CN105973450B - Optical fiber Fizeau interference arrays distributed vibration sensing system and method - Google Patents
Optical fiber Fizeau interference arrays distributed vibration sensing system and method Download PDFInfo
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- CN105973450B CN105973450B CN201610277420.3A CN201610277420A CN105973450B CN 105973450 B CN105973450 B CN 105973450B CN 201610277420 A CN201610277420 A CN 201610277420A CN 105973450 B CN105973450 B CN 105973450B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
Abstract
The invention discloses a kind of optical fiber Fizeau interference arrays distributed vibration sensing system and methods,Wherein system includes laser light source,First fiber coupler,First optical frequency shifter,Second optical frequency shifter,Second fiber coupler,Delayer,Optical circulator and optical fiber Fizeau interference arrays,The system further includes photodetector,Data acquire and control card,First radio-frequency signal source and the second radio-frequency signal source,The light that laser light source is sent out is divided into two-beam through the first fiber coupler,Light beam and the second beam light pass through the first optical frequency shifter respectively,Second optical frequency shifter generates frequency displacement and is modulated into frequency different the first light pulse and the second light pulse,After second light pulse is delayed using delayer,With the first light pulse pulse pair is coupled at the second fiber coupler,Pulse by optical circulator to entering optical fiber Fizeau interference arrays,Generate multiple reflected impulses pair,Return optical circulator；And difference interference occurs at photodetector.
Description
Technical field
The present invention relates to fiber optic sensor technology fields more particularly to a kind of optical fiber Fizeau interference array distributions to vibrate
Sensor-based system and method.
Background technology
Distributed optical fiber vibration sensing is realized and is vibrated to Inductive links periphery using optical fiber as sensing element and transmission medium
The technology that signal is detected not only has simple fiber sensing technology high sensitivity, high temperature resistant, anticorrosive and anti-electromagnetism dry
The advantages that disturbing characteristic, and the advantage of fiber distribution extension can be more embodied, any point can signal vibrated in Inductive links
Modulation, to realize that being detected without leak source for vibration signal, interference type distributed optical fiber vibration sensing technology are dry based on light wave
The vibrating sensing technology of modulation principle is related to, there is outstanding advantages of high sensitivity, dynamic range is big and response frequency is high, by 30
Development for many years, interference-type optical fiber vibrating sensing technology achieve plentiful and substantial achievement in research, it is proposed that Mach-Zehnder interferes
Instrument, Michelson interferometers and a variety of compound interference structures such as Sagnac interferometers and MZI-MZI, SI-SI.
That has studied is designed based on the interference structures such as Mach-Zehnder interferometers and Michelson interferometers
Vibration sensing system is single armed sensing, and reference light and signal light are advanced not in same light path so two-arm is highly prone to not
Interference with ambient noise is unstable so as to cause interference fringe.Fizeau interference is when being transmitted in optical system using light
First reflection light, which is used as, refers to light, and second of reflected light is as signal light, reference light and signal light along same light path row
Into and interfere, signal light advances from reference light in same light path to overcome because the different external worlds are done in Fizeau interference
The problems such as interference fringe caused by disturbing (such as vibration, temperature fluctuation etc.) is unstable.
Not with the gradual ripe and time-division of interference type distributed optical fiber vibration sensing technology and wavelength-division multiplex technique
Disconnected development, in order to realize sensor-based system networking, a wide range of, quasi- distribution measurement, various structures, scale and distance sensing
Optical fiber vibration sensing array has obtained extensive research, current various composite sensor array technologies has been made a general survey of, it is difficult to have one
Kind technology can be provided simultaneously with superior performance in detection range, array scale, linear array diameter and measurement sensitivity etc..
Invention content
To overcome Mach-Zehnder interferometers and Michelson interferometers etc., because signal light and reference light are not being shared the same light
Traveling is asked to cause the interference fringe caused by different external interferences (such as vibration, temperature fluctuation) unstable etc. in road
Topic provides a kind of optical fiber Fizeau interference arrays distributed vibration sensing system and method.
The technical solution adopted by the present invention to solve the technical problems is：
A kind of optical fiber Fizeau interference array distributed vibration sensing systems, including laser light source, the first optical fiber coupling are provided
Clutch, the first optical frequency shifter, the second optical frequency shifter, the second fiber coupler, delayer, optical circulator and optical fiber Fizeau interference
Array, the light that laser light source is sent out are divided into two-beam through the first fiber coupler, and light beam and the second beam light pass through respectively
One optical frequency shifter, the second optical frequency shifter generate frequency displacement and are modulated into the first light pulse and the second light pulse of different frequency, and second
After light pulse is delayed using delayer, pulse pair is coupled at the second fiber coupler with the first light pulse, pulse is to logical
It crosses optical circulator and enters optical fiber Fizeau interference arrays, generate multiple reflected impulses pair, return optical circulator；
The system further includes photodetector, data acquisition and control card, the first radio-frequency signal source and the second radiofrequency signal
Source, photodetector are connect with optical circulator, data acquisition with control card, and the first radio-frequency signal source and the first optical frequency shifter connect
It connects, the second radio-frequency signal source is connect with the second optical frequency shifter；The two neighboring previous reflected impulse centering of reflected impulse centering
The latter pulse, which is used as, refers to light, and the previous pulse of the latter reflected impulse centering is as signal light, and the two is in photodetection
Difference interference occurs at device, generates interference beat signal；Interference beat signal exports through photodetector and acquires and control to data
Fabrication is demodulated.
In system of the present invention, optical fiber Fizeau interference arrays include multipair fiber reflection point, each pair of fiber reflection
It is connected with optical fiber between point.
In system of the present invention, fiber reflection point is that either chirp grating or optical fiber are anti-for fiber bragg grating
Exit point is the refractive index catastrophe point as caused by laser irradiating fiber.
In system of the present invention, the first optical frequency shifter and the second optical frequency shifter are acousto-optic modulator.
In system of the present invention, delayer is time delay optical fiber, the length of time delay optical fiber be each pair of fiber reflection point it
Between twice of fiber lengths.
The present invention also provides a kind of optical fiber Fizeau interference arrays distribution vibration sensing methods, include the following steps：
Generate frequency different the first light pulse and the second light pulse；
To the second light pulse into line delay, the second light pulse after delay closes beam with the first light pulse and forms light pulse pair；
Optical pulse strikes generate multiple reflected impulses pair to optical fiber Fizeau interference arrays；
The latter pulse of the two neighboring previous reflected impulse centering of reflected impulse centering, which is used as, refers to light, and the latter is anti-
The previous pulse of pulse centering is penetrated as signal light, difference interference occurs for the two, generates interference beat signal；
Output interference beat signal is simultaneously demodulated.
The beneficial effect comprise that：The light modulation for sending out light source in the present invention is incident on light at dual-pulse
Fine Fizeau interference arrays, generate multiple reflected impulses pair, utilize the two neighboring previous reflected impulse pair of reflected impulse centering
In the latter pulse as with reference to light, the latter reflected impulse centering previous pulse as signal light carrying neighboring reflection
Phase perturbation between point caused by vibration suffered on optical fiber, by controlling optical fiber between pulse distance and neighboring reflection point
Length is identical to realize the interference of reference light and signal light, avoids and carries out interfering caused system using non-equilibrium interfere arm
System noise and the volume for reducing sensor make reference light with signal light in same light path by using Fizeau interference structures
In be transmitted, transmit in different light paths thus because not to overcome reference light and signal optical transport in conventional interference structure
The problems such as unstable with interference fringe caused by external interference；And large-scale sensor is multiplexed on simple optical fiber, detection away from
It is all improved from aspect of performance such as, array scale and measurement sensitivities.
Description of the drawings
Present invention will be further explained below with reference to the attached drawings and examples, in attached drawing：
Fig. 1 is the structural schematic diagram of the embodiment of the present invention；
Fig. 2 is the comparison diagram of measuring results and wave detector testing result；
Specific implementation mode
In order to make the purpose , technical scheme and advantage of the present invention be clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that described herein, specific examples are only used to explain the present invention, not
For limiting the present invention.
Fig. 1 is the structural schematic diagram of one embodiment of the invention, optical fiber Fizeau interference array distributed vibration sensing systems
Including laser light source 1, the first fiber coupler 2, the first optical frequency shifter 4, the second optical frequency shifter 7, the second fiber coupler 11, prolong
When device, optical circulator 13 and optical fiber Fizeau interference arrays 14, the light that laser light source 1 is sent out is divided into through the first fiber coupler 2
Two-beam, light beam and the second beam light generate frequency displacement by the first optical frequency shifter 4, the second optical frequency shifter 7 respectively and are modulated into
Frequency different the first light pulse and the second light pulse, after the second light pulse is delayed using delayer, exist with the first light pulse
Pulse pair is coupled at optical circulator 13, pulse is to entering optical fiber Fizeau interference arrays 14, through optical fiber Fizeau interference arrays
Multiple reflected impulses pair are generated after 14 multiple fiber reflection point reflections, and reflect back into ring of light shape through Fizeau interference arrays 14
Device 13.
The system further includes photodetector 15, data acquisition and control card 17, the first radio-frequency signal source 8 and the second radio frequency
Signal source 9, photodetector 15 are connect with optical circulator 13, data acquisition with control card 17, the first radio-frequency signal source 8 and first
Optical frequency shifter 4 connects, and the second radio-frequency signal source 9 is connect with the second optical frequency shifter 7.Pulse after reflection is to passing through optical circulator 13
Into photodetector 15, difference interference occurs at photodetector 15, generates interference beat signal；Interfere beat signal warp
The output of photodetector 15 is acquired to data to be demodulated with control card 17.
Wherein, the first optical frequency shifter 4 and the second optical frequency shifter 7 select acousto-optic modulator.Time delay optical fiber can be selected in delayer
10, twice of the fiber lengths of the length of time delay optical fiber 10 between each pair of fiber reflection point.
It is f that first beam, which detects light to enter 4 frequency displacement of the first optical frequency shifter by the first connection optical fiber 3 and be modulated into frequency,1+υ
Light pulse after a port 11.1 of the second fiber coupler 11 (3dB) is injected by the second connection optical fiber 5；Second beam
Detection light connects optical fiber 6 into the generation frequency displacement of the second optical frequency shifter 7 by third and is modulated into frequency f2After the light pulse that+υ is
Delay injection is carried out to second port 11.2 of the second fiber coupler by time delay optical fiber 10.
Light arteries and veins is formed after beam is closed in the light pulse of first port and second port input by the second fiber coupler 11 (3dB)
Punching pair is incident on light after the output of the third port 11.3 of the second fiber coupler 11 (3dB) by the 4th section of connection optical fiber 12
The first port 13.1 of circulator 13, the light pulse that the second port 13.2 of optical circulator exports are dry to being incident on optical fiber Fizeau
Relate to array 14.
Optical fiber Fizeau interference arrays include multipair fiber reflection point, and optical fiber is connected between each pair of fiber reflection point.Light
Fine pip can be that either chirp grating or fiber reflection point are the folding as caused by laser irradiating fiber to fiber bragg grating
Penetrate rate catastrophe point.
In one embodiment of the present of invention, optical fiber Fizeau interference arrays are utilized in the method profit that line prepares superweak grating
Be made with drawing optical fibers and online grid dedicated platform processed, inside inscribe 1005 Bragg gratings altogether, Bragg grating it
Between between be divided into 10m, the reflectivity of grating is -35dB--40dB.
The third port 13.3 of optical circulator is connect with photodetector 15, and the electricity output mouth of photodetector 15 passes through
Five connection optical fiber 16 are connected to the input port 17.3 of data acquisition and control card 17, the first control mouth of data acquisition and control card
17.1 connect the control realized to the first radio-frequency signal source, signal processing with the control input port 8.1 of first radio-frequency signal source 8
Realization is connect with the second control mouth 17.2 of control card with the control input port 9.1 of second radio-frequency signal source 9 to the second radio frequency
The control of signal source.
The radio frequency delivery outlet 8.2 of first radio-frequency signal source 8 is connected to the rf input port 4.3 of the first optical frequency shifter；Second
The radio frequency delivery outlet 9.2 of radio-frequency signal source 9 is connected to the rf input port 7.3 of the second optical frequency shifter.
Using frequency different two pulses difference interference occurs for the present invention, by being demodulated to beat signal, obtains
Extraneous vibration signal can be applied in the design of interference type optical fiber hydrophone, can effectively be carried using the demodulation of outer difference detection method
The system detectio sensitivity of high fibre optic hydrophone and dynamic range, while environmental perturbation can be overcome and system can carry letter
Number with roomy.
The method for sensing realized using above-described embodiment optical fiber Fizeau interference array distributed vibration sensing systems, mainly
Include the following steps：
The light that sends out of light that laser light source 1 exports is divided into two beams detection light by the first fiber coupler 2, and respectively first
Beam detects light and the second beam detects light；
First beam detects light and generates frequency displacement into the first optical frequency shifter 4 by the first connection optical fiber 3 and be modulated into frequency
f1The a port 11.1 of the second fiber coupler 11 is injected into after the light pulse of+υ by the second connection optical fiber 5；Second beam
It is f that detection light connects optical fiber 6 to enter 7 device of the second optical frequency shifter to generate frequency displacement and be modulated into frequency by third2The light pulse of+υ
Second port 11.2 of the second fiber coupler is injected by time delay optical fiber 10 afterwards.
4th section of company will be passed through after first port and the light pulse conjunction beam of second port input by the second fiber coupler
Connect the first port 13.1 that optical fiber 12 is incident on optical circulator 13, the optical pulse strikes of the output of second port 13.2 of optical circulator
To optical fiber Fizeau interference arrays 14；
By the light pulse of first Bragg grating reflection to returning to optical circulator, it is emitted from the third port of optical circulator
Enter photodetector by the 5th section of connection optical fiber, electric field strength is expressed as：
E1-2For by the electric-field strength of the latter pulse of the optical time domain reflection pulse centering of first Bragg grating reflection
Degree, c are the light velocity in vacuum, and L is the length of delay line,The total phase introduced for connection optical fiber and time delay optical fiber.
It is to returning to optical circulator, the fiber lengths between two pips by the light pulse of second Bragg grating reflection
l；Enter photodetector from the outgoing of the third port of circulator by the 5th section of connection optical fiber, electric field strength is expressed as:
E2-1For by the electric-field strength of the previous pulse of the optical time domain reflection pulse centering of second Bragg grating reflection
Degree, c are the light velocity in vacuum, the length of l optical fiber between first fiber reflection point and second fiber reflection point, neffFor
The effective refractive index of optical fiber between first fiber reflection point and second fiber reflection point,It is introduced for connection optical fiber total
Phase.
Fiber lengths between time delay optical fiber length and adjacent Bragg grating meet following relationship：
L=2l
The latter light pulse by first pulse centering of first Bragg grating reflection and second Prague light
The previous pulse of the pulse centering of grid reflection forms synchronous difference interference at photodetector, and the two-way after interference detects light
Response I in balanced detector1,2It is represented by：
The output I of detector is：
Here it has ignoredFixed skew.
When the optical fiber between first Bragg grating and second Bragg grating is vibrated, neffIt can become
Change, from the above equation, we can see that the light intensity of interference beat signal c1 changes.Photodetector, data acquisition receive dry with control card
Relate to beat signal c1 and it is demodulated after restore optical fiber institute between first fiber reflection point and second fiber reflection point
The extraneous vibration being subject to.In experiment, one wave detector of placement is detected vibration signal at oscillation point, and Fig. 2 is that system is surveyed
The comparison diagram of result and wave detector testing result is measured, the suffered extraneous vibration signal of system is demodulated out as can be seen from Figure
Come, it is consistent with the vibration signal that wave detector is detected.
Double light arteries and veins liquidate passes through third Bragg grating and the 4th Bragg grating into Fizeau interference arrays
After can repeat above step, generate interference beat signal c2, due to interference beat signal c1 and interfere the reception of beat signal c2
Time is different, it is possible to the interference beat signal of the optical fiber between different adjacent Bragg gratings is measured respectively, thus according to
It is secondary to demodulate extraneous vibration suffered on optical fiber between different adjacent Bragg gratings.
To sum up, the light modulation sent out light source in the present invention is at dual-pulse, before two neighboring reflected impulse centering
The latter pulse of one reflected impulse centering is as the previous pulse with reference to light, the latter reflected impulse centering as signal
Light carries the phase perturbation caused by vibration suffered on optical fiber between neighboring reflection point, by control pulse distance with it is adjacent
Fiber lengths are identical to realize the interference of reference light and signal light between pip, avoid and carried out using non-equilibrium interfere arm
System noise caused by interference and the volume for reducing sensor make reference light and letter by using Fizeau interference structures
Number light is transmitted in same light path, to overcome in conventional interference structure reference light with signal optical transport in different light paths
Middle transmission is multiplexed extensive pass to the problems such as interference fringe is unstable caused by different external interferences on simple optical fiber
Sensor is all improved in aspect of performance such as detection range, array scale and measurement sensitivities.
It should be understood that for those of ordinary skills, it can be modified or changed according to the above description,
And all these modifications and variations should all belong to the protection domain of appended claims of the present invention.
Claims (6)
1. a kind of optical fiber Fizeau interference array distributed vibration sensing systems, which is characterized in that including laser light source, the first light
Fine coupler, the first optical frequency shifter, the second optical frequency shifter, the second fiber coupler, delayer, optical circulator and optical fiber Fizeau
Interference array, the light that laser light source is sent out are divided into two-beam through the first fiber coupler, and light beam and the second beam light lead to respectively
It crosses the first optical frequency shifter, the generation frequency displacement of the second optical frequency shifter and is modulated into frequency different the first light pulse and the second light pulse,
After second light pulse is delayed using delayer, pulse pair, pulse are coupled at the second fiber coupler with the first light pulse
To entering optical fiber Fizeau interference arrays by optical circulator and returning optical circulator through its reflection；
The system further includes photodetector, data acquisition and control card, the first radio-frequency signal source and the second radio-frequency signal source, light
Electric explorer is connect with optical circulator, data acquisition with control card, and the first radio-frequency signal source is connect with the first optical frequency shifter, and second
Radio-frequency signal source is connect with the second optical frequency shifter；The latter pulse of previous reflected impulse centering, which is used as, refers to light, the latter
As signal light, difference interference occurs at photodetector for the two for the previous pulse of reflected impulse centering, generates interference and claps
Frequency signal；Interference beat signal is exported to acquire to data through photodetector and be demodulated with control card.
2. system according to claim 1, which is characterized in that optical fiber Fizeau interference arrays include multipair fiber reflection
Point is connected with optical fiber between each pair of fiber reflection point.
3. system according to claim 2, which is characterized in that fiber reflection point is fiber bragg grating or chirped light
Grid or fiber reflection point are the refractive index catastrophe point as caused by laser irradiating fiber.
4. system according to claim 1, which is characterized in that the first optical frequency shifter and the second optical frequency shifter are acousto-optic modulation
Device.
5. system according to claim 2, which is characterized in that delayer is time delay optical fiber, and the length of time delay optical fiber is every
Twice of fiber lengths between fiber reflection point.
6. a kind of optical fiber Fizeau interference arrays distribution vibration sensing method, which is characterized in that include the following steps：
Generate frequency different the first light pulse and the second light pulse；
To the second light pulse into line delay, the second light pulse after delay closes beam with the first light pulse and forms light pulse pair；
Light pulse is to being incident on optical fiber Fizeau interference arrays, after reflection, the latter pulse of previous reflected impulse centering
As with reference to light, as signal light, difference interference occurs for the two, generates interference for the previous pulse of the latter reflected impulse centering
Beat signal；
Output interference beat signal is simultaneously demodulated.
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| CN112729353A (en) * | 2020-12-03 | 2021-04-30 | 中国地质大学（武汉） | phi-OTDR double-pulse detection system for compensating frequency drift based on interferometer |
| CN113219205B (en) * | 2021-03-24 | 2023-04-25 | 西北大学 | Fiber bragg grating distributed acceleration monitoring device and method |
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