CN109084883A - Based on phase-BOTDR optical fiber distributed type Brillouin's vibrating sensing measurement method - Google Patents

Based on phase-BOTDR optical fiber distributed type Brillouin's vibrating sensing measurement method Download PDF

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Publication number
CN109084883A
CN109084883A CN201810904352.8A CN201810904352A CN109084883A CN 109084883 A CN109084883 A CN 109084883A CN 201810904352 A CN201810904352 A CN 201810904352A CN 109084883 A CN109084883 A CN 109084883A
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phase
brillouin
light
variation
scattering
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姜海明
赵蕊月
张令春
谢康
刘晨
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Hefei University of Technology
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Hefei University of Technology
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01HMEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
    • G01H9/004Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors

Abstract

The invention proposes one kind to be based on phase-BOTDR Brillouin fiber optic distribution vibrating sensing measurement method, the continuous light pulse modulated device that light source issues is modulated into pulsed light, it is amplified by erbium-doped fiber amplifier, amplified pulsed light enters single mode sensor fibre through optical circulator, the backward Brillouin scattering light at vibration change location occurs and enters fiber bragg grating through optical circulator again, filter out noise, Brillouin scattering is interfered through non-equilibrium Mach Zehnder interferometer, three road light of output are handled after being received by a photoelectric detector by data acquisition processing system.Utilize non-equilibrium Mach Zehnder interferometer structure, convert the Brillouin shift variable quantity of back scattering to the variation of interference light output phase, using phase demodulating method, utilize antitrigonometric function method demodulation phase, obtain Brillouin shift variation, it is higher than the phase accuracy that differential multiplication cross method obtains to realize the measurement of optical fiber dynamic strain.

Description

Based on phase-BOTDR optical fiber distributed type Brillouin's vibrating sensing measurement method
Technical field
It is specifically a kind of based on phase-BOTDR Brillouin fiber optic point the present invention relates to Distributed Optical Fiber Sensing Techniques field The measurement of formula cloth vibrating sensing.
Background technique
Distributed fiber optic sensing is widely used in urban construction Bridge, railway monitoring, rocket propulsion system and oil well inspection Survey etc., it mainly uses the light scattering theory in optical fiber, including Rayleigh scattering, Raman scattering and Brillouin scattering.Mesh In preceding domestic and international optical fiber sensing system, the Distributed Optical Fiber Sensing Techniques based on Rayleigh scattering are usually used in breakpoints of optical fiber and decaying is special The qualitative detection of sign also has been reported that and carries out strain measurement (bibliography Masoudi A, Belal to Rayleigh scattering using after optical fiber M,Newson T P.A distributed optical fibre dynamic strain sensor based on phase-OTDR[J].Measurement Science&Technology,2013,24(8):085204.);Raman scattering is main It is measured for temperature sensing;Brillouin scattering can be used for the detection of remote temperature strain and vibration, be current high-precision sensing The big hot spot of the one of fields of measurement.
Realize remote, high spatial resolution, high sensitivity Fibre Optical Sensor, main limited resource includes: excessive arteries and veins The nonlinear effect for rushing power generation influences;Dynamic range caused by pulse width changes can not get both with resolution ratio;It is faint to dissipate Penetrate the detection of signal and the processing of Dynamic Signal etc..Overcome the challenge encountered in high-precision Distributed Optical Fiber Sensing Techniques, Meet the actual demand for solving national economy and the people's livelihood.High-precision distributed sensing technology based on Brillouin scattering mainly has Brillouin light Time-domain analysis half-light pulse technique, Brillouin light domain of dependence analytical technology and Brillouin light frequency-domain analysis technology.About dynamically answering The measurement of change is had been reported that before using phase sensitive optical time domain detection technique (bibliography Zhang X, Sun Z, Shan Y, et al.A high performance distributed optical fiber sensor based onΦ-OTDR for Dynamic strain measurement [J] .IEEE Photonics Journal, 2017, PP (99): 1-1.), Brillouin Phase-shift measurement and Brillouin's dynamic raster combined technology (bibliography Bergman A, Langer T, Tur M.Phase- based,high spatial resolution and distributed,static and dynamic strain sensing using Brillouin dynamic gratings in optical fibers.[J].Optics Express,2017,25(5):5376.).It is moved herein using based on phase sensitive Brillouin light time domain reflection technology State stress measurement is obtained Brillouin shift variation, realized using phase demodulating method using antitrigonometric function method demodulation phase Fiber-optic vibration measurement.
Summary of the invention
The invention proposes a kind of phase demodulation algorithms that strain is surveyed based on spontaneous brillouin scattering, to realize distributed light The dynamic strain measurement of phase sensitive in fibre sensing.
In order to achieve the above object, the technical scheme adopted by the invention is as follows:
One kind being based on phase-BOTDR Brillouin fiber optic distribution vibrating sensing measurement method, includes that distributed Feedback swashs Light source, Polarization Controller, pulse-modulator, erbium-doped fiber amplifier, optical circulator, single mode sensor fibre, optical fiber Bragg light Grid, non-equilibrium Mach Zehnder interferometer, photodetector and data acquisition processing system, the distributed feedback laser source hair Continuous light out is successively modulated into pulsed light through Polarization Controller, pulse-modulator, is amplified by erbium-doped fiber amplifier, Amplified pulsed light enters single mode sensor fibre through optical circulator, and the backward Brillouin scattering light at vibration variation occurs and passes through again Optical circulator enters fiber bragg grating, and Brillouin scattering is interfered through non-equilibrium Mach Zehnder interferometer, output Three road light are handled after being received by a photoelectric detector by data acquisition processing system, and non-equilibrium Mach Zehnder interferometer knot is utilized Structure converts the Brillouin shift variable quantity of back scattering to the variation of interference light output phase, according to different moments phase Variation demodulates Brillouin shift variable quantity, and then obtains the variation of the vibration along sensor fibre.
Using non-equilibrium Mach Zehnder interferometer structure, interference light is converted by the Brillouin shift variable quantity of back scattering The variation of phase is obtained Brillouin shift variation, realized using phase demodulating method using antitrigonometric function method demodulation phase Fiber-optic vibration measurement, the specific steps are as follows:
A. optical signal is acquired, three tunnel output optical signals are detected by photoelectric detector, backward Brillouin scattering light is by non- The three road light exported after the interference of balanced Mach Zehnder interferometer respectively indicate are as follows:
In above formula, I0For Brillouin scattering light intensity, M and N are constant, and the phase difference of 2 π/3 is differed between three tunnel output lights;
B. disappear DC component, and three road output intensity phase adductions average to obtain DC component, tri- tunnel output optical signal of Zai Yong DC component is subtracted, if DC component is in (1) formula
(3) formula is subtracted with (1) formula to obtain
C. phase to be measured is asked using antitrigonometric function;
Δ L indicates reference arm delay line length in interferometer, vBIndicate Brillouin shift, cnIndicate the light velocity in medium;
vB(t)=vB0(1+0.048×106ε) (6)
Find out that strain will lead to Brillouin shift and change by (5) (6) formula, changes, adopt so as to cause phase difference Phase demodulating is carried out with antitrigonometric function method, Brillouin shift variable quantity can be demodulated according to the variation of different moments phase, Obtain the vibration variation along sensor fibre.
Stimulated Brillouin scattering threshold value is lower than using pump power when spontaneous brillouin scattering.
The beneficial effects of the present invention are:
(1) pump power is lower than stimulated Brillouin scattering threshold value when surveying strain variation using spontaneous brillouin scattering, one Determine pump power needed for transmission same distance in SNR ranges to be lower than based on pump power needed for Rayleigh scattering sensing.
(2) phase demodulating is carried out using antitrigonometric function method, it is higher than the phase accuracy that differential multiplication cross method obtains.
Detailed description of the invention
Fig. 1 is antitrigonometric function method demodulation phase algorithm pattern.
Fig. 2 is to survey stress change principle figure based on spontaneous Brillouin back scattering.
Fig. 3 is the comparison diagram of the antitrigonometric function method that the present invention uses and differential multiplication cross method demodulation phase.
Specific embodiment
The invention proposes one kind to be based on phase-BOTDR Brillouin fiber optic distribution vibrating sensing measurement method, to realize The dynamic strain measurement of phase sensitive in distributing optical fiber sensing.Specific embodiment is as described below, includes distributed Feedback Laser source, Polarization Controller, pulse-modulator, erbium-doped fiber amplifier, optical circulator, single mode sensor fibre, optical fiber Bragg Grating, non-equilibrium Mach Zehnder interferometer, photodetector and data acquisition processing system, the distributed feedback laser source The continuous light issued is successively modulated into pulsed light through Polarization Controller, pulse-modulator, is put by erbium-doped fiber amplifier Greatly, amplified pulsed light enters single mode sensor fibre through optical circulator, and the backward Brillouin scattering light at vibration variation occurs Enter fiber bragg grating through optical circulator again, Brillouin scattering is interfered through non-equilibrium Mach Zehnder interferometer, defeated Tri- road light of Chu is handled after being received by a photoelectric detector by data acquisition processing system, is interfered using non-equilibrium Mach Zehnder Instrument structure converts the Brillouin shift variable quantity of back scattering to the variation of interference light output phase, according to different moments phase The variation of position demodulates Brillouin shift variable quantity, and then obtains the variation of the vibration along sensor fibre.
Using non-equilibrium Mach Zehnder interferometer structure, interference light is converted by the Brillouin shift variable quantity of back scattering The variation of phase is obtained Brillouin shift variation, realized using phase demodulating method using antitrigonometric function method demodulation phase Fiber-optic vibration measurement, the specific steps are as follows:
A. optical signal is acquired, three tunnel output optical signals are detected by photoelectric detector, backward Brillouin scattering light is by non- The three road light exported after the interference of balanced Mach Zehnder interferometer respectively indicate are as follows:
In above formula, I0For Brillouin scattering light intensity, M and N are constant, and the phase difference of 2 π/3 is differed between three tunnel output lights;
B. disappear DC component, and three road output intensity phase adductions average to obtain DC component, tri- tunnel output optical signal of Zai Yong DC component is subtracted, if DC component is in (1) formula
(3) formula is subtracted with (1) formula to obtain
C. phase to be measured is asked using antitrigonometric function;
Δ L indicates reference arm delay line length in interferometer, vBIndicate Brillouin shift, cnIndicate the light velocity in medium;
vB(t)=vB0(1+0.048×106ε) (6)
It can be seen that strain will lead to Brillouin shift and change by (5) (6) formula, as shown in Figure 1, 2.So as to cause phase Potential difference changes.Phase demodulating is carried out using antitrigonometric function method, as shown in Figure 3.It can according to the variation of different moments phase To demodulate Brillouin shift variable quantity, and then obtain the variation of the vibration along sensor fibre.

Claims (2)

1. one kind is based on phase-BOTDR Brillouin fiber optic distribution vibrating sensing measurement method, it is characterised in that: include point Cloth feedback laser source, Polarization Controller, pulse-modulator, erbium-doped fiber amplifier, optical circulator, single mode sensor fibre, light Fine Bragg grating, non-equilibrium Mach Zehnder interferometer, photodetector and data acquisition processing system, the distribution are anti- The continuous light that feedback laser source issues successively is modulated into pulsed light through Polarization Controller, pulse-modulator, passes through Erbium-doped fiber amplifier Device amplifies, and amplified pulsed light enters single mode sensor fibre through optical circulator, occurs in the backward cloth at vibration variation Deep pool scattering light enters fiber bragg grating through optical circulator again, and Brillouin scattering occurs through non-equilibrium Mach Zehnder interferometer Interference, three road light of output are handled after being received by a photoelectric detector by data acquisition processing system, and non-equilibrium Mach is utilized Zehnder interferometer structure converts the Brillouin shift variable quantity of back scattering to the variation of interference light output phase, according to not The variation of phase demodulates Brillouin shift variable quantity in the same time, and then obtains the variation of the vibration along sensor fibre.
2. according to claim 1 be based on phase-BOTDR Brillouin fiber optic distribution vibrating sensing measurement method, spy Sign is: utilizing non-equilibrium Mach Zehnder interferometer structure, converts interference light for the Brillouin shift variable quantity of back scattering The variation of phase is obtained Brillouin shift variation, realized using phase demodulating method using antitrigonometric function method demodulation phase Fiber-optic vibration measurement, the specific steps are as follows:
A. optical signal is acquired, three tunnel output optical signals are detected by photoelectric detector, backward Brillouin scattering light is by non-equilibrium The three road light exported after Mach Zehnder interferometer interference respectively indicate are as follows:
In above formula, I0For Brillouin scattering light intensity, M and N are constant, and the phase difference of 2 π/3 is differed between three tunnel output lights;
B. disappear DC component, and three road output intensity phase adductions average to obtain DC component, and tri- tunnel output optical signal of Zai Yong subtracts DC component, if DC component is in (1) formula
(3) formula is subtracted with (1) formula to obtain
C. phase to be measured is asked using antitrigonometric function;
Δ L indicates reference arm delay line length in interferometer, vBIndicate Brillouin shift, cnIndicate the light velocity in medium;
vB(t)=vB0(1+0.048×106ε) (6)
Find out that strain will lead to Brillouin shift and change by (5) (6) formula, changes so as to cause phase difference, using anti- Trigonometric function method carries out phase demodulating, can demodulate Brillouin shift variable quantity according to the variation of different moments phase, obtain Vibration variation along sensor fibre.
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CN111289222A (en) * 2020-01-21 2020-06-16 丽水正阳电力建设有限公司 Optical fiber breakpoint monitoring device based on phase-sensitive optical time domain reflection technology
CN111458059A (en) * 2019-01-21 2020-07-28 中国科学院上海光学精密机械研究所 Continuous vehicle collision detection system and method thereof
CN113155165A (en) * 2021-05-14 2021-07-23 武汉理工大学 Interference type demodulation system and method for large-capacity fiber grating sensor network
CN114061638A (en) * 2021-10-26 2022-02-18 广东工业大学 Brillouin optical time domain reflectometer and phase demodulation method and device thereof

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CN111458059A (en) * 2019-01-21 2020-07-28 中国科学院上海光学精密机械研究所 Continuous vehicle collision detection system and method thereof
CN111289222A (en) * 2020-01-21 2020-06-16 丽水正阳电力建设有限公司 Optical fiber breakpoint monitoring device based on phase-sensitive optical time domain reflection technology
CN113155165A (en) * 2021-05-14 2021-07-23 武汉理工大学 Interference type demodulation system and method for large-capacity fiber grating sensor network
CN113155165B (en) * 2021-05-14 2022-07-05 武汉理工大学 Interference type demodulation system and method for large-capacity fiber grating sensor network
CN114061638A (en) * 2021-10-26 2022-02-18 广东工业大学 Brillouin optical time domain reflectometer and phase demodulation method and device thereof
CN114061638B (en) * 2021-10-26 2024-03-26 广东工业大学 Brillouin optical time domain reflectometer and phase demodulation method and device thereof

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Application publication date: 20181225