintaining output, a power and wavelength tunable light source with a power range of 10-30 mW and a wavelength range of 1549.80 nm-1551.80 nm.

[0012] Furthermore, the first fiber coupler 2 is a 1×2 polarization-maintaining coupler with a splitting ratio of 98:2; the second fiber coupler 3, the third fiber coupler 10 and the fourth fiber coupler 17 are 1×2 polarization-maintaining couplers with a splitting ratio of 50:50; the fifth fiber coupler 22, the sixth fiber coupler 23 and the seventh fiber coupler 28 are 2×2 couplers with a splitting ratio of 50:50.

[0013] Furthermore, the first electro-optic modulator 4 is a polarization-maintaining modulator with a bandwidth of 20 GHz and an extinction ratio of 30 dB; the second electro-optic modulator 14 is a polarization-maintaining modulator with a bandwidth of 2 GHz and an extinction ratio of 28 dB; the first acousto-optic modulator 7 and the second acousto-optic modulator 18 are polarization-maintaining modulators with a carrier frequency of 200 MHz and an extinction ratio of 50 dB.

[0014] Furthermore, the fiber Bragg grating 6 is a polarization-maintaining grating with a central wavelength of 1550.08 nm and a 3 dB reflection bandwidth of 0.08 nm.

[0015] Furthermore, the 3 dB operating bandwidth of the first photoelectric balanced detector 24 and the second photoelectric balanced detector 29 is 2 GHz.

[0016] Furthermore, the center frequency of the filter and detector 25 is 300 MHz, and the passband width is 100 MHz.

[0017] Furthermore, the sampling rate of the data acquisition card 26 is 5 GS / s, and the sampling resolution is 14 bits.

[0018] According to another aspect of the present invention, a working method of a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR is proposed, and the working method is implemented based on the multi-parameter sensing system described above; the working method comprises:

[0019] The single-wavelength continuous optical signal output by the first laser 1 is divided into an upper branch and a lower branch through the first optical fiber coupler 2. The lower branch is used as the reference light of the TGD-OFDR system. The upper branch separated by the first optical fiber coupler 2 is further divided into an upper branch and a lower branch through the second optical fiber coupler 3.

[0020] The upper branch separated by the second optical fiber coupler 3 is used as the pump light of the OCC-BOTDR system. The microwave signal output by the microwave source 31 is loaded on the first electro-optic modulator 4 to realize double-sideband modulation. The carrier frequency of the double-sideband continuous light is suppressed by the DC power supply 30 and then injected into the first optical fiber circulator 5, and then enters the fiber Bragg grating 6 to filter out the upper sideband. The retained up-shifted continuous light is injected into the first acousto-optic modulator 7 to be periodically modulated into a pump pulse light, and the peak power is amplified by the first erbium-doped fiber amplifier 8, and the polarization state is disrupted by the random polarization scrambler 9 and then injected into the third optical fiber coupler 10;

[0021] The lower branch separated by the second optical fiber coupler 3 is modulated into an optical chirp chain by the second electro-optic modulator 14 controlled by the chirp RF signal periodically output by the arbitrary waveform generator 32, and the carrier light is suppressed by the DC power supply 30 and then injected into the third optical fiber circulator 15, and then injected into the second laser 16 to achieve injection locking, amplify the lower sideband light while filtering out the upper sideband light, and then pass through the third optical fiber circulator 15 and be divided into upper and lower parts by the fourth optical fiber coupler 17, which are used as the detection light of the TGD-OFDR system and the reference light of the OCC-BOTDR system respectively;

[0022] The upper part separated by the fourth optical fiber coupler 17 is modulated into a chirped pulse light by the second acousto-optic modulator 18, and the peak power is increased by the second erbium-doped fiber amplifier 19 and then injected into the third optical fiber coupler 10 through the delay fiber 20; the pump pulse light and the chirped pulse light output by the third optical fiber coupler 10 are injected into the second optical fiber circulator 11, and then injected into the sensing optical fiber, the piezoelectric ceramic tube 12 and the heating vessel 13 in sequence; the backward spontaneous Brillouin scattered light signal and the backward Rayleigh scattered light generated in the sensing optical fiber are injected into the third erbium-doped fiber amplifier 21 through the second optical fiber circulator 11, and the scattered light is output through the fifth optical fiber coupler 22 after the power is increased;

[0023] The lower part of the OCC-BOTDR system reference light separated by the fourth optical fiber coupler 17 and the scattered light output by the fifth optical fiber coupler 22 are coherently beat through the sixth optical fiber coupler 23, and the beat signal is photoelectrically converted by the first photoelectric balance detector 24, and the photocurrent signal is band-pass filtered and envelope extracted by the filter and detector 25, and finally recorded by the data acquisition card 26, so as to realize the OCC-BOTDR system for detecting the temperature and strain information of the environment along the sensing optical fiber.

[0024] The reference light of the downlink TGD-OFDR system separated by the first optical fiber coupler 2 is coherently beat with the scattered light output by the fifth optical fiber coupler 22 through the seventh optical fiber coupler 28 after the polarization state is adjusted by the polarization controller 27. The beat signal is photoelectrically converted by the second photoelectric balance detector 29, and the photocurrent signal is recorded by the data acquisition card 26 to realize the TGD-OFDR system for detecting the vibration information of the environment along the sensing optical fiber.

[0025] Furthermore, the microwave signal output by the microwave source 31 is loaded on the first electro-optic modulator 4 to implement double-sideband modulation, and the continuous light is expressed as:

[0026]

[0027] In the formula, f c , A c and are the light wave frequency, amplitude and initial phase of the first laser 1 respectively; A m and f m is the amplitude and frequency of the modulation signal output by the microwave source 31; t is time;

[0028] The retained up-shifted continuous light injected into the first acousto-optic modulator 7 is periodically modulated into the electric field intensity of the pump pulse light, which is expressed as:

[0029]

[0030] Where A1 represents the pump pulse light e p (t) is the amplitude; Δf1 is the carrier frequency of the first acousto-optic modulator 7; T p1 is the width of the pump pulse light; rect(.) is the rectangular function.

[0031] Furthermore, the electric field intensity of the lower branch separated by the second optical fiber coupler 3 and modulated into an optical chirp chain by the second electro-optic modulator 14 controlled by the arbitrary waveform generator 32 which periodically outputs the chirp RF signal is expressed as:

[0032]

[0033] In the formula, Am1 , f1, Δf a and T are respectively the amplitude, starting frequency, bandwidth and chirp period of the chirp RF signal output by the arbitrary waveform generator 32;

[0034] The electric field intensity of the optical chirp chain output after the carrier light is suppressed by the DC power supply 30 and then injected into the third optical fiber circulator 15 and then injected into the second laser 16 to achieve injection locking is expressed as:

[0035]

[0036] In the formula, A m2 for e occ (t) amplitude;

[0037] The electric field intensity of the upper part separated by the fourth optical fiber coupler 17 and modulated into the chirped pulse light by the second acousto-optic modulator 18 is expressed as:

[0038]

[0039] In the formula, A m3 For E chip (t); Δf2 is the carrier frequency of the second acousto-optic modulator (18); T p2 is the width of the chirped pulse light.

[0040] Furthermore, the starting frequency f of the chirped pulse light of the TGD-OFDR system is c +f1+Δf2 and the frequency f of the pump pulse light of the OCC-BOTDR system c +f m +Δf1 satisfies the following relationship:

[0041] f c +f1+Δf2>f c +f m +Δf1-f B

[0042] In the formula, f B is the Brillouin frequency shift of the sensing fiber.

[0043] Furthermore, the sampling rate S of the data acquisition card 26 satisfies the following relationship:

[0044] S≥2(f1+Δf2+Δf a ).

[0045] The beneficial technical effects of the present invention are:

[0046] The present invention proposes a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR and a working method thereof, which can realize the simultaneous characterization of multiple parameters: integrating the TGD-OFDR / OCC-BOTDR system, realizing the detection of vibration, temperature / strain along the line through a single sensing optical fiber; having the advantages of fast measurement speed: the measurement time of the OCC-BOTDR system is only related to the optical fiber length and the average number of times, compared with the traditional sweep frequency scheme, the measurement time of the present invention is independent of the number of sweep frequencies, and the present invention can effectively improve the system sampling rate when the sensing parameters are the same; and the response speed of the TGD-OFDR system is also only related to the sensing optical fiber length, so the present invention integrates the TGD-OFDR / OCC- The multi-parameter sensing system of BOTDR has the ability of rapid measurement; it has the advantage of high spatial resolution: the TGD-OFDR system uses chirped pulse light for sensing, combined with pulse compression technology, the spatial resolution depends on the chirp frequency bandwidth and has nothing to do with the pulse light width; it has the advantages of high integration and low cost: the chirped pulse light source of the TGD-OFDR system is based on the secondary modulation of the reference light beam of the OCC-BOTDR system, and combined with time division-frequency division multiplexing technology to avoid cross-aliasing and power competition of optical pulses between subsystems; the carefully designed modulation frequency on each branch effectively strips off the Rayleigh scattering signal and the Brillouin scattering signal, realizing a single sensor to simultaneously measure vibration, temperature / strain, with high integration and effective cost control. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, in which:

[0048] Figure 1 A schematic diagram of the structure of a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR according to an embodiment of the present invention;

[0049] Figure 2 A diagram showing a detection pulse model of a TGD-OFDR system and a reference light model of an OCC-BOTDR system in an embodiment of the present invention;

[0050] Figure 3 This is a model diagram of the detection pulse of the TGD-OFDR system and the pump pulse of the OCC-BOTDR system after time-frequency division multiplexing in an embodiment of the present invention;

[0051] Figure 4 This is an example diagram of temperature data along the sensing optical fiber measured by the OCC-BOTDR system in an embodiment of the present invention;

[0052] Figure 5This is an example diagram of vibration data along the sensing optical fiber measured by the TGD-OFDR system in an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The principles and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are provided only to enable those skilled in the art to better understand and implement the present invention, and are not intended to limit the scope of the present invention in any way. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0054] In order to solve the problem that the characterization of the external environment is one-sided due to the single measurement parameter of the distributed optical fiber sensing system with a single scattering mechanism, the present invention proposes a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR and its working method. The OCC-BOTDR (Optical Chirp Chain Brillouin Optical Time-Domain Reflector) system is a Brillouin optical time-domain reflectometry (BOTDR) system based on optical chirp chain (OCC) technology. The TGD-OFDR (Time-gated Digital Optical Frequency Domain Reflectometry system is a time-gated digital optical frequency domain reflectometer. The DOFS system integrating multiple scattering mechanisms can realize the measurement of multiple parameters along the sensing optical fiber. The highly integrated sensing structure can effectively reduce the cost of sensors and can be used more efficiently in the field of industrial monitoring.

[0055] The embodiment of the present invention proposes a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR, such as Figure 1As shown, the multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR includes: a first laser 1, a first fiber coupler 2, a second fiber coupler 3, a first electro-optic modulator 4, a first fiber circulator 5, a fiber Bragg grating 6, a first acousto-optic modulator 7, a first erbium-doped fiber amplifier 8, a random polarization scrambler 9, a third fiber coupler 10, a second fiber circulator 11, a piezoelectric ceramic tube 12, a heating vessel 13, a second electro-optic modulator 14, a third fiber circulator 15, a second laser 16, a fourth fiber coupler 17, a second acousto-optic modulator 18, a second erbium-doped fiber amplifier 19, a delay fiber 20, a third erbium-doped fiber amplifier 21, a fifth fiber coupler 22, a sixth fiber coupler 23, a first photoelectric balanced detector 24, a filter and detector 25, a data acquisition card 26, a polarization controller 27, a seventh fiber coupler 28, a second photoelectric balanced detector 29, a DC power supply 30, a microwave source 31, and an arbitrary waveform generator 32; wherein,

[0056] The optical signal output end of the first laser 1 is connected to the optical signal input end of the first optical fiber coupler 2, the first optical signal output end 2-1 of the first optical fiber coupler 2 is connected to the optical signal input end of the second optical fiber coupler 3, and the second optical signal output end 2-2 of the first optical fiber coupler 2 is connected to the optical signal input end of the polarization controller 27;

[0057] The first optical signal output end 3-1 of the second optical fiber coupler 3 is connected to the optical signal input end of the first electro-optic modulator 4, the optical signal output end of the first electro-optic modulator 4 is connected to the first port 5-1 of the first optical fiber circulator 5, the second port 5-2 of the first optical fiber circulator 5 is connected to the fiber Bragg grating 6, the third port 5-3 of the first optical fiber circulator 5 is connected to the optical signal input end of the first acousto-optic modulator 7, the optical signal output end of the first acousto-optic modulator 7 is connected to the optical signal input end of the first erbium-doped fiber amplifier 8, The optical signal output end of the first erbium-doped fiber amplifier 8 is connected to the optical signal input end of the random polarization scrambler 9, the optical signal output end of the random polarization scrambler 9 is connected to the first optical signal input end 10-1 of the third optical fiber coupler 10, the optical signal output end of the third optical fiber coupler 10 is connected to the first port 11-1 of the second optical fiber circulator 11, the second port 11-2 of the second optical fiber circulator 11 is connected to one end of the sensing optical fiber, the other end of the sensing optical fiber is connected to the piezoelectric ceramic tube 12, and the piezoelectric ceramic tube 12 is connected to the heating vessel 13;

[0058] The second optical signal output end 3-2 of the second optical fiber coupler 3 is connected to the optical signal input end of the second electro-optic modulator 14, the optical signal output end of the second electro-optic modulator 14 is connected to the first port 15-1 of the third optical fiber circulator 15, the second port 15-2 of the third optical fiber circulator 15 is connected to the optical signal output end of the second laser 16, the third port 15-3 of the third optical fiber circulator 15 is connected to the optical signal input end of the fourth optical fiber coupler 17, the first optical signal output end 17-1 of the fourth optical fiber coupler 17 is connected to the optical signal input end of the second acousto-optic modulator 18, the optical signal output end of the second acousto-optic modulator 18 is connected to the optical signal input end of the second erbium-doped fiber amplifier 19, the optical signal output end of the second erbium-doped fiber amplifier 19 is connected to one end of the delay optical fiber 20, and the other end of the delay optical fiber 20 is connected to the second optical signal input end 10-2 of the third optical fiber coupler 10;

[0059] The third port 11-3 of the second optical fiber circulator 11 is connected to the optical signal input end of the third erbium-doped fiber amplifier 21, the optical signal output end of the third erbium-doped fiber amplifier 21 is connected to the optical signal input end of the fifth optical fiber coupler 22, the second optical signal output end 17-2 of the fourth optical fiber coupler 17 and the first optical signal output end 22-1 of the fifth optical fiber coupler 22 are respectively connected to the first optical signal input end 23-1 and the second optical signal input end 23-2 of the sixth optical fiber coupler 23, the optical signal output end of the sixth optical fiber coupler 23 is connected to the optical signal input end of the first photoelectric balanced detector 24, the electrical signal output end of the first photoelectric balanced detector 24 is connected to the electrical signal input end of the filter and detector 25, and the electrical signal output end of the filter and detector 25 is connected to the electrical signal input end of the data acquisition card 26;

[0060] The second optical signal output end 22-2 of the fifth optical fiber coupler 22 and the optical signal output end of the polarization controller 27 are respectively connected to the first optical signal input end 28-1 and the second optical signal input end 28-2 of the seventh optical fiber coupler 28, the optical signal output end of the seventh optical fiber coupler 28 is connected to the optical signal input end of the second photoelectric balance detector 29, and the electrical signal output end of the second photoelectric balance detector 29 is connected to the electrical signal input end of the data acquisition card 26;

[0061] The output end of the DC power supply 30 is respectively connected to the bias voltage input end of the first electro-optic modulator 4 and the bias voltage input end of the second electro-optic modulator 14; the microwave signal output end of the microwave source 31 is connected to the radio frequency signal input end of the first electro-optic modulator 4; the radio frequency output end of the arbitrary waveform generator 32 is respectively connected to the radio frequency signal input end of the first acousto-optic modulator 7, the radio frequency signal input end of the second electro-optic modulator 14, the radio frequency signal input end of the second acousto-optic modulator 18 and the trigger signal input end of the data acquisition card 26.

[0062] In this embodiment, preferably, the first laser 1 is a polarization-maintaining output with a power of 30 mW and a wavelength of 1550.16 nm; the second laser 17 is a polarization-maintaining output, a power and wavelength tunable light source with a power range of 10-30 mW and a wavelength range of 1549.80 nm-1551.80 nm.

[0063] In this embodiment, preferably, the first fiber coupler 2 is a 1×2 polarization-maintaining coupler with a splitting ratio of 98:2; the second fiber coupler 3, the third fiber coupler 10 and the fourth fiber coupler 17 are 1×2 polarization-maintaining couplers with a splitting ratio of 50:50; the fifth fiber coupler 22, the sixth fiber coupler 23 and the seventh fiber coupler 28 are 2×2 couplers with a splitting ratio of 50:50.

[0064] In this embodiment, preferably, the first electro-optic modulator 4 is a polarization-maintaining modulator with a bandwidth of 20 GHz and an extinction ratio of 30 dB; the second electro-optic modulator 14 is a polarization-maintaining modulator with a bandwidth of 2 GHz and an extinction ratio of 28 dB; the first acousto-optic modulator 7 and the second acousto-optic modulator 18 are polarization-maintaining modulators, both of which have a carrier frequency of 200 MHz and an extinction ratio of 50 dB.

[0065] In this embodiment, preferably, the fiber Bragg grating 6 is a polarization-maintaining grating with a central wavelength of 1550.08 nm and a 3dB reflection bandwidth of 0.08 nm.

[0066] In this embodiment, preferably, the 3 dB operating bandwidth of the first photoelectric balanced detector 24 and the second photoelectric balanced detector 29 is 2 GHz.

[0067] In this embodiment, preferably, the center frequency of the filter and detector 25 is 300 MHz, and the passband width is 100 MHz.

[0068] In this embodiment, preferably, the sampling rate of the data acquisition card 26 is 5 GS / s, and the sampling resolution is 14 bits.

[0069] Another embodiment of the present invention provides a working method of a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR, and the working method is implemented based on the multi-parameter sensing system described above; the working method includes:

[0070] The single-wavelength continuous optical signal output by the first laser 1 is divided into an upper branch and a lower branch through the first output terminal 2-1 and the second output terminal 2-2 of the first optical fiber coupler 2. The lower branch is used as the reference light of the TGD-OFDR system. The upper branch separated by the first optical fiber coupler 2 is further divided into an upper branch and a lower branch through the first output terminal 3-1 and the second output terminal 3-2 of the second optical fiber coupler 3.

[0071] The upper branch separated by the second optical fiber coupler 3 is used as the pump light of the OCC-BOTDR system. The microwave source 31 outputs a 10.8 GHz microwave signal which is loaded on the first electro-optic modulator 4 to realize double-sideband modulation. The DC power supply 30 suppresses the carrier frequency of the double-sideband continuous light and then injects it into the first port 5-1 of the first optical fiber circulator 5. The upper sideband is filtered out by the fiber Bragg grating 6 through the second port 5-2 of the first optical fiber circulator 5. The retained up-shifted continuous light is injected into the first acousto-optic modulator 7 through the third port 5-3 of the first optical fiber circulator 5 to be periodically modulated into the pump pulse light. The peak power is amplified by the first erbium-doped fiber amplifier 8. The polarization state is disrupted by the random polarization scrambler 9 and then injected into the first input port 10-1 of the third optical fiber coupler 10.

[0072] The lower branch separated by the second optical fiber coupler 3 is modulated into an optical chirp chain by the second electro-optic modulator 14 controlled by the chirp RF signal periodically output by the arbitrary waveform generator 32, and the carrier light is suppressed by the DC power supply 30 and then injected into the first port 15-1 of the third optical fiber circulator 15, and then injected into the second laser 16 through the second port 15-2 of the third optical fiber circulator 15 to achieve injection locking, and the lower sideband light is amplified while the upper sideband light is filtered out, and then the third port 15-3 of the third optical fiber circulator 15 is divided into upper and lower parts by the first output port 17-1 and the second output port 17-2 of the fourth optical fiber coupler 17, which are used as the detection light of the TGD-OFDR system and the reference light of the OCC-BOTDR system respectively;

[0073] The upper part separated by the fourth optical fiber coupler 17 is modulated into a chirped pulse light by the second acousto-optic modulator 18, and the peak power is increased by the second erbium-doped fiber amplifier 19, and then injected into the second input end 10-2 of the third optical fiber coupler 10 through the delay fiber 20. The pump pulse light and the chirped pulse light output by the third optical fiber coupler 10 are injected into the first port 11-1 and the second port 11-2 of the second optical fiber circulator 11, and are injected into the sensing optical fiber, the piezoelectric ceramic tube 12 and the heating vessel 13 in sequence; the back-directed spontaneous Brillouin scattered light signal and the back-directed Rayleigh scattered light generated in the sensing optical fiber are injected into the third port 11-1 and the second port 11-2 of the second optical fiber circulator 11. -3 is injected into the third erbium-doped fiber amplifier 21, and the scattered light outputted from the first output port 22-1 of the fifth fiber coupler 22 after power boosting is coherently beat with the OCC-BOTDR system reference light outputted from the second output port 17-2 of the fourth fiber coupler 17 through the sixth fiber coupler 23, and the beat signal is photoelectrically converted by the first photoelectric balanced detector 24, and the photocurrent signal is band-pass filtered and envelope extracted by the filter and detector 25, and finally recorded by the data acquisition card 26, so as to realize the OCC-BOTDR system for detecting the temperature and strain information of the environment along the sensing optical fiber;

[0074] The reference light of the downlink TGD-OFDR system outputted from the second output port 2-2 of the first optical fiber coupler 2 is coherently beat with the scattered light outputted from the second output port 22-2 of the fifth optical fiber coupler 22 through the seventh optical fiber coupler 28 after the polarization state is adjusted by the polarization controller 27. The beat signal is photoelectrically converted by the second photoelectric balanced detector 29, and the photocurrent signal is recorded by the data acquisition card 26, so as to realize the TGD-OFDR system for detecting the vibration information of the environment along the sensing optical fiber.

[0075] The rapid measurement and characterization of external environmental vibration, temperature / strain along the sensing optical fiber can be simultaneously achieved in a single sensing optical fiber. Multi-parameter measurement brings more valuable information for the effective identification of fault events. Figure 2 The detection pulse model of the TGD-OFDR system and the reference light model of the OCC-BOTDR system in the system. It can be seen that the detection pulse of the TGD-OFDR system is a linear frequency-sweep chirp; the reference light of the OCC-BOTDR system is a chirp chain; Figure 3 The detection pulse model of the TGD-OFDR system and the pump pulse model of the OCC-BOTDR system after time-frequency division multiplexing; Figure 4 The temperature information along the sensing optical fiber measured by the OCC-BOTDR system shows obvious temperature changes at the 40.4km position; Figure 5 The vibration information along the sensing optical fiber measured by the TGD-OFDR system in the multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR described in the present invention has an obvious continuous vibration signal at the 40.4km position.

[0076] In this embodiment, preferably, the process of modulating the first electro-optic modulator 4 and the first acousto-optic modulator 7 to generate the pump pulse light of the OCC-BOTDR system is as follows:

[0077] First, define f c , A c and are the frequency, amplitude and initial phase of the light wave of the first laser source 1 respectively; the electric field intensity of the light wave is:

[0078]

[0079] Definition A m and f m is the amplitude and frequency of the modulation signal output by the microwave source 31, and the modulation signal is:

[0080]

[0081] When the modulation signal m(t) is loaded on the first electro-optic modulator 4, the continuous light e(t) output by the first laser source 1 is modulated as follows:

[0082]

[0083] The DC power supply 30 and the fiber Bragg grating 6 suppress the carrier component of the continuous light e(t) and filter out the low-frequency component of the down-shifted frequency. The retained up-shifted continuous light is modulated again by the first acousto-optic modulator 7 into the pump pulse light of the OCC-BOTDR system. The electric field intensity is expressed as follows:

[0084]

[0085] Among them, A1 is the pump pulse light e p (t) is the amplitude; Δf1 is the carrier frequency of the first acousto-optic modulator 7; T p1 is the width of the pump pulse light; rect(.) is the rectangular function.

[0086] In this embodiment, preferably, the second electro-optic modulator 14 continuously modulates the optical chirp chain, and the fourth fiber coupler 17 splits the beams, one of which is used as the reference light of the OCC-BOTDR system; the other beam is modulated again by the second acousto-optic modulator 18 into the chirped pulse light of the TGD-OFDR system. The process is as follows:

[0087] First, define A m1 , f1, Δf a and T are respectively the amplitude, starting frequency, bandwidth and chirp period of the chirp RF signal output by the arbitrary waveform generator 32; the electric field strength is:

[0088]

[0089] When the chirped RF signal S(t) is loaded on the second electro-optical modulator 14, the electric field expression of the modulated continuous light is:

[0090]

[0091] The continuous light is suppressed by the DC power supply 30 chip After the carrier component of (t), it is expressed as:

[0092]

[0093] e chip (t) After the injection locking is achieved by injecting the second laser 16 through the third fiber circulator 15, the high frequency component is amplified and the low frequency component is filtered out. The expression of the realized optical chirp chain is:

[0094]

[0095] Among them, A m2 for e occ f1 is less than or equal to the carrier frequency Δf1 of the first AOM 7.occ (t) After being split by the fourth optical fiber coupler 17, one beam is used as the reference light of the OCC-BOTDR system; the other beam is modulated by the second acousto-optic modulator 18 into the chirped pulse light of the TGD-OFDR system, and its electric field expression is:

[0096]

[0097] Among them, A m3 For E chip (t) is the amplitude; Δf2 is the carrier frequency of the second AOM 18; T p2 is the width of the chirped pulse light.

[0098] Assume the Brillouin frequency shift of the sensing fiber is f B , the starting frequency f of the chirped pulse light of the TGD-OFDR system c +f1+Δf2 and the frequency f of the pump pulse light of the OCC-BOTDR system c +f m +Δf1 should satisfy the following relationship:

[0099]

[0100] Furthermore, the 3 dB working bandwidth of the first photoelectric balanced detector 25 and the second photoelectric balanced detector 30 should be greater than or equal to f m +Δf1-f B and f1+Δf2+Δf a .

[0101] The sampling rate S of the data acquisition card 27 should satisfy the following relationship:

[0102] S≥2(f1+Δf2+Δf a ) (11)

[0103] The present invention proposes a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR and a working method thereof, 1) can realize simultaneous characterization of multiple parameters: integrating TGD-OFDR / OCC-BOTDR system, realizing the detection of vibration, temperature / strain along the line through a single sensing optical fiber; 2) having the advantage of fast measurement speed: the measurement time of the OCC-BOTDR system is only related to the optical fiber length and the average number of times, compared with the traditional frequency sweeping scheme, the measurement time of the present invention is not related to the number of frequency sweeping, and the present invention can effectively improve the system sampling rate under the same sensing parameters; and the response speed of the TGD-OFDR system is also only related to the sensing optical fiber length; so the present invention integrates TGD-OFDR / OCC- The multi-parameter sensing system of BOTDR has the ability of rapid measurement; 3) It has the advantage of high spatial resolution: the TGD-OFDR system uses chirped pulse light for sensing, combined with pulse compression technology. The spatial resolution depends on the chirp frequency bandwidth and is independent of the pulse light width; 4) It has the advantages of high integration and low cost: the chirped pulse light source of the TGD-OFDR system is based on the secondary modulation of the reference light beam of the OCC-BOTDR system, and combined with time division-frequency division multiplexing technology to avoid cross-aliasing and power competition of optical pulses between subsystems; the carefully designed modulation frequency on each branch effectively strips off the Rayleigh scattering signal and the Brillouin scattering signal, realizing a single sensor to simultaneously measure vibration, temperature / strain, with high integration and effective cost control.

[0104] Although the spirit and principle of the present invention have been described with reference to several specific embodiments, it should be understood that the present invention is not limited to the disclosed specific embodiments, and the division of various aspects does not mean that the features in these aspects cannot be combined to benefit, and such division is only for the convenience of expression. The present invention is intended to cover various modifications and equivalent arrangements included in the spirit and scope of the attached claims.

Claims

1. A multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR, characterized in that: include: A first laser (1), a first optical fiber coupler (2), a second optical fiber coupler (3), a first electro-optic modulator (4), a first optical fiber circulator (5), an optical fiber Bragg grating (6), a first acousto-optic modulator (7), a first erbium-doped optical fiber amplifier (8), a random polarization scrambler (9), a third optical fiber coupler (10), a second optical fiber circulator (11), a piezoelectric ceramic tube (12), a heating vessel (13), a second electro-optic modulator (14), a third optical fiber circulator (15), a second laser (16), and a fourth optical fiber coupler. (17), a second acousto-optic modulator (18), a second erbium-doped fiber amplifier (19), a time-delay fiber (20), a third erbium-doped fiber amplifier (21), a fifth fiber coupler (22), a sixth fiber coupler (23), a first photoelectric balanced detector (24), a filter and detector (25), a data acquisition card (26), a polarization controller (27), a seventh fiber coupler (28), a second photoelectric balanced detector (29), a DC power supply (30), a microwave source (31), and an arbitrary waveform generator (32); wherein, The optical signal output end of the first laser (1) is connected to the optical signal input end of the first optical fiber coupler (2), the first optical signal output end (2-1) of the first optical fiber coupler (2) is connected to the optical signal input end of the second optical fiber coupler (3), and the second optical signal output end (2-2) of the first optical fiber coupler (2) is connected to the optical signal input end of the polarization controller (27); The first optical signal output end (3-1) of the second optical fiber coupler (3) is connected to the optical signal input end of the first electro-optic modulator (4), the optical signal output end of the first electro-optic modulator (4) is connected to the first port (5-1) of the first optical fiber circulator (5), the second port (5-2) of the first optical fiber circulator (5) is connected to the optical fiber Bragg grating (6), the third port (5-3) of the first optical fiber circulator (5) is connected to the optical signal input end of the first acousto-optic modulator (7), and the optical signal output end of the first acousto-optic modulator (7) is connected to the optical signal input end of the first erbium-doped optical fiber amplifier (8). The optical signal output end of the first erbium-doped fiber amplifier (8) is connected to the optical signal input end of the random polarization scrambler (9), the optical signal output end of the random polarization scrambler (9) is connected to the first optical signal input end (10-1) of the third optical fiber coupler (10), the optical signal output end of the third optical fiber coupler (10) is connected to the first port (11-1) of the second optical fiber circulator (11), the second port (11-2) of the second optical fiber circulator (11) is connected to one end of the sensing optical fiber, the other end of the sensing optical fiber is connected to the piezoelectric ceramic tube (12), and the piezoelectric ceramic tube (12) is connected to the heating vessel (13); The second optical signal output end (3-2) of the second optical fiber coupler (3) is connected to the optical signal input end of the second electro-optical modulator (14), the optical signal output end of the second electro-optical modulator (14) is connected to the first port (15-1) of the third optical fiber circulator (15), the second port (15-2) of the third optical fiber circulator (15) is connected to the optical signal output end of the second laser (16), the third port (15-3) of the third optical fiber circulator (15) is connected to the optical signal output end of the fourth optical fiber coupler (17), and the optical signal output end of the second optical fiber coupler (17) is connected to the optical signal output end of the second laser (16). The first optical signal output end (17-1) of the fourth optical fiber coupler (17) is connected to the optical signal input end of the second acousto-optic modulator (18), the optical signal output end of the second acousto-optic modulator (18) is connected to the optical signal input end of the second erbium-doped fiber amplifier (19), the optical signal output end of the second erbium-doped fiber amplifier (19) is connected to one end of the delay optical fiber (20), and the other end of the delay optical fiber (20) is connected to the second optical signal input end (10-2) of the third optical fiber coupler (10); The third port (11-3) of the second optical fiber circulator (11) is connected to the optical signal input end of the third erbium-doped optical fiber amplifier (21), the optical signal output end of the third erbium-doped optical fiber amplifier (21) is connected to the optical signal input end of the fifth optical fiber coupler (22), the second optical signal output end (17-2) of the fourth optical fiber coupler (17) and the first optical signal output end (22-1) of the fifth optical fiber coupler (22) are respectively connected to the first optical signal input end (23-1) and the second optical signal input end (23-2) of the sixth optical fiber coupler (23), the optical signal output end of the sixth optical fiber coupler (23) is connected to the optical signal input end of the first photoelectric balanced detector (24), the electrical signal output end of the first photoelectric balanced detector (24) is connected to the electrical signal input end of the filter and detector (25), and the electrical signal output end of the filter and detector (25) is connected to the electrical signal input end of the data acquisition card (26); The second optical signal output end (22-2) of the fifth optical fiber coupler (22) and the optical signal output end of the polarization controller (27) are respectively connected to the first optical signal input end (28-1) and the second optical signal input end (28-2) of the seventh optical fiber coupler (28); the optical signal output end of the seventh optical fiber coupler (28) is connected to the optical signal input end of the second photoelectric balance detector (29); and the electrical signal output end of the second photoelectric balance detector (29) is connected to the electrical signal input end of the data acquisition card (26); The output end of the direct current power supply (30) is respectively connected to the bias voltage input end of the first electro-optic modulator (4) and the bias voltage input end of the second electro-optic modulator (14); the microwave signal output end of the microwave source (31) is connected to the radio frequency signal input end of the first electro-optic modulator (4); and the radio frequency output end of the arbitrary waveform generator (32) is respectively connected to the radio frequency signal input end of the first acousto-optic modulator (7), the radio frequency signal input end of the second electro-optic modulator (14), the radio frequency signal input end of the second acousto-optic modulator (18), and the trigger signal input end of the data acquisition card (26).

2. A multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR according to claim 1, characterized in that: The first laser (1) is a polarization-maintaining output laser with a power of 30 mW and a wavelength of 1550.16 nm; the second laser (16) is a polarization-maintaining output laser with a power and wavelength tunable light source with a power range of 10-30 mW and a wavelength range of 1549.80 nm-1551.80 nm.

3. A multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR according to claim 1, characterized in that: The first optical fiber coupler (2) is a 1×2 polarization-maintaining coupler with a splitting ratio of 98:2; the second optical fiber coupler (3), the third optical fiber coupler (10) and the fourth optical fiber coupler (17) are all 1×2 polarization-maintaining couplers with a splitting ratio of 50:50; the fifth optical fiber coupler (22), the sixth optical fiber coupler (23) and the seventh optical fiber coupler (28) are all 2×2 couplers with a splitting ratio of 50:

50.

4. A multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR according to claim 1, characterized in that: The first electro-optic modulator (4) is a polarization-maintaining modulator with a bandwidth of 20 GHz and an extinction ratio of 30 dB; the second electro-optic modulator (14) is a polarization-maintaining modulator with a bandwidth of 2 GHz and an extinction ratio of 28 dB; the first acousto-optic modulator (7) and the second acousto-optic modulator (18) are polarization-maintaining modulators with a carrier frequency of 200 MHz and an extinction ratio of 50 dB.

5. The multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR according to claim 1, characterized in that: The fiber Bragg grating (6) is a polarization-maintaining grating, with a central wavelength of 1550.08 nm and a 3dB reflection bandwidth of 0.08 nm; the 3dB working bandwidths of the first photoelectric balanced detector (24) and the second photoelectric balanced detector (29) are both 2 GHz; the central frequency of the filter and detector (25) is 300 MHz, and the passband width is 100 MHz; the sampling rate of the data acquisition card (26) is 5 GS / s, and the sampling resolution is 14 bits.

6. A working method of a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR, characterized in that: The working method is implemented based on the multi-parameter sensing system described in any one of claims 1 to 5; the working method comprises: The single-wavelength continuous optical signal output by the first laser (1) is divided into an upper branch and a lower branch via a first optical fiber coupler (2), the lower branch being used as the reference light of the TGD-OFDR system, and the upper branch separated by the first optical fiber coupler (2) is further divided into an upper branch and a lower branch via a second optical fiber coupler (3); wherein, The upper branch separated by the second optical fiber coupler (3) is used as the pump light of the OCC-BOTDR system. The microwave signal output by the microwave source (31) is loaded on the first electro-optic modulator (4) to realize double-sideband modulation. The carrier frequency of the double-sideband continuous light is suppressed by the direct current power supply (30) and then injected into the first optical fiber circulator (5). Then, the double-sideband continuous light enters the optical fiber Bragg grating (6) to filter out the upper sideband. The retained up-shifted continuous light is injected into the first acousto-optic modulator (7) to be periodically modulated into pump pulse light. The peak power is amplified by the first erbium-doped optical fiber amplifier (8). After the polarization state is disrupted by the random polarization scrambler (9), the light is injected into the third optical fiber coupler (10). The lower branch separated by the second optical fiber coupler (3) is modulated into an optical chirp chain by the second electro-optic modulator (14) controlled by the periodic chirp radio frequency signal output by the arbitrary waveform generator (32), and the carrier light is suppressed by the direct current power supply (30) and then injected into the third optical fiber circulator (15), and then injected into the second laser (16) to achieve injection locking, amplifying the lower sideband light while filtering out the upper sideband light, and then passing through the third optical fiber circulator (15) and being divided into upper and lower parts by the fourth optical fiber coupler (17), which are respectively used as the detection light of the TGD-OFDR system and the reference light of the OCC-BOTDR system; The upper part separated by the fourth optical fiber coupler (17) is modulated into a chirped pulse light by a second acousto-optic modulator (18), and the peak power is increased by a second erbium-doped optical fiber amplifier (19), and then injected into the third optical fiber coupler (10) through a delay optical fiber (20); the pump pulse light and the chirped pulse light output by the third optical fiber coupler (10) are injected into the second optical fiber circulator (11), and then injected into the sensing optical fiber, the piezoelectric ceramic tube (12) and the heating vessel (13) in sequence; the backward spontaneous Brillouin scattered light signal and the backward Rayleigh scattered light generated in the sensing optical fiber are then injected into the third erbium-doped optical fiber amplifier (21) through the second optical fiber circulator (11), and the scattered light is output through a fifth optical fiber coupler (22) after the power is increased; The lower part of the OCC-BOTDR system reference light separated by the fourth optical fiber coupler (17) and the scattered light output by the fifth optical fiber coupler (22) are coherently beat through the sixth optical fiber coupler (23), the beat signal is photoelectrically converted by the first photoelectric balance detector (24), the photocurrent signal is band-pass filtered and envelope extracted by the filter and detector (25), and finally recorded by the data acquisition card (26), so as to realize the OCC-BOTDR system for detecting the temperature and strain information of the environment along the sensing optical fiber; The reference light of the downlink TGD-OFDR system separated by the first optical fiber coupler (2) is subjected to coherent beat frequency with the scattered light output by the fifth optical fiber coupler (22) after the polarization state is adjusted by the polarization controller (27) through the seventh optical fiber coupler (28); the beat frequency signal is subjected to photoelectric conversion by the second photoelectric balance detector (29); the photocurrent signal is recorded by the data acquisition card (26), and the TGD-OFDR system is realized for detecting vibration information of the environment along the sensing optical fiber.

7. The working method of a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR according to claim 6, characterized in that: The microwave signal output by the microwave source (31) is loaded on the first electro-optical modulator (4) to achieve double-sideband modulation, and the continuous light is expressed as: In the formula, f c , A c and are the frequency, amplitude and initial phase of the light wave of the first laser (1); A m and f m are the amplitude and frequency of the modulation signal output by the microwave source (31); t is time; The retained up-shifted continuous light is injected into the first acousto-optic modulator (7) and is periodically modulated into the electric field intensity of the pump pulse light, which is expressed as: Where A1 represents the pump pulse light e p (t); Δf1 is the carrier frequency of the first acousto-optic modulator (7); T p1 is the width of the pump pulse light; rect(.) is the rectangular function.

8. The working method of a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR according to claim 7, characterized in that: The electric field intensity of the lower branch separated by the second optical fiber coupler (3) and modulated into an optical chirp chain by the second electro-optic modulator (14) controlled by the arbitrary waveform generator (32) to periodically output a chirp radio frequency signal is expressed as: In the formula, A m1 , f1, Δf a and T are respectively the amplitude, starting frequency, bandwidth and chirp period of the chirp radio frequency signal output by the arbitrary waveform generator (32); The electric field intensity of the optical chirp chain output after the carrier frequency light is suppressed by the DC power supply (30) and then injected into the third optical fiber circulator (15), and then injected into the second laser (16) to achieve injection locking is expressed as: In the formula, A m2 for e occ (t) amplitude; The electric field intensity of the upper part separated by the fourth optical fiber coupler (17) and modulated into chirped pulse light by the second acousto-optic modulator (18) is expressed as: In the formula, A m3 For E chip (t); Δf2 is the carrier frequency of the second acousto-optic modulator (18); T p2 is the width of the chirped pulse light.

9. The working method of a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR according to claim 8, characterized in that: The starting frequency f of the chirped pulse light of the TGD-OFDR system c +f1+Δf2 and the frequency f of the pump pulse light of the OCC-BOTDR system c +f m +Δf1 satisfies the following relationship: f c +f1+Δf2>f c +f m +Δf1-f B In the formula, f B is the Brillouin frequency shift of the sensing fiber.

10. The working method of a multi-parameter sensing system integrating TGD-OFDR / OCC-BOTDR according to claim 9, characterized in that: The sampling rate S of the data acquisition card (26) satisfies the following relationship: S≥2(f1+Δf2+Δf a )。

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