CN106643832A - Phase-sensitive optical time-domain reflectometer based on linear frequency-modulation pulse and measurement method of phase-sensitive optical time-domain reflectometer - Google Patents
Phase-sensitive optical time-domain reflectometer based on linear frequency-modulation pulse and measurement method of phase-sensitive optical time-domain reflectometer Download PDFInfo
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Abstract
The invention relates to a phase-sensitive optical time-domain reflectometer based on a linear frequency-modulation pulse and a measurement method of the phase-sensitive optical time-domain reflectometer. The phase-sensitive optical time-domain reflectometer comprises a laser device, a single side band modulator SSBM, an acoustic optical modulator AOM, an erbium-doped optical fiber amplifier EDFAI, an EDFAII, an arbitrary waveform generator AWG, an optical fiber circulator, a fiber Bragg grating filter FBG, a photoelectric detector, a data collection module and a to-be-measured optical fiber, wherein laser enters the single side band modulator SSBM and is modulated into pulsed light by virtue of the acoustic optical modulator AOM, and the pulsed light is amplified by virtue of the erbium-doped optical fiber amplifier EDFAI and enters the to-be-measured optical fiber through the optical fiber circulator; and a backward Rayleigh scattering signal is output through the optical fiber circulator, a backward Rayleigh scattering optical signal is amplified by virtue of the erbium-doped optical fiber amplifier EDFAII and is detected and converted into an electric signal through the fiber Bragg grating filter FBG, and the data collection module executes data collection and data analysis. By the utilizing linear frequency-modulation pulse, the measurement time is shortened, and the dynamic performance of a system is improved; and the scheme provided by the invention is convenient and feasible, and the structure of the system is relatively simple.
Description
Technical field
The present invention relates to phase sensitive optical time domain reflectometer, more particularly to a kind of phase sensitive based on chirp
Optical time domain reflectometer and measuring method.
Background technology
Distributed Optical Fiber Sensing Techniques using sensor fibre itself simultaneously as information transmitting medium and sensing unit, using elder generation
The method and technology for entering, it is possible to achieve to measuring while external physical quantity at hundreds of thousands point on optical fibre channel, and optical fiber sheet
Body has small volume, lightweight, corrosion-resistant, electric insulation, and low cost is passive, the features such as reelability is good, which dictates that distributed light
Fiber sensor system has unrivaled advantage compared to common electric sensor：Corrosion-resistant, good insulating, anti-strong electromagnetic is done
Disturb；Small volume and lightweight, with plastic profile；Sensitivity is high；Measurement object is extensive；It is easy to networking, is multiplexed；It is with low cost；
Suitable for over long distances, monitoring on a large scale.
Phase sensitive optical time domain reflectometer is passed as one kind of Distributed Optical Fiber Sensing Techniques with above distribution type fiber-optic
The institute of sense technology is advantageous, and in addition phase sensitive optical time domain reflectometer is different from traditional optical time domain reflection technology, what it was used
Narrow linewidth light source, to ensure optical fiber in backward Rayleigh scattering light between it is highly coherent.Meanwhile, narrow linewidth light source ensure that and be
System can respond backward Rayleigh scattering light phase place change information, and Light source line width is narrower, interferes stronger between scattered signal, system
The sensitivity of the extraneous change of response is also higher, by the amplitude information for demodulating backscatter signal, can be to there is external disturbance
Position be accurately positioned, current phase sensitive optical time domain reflectometer technology have been widely used for circumference security monitor neck
Domain.For example, filed in 29 days July in 2011, the Chinese patent " distribution based on Φ-OTDR of Publication No. CN102280001B
The intrusion detection of formula fiber fence and localization method " and filed in 4 days January in 2015, the China of Publication No. CN104574742A
Patent " a kind of optical fiber perimeter safety-protection system based on Φ-OTDR technique ".Although Φ-OTDR technique advantage is numerous, due to
The amplitude of its backscatter signal be by scattered light coherent superposition in pulse width into, due to optical fiber index distribution not
Uniformly, it interferes superposition that there is the quantitative relationship between randomness, therefore changes in amplitude and strain to be difficult to determine, therefore for all
Such as strain, temperature need the physical parameter of quantitative measurment, above technical scheme just cannot realize.
Both at home and abroad researcher seeks corresponding solution for problem above.2009, Yahei researcher proposed to pass through
The method of LASER Light Source frequency sweep is compensated due to phase change caused by strain or temperature so as to which scattered signal waveform is completely extensive
It is multiple, and then strain or the monitoring of temperature accurate quantification are realized, but this technical scheme frequency sweep process is time-consuming longer, it is difficult to realizes dynamic
State strain monitoring (Yahei, Mutsumi, Kenya, Kazuo.Feiber-Optic Distributed Strain and
Temperature Sensing With Very High Measurand Resolution Over Long Range Using
Coherent OTDR[J].IEEE Journal of Lightwave Technology.2009,27(9):1142-1146.)。
Another kind of technical scheme is the phase place by demodulating backward Rayleigh scattering light, the quantitative pass set up between phase place and strain or temperature
System, and then realize quantitative measurment.For example, filed in September in 2015 18 days, the Chinese patent of Publication No. CN105222815A
" the phase sensitive optical time domain reflectometer based on 120 degree of difference interferometers ", and demodulated using coherent detection and IQ demodulation techniques
Backward Rayleigh scattering light phase, realization is received and strains quantitative measurment (Dong Yongkang, et al.Quantitative
measurement of dynamic nanostrain based on a phase-sensitive optical time
domain reflectometer[J].Applied Optics,2016,55(28):7810-7815.), but both the above skill
Art scheme needs demodulation phase information, therefore its system architecture and demodulation method comparison are complicated.
The content of the invention
The purpose of the present invention is for the problems such as current technical scheme dynamic property is low, demodulation techniques are complicated, there is provided a kind of
Phase sensitive optical time domain reflectometer and measuring method based on chirp, with simple structure, demodulation techniques are convenient can
Row, in real time dynamic distributed phase sensitive optical time domain reflectometer, are applicable to the real-time dynamic quantitative prison of strain, temperature, vibration
Survey.
Inventive technique scheme：
A kind of phase sensitive optical time domain reflectometer based on chirp, including laser instrument, single side-band modulator
SSBM, acousto-optic modulator AOM, erbium-doped optical fiber amplifier EDFA 1, erbium-doped optical fiber amplifier EDFA 2, AWG AWG,
Optical fiber circulator, fiber Bragg grating filter FBG, photodetector, data acquisition module and testing fiber；
The output end of the laser instrument is connected with the input of single side-band modulator SSBM, for laser instrument output
The single-frequency continuous laser of narrow linewidth is entered in single side-band modulator SSBM；
The AWG AWG is located at single side-band modulator SSBM top, for AWG
The microwave signal of AWG output frequency linear changes is loaded in single side-band modulator SSBM；The AWG AWG is also
It is connected with the acousto-optic modulator AOM, continuous laser is modulated to into pulse for AWG AWG output pulse signals
Light；
The output end of single side-band modulator SSBM is connected with the input of the acousto-optic modulator AOM, for laser
Carry out being entered in acousto-optic modulator AOM after linear frequency modulation；
The output end of the acousto-optic modulator AOM is connected with the input of the EDFA Erbium-Doped Fiber Amplifier EDFA1, described to mix
The output end of bait fiber amplifier EDFA1 is connected with the output port of the optical fiber circulator first, for pulsed light to be passed through into institute
State erbium-doped optical fiber amplifier EDFA 1 to be amplified power, then enter to be measured by the output port of the optical fiber circulator first
Optical fiber；
The output port of the optical fiber circulator the 3rd is connected with the input of EDFA Erbium-Doped Fiber Amplifier EDFA2, passes through afterwards
The backward Rayleigh scattering optical signal of erbium-doped optical fiber amplifier EDFA 2 pairs is amplified；
The input of the output end of the EDFA Erbium-Doped Fiber Amplifier EDFA2 and the fiber Bragg grating filter FBG
Connection, the output end of the fiber Bragg grating filter FBG is connected with the input of the photodetector, for described
Fiber Bragg grating filter FBG filters spontaneous emission noise, and photodetector detection described in Jing is converted into electric signal；
The output end of the photodetector is connected with the data acquisition module, is carried out by the data acquisition module
Data acquisition and data analysis；The chirped microwave signal of the AWG AWG synchronism outputs and pulse simultaneously
Modulated signal, synchronous trigger data acquisition module carries out data acquisition.
Further：When chirp light is propagated in the testing fiber, Rayleigh scattering effect will constantly occur,
And backward Rayleigh scattering light interferes superposition in pulse width, backward Rayleigh scattering optical signal passes through the optical fiber circulator
Second output port, and from the output of the port of the optical fiber circulator 3.
Further：Laser pulse employs linear frequency modulation, and in pulse width, laser frequency is to change linearly over time
's.Further：Using AWG AWG with a width of 32GHz, but be limited to bandwidth and the spy of single side-band modulator
Device bandwidth is surveyed, actual linear FM bandwidth is 20GHz.
Further：Centre wavelength difference 1-10nm between the optical fiber bragg grating FBG.
A kind of measuring method of the phase sensitive optical time domain reflectometer based on chirp, comprises the following steps：Step
Rapid one, laser is entered in single side-band modulator SSBM；Step 2, AWG AWG output frequency linear changes
Microwave signal is loaded in single side-band modulator SSBM；Enter in acousto-optic modulator AOM after step 3, laser linear frequency modulation；Step
Rapid four, continuous laser is modulated to into pulsed light, is amplified by EDFA Erbium-Doped Fiber Amplifier EDFAI；Step 5, by fiber optic loop
The output port of shape device first enters testing fiber；Step 6, backward Rayleigh scattering signal pass through the output end of optical fiber circulator second
Mouthful, exported by the output port of optical fiber circulator the 3rd；Step 7, EDFA Erbium-Doped Fiber Amplifier EDFAII are to backward Rayleigh scattering light
Signal is amplified；Step 8, fiber Bragg grating filter FBG filter spontaneous emission noise, the detection of Jing photodetectors
Electric signal is converted into, data acquisition and data analysis are carried out by data acquisition module；Step 9, AWG AWG
The chirped microwave signal of synchronism output and pulse-modulated signal, and synchronous trigger data acquisition module carries out data acquisition.
The present invention has the advantages that for prior art：During a kind of phase sensitive light based on chirp
Domain reflectometer, using chirp rather than sweep method, reduces time of measuring, substantially increases the dynamic of system
Energy；Linear frequency modulation to continuous laser is realized using the scheme of external modulation, be it is advantageous that and be can ensure that frequency change with good
The good linearity, certainty of measurement of the lift system to strain/temperature；The AWG AWG for adopting in addition is with a width of
32GHz, but the bandwidth and detector bandwidth of single side-band modulator are limited to, actual linear FM bandwidth is 20GHz, is expanded significantly
Strain/the temperature measurement range of system is opened up；The strength information of backward Rayleigh scattering signal need to be only measured in the present invention program, no
Further demodulating algorithm, the present invention program is needed to facilitate feasible, system architecture is also fairly simple.
Description of the drawings
Fig. 1 is the structural representation of the embodiment of the present invention；
Fig. 2 is backward Rayleigh scattering waveform diagram of the chirp Jing after testing fiber scattering；
Fig. 3 be apply it is differently strained in the case of backward Rayleigh scattering waveform translation experimental result schematic diagram；
1- laser instruments in figure；2- single side-band modulators SSBM；3- acousto-optic modulator AOM；4- erbium-doped fiber amplifiers
EDFAI；5- erbium-doped optical fiber amplifier EDFA II；6- AWG AWG；7- optical fiber circulators；8- optical fiber Bragg light
Grating filter FBG；9- photodetectors；10- data acquisition modules；11- testing fibers.
Specific embodiment
Below with reference to accompanying drawing, the present invention is described in detail.
A kind of phase sensitive optical time domain reflectometer based on chirp, including laser instrument 1, single side-band modulator
SSBM2, acousto-optic modulator AOM3, erbium-doped optical fiber amplifier EDFA I4, erbium-doped optical fiber amplifier EDFA II5, random waveform occur
Device AWG6, optical fiber circulator 7, fiber Bragg grating filter FBG8, photodetector 9, data acquisition module 10 and to be measured
Optical fiber 11；
The output end of the laser instrument 1 is connected with the input of single side-band modulator SSBM2, defeated for laser instrument 1
The single-frequency continuous laser of the narrow linewidth for going out is entered in single side-band modulator SSBM2；
The AWG AWG6 is located at single side-band modulator SSBM2 top, for random waveform generation
The microwave signal of device AWG6 output frequency linear changes is loaded in single side-band modulator SSBM2；The AWG
AWG6 is also connected with the acousto-optic modulator AOM3, adjusts continuous laser for AWG AWG6 output pulse signals
It is made as pulsed light；
The output end of single side-band modulator SSBM2 is connected with the input of the acousto-optic modulator AOM3, for swashing
Light carries out being entered in acousto-optic modulator AOM3 after linear frequency modulation；
The output end of the acousto-optic modulator AOM3 is connected with the input of the EDFA Erbium-Doped Fiber Amplifier EDFAI4, described
The output end of EDFA Erbium-Doped Fiber Amplifier EDFAI4 is connected with the output port of the optical fiber circulator 7 first, for pulsed light to be led to
Cross the erbium-doped optical fiber amplifier EDFA I4 to be amplified power, then entered by the output port of the optical fiber circulator 7 first
Enter testing fiber 11；
The output port of the optical fiber circulator 7 the 3rd is connected with the input of EDFA Erbium-Doped Fiber Amplifier EDFAII5, Zhi Houtong
Cross erbium-doped optical fiber amplifier EDFA II5 to be amplified backward Rayleigh scattering optical signal；
The input of the output end of the EDFA Erbium-Doped Fiber Amplifier EDFAII5 and the fiber Bragg grating filter FBG8
End connection, the output end of the fiber Bragg grating filter FBG8 is connected with the input of the photodetector 9, is used for
The fiber Bragg grating filter FBG8 filters spontaneous emission noise, and the detection of photodetector 9 described in Jing is converted into telecommunications
Number；
The output end of the photodetector 9 is connected with the data acquisition module 10, by the data acquisition module
10 carry out data acquisition and data analysis；The simultaneously chirped microwave signal of the AWG AWG6 synchronism outputs
And pulse-modulated signal, synchronous trigger data acquisition module 10 carries out data acquisition.
Specifically, when chirp light is propagated in the testing fiber, Rayleigh scattering effect will constantly occur, and
Backward Rayleigh scattering light interferes superposition in pulse width, and backward Rayleigh scattering optical signal passes through the optical fiber circulator 7
Second output port, and from the output of the output port of the optical fiber circulator 7 the 3rd.
Specifically, laser pulse employs linear frequency modulation, and in pulse width, laser frequency is to change linearly over time
's.
Specifically, the AWG AWG6 of employing is with a width of 32GHz, but is limited to the bandwidth of single side-band modulator
And detector bandwidth, actual linear FM bandwidth is 20GHz.
Specifically, the centre wavelength difference 1-10nm between the optical fiber bragg grating FBG 8.
Laser light incident will constantly occur Rayleigh scattering effect in sensor fibre, be detected by detector, data acquisition module
Block is gathered, and can obtain its scattered signal waveform.When the external world has strain to be applied on optical fiber, then at the position optical fiber refraction
Rate will change, and scattered signal waveform will change.It is this that laser can be passed through by waveform change caused by strain
Frequency change compensating, waveform is recovered completely.Used in due to sensor plan is chirp, i.e., in pulse
Optical frequency is linear change with the time in width.Therefore, finally may be used by the change of optical fiber position refractive index caused by strain
To be embodied in the translation of backward Rayleigh scattering waveform at the position, the big of strain can be determined by the translational movement of measured waveform
It is little.Theory analysis in detail is as follows：
Under without strained situation, it is considered in the single quasi- monochromatic pulses cycle, ignore fiber transmission attenuation, to Rayleigh after optical fiber
The one-dimensional pulse response model of scattering light amplitude can be expressed as：
A in formulaiFor scattering coefficient, ν0The centre frequency of the monochromatic pulses that are defined light, τiDissipate for i-th in the individual pulse cycle
The time delay of pulsed light is penetrated, N is the scattering center number of whole sensor fibre, and W is pulse width,Represent light
The change of pulse scattering volume in communication process, whenWhen,WhenOr
When,
The luminous power expression formula of backward Rayleigh scattering light is drawn by formula (1)：
φ in formula (2)ijIndicate without i-th backward Rayleigh scattering ripple during strain and j-th backward scattered wave scattering center
Relative phase difference, time delay τiWith i-th scattering center position ziRelation be τi=2nzi/ c, n are effectively reflected for optical fiber
Rate, c is the light velocity in vacuum.φijThe form that embodies be：
φij=2 π ν0(τi-τjThe π ν of)=40n(zi-zj)/c (3)
From formula (2) and formula (3), strain will cause optical fibre refractivity n to change, relative phase difference φijAlso therewith
Change, and then backward Rayleigh scattering photosignal waveform also changes therewith, now can be made up by changing laser frequency due to
The change of waveform caused by strain.As optical fibre refractivity variable quantity △ n ＜ ＜ n, △ n and laser frequency variable quantity △ ν are present
Linear relationshipSimultaneously there is linear relationship △ n=C in optical fibre refractivity variable quantity △ n and dependent variable △ εε△ ε,
Wherein, CεCan be expressed as the relation between the refractive index coefficient of strain, therefore dependent variable △ ε and laser frequency variable quantity △ ν：
In the present invention, laser pulse employs linear frequency modulation, i.e., in pulse width, laser frequency is linearly over time
Change, it is represented byδ ν are linear FM bandwidth, and both members take differential, can obtain simultaneously
Bring formula (4) into, can obtain：
From formula (5), by way of the chirp that this programme is taken, can set up dependent variable △ ε and when
Between linear relationship between variable quantity △ t, therefore can by time of measuring variable quantity △ t, i.e., backward Rayleigh scattering waveform it is flat
Shifting amount quantitative determining dependent variable △ ε, in the same manner, also can quantitative measurment temperature variation △ T using this kind of scheme.
The single-frequency continuous laser of the narrow linewidth of laser instrument output is entered in single side-band modulator SSBM, AWG
The microwave signal of output frequency linear change is loaded in single side-band modulator SSBM, and to laser linear frequency modulation is carried out, it is laggard
In entering acousto-optic modulator AOM, continuous laser is modulated to pulsed light by AWG output pulse signal, by er-doped light
Fiber amplifier EDFA1 is amplified pulse luminous power, and by the output port of optical fiber circulator first testing fiber is entered；
When chirp light is propagated in testing fiber, Rayleigh scattering effect, backward Rayleigh scattering will constantly occur
Light interferes superposition in pulse width, backward Rayleigh scattering optical signal by the output port of optical fiber circulator second, and from
The output port of optical fiber circulator the 3rd is exported, and is entered by 2 pairs of backward Rayleigh scattering optical signals of erbium-doped optical fiber amplifier EDFA afterwards
Row amplifies, and filters spontaneous emission noise by fiber Bragg grating filter FBG, after the detection conversion of Jing photodetectors
For electric signal, data acquisition and data analysis are carried out by data acquisition module；
The chirped microwave signal of AWG AWG synchronism outputs and pulse-modulated signal, and synchronously trigger
Data acquisition module carries out data acquisition.
Fig. 3 be apply it is differently strained in the case of backward Rayleigh scattering waveform translation experimental result schematic diagram.Optical fiber in experiment
Length is 50m, and at optical fiber 10m-20m, stress is applied to optical fiber makes optical fiber produce strain.1n ε represent unit length for 1m's
There is strain size produced during 1nm deformation (elongating or shortening) in optical fiber.As shown in figure 3, at optical fiber 10m-20m, to light
Fine uniform applying strain, at this there is from right to left uniform movement in scattered signal waveform, therefore can be by measuring scattered signal ripple
The linear relationship that the translational movement of shape is set up between dependent variable and translational movement, and then realize the quantitative measurment of strain.Do not apply in optical fiber
Plus the region of strain, scattering waveform is completely superposed, therefore can realize the distributed quantitative measurment for straining.Above experimental result is managed
It coincide by analysis result, further demonstrates the feasibility of the program.
It is an advantage of the current invention that using chirp rather than sweep method, reducing time of measuring, greatly improve
The dynamic property of system；Linear frequency modulation to continuous laser is realized using the scheme of external modulation, be it is advantageous that and be can ensure that
Frequency change has the good linearity, certainty of measurement of the lift system to strain/temperature；The random waveform for adopting in addition occurs
Device AWG is limited to the bandwidth and detector bandwidth of single side-band modulator with a width of 32GHz, and actual linear FM bandwidth is
20GHz, greatly expands the strain/temperature measurement range of system；The intensity of backward Rayleigh scattering signal need to be only measured in scheme
Information, it is not necessary to further demodulating algorithm, therefore demodulation scheme facilitates feasible, system architecture is also fairly simple.
Claims (6)
1. a kind of phase sensitive optical time domain reflectometer based on chirp, it is characterised in that including laser instrument (1), single
Sideband modulator SSBM (2), acousto-optic modulator AOM (3), erbium-doped optical fiber amplifier EDFA 1 (4), erbium-doped optical fiber amplifier EDFA 2
(5), AWG AWG (6), optical fiber circulator (7), fiber Bragg grating filter FBG (8), photodetector
(9), data acquisition module (10), testing fiber (11)；
The output end of the laser instrument (1) is connected with the input of single side-band modulator SSBM (2), for laser instrument (1)
The single-frequency continuous laser of the narrow linewidth of output is entered in single side-band modulator SSBM (2)；
The AWG AWG (6) occurs positioned at single side-band modulator SSBM (2) top for random waveform
The microwave signal of device AWG (6) output frequency linear change is loaded in single side-band modulator SSBM (2)；The random waveform is sent out
Raw device AWG (6) is also connected with the acousto-optic modulator AOM (3), will for AWG AWG (6) output pulse signal
Continuous laser is modulated to pulsed light；
The output end of single side-band modulator SSBM (2) is connected with the input of the acousto-optic modulator AOM (3), for swashing
Light carries out being entered in acousto-optic modulator AOM (3) after linear frequency modulation；
The output end of the acousto-optic modulator AOM (3) is connected with the input of the EDFA Erbium-Doped Fiber Amplifier EDFAI (4), described
The output end of EDFA Erbium-Doped Fiber Amplifier EDFAI (4) is connected with the output port of the optical fiber circulator (7) first, for by pulse
Light is amplified power by the erbium-doped optical fiber amplifier EDFA I (4), then defeated by the optical fiber circulator (7) first
Exit port enters testing fiber (11)；
The output port of the optical fiber circulator (7) the 3rd is connected with the input of EDFA Erbium-Doped Fiber Amplifier EDFAII (5), by mixing
Doped fiber amplifier EDFAII (5) is amplified to backward Rayleigh scattering optical signal；
The input of the output end of the EDFA Erbium-Doped Fiber Amplifier EDFAII (5) and the fiber Bragg grating filter FBG (8)
End connection, the output end of the fiber Bragg grating filter FBG (8) is connected with the input of the photodetector (9),
Spontaneous emission noise is filtered for the fiber Bragg grating filter FBG (8), photodetector (9) detection described in Jing turns
Turn to electric signal；
The output end of the photodetector (9) is connected with the data acquisition module (10), by the data acquisition module
(10) data acquisition and data analysis are carried out；The simultaneously chirped microwave of AWG AWG (6) synchronism output
Signal and pulse-modulated signal, synchronous trigger data acquisition module (10) carries out data acquisition.
2. a kind of phase sensitive optical time domain reflectometer based on chirp according to claim 1, its feature exists
In, when chirp light is propagated in the testing fiber, Rayleigh scattering will constantly occur and act on, and backward Rayleigh scattering
Light interferes superposition in pulse width, and backward Rayleigh scattering optical signal is by the output end of the optical fiber circulator (7) second
Mouthful, and from the output of the output port of the optical fiber circulator (7) the 3rd.
3. a kind of phase sensitive optical time domain reflectometer based on chirp according to claim 2, its feature exists
In laser pulse employs linear frequency modulation, and in pulse width, laser frequency changes linearly over time.
4. a kind of phase sensitive optical time domain reflectometer based on chirp according to claim 3, its feature exists
In the AWG AWG (6) of employing is limited to the bandwidth and detector strip of single side-band modulator with a width of 32GHz
Width, actual linear FM bandwidth is 20GHz.
5. a kind of phase sensitive optical time domain reflectometer based on chirp according to claim 4, its feature exists
In the centre wavelength difference 1-10nm between the optical fiber bragg grating FBG (8).
6. a kind of measurement side of the phase sensitive optical time domain reflectometer based on chirp being based on described in claim 1
Method, it is characterised in that comprise the following steps：Step one, laser are entered in single side-band modulator SSBM (2)；Step 2, arbitrarily
The microwave signal of waveform generator AWG (6) output frequency linear change is loaded in single side-band modulator SSBM (2)；Step 3,
Enter in acousto-optic modulator AOM (3) after laser linear frequency modulation；Step 4, continuous laser is modulated to into pulsed light, by mixing bait light
Fiber amplifier EDFAI (4) is amplified；Step 5, testing fiber is entered by the output port of optical fiber circulator (7) first
(11)；Step 6, backward Rayleigh scattering signal by the output port of optical fiber circulator (7) second, by optical fiber circulator (7) the
Three output ports are exported；Step 7, EDFA Erbium-Doped Fiber Amplifier EDFAII (5) are amplified to backward Rayleigh scattering optical signal；Step
Rapid eight, fiber Bragg grating filter FBG (8) filters spontaneous emission noise, and Jing photodetectors (9) detection is converted into telecommunications
Number, data acquisition and data analysis are carried out by data acquisition module (10)；Step 9, AWG AWG (6) are synchronous
The microwave signal and pulse-modulated signal of output linearity frequency modulation, and synchronous trigger data acquisition module (10) carries out data acquisition.
Priority Applications (1)
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| CN107329162A (en) * | 2017-08-04 | 2017-11-07 | 上海交通大学 | Gamma radiation real-time measurement apparatus and its system based on Bragg grating |
| CN108801153A (en) * | 2018-06-20 | 2018-11-13 | 苏州六幺四信息科技有限责任公司 | Optical fibre length measurement method and measuring device |
| CN109039438A (en) * | 2018-06-19 | 2018-12-18 | 武汉邮电科学研究院有限公司 | A kind of optical fiber link detection system and method based on digital chirp signal |
| CN109217919A (en) * | 2018-11-01 | 2019-01-15 | 哈尔滨工业大学 | Based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace and measurement method |
| CN109238321A (en) * | 2018-11-01 | 2019-01-18 | 哈尔滨工业大学 | Based on the relevant phase-sensitive optical time domain reflectometer of multifrequency time domain and measurement method |
| CN109443590A (en) * | 2018-11-01 | 2019-03-08 | 哈尔滨工业大学 | Phase sensitivity type OTDR and measurement method based on frequency-airspace matching and injection locking technique |
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| CN112697181A (en) * | 2020-12-02 | 2021-04-23 | 广东工业大学 | Phase sensitive optical time domain reflection device and method based on frequency modulation |
| CN113804282A (en) * | 2021-09-02 | 2021-12-17 | 太原理工大学 | Frequency-stabilized phase-sensitive optical time domain reflectometer modulated by microwave |
| CN113804282B (en) * | 2021-09-02 | 2023-05-26 | 太原理工大学 | Microwave-modulated frequency-stabilizing phase-sensitive optical time domain reflectometer |
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| CN114543973A (en) * | 2022-02-28 | 2022-05-27 | 华中科技大学 | Distributed ultrahigh frequency vibration signal measuring method and optical fiber sensor |
| CN114543973B (en) * | 2022-02-28 | 2023-07-25 | 华中科技大学 | Distributed ultrahigh frequency vibration signal measurement method and optical fiber sensor |
| CN114777901A (en) * | 2022-04-18 | 2022-07-22 | 江苏朗普达光电科技有限公司 | Interference type optical fiber hydrophone system and linear frequency modulation method thereof |
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| EP4390523A1 (en) * | 2022-12-23 | 2024-06-26 | NKT Photonics A/S | Optical intensity modulation apparatus |
| WO2024133241A1 (en) * | 2022-12-23 | 2024-06-27 | Nkt Photonics A/S | Optical intensity modulation apparatus and laser systems |
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