CN108827175B - Distributed optical fiber dynamic strain sensing device and method based on broadband chaotic laser - Google Patents
Distributed optical fiber dynamic strain sensing device and method based on broadband chaotic laser Download PDFInfo
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Abstract
The invention discloses a distributed optical fiber dynamic strain sensing device based on broadband chaotic laser, which comprises a broadband chaotic laser source (1), a 1 x 2 optical fiber coupler (2), a first polarization controller (3), a high-speed electro-optic modulator (4), a programmable optical delay generator (5), a first optical amplifier (6), an optical polarization scrambler (7), an optical isolator (8), a sensing optical fiber (9), an optical circulator (10), a second optical amplifier (11), a semiconductor optical amplifier (12), a second polarization controller (13), a pulse signal generator (14), a broadband microwave signal source (15), a high-speed data acquisition and analysis system (16), a photoelectric detector (17) and a tunable optical filter (18). The invention utilizes the pulse signal generator to generate high-speed pulse signals, realizes the synchronous control of the broadband microwave signal source, the semiconductor optical amplifier and the high-speed data acquisition and analysis system, and ensures the accuracy and the real-time performance of the measurement of the sensing system.
Description
Technical Field
The invention relates to a distributed optical fiber sensing system, in particular to a distributed optical fiber dynamic strain sensing device and method based on broadband chaotic laser.
Background
The distributed optical fiber sensing is realized by taking optical fibers as sensing elements and transmission elements and can realize continuous distributed measurement of physical parameters such as temperature, strain and the like at different positions of the whole optical fiber. The distributed optical fiber sensing technology has been widely applied to various fields of petrochemical engineering, civil engineering, electrical transmission, aerospace, transportation and the like as an important part of a health and safety monitoring network of a large building structure, and real-time and high-precision monitoring of multiple parameters such as temperature, vibration, strain and the like becomes a great research hotspot.
At present, a distributed optical fiber sensing system based on brillouin scattering has been the research focus in the field of distributed optical fiber sensing because of the simultaneous measurement of temperature and strain, and the advantages in the aspects of measurement accuracy, measurement distance, spatial resolution, and the like. The large engineering health monitoring puts forward the requirements of long distance, high resolution, large dynamic range and real-time rapidness to strain measurement, and under the prior art condition, the research of the distributed optical fiber dynamic strain monitoring field aiming at the strain measurement range and the monitoring instantaneity has been developed primarily. Yair Peled et al, university of Telaviv, Israel, proposed a slope-assisted Brillouin optical time domain analysis technique (SA-BOTDA) to finally achieve 100Hz dynamic strain measurements on 20m long fibers with a spatial resolution of 1m (Optics Express, 2013, 21(9): 10697-. In order to expand the sensing distance, the Dougong professor group of Harbin university of industry realizes the rapid measurement of strain of tens of hertz in the short-distance polarization-maintaining optical fiber by utilizing a plurality of technologies such as differential double pulse and second-order sideband modulation (IEEE Photonics Journal, 2013, 5(3): 2600407), multiple slope assistance (Optics Express, 2016, 24(9): 9781-. Meanwhile, Spanish Navala university A, Loaysas and the like use multi-frequency pumping pulses to adjust a Brillouin gain spectral region (IEEE Photonics Journal, 2017, 9(3): 6802710), so that the dynamic range of strain measurement is expanded; the Brillouin gain is fused with the Brillouin phase by Shanghai traffic university Hozu et al, and a new parameter Brillouin phase-gain ratio is used for representing and realizing the expansion of the dynamic range (Journal of Lightwave Technology,2017, 35(20): 4451-. The technology adopts a Brillouin optical time domain analysis system, the system takes pulse signals as pump signals to realize positioning and sensing along the optical fiber, the advantage is that the measurement distance is longer, but the measurement distance is limited by the service life of phonons, the spatial resolution of the system is lower, the maximum resolution is only sub-meter level, and the dynamic strain measurement which can not realize both long distance and high resolution can not be realized.
Compared with a time domain system, the Brillouin optical coherent domain system injects probe light and pump light which are modulated by coherent frequencies into the sensing optical fiber in opposite directions from two ends of the optical fiber to generate a nonlinear stimulated Brillouin scattering effect, and distributed measurement of the sensing optical fiber can be realized by solving a coherent function of the probe light and the pump light. In the field of distributed dynamic strain measurement, K.hotate et al of Tokyo university of Japan utilizes a differential frequency modulation Brillouin optical coherence domain analysis system (DFM-BOCDA) to realize the measurement of 20Hz dynamic strain of a 100m ordinary single-mode optical fiber (Optics Letters, 2011, 36(11): 2062-. Further, Nakamura et al, Tokyo university of Japan, propose a slope-assisted Brillouin optical coherence domain reflectometry (SA-BOCDR) and achieve short-distance highly sensitive dynamic strain measurement in a high-loss plastic optical fiber (Journal of Lightwave Technology,2017, 35(11): 2304-2310). However, the conventional brillouin optical coherence domain system adopts a light source modulated by sine frequency to transmit in an optical fiber to be measured to generate periodic correlation peaks, a stimulated brillouin acoustic field is limited in the correlation peaks with the full width at half maximum of a sub-centimeter or millimeter order to realize high-resolution measurement, meanwhile, in order to avoid crosstalk of adjacent correlation peaks, it is ensured that only one peak in the optical fiber to be measured causes serious limitation on sensing distance, and large-range dynamic strain real-time measurement with both long distance and high resolution cannot be realized.
Based on this, it is necessary to invent a brand new distributed optical fiber dynamic strain measurement system to overcome the difficulty that the large-range dynamic strain real-time measurement with long distance and high resolution cannot be realized in the prior art, and realize the real-time and rapid distributed dynamic strain measurement with long distance, high spatial resolution, large dynamic range.
Disclosure of Invention
The invention provides a distributed optical fiber dynamic strain sensing device and method based on broadband chaotic laser, aiming at solving the difficulty that the existing distributed optical fiber sensing technology cannot realize large-range dynamic strain real-time monitoring with long distance and high resolution.
The invention is realized by adopting the following technical scheme:
a distributed optical fiber dynamic strain sensing device based on broadband chaotic laser comprises a broadband chaotic laser source, a 1 x 2 optical fiber coupler, a first polarization controller, a high-speed electro-optical modulator, a programmable optical delay generator, a first optical amplifier, an optical deflector, an optical isolator, a sensing optical fiber, an optical circulator, a second optical amplifier, a semiconductor optical amplifier, a second polarization controller, a pulse signal generator, a broadband microwave signal source, a tunable optical filter, a photoelectric detector and a high-speed data acquisition and analysis system.
Wherein, the output end of the broadband chaotic laser source is connected with the input end of the 1 multiplied by 2 optical fiber coupler; the first output end of the 1 multiplied by 2 optical fiber coupler is connected with the input end of the first polarization controller; the output end of the first polarization controller is connected with the optical fiber input end of the high-speed electro-optic modulator; the radio frequency output end of the broadband microwave signal source is connected with the radio frequency input end of the high-speed electro-optical modulator through a high-frequency coaxial cable; the optical fiber output end of the high-speed electro-optical modulator is connected with the input end of the programmable optical delay generator through a single-mode optical fiber jumper; the output end of the programmable optical delay generator is connected with the input end of the first optical amplifier through a single-mode optical fiber jumper; the output end of the first optical amplifier is connected with the input end of the optical polarization scrambler through a single-mode optical fiber jumper; the output end of the optical polarization scrambler is connected with the input end of the optical isolator through a single-mode optical fiber jumper; the output end of the optical isolator is connected with one end of the sensing optical fiber; the other end of the sensing optical fiber is connected with the reflecting end of the optical circulator; the second output end of the 1 multiplied by 2 optical fiber coupler is connected with the input end of the second polarization controller; the output end of the second polarization controller is connected with the input end of the semiconductor optical amplifier through a single-mode optical fiber jumper; the output end of the semiconductor optical amplifier is connected with the input end of the second optical amplifier through a single-mode optical fiber jumper: the output end of the second optical amplifier is connected with the input end of the optical circulator through a single-mode optical fiber jumper; the output end of the optical circulator is connected with the input end of the tunable optical filter; the output end of the tunable optical filter is connected with the photoelectric detector through a single-mode optical fiber jumper; the output end of the photoelectric detector is connected with a data acquisition port of the high-speed data acquisition and analysis system through a high-frequency coaxial cable; the radio frequency output end I of the pulse signal generator is connected with the radio frequency input end of the semiconductor optical amplifier through a high-frequency coaxial cable, the radio frequency output end II of the pulse signal generator is connected with the radio frequency control port of the high-speed data acquisition card through the high-frequency coaxial cable, and the radio frequency output end III of the pulse signal generator is connected with the external trigger port of the broadband microwave signal source through the high-frequency coaxial cable.
Based on the device, the distributed optical fiber dynamic strain sensing method based on the broadband chaotic laser specifically comprises the following steps:
the wide-frequency chaotic laser source outputs chaotic laser to enter the 1 multiplied by 2 optical fiber coupler, and the chaotic laser is divided into two paths through the 1 multiplied by 2 optical fiber coupler: one path is used as probe light, and the other path is used as pump light.
The detection light is incident to the high-speed electro-optical modulator through the first polarization controller, wherein the high-speed electro-optical modulator is modulated by a sinusoidal signal output by a broadband microwave signal source, so that the center frequency of the detection light is shifted by an amount equal to the Brillouin frequency shift value (v) of the sensing optical fiber
B≈10.6GH
Z) (ii) a The optical signal after frequency shift of the high-speed electro-optical modulator is input into a programmable optical delay generator, the optical path of the detection light is adjusted through the programmable optical delay generator, then the optical signal is incident into a first optical amplifier, the detection light is amplified through the first optical amplifier, then the optical signal is incident into an optical deflector, the optical deflector is incident into an optical isolator, the optical deflector outputs the detection light, and the detection light is injected into one end of a sensing optical fiber.
And pumping light enters the semiconductor optical amplifier through the second polarization controller, wherein the semiconductor optical amplifier is modulated by a high-speed pulse signal output by the pulse signal generator, and a chaotic optical signal after pulse modulation enters the second optical amplifier, is amplified by the second optical amplifier and is output to the input end of the optical circulator.
The detection light and the pumping light which are transmitted in opposite directions meet at a certain position in the sensing optical fiber, and simultaneously, the stimulated Brillouin amplification effect is generated, the amplified detection light signal enters the tunable optical filter after circulating through the optical circulator, and only Brillouin Stokes light is reserved after filtering unnecessary signals; and the filtered optical signals are accessed into a photoelectric detector to be converted into electric domain signals, and are transmitted to a high-speed data acquisition and analysis system through a high-frequency coaxial cable.
The method comprises the steps that chaotic detection light and pumping light can generate Brillouin gain at the meeting position of sensing optical fibers, Brillouin frequency difference is locked at the middle point of a Brillouin gain spectral region through a broadband microwave signal source, a photoelectric detector is used for carrying out real-time Brillouin gain acquisition, a high-speed data acquisition and analysis system is used for carrying out real-time data processing and analysis, and meanwhile a programmable light delay generator (5) is used for adjusting the optical path of the detection light, so that stimulated Brillouin amplification effect is generated at different positions of the detection light and the pumping light in the sensing optical fibers, chaotic Brillouin gain spectrum information is obtained, and strain information at any position of the sensing optical.
Compared with the existing distributed optical fiber dynamic strain measurement system, the distributed optical fiber dynamic strain sensing device and method based on the broadband chaotic laser have the advantages and positive effects that:
compared with a traditional time domain system, the distributed optical fiber dynamic strain sensing device based on the broadband chaotic laser belongs to a coherent domain system, and has higher spatial resolution, namely the spatial resolution can be improved by 2-3 orders of magnitude.
Secondly, the coherent domain system based on the sinusoidal frequency modulation has the contradiction between the sensing distance and the spatial resolution, and the coherent function generated by the laser signal modulated by the sinusoidal signal frequency has periodicity, so that the increase of the sensing distance is further limited. The distributed optical fiber dynamic strain sensing device based on the broadband chaotic laser adopts the continuous chaotic laser without time delay as a detection signal, can ensure that only one related peak exists in a sensing optical fiber with enough length, avoids the crosstalk of the related peak, and greatly expands the sensing distance.
Thirdly, the distributed optical fiber dynamic strain sensing system based on the broadband chaotic laser uses the broadband chaotic signal with flat frequency spectrum as a light source: (1) the chaotic laser is divided into probe light and pump light which are in the same-phase dry state but are not frequency-tuned, the probe light and the pump light are respectively injected into optical fibers, when the pump light contains different frequency components, each frequency component can generate different Brillouin gains, and the Brillouin gain spectrum obtained by measurement is linear superposition of the gains of the frequency components; the pumping path of the system is a broadband chaotic signal, each frequency component can generate stable stimulated Brillouin gain, and a Brillouin gain spectrum with increased spectral width and a flat linear region can be obtained through demodulation by single measurement. (2) The optical fiber can be demodulated at any position of the optical fiber under the same environment to obtain completely same Brillouin gain spectrums, the shape of the Brillouin gain spectrums can be regulated and controlled by regulating the frequency spectrum of the chaotic signal, and a larger linear slope range and better linearity can be obtained by the method; the method comprises the steps that the middle point of a linear region in a low frequency band of a gain spectrum is used as a reference, the frequency detuning quantity of probe light and pump light is locked to be a frequency value at the middle point, a single-side slope regulation and control model of the chaotic Brillouin gain spectrum is established through measurement of Brillouin gain at a single frequency point, and the gain value is stable and unchanged in the same environment; when a certain position of an optical fiber is located in a special environment, Brillouin frequency shift caused by dynamic strain causes the middle point of a linear region of a low frequency band of a gain spectrum to shift, at the moment, the Brillouin gain value at a reference point changes obviously, namely, the actual Brillouin frequency shift amount is finally mapped to the change of the Brillouin gain, the real-time demodulation of the frequency shift amount is realized by utilizing the single-sided slope regulation and control model of the Brillouin gain spectrum, and the high-resolution measurement of the dynamic strain can be realized through real-time power acquisition.
Fourthly, for a dynamic distributed Brillouin optical fiber sensing device and method (Chinese patent invention, ZL 2013102334483) adopting a frequency agility technology, the dynamic distributed Brillouin optical fiber sensing device and method (Chinese patent invention, ZL 2015101224127) adopting slope assistance and coherent detection technology combined, and a long-distance distributed large-measurement-range fast response optical fiber dynamic strain sensing device (Chinese patent invention, ZL 2014101334620) adopting a multi-frequency modulation detection optical technology. The device and the method both adopt a traditional time domain system, and the spatial resolution is still limited; the frequency agility technology cannot realize real-time monitoring of strain information, and the traditional slope auxiliary method has a narrow Brillouin gain spectral region, so that the dynamic strain measurement range is severely limited; the Brillouin gain spectrum splicing of the multi-frequency modulation continuous detection light needs a plurality of high-speed electro-optical modulation modules and arbitrary waveform generators, so that the system cost is high and the modulation width is limited; the coherent detection technology has a complex structure, is difficult to implement and is greatly influenced by the external environment. The distributed optical fiber dynamic strain sensing system based on the broadband chaotic laser obtains a Brillouin gain spectrum with increased spectrum width and flat linear region by taking the chaotic laser with no time delay, flat frequency spectrum and wide frequency band as a detection signal, simplifies the system structure and reduces the cost without complex modulation means, develops a Brillouin gain spectrum single-side slope regulation and control technology to measure dynamic strain on the basis of overcoming the problem that long sensing distance and high spatial resolution cannot be considered, absorbs the advantage of short measurement time of a slope auxiliary system, and realizes real-time measurement of long distance, high spatial resolution and large-range dynamic strain.
Fifthly, the distributed optical fiber dynamic strain sensing system based on the broadband chaotic laser generates a high-speed pulse signal by using a pulse signal generator, realizes the synchronous control of a broadband microwave signal source, a semiconductor optical amplifier and a high-speed data acquisition and analysis system, and ensures the accuracy and the real-time performance of the measurement of the sensing system; compared with a plurality of high-speed signal generators and broadband electro-optical modulator cascaded modulation models in the traditional Brillouin optical time domain analysis system, the sensing system disclosed by the invention is simple in structure, easy to integrate instrumentation and measurement equipment and capable of realizing large-scale engineering monitoring application.
Drawings
Fig. 1 shows a schematic structural view of the apparatus of the present invention.
In the figure: the device comprises a 1-broadband chaotic laser source, a 2-1 x 2 optical fiber coupler, a 3-first polarization controller, a 4-high-speed electro-optical modulator, a 5-programmable optical delay generator, a 6-first optical amplifier, a 7-optical polarization scrambler, an 8-optical isolator, a 9-sensing optical fiber, a 10-optical circulator, a 11-second optical amplifier, a 12-semiconductor optical amplifier, a 13-second polarization controller, a 14-pulse signal generator, a 15-broadband microwave signal source, a 16-high-speed data acquisition and analysis system, a 17-photoelectric detector and a 18-tunable optical filter.
Detailed Description
The following detailed description of specific embodiments of the invention refers to the accompanying drawings.
A distributed optical fiber dynamic strain sensing device based on broadband chaotic laser is shown in figure 1 and comprises a broadband chaotic laser source 1, a 1 x 2 optical fiber coupler 2, a first polarization controller 3, a high-speed electro-optical modulator 4, a programmable optical delay generator 5, a first optical amplifier 6, an optical polarization scrambler 7, an optical isolator 8, a sensing optical fiber 9, an optical circulator 10, a second optical amplifier 11, a semiconductor optical amplifier 12, a second polarization controller 13, a pulse signal generator 14, a broadband microwave signal source 15, a tunable optical filter 18, a photoelectric detector 17 and a high-speed data acquisition and analysis system 16.
Wherein, the output end of the broadband chaotic laser source 1 is connected with the input end of the 1 multiplied by 2 optical fiber coupler 2; the first output end of the 1 multiplied by 2 optical fiber coupler 2 is connected with the input end of the first polarization controller 3; the output end of the first polarization controller 3 is connected with the optical fiber input end of the high-speed electro-optical modulator 4; the radio frequency output end of the broadband microwave signal source 15 is connected with the radio frequency input end of the high-speed electro-optical modulator 4 through a high-frequency coaxial cable; the optical fiber output end of the high-speed electro-optical modulator 4 is connected with the input end of the programmable optical delay generator 5 through a single-mode optical fiber jumper; the output end of the programmable optical delay generator 5 is connected with the input end of the first optical amplifier 6 through a single-mode optical fiber jumper; the output end of the first optical amplifier 6 is connected with the input end of the optical polarization scrambler 7 through a single-mode optical fiber jumper; the output end of the optical polarization scrambler 7 is connected with the input end of the optical isolator 8 through a single-mode optical fiber jumper; the output end of the optical isolator 8 is connected with one end of the sensing optical fiber 9; the other end of the sensing optical fiber 9 is connected with the reflection end of the optical circulator 10; the second output end of the 1 × 2 optical fiber coupler 2 is connected with the input end of the second polarization controller 13; the output end of the second polarization controller 13 is connected with the input end of the semiconductor optical amplifier 12 through a single-mode optical fiber jumper; the output end of the semiconductor optical amplifier 12 is connected with the input end of the second optical amplifier 11 through a single-mode optical fiber jumper: the output end of the second optical amplifier 11 is connected with the input end of the optical circulator 10 through a single-mode optical fiber jumper; the output end of the optical circulator 10 is connected with the input end of the tunable optical filter 18; the output end of the tunable optical filter 18 is connected with the photoelectric detector 17 through a single-mode optical fiber jumper; the output end of the photoelectric detector 17 is connected with a data acquisition port of the high-speed data acquisition and analysis system 16 through a high-frequency coaxial cable; the radio frequency output end I of the pulse signal generator 14 is connected with the radio frequency input end of the semiconductor optical amplifier 12 through a high frequency coaxial cable, the radio frequency output end II of the pulse signal generator 14 is connected with the radio frequency control port of the high speed data acquisition and analysis system 16 through a high frequency coaxial cable, and the radio frequency output end III of the pulse signal generator 14 is connected with the external trigger port of the broadband microwave signal source 15 through a high frequency coaxial cable.
In specific implementation, the center wavelength of the broadband chaotic laser source is 1550nm, the spectral line width is greater than 6GHz, and the spectral bandwidth is greater than 10 GHz. The high-speed electro-optical modulator 4 adopts a MX-LN-10 type lithium niobate electro-optical intensity modulator with a high extinction ratio. The programmable optical delay generator 5 adopts an ODG-101 high-precision programmable optical delay line. The first optical amplifier 6 is a common erbium-doped fiber amplifier. The optical polarization scrambler 7 adopts a PCD-104 type polarization scrambler. The sensing fiber 12 is G652 single-mode fiber or G655 single-mode fiber, and the length of the sensing fiber is 50 km. The second optical amplifier 11 is a pulse erbium-doped fiber amplifier. The semiconductor optical amplifier 12 employs KG-SOA-C-BAND series amplifiers. The pulse signal generator 14 is an Agilent-81150A type signal generator. The broadband microwave signal source 15 adopts an EXG-N5173B type microwave signal source. The photodetector 17 employs a low bandwidth high speed detector. The tunable optical filter 18 employs an XTM-50 bandwidth wavelength tunable filter.
A distributed optical fiber dynamic strain sensing method based on broadband chaotic laser comprises the following steps:
the wide-frequency chaotic laser source 1 outputs continuous chaotic laser with no time delay, flat frequency spectrum and wide frequency band, and is injected into the 1 x 2 optical fiber coupler 2, and is divided into two paths through the 1 x 2 optical fiber coupler 2: one path is used as probe light, and the other path is used as pump light. The detection light is incident to the high-speed electro-optical modulator 4 through the first polarization controller 3, wherein the high-speed electro-optical modulator 4 is modulated by a sinusoidal signal output by the broadband microwave signal source 15, so that the center frequency of the detection light is shifted by an amount close to the Brillouin frequency shift of the sensing optical fiber. The optical signal frequency-shifted by the high-speed electro-optical modulator 4 is input to the programmable optical delay generator 5, and the optical path of the probe light is adjusted by the programmable optical delay generator 5 and then enters the first optical amplifier 6. The probe light is amplified by a first optical amplifier 6, compensates for the optical signal loss caused by the programmable optical delay generator, and is then incident on an optical scrambler 7. The optical scrambler is used for reducing the influence of the polarization state when the detection light and the pump light are interfered in the sensing optical fiber, and the detection light and the pump light enter the optical isolator 8 after passing through the optical scrambler 7. The optical isolator 8 ensures that the detection light passes through in one direction to avoid the influence of the backward scattering light on the detection light. After being output by the optical isolator 8, the detection light is injected into one end of the sensing optical fiber 9, and the other end of the sensing optical fiber 9 is connected with the reflection end of the optical circulator 10. The other path of pump light is incident to the semiconductor optical amplifier 12 through the second polarization controller 13, wherein the semiconductor optical amplifier 12 is modulated by the high-speed pulse signal output by the pulse signal generator 14, and pulse positioning and time domain control of the sensing system are realized. The chaotic light signal after pulse modulation enters the second optical amplifier 11, and is amplified by the second optical amplifier 11 and then output to the input end of the optical circulator 10. The detection light and the pump light which are transmitted in opposite directions meet at a certain position in the sensing optical fiber 9, and meanwhile, the stimulated Brillouin amplification effect is generated, the amplified detection light signal enters the tunable optical filter 18 after being circulated by the optical circulator 10, useless signals (including Rayleigh scattering light, noise and the like) are filtered, and only Brillouin Stokes light is reserved; the filtered optical signal is connected to the photoelectric detector 17 to be converted into an electric domain signal, and is transmitted to the high-speed data acquisition and analysis system 16 through a high-frequency coaxial cable. The chaotic detection light and the pumping light can generate Brillouin gain at the meeting position of the sensing optical fiber 9, because of the linear relation between the Brillouin frequency shift amount and the strain, the Brillouin frequency difference is locked at the middle point of a Brillouin gain spectral region through the broadband microwave signal source 15, the photoelectric detector 17 is used for carrying out real-time Brillouin gain acquisition, the high-speed data acquisition and analysis system 16 controlled by pulse synchronization is used for carrying out real-time data processing and analysis, meanwhile, the optical path of the detection light can be adjusted by the programmable light delay generator 5, so that the stimulated Brillouin amplification effect is generated at different positions of the detection light and the pumping light in the sensing optical fiber 9, and the strain information at any position of the sensing optical fiber can be obtained by combining.
It should be noted that modifications and applications may occur to those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (2)
1. A distributed optical fiber dynamic strain sensing device based on broadband chaotic laser is characterized in that: the broadband optical fiber chaotic laser device comprises a broadband chaotic laser source (1), a 1 x 2 optical fiber coupler (2), a first polarization controller (3), a high-speed electro-optical modulator (4), a programmable optical delay generator (5), a first optical amplifier (6), an optical deflector (7), an optical isolator (8), a sensing optical fiber (9), an optical circulator (10), a second optical amplifier (11), a semiconductor optical amplifier (12), a second polarization controller (13), a pulse signal generator (14), a broadband microwave signal source (15), a high-speed data acquisition and analysis system (16), a photoelectric detector (17) and a tunable optical filter (18);
the output end of the broadband chaotic laser source (1) is connected with the input end of the 1 multiplied by 2 optical fiber coupler (2); the first output end of the 1 multiplied by 2 optical fiber coupler (2) is connected with the input end of the first polarization controller (3); the output end of the first polarization controller (3) is connected with the optical fiber input end of the high-speed electro-optical modulator (4); the radio frequency output end of the broadband microwave signal source (15) is connected with the radio frequency input end of the high-speed electro-optical modulator (4) through a high-frequency coaxial cable; the optical fiber output end of the high-speed electro-optical modulator (4) is connected with the input end of the programmable optical delay generator (5) through a single-mode optical fiber jumper; the output end of the programmable optical delay generator (5) is connected with the input end of the first optical amplifier (6) through a single-mode optical fiber jumper; the output end of the first optical amplifier (6) is connected with the input end of the optical polarization scrambler (7) through a single-mode optical fiber jumper; the output end of the optical polarization scrambler (7) is connected with the input end of the optical isolator (8) through a single-mode optical fiber jumper; the output end of the optical isolator (8) is connected with one end of the sensing optical fiber (9); the other end of the sensing optical fiber (9) is connected with the reflection end of the optical circulator (10); the second output end of the 1 multiplied by 2 optical fiber coupler (2) is connected with the input end of a second polarization controller (13); the output end of the second polarization controller (13) is connected with the input end of the semiconductor optical amplifier (12) through a single-mode optical fiber jumper; the output end of the semiconductor optical amplifier (12) is connected with the input end of the second optical amplifier (11) through a single-mode optical fiber jumper: the output end of the second optical amplifier (11) is connected with the input end of the optical circulator (10) through a single-mode optical fiber jumper; the output end of the optical circulator (10) is connected with the input end of the tunable optical filter (18); the output end of the tunable optical filter (18) is connected with the photoelectric detector (17) through a single-mode optical fiber jumper; the output end of the photoelectric detector (17) is connected with a data acquisition port of a high-speed data acquisition and analysis system (16) through a high-frequency coaxial cable; the radio frequency output end I of the pulse signal generator (14) is connected with the radio frequency input end of the semiconductor optical amplifier (12) through a high-frequency coaxial cable, the radio frequency output end II of the pulse signal generator (14) is connected with the radio frequency control port of the high-speed data acquisition and analysis system (16) through the high-frequency coaxial cable, and the radio frequency output end III of the pulse signal generator (14) is connected with the external trigger port of the broadband microwave signal source (15) through the high-frequency coaxial cable.
2. A distributed optical fiber dynamic strain sensing method based on broadband chaotic laser is characterized in that: the wide-frequency chaotic laser source (1) outputs chaotic laser to enter the 1 x 2 optical fiber coupler (2), and the chaotic laser is divided into two paths through the 1 x 2 optical fiber coupler (2): one path is used as detection light, and the other path is used as pumping light;
the detection light is incident to a high-speed electro-optical modulator (4) through a first polarization controller (3), wherein the high-speed electro-optical modulator (4) is modulated by a sinusoidal signal output by a broadband microwave signal source (15), so that the center frequency of the detection light is shifted; an optical signal subjected to frequency shift by the high-speed electro-optical modulator (4) is input into the programmable optical delay generator (5), the optical path of probe light is adjusted by the programmable optical delay generator (5), the probe light is incident into the first optical amplifier (6), the probe light is amplified by the first optical amplifier (6), the probe light is incident into the optical polarization scrambler (7), the probe light is incident into the optical isolator (8) after passing through the optical polarization scrambler (7), and the probe light is injected into one end of the sensing optical fiber (9) after being output by the optical isolator (8);
the pump light is incident to the semiconductor optical amplifier (12) through the second polarization controller (13), wherein the semiconductor optical amplifier (12) is modulated by a high-speed pulse signal output by the pulse signal generator (14), the chaotic optical signal after pulse modulation is incident to the second optical amplifier (11), and the chaotic optical signal is amplified by the second optical amplifier (11) and then output to the input end of the optical circulator (10);
the detection light and the pumping light which are transmitted in opposite directions meet at a certain position in the sensing optical fiber (9), meanwhile, the stimulated Brillouin amplification effect is generated, the amplified detection light signal enters the tunable optical filter (18) after circulating through the optical circulator (10), and only Brillouin Stokes light is reserved after filtering useless signals; the filtered optical signals are accessed into a photoelectric detector (17) to be converted into electric domain signals, and the electric domain signals are transmitted to a high-speed data acquisition and analysis system (16) through a high-frequency coaxial cable;
the chaotic detection light and the pumping light can generate Brillouin gain at the meeting position of the sensing optical fiber (9), Brillouin frequency difference is locked at the middle point of a Brillouin gain spectral region through a broadband microwave signal source (15), real-time Brillouin gain acquisition is carried out through a photoelectric detector (17), real-time data processing and analysis are carried out through a high-speed data acquisition and analysis system (16), and meanwhile, the optical path of the detection light is adjusted through a programmable light delay generator (5), so that stimulated Brillouin amplification effect is generated at different positions of the detection light and the pumping light in the sensing optical fiber (9), chaotic Brillouin gain spectrum information is obtained, and strain information at any position of the sensing optical fiber is obtained.
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| CN110632763B (en) * | 2019-10-31 | 2021-04-23 | 太原理工大学 | Method for generating chaotic light based on feedback interference principle |
| CN110632762B (en) * | 2019-10-31 | 2021-04-23 | 太原理工大学 | Device for generating chaotic light based on feedback interference principle |
| CN111307054B (en) * | 2020-02-29 | 2021-03-30 | 太原理工大学 | High-precision dynamic strain monitoring device and method based on time-delay-free chaotic laser |
| CN111637846B (en) * | 2020-05-26 | 2022-02-08 | 太原理工大学 | Multipoint parallel high-speed chaotic Brillouin dynamic strain monitoring device and method |
| CN111637910B (en) * | 2020-05-26 | 2021-10-22 | 太原理工大学 | Time domain differential high-speed chaotic Brillouin optical coherent domain monitoring device and method |
| CN111721338B (en) * | 2020-06-08 | 2022-05-10 | 太原理工大学 | Brillouin optical time domain analysis system for alternately modulating high frequency and low frequency of pump light |
| CN111998968B (en) * | 2020-08-13 | 2022-07-22 | 鞍山睿科光电技术有限公司 | Wide temperature range demodulation device and method based on low-frequency agility and sliding window |
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