CN105784190B - A kind of differential type temperature sensor based on stimulated Brillouin effect - Google Patents
A kind of differential type temperature sensor based on stimulated Brillouin effect Download PDFInfo
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- CN105784190B CN105784190B CN201410815888.4A CN201410815888A CN105784190B CN 105784190 B CN105784190 B CN 105784190B CN 201410815888 A CN201410815888 A CN 201410815888A CN 105784190 B CN105784190 B CN 105784190B
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Abstract
The present invention provides a kind of differential type temperature sensor based on stimulated Brillouin effect, light generates the continuous light that unit generates and obtains the signal comprising stokes light and anti-Stokes light by the first modulation amplifying unit, then phase modulated signal is generated by the second modulation amplifying unit, the modulated signal filters out stokes light and anti-Stokes light by filter, stokes light is after time delay optical fiber and anti-Stokes light passes through the extraction after three-dB coupler synthesis all the way optical signal by polarizer progress polarised light, the polarised light of extraction modulates amplifying unit by third and obtains pumping pulse light, it is then injected into the beginning of sensor fibre；The detection light of another wing is squeezed into after scrambler is by an isolator from sensor fibre tail end, occurs to be converted into electric signal by photodetector by circulator after excited Brillouin acts on pumping pulse light in optical fiber.The present invention can realize higher temperature resolution and longer distance sensing under the premise of high spatial resolution.
Description
Technical field
The present invention relates to temperature or strain gauge technical field more particularly to a kind of differences based on stimulated Brillouin effect
Fraction temperature sensor.
Background technique
Distributed fiber optic temperature, stress sensing system based on stimulated Brillouin effect are using light wave as transducing signal, with light
Fibre is transmission medium, perception and the extraneous dut temperature of detection or stress signal, it not only has the advantages that general fibre optical sensor,
And the continuously distributed information of temperature or stress at any time with space can be obtained simultaneously.Since optical fiber itself is not charged, volume
Small, light weight, flexible, electromagnetism interference, radiation resistance are good, can especially be suitble to dry in inflammable, explosive and strong electromagnetic
It disturbs etc. and to be used under adverse circumstances, so that it is in the following smart grid, Oilfield Pipelines security monitoring, the weight such as communication line attack early warning
Field is wanted to have a wide range of applications demand.
Currently, the sensor-based system based on stimulated Brillouin effect specifically include that Brillouin light domain reflectometer (BOTDR),
Brillouin optical time domain analysis (BOTDA), Brillouin light frequency-domain analysis (BOFDA).Wherein, BOTDA is high with its measurement accuracy, and compared with
Short response time and receive extensive attention and study.Its basic principle can be summarized as: have the pumping pulse light of fixed frequency difference
Cause optical fibre refractivity at any time by electrostriction effect in the place that optical fiber meets with the continuous probe light of reverse transfer and
Space periodicity rises and falls, and is excited acoustic wavefield to generate, and under the action of the acoustic wavefield, energy occurs between pump light and detection light
The transfer of amount forms stimulated Brillouin scattering.Lorentz lorentz type of the continuous light under different frequency difference is obtained by constantly frequency sweep
Gain spectral, the gain spectral obtain maximum at Brillouin shift, and experiment discovery Brillouin shift and temperature or stress have pole
Strong linear dependence.Therefore, as long as detecting that the variation of Brillouin shift in optical fiber can be obtained by temperature or stress in light
Distribution on fibre.When realizing that the system needs the key technical indexes solved to include: spatial resolution, temperature resolution, measurement
Between, measurement distance.
In order to effectively promote above-mentioned four indices, the various improvement projects in recent years based on traditional BOTDA system are answered
It transports and gives birth to.Specifically include that it is lower to be previously implanted power before pumping pulse enters sensor fibre for pre- pumping method, this method
One section of long pulse, such that prepulsing just generates the phonon of stable state with detection light action before pumping pulse arrival.
This method effectively breaches limitation of the phonon relaxation time to spatial resolution, improves spatial resolution；Dark pulse method, with
Bright pulse is on the contrary, pumping when no pulse has stronger power, and pumping has extremely low function when having pulse
Rate.In this way before dark pulse arrival, phonon can be full of whole section of sensor fibre, and the brillouin gain that detection light obtains whole section of optical fiber is total
With, once dark pulse arrive, detection light will lack the corresponding brillouin gain in dark pulse part, to realize higher space
Resolution ratio；π impulse method, this method is similar with dark pulse method, is only identical with other parts power by dark pulse partial replacement
π phase impulse.Equally, when π pulse arrives, detection light missing is not only that the corresponding Brillouin in dark pulse part increases
Benefit, and there are also bring gain on light is detected since π pulse-echo is added to, signal-to-noise ratio has the promotion for showing play, about
2 times of dark pulse；Differential pulse is to method, i.e., with the BOTDA scheme measurement 2 for having two pairs of pulse pairs of small difference in pulse width traditional
Secondary, the difference of 2 measuring signals is brillouin gain corresponding to the tiny differential pulse.The program is theoretically available
Ultimate attainment spatial resolution, and avoid the brillouin gain spectrum widening problem as caused by short pulse and phonon relaxation
Limitation.
In realizing process of the present invention, at least there are the following problems in the prior art for inventor's discovery:
Traditional BOTDA system, due to being limited by phonon relaxation, when pulse width can not be less than phonon relaxation
Between, it otherwise will lead to phonon and stable state be not achieved, signal-to-noise ratio is caused to decline, brillouin gain spectrum widening, frequency resolution reduces, this
Sample significantly limits further increasing for spatial resolution.Pre- pumping method is by one section of pulse of pre- pumping in advance to a certain degree
On solve the limitation of phonon relaxation, but distance sensing is limited, and the sensing of long range will lead to Brillouin's increasing of pulse pedestal
Benefit is greater than pulse bring gain itself.Dark pulse method due to the pumping pulse of dark pulse part and detection light between almost without
Inspire phonon, cause within a period of time after dark pulse, due to phonon deficiency and produce the damage of brillouin gain
It loses, i.e., " secondary echo ", and then the error for calculating Brillouin shift can be made to increase.And impulse method is although its signal-to-noise ratio
It doubles than dark pulse, but still will receive defect same with dark pulse, influence the practicability of system.As for differential pulse pair
Method can obtain high spatial resolution and frequency resolution and long-distance sensing really, but due to needing to measure 2 times, consume
Duration, response time are 2 times of traditional BOTDA.
Summary of the invention
(1) technical problems to be solved
The present invention proposes a kind of differential type temperature sensor based on stimulated Brillouin effect, while realizing high-space resolution
Rate and long measurement Distance-sensing, realize higher frequency resolution.
(2) technical solution
In order to solve the above technical problems, the present invention provides a kind of differential type temperature sensing based on stimulated Brillouin effect
Device, comprising:
For generate pump light and detect light light generate unit, first modulation amplifying unit, second modulation amplifying unit,
Filter, time delay optical fiber, three-dB coupler, the polarizer, third modulate amplifying unit, scrambler, isolator, sensor fibre, annular
Device and photodetector；
The light generates the pump light that unit generates and is obtained by the first modulation amplifying unit progress double sideband modulation
Then signal comprising stokes light and anti-Stokes light carries out phase-modulation by the second modulation amplifying unit, obtains
Phase modulated signal, the phase modulated signal filters out stokes light and anti-Stokes light by the filter, described
Stokes light passes through the three-dB coupler and synthesizes optical signal all the way after the time delay optical fiber with the anti-Stokes light
The extraction of polarised light is carried out by the polarizer afterwards, the polarised light extracted is modulated amplifying unit by the third and carried out in advance
If the modulation and amplification of intensity obtain pumping pulse light, the pumping pulse light is injected to the first end of the sensor fibre；
The light generates the detection light that unit generates and injects the sensing by the isolator after the scrambler
The other end of optical fiber passes through the annular after excited Brillouin effect occurs with the pumping pulse light in the sensor fibre
Device is transferred to the photodetector, is converted into electric signal by the photodetector.
Preferably, the differential type temperature sensor based on stimulated Brillouin effect further includes oscillograph, with the light
The output end of electric explorer connects, and the electric signal for being formed to the photodetector carries out output and shows.
Preferably, it includes sequentially connected laser and fiber coupler that the light, which generates unit, and the laser is used for
Launch wavelength is 1550nm, and power is the laser of 15.5dBm, and the fiber coupler is used for the laser for emitting the laser
It is divided into pump light and detection light.
Preferably, the splitting ratio of the fiber coupler is 10:90.
Preferably, the first modulation amplifying unit includes sequentially connected first electrooptic modulator and the first fiber amplifier
Device；
First electrooptic modulator is used to pump light being modulated to suppressed-carrier double side band signal, described bilateral to take a message
Number include stokes light and anti-Stokes light, the double-sideband signal by first fiber amplifier carry out signal put
Greatly.
Preferably, the second modulation amplifying unit includes sequentially connected second electrooptic modulator and the second fiber amplifier
Device；
Second electrooptic modulator is used to carry out phase to the double-sideband signal of the first modulation amplifying unit output
It modulates, the signal after phase-modulation carries out signal amplification by second fiber amplifier.
Preferably, the third modulation amplifying unit includes sequentially connected third electrooptic modulator and third fiber amplifier
Device；
The polarised light that the third electrooptic modulator is used to extract the polarizer carries out the intensity tune that width is 60ns
System, obtains pumping pulse light, the pumping pulse light is amplified by third fiber amplifier.
Preferably, the differential type temperature sensor based on stimulated Brillouin effect further includes several Polarization Controls
Device, several described Polarization Controllers keep identical peak power for controlling the stokes light and anti-Stokes light
Enter the third electrooptic modulator with polarization state.
Preferably, the sensor fibre is single mode optical fiber.
(3) beneficial effect
Differential type temperature sensor provided by the invention based on stimulated Brillouin effect, so that sensor can only detect
The difference component of temperature change on optical fiber, that is where the change detection light of where is it temperature will undergo brillouin gain,
And when there is no temperature change, the brillouin gain difference of detection light experience remains 0.And in no increase time of measuring
Under the premise of, the present invention can be achieved at the same time high spatial resolution and long measurement Distance-sensing, it is often more important that it is to temperature change
And its it is sensitive, it can be realized higher frequency resolution.
Detailed description of the invention
The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, and attached drawing is schematically without that should manage
Solution is carries out any restrictions to the present invention, in the accompanying drawings:
Fig. 1 is a kind of structural block diagram of the differential type temperature sensor based on stimulated Brillouin effect proposed by the present invention；
Fig. 2 is that a kind of working principle of the differential type temperature sensor based on stimulated Brillouin effect proposed by the present invention is shown
It is intended to；
Fig. 3 is a kind of experiment for differential type temperature sensor based on stimulated Brillouin effect that the embodiment of the present invention proposes
Conceptual scheme；
Fig. 4 (a) is showing for the three-dimensional brillouin gain spectrum scanned in the embodiment of the present invention with the frequency interval of 2KHz
It is intended to；
Fig. 4 (b) be in the embodiment of the present invention brillouin gain that is scanned with the frequency interval of 2KHz with frequency and position
Set the three-dimensional figure of variation；
Fig. 5 (a) is in the embodiment of the present invention when temperature variant area and the Brillouin shift difference in temperature-resistant region are
The three-dimensional brillouin gain spectrum schematic diagram emulated when 1MHz；
Fig. 5 (b) is existing π impulse method when the Brillouin shift difference in temperature variant area and temperature-resistant region is 1MHz
When the three-dimensional brillouin gain spectrum schematic diagram that emulates
Fig. 6 be the embodiment of the present invention in temperature variant area end (at 13.7m) three typical frequencies at Brillouin
The time-domain curve of gain；
Fig. 7 (a) is for the embodiment of the present invention from existing π impulse method for different temperature variant areas and temperature-resistant region
Interior Brillouin shift difference is in the corresponding brillouin gain spectrum in the place 13.7m；
Fig. 7 (b) is the schematic diagram that the Fitting Calculation of the embodiment of the present invention obtains the Brillouin shift in temperature variant area.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is
A part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art
Every other embodiment obtained without making creative work, shall fall within the protection scope of the present invention.
Fig. 1 is a kind of structural block diagram of the differential type temperature sensor based on stimulated Brillouin effect proposed by the present invention,
As shown in Figure 1, comprising:
Light for generating pump light and detection light generates unit 1, first and modulates the modulation amplification list of amplifying unit 2, second
Member 3, filter 4, time delay optical fiber 5, three-dB coupler 6, the polarizer 7, third modulation amplifying unit 8, scrambler 9, isolator 10,
Sensor fibre 11, circulator 12 and photodetector 13；
The light generates the pump light that unit 1 generates and is obtained by the first modulation progress of amplifying unit 2 double sideband modulation
To the signal comprising stokes light and anti-Stokes light, phase-modulation is then carried out by the second modulation amplifying unit 3, is obtained
To phase modulated signal, the phase modulated signal filters out stokes light and anti-Stokes light by the filter 4, institute
Stokes light is stated after the time delay optical fiber 5 and the anti-Stokes light passes through the three-dB coupler 6 synthesis light all the way
The extraction of polarised light is carried out after signal by the polarizer 7, the polarised light extracted modulates amplifying unit 8 by the third
The modulation and amplification for carrying out preset strength obtain pumping pulse light, and the pumping pulse light is injected the of the sensor fibre 11
One end；
The detection light that the light generates the generation of unit 1 is injected after the scrambler 9 by the isolator 10 described
The other end of sensor fibre 11 passes through after excited Brillouin effect occurs with the pumping pulse light in the sensor fibre 11
The circulator 12 is transferred to the photodetector 13, is converted into electric signal by the photodetector 13.
Fig. 2 is that a kind of working principle of the differential type temperature sensor based on stimulated Brillouin effect proposed by the present invention is shown
It is intended to；
As shown in Fig. 2, the working principle of the differential type temperature sensor based on stimulated Brillouin effect specifically:
Include anti-Stokes frequency v0+fmWith stokes frequency v0-fmPump light from one section of optical fiber inject, they
After being phase-modulated simultaneously, two-way is divided by filter, so that the wherein relatively other sideband delay T of a sideband, is then adjusted
The Polarization Controller that takes of section both sides keeps their peak power is consistent with polarization state to pass through three-dB coupler they are synthesized one
Lu Hou, then they are modulated into the pulse that width is 60ns, after the amplification of fiber amplifier and the frequency of reverse transfer is
v0Detection light meet in sensor fibre and excite Brillouin scattering.Common portion of the light before two pulses is detected, is received anti-
The amplification of stokes pulse and the decaying of stokes pulse, the common portion of two pulses are used only for forming the sound of stable state
Son, the influence to carrier power are just cancelled out each other.And in the delay part T, detect anti-Stokes of the light due to encountering π phase
The gain amplifier of equivalent anti-Stokes pulse is reflected in pulse, so that detection light receives anti-Stokes pulse and Si Tuo simultaneously
The decaying of gram this pulse, signal-to-noise ratio is aobvious acute to be promoted.After delay component, upper and lower two sideband is mainly shown as π phase phonon
And gradually tending to stable state, the influence of anti-Stokes pulse and stokes pulse to carrier power is slowly just mutually supported again
Disappear.Carrier component is filtered out by filter, it can be learnt that along the temperature or stress information of fiber lengths distribution.
Sensor fibre 11 in the embodiment of the present invention is single mode optical fiber.
The differential type temperature sensor based on stimulated Brillouin effect that the embodiment of the present invention proposes, further includes oscillograph,
The connection of the output end of the oscillograph and photodetector, the electric signal for being formed to photodetector carry out output and show.
In the embodiment of the present invention, it includes sequentially connected laser and fiber coupler, the laser that light, which generates unit 1,
It is 1550nm for launch wavelength, power is the laser of 15.5dBm, what the fiber coupler was used to emit in the laser
Laser is divided into pump light and detection light.Wherein, the splitting ratio of fiber coupler is 10:90.
In the embodiment of the present invention, the first modulation amplifying unit 2 includes sequentially connected first electrooptic modulator and the first light
Fiber amplifier；
First electrooptic modulator is used to pump light being modulated to suppressed-carrier double side band signal, described bilateral to take a message
Number include stokes light and anti-Stokes light, the double-sideband signal by first fiber amplifier carry out signal put
Greatly.
In the embodiment of the present invention, the second modulation amplifying unit 3 includes sequentially connected second electrooptic modulator and the second light
Fiber amplifier；
Second electrooptic modulator is used to carry out phase to the double-sideband signal of the first modulation amplifying unit output
It modulates, the signal after phase-modulation carries out signal amplification by second fiber amplifier.
In the embodiment of the present invention, it includes sequentially connected third electrooptic modulator and third light that third, which modulates amplifying unit 8,
Fiber amplifier；The polarised light that the third electrooptic modulator is used to extract the polarizer carries out the intensity tune that width is 60ns
System, obtains pumping pulse light, the pumping pulse light is amplified by third fiber amplifier.
It further include several in the differential type temperature sensor based on stimulated Brillouin effect that the embodiment of the present invention proposes
Polarization Controller, several described Polarization Controllers keep identical for controlling the stokes light and anti-Stokes light
Peak power and polarization state enter the third electrooptic modulator.
Technical solution proposed by the present invention is described in detail below by specific embodiment.
Fig. 3 is a kind of experiment for differential type temperature sensor based on stimulated Brillouin effect that the embodiment of the present invention proposes
Conceptual scheme.
The embodiment of the present invention as shown in figure 3, a wavelength be 1550nm narrow linewidth laser, issue the laser of 15.5dBm,
Two-way is divided by the fiber coupler of 10:90, wherein upper road is as pump light, and lower road is as detection light.The continuous pumping on upper road
Light is first modulated to suppressed-carrier double side band signal by the first electrooptic modulator (EOM1), that is, includes Stokes and anti-stoke
This frequencies of light is done phase-modulation by the second electrooptic modulator (EOM2) after the first fiber amplifier (EDFA1) amplification, then is passed through
It crosses after the second fiber amplifier (EDFA2) amplification and Si Tuo is filtered out by programmable filter (Wave shaper 4000S) respectively
Ke Si light and anti-Stokes light, wherein stokes light is after one section of time delay optical fiber and anti-Stokes light passes through 3dB coupling
Clutch synthesizes adjusts both Polarization Controller PC1-PC5 holdings of two branch paths all the way afterwards by a polarizer with phase respectively
Same peak power and polarization state enters third electrooptic modulator (EOM3) and does the intensity modulated that width is 60ns, pumping out
Sensor fibre is injected after the amplification that pulsed light passes through third fiber amplifier (EDFA3).On the other hand, detection light is logical through scrambler
It crosses an isolator to squeeze into from sensor fibre tail end, occur after excited Brillouin acts on pumping pulse light by annular in optical fiber
Device is converted into electric signal by photodetector and is output on oscillograph.
Sensor fibre in the embodiment of the present invention is the general single mode fiber that a segment length is 21.5m, cloth at room temperature
In deep frequency be 10.873GHz, wherein having the heating region of one section of 50cm in the section 13.2m to 13.7m, temperature is higher than room temperature by 40
Degree left and right, corresponding theory Brillouin's frequency is 10.909GHz.Increased with the Brillouin obtained after the frequency interval scanning of 2MHz
Benefit is shown with three-dimensional figure such as Fig. 4 (a) and Fig. 4 (b) that position and frequency change, and Fig. 4 (a) is the embodiment of the present invention with the frequency of 2KHz
The schematic diagram for the three-dimensional brillouin gain spectrum that rate interval scan obtains；Fig. 4 (b) is the embodiment of the present invention with the frequency interval of 2KHz
Obtained brillouin gain is scanned with the three-dimensional figure of frequency and change in location；By Fig. 4 (a) and Fig. 4 (b) as it can be seen that heating region
Temperature change is significantly detected, and the brillouin gain in other non-heated regions is zero.In order to further prove this
The validity of invention, compare the scheme of technical solution of the present invention and tradition π impulse method temperature variant area with it is temperature-resistant
Shown in three-dimensional brillouin gain spectrum such as Fig. 5 (a) and Fig. 5 (b) when Brillouin shift difference in region is 1MHz, Fig. 5 (a) is
The embodiment of the present invention emulated when the Brillouin shift difference in temperature variant area and temperature-resistant region is 1MHz three
Tie up brillouin gain spectrum schematic diagram；Fig. 5 (b) is existing π impulse method when in the cloth in temperature variant area and temperature-resistant region
The three-dimensional brillouin gain spectrum schematic diagram that deep frequency displacement difference emulates when being 1MHz；Compare Fig. 4 (a) and Fig. 5 (a), it is seen that use
The three-dimensional brillouin gain spectrum that differential type temperature sensor proposed by the present invention based on stimulated Brillouin effect obtains conscientiously may be used
Letter, feasibility of the invention is also demonstrated from emulation.And the comparison of Fig. 5 (a) and Fig. 5 (b) can be seen that proposition of the present invention
The differential type temperature sensor based on stimulated Brillouin effect only detect the differential gain of temperature change, and filter automatically
Direct current component gain detects for the direct current component gain and differential gain of temperature change simultaneously compared to other traditional schemes,
Effectively improve signal-to-noise ratio.Also, from this two width figure it can also be seen that in the case where temperature change is minimum, such as 1MHz
Frequency shift (FS), traditional π impulse method can not detect the region of the variation of temperature, and the present invention can be apparent ground
Detect the variation of temperature.Therefore, the differential type temperature sensor proposed by the present invention based on stimulated Brillouin effect can have
Slight temperature variation in effect ground detection sensor fibre.
Fig. 6 is temperature change end (at 13.7m) brillouin gain at three typical frequencies in the embodiment of the present invention
Time-domain curve, such as Fig. 6, for different frequency shift (FS)s, the time-domain curve for the brillouin gain that the present invention detects shows
Antisymmetry type, it is higher compared to unimodal Lorentz lorentz's type fitting precision, Brillouin's frequency calculate it is more acurrate, and its peak gain with
Frequency shift (FS) and obviously increase.And traditional π impulse method, the higher Lip river logical sequence of signal-to-noise ratio has just been showed in no temperature change
Hereby type gain spectral, with the offset of frequency, which only has faint offset, there are system noise the case where
Under, it is to be difficult that the two corresponding Brillouin's frequency at peak gain is recognized accurately.
Fig. 7 (a) is for the embodiment of the present invention from existing π impulse method for different temperature variant areas and temperature-resistant region
Interior Brillouin shift difference is in the corresponding brillouin gain spectrum in the place 13.7m；；Fig. 7 (b) is that the Fitting Calculation of the embodiment of the present invention obtains
The schematic diagram of Brillouin shift in temperature variant area.As shown in fig. 7, temperature variant area and temperature different in Fig. 7 (a)
Brillouin shift difference is in the corresponding gain spectral in the place z=13.7m in invariant region, and wherein solid line is of the invention as a result, dotted line
For the result of traditional π impulse method；In order to embody the spatial resolution of the example, Fig. 7 (b) passes through each in fitting temperature variant area
Point Brillouin's frequency and calculate its center frequency value, compare the response time of 10% to 90% power of curve, can obtain
Out, it is proposed that scheme in spatial resolution, the phase delay for being solely dependent upon two pumping pulses really is poor.
Differential type temperature sensor provided by the invention based on stimulated Brillouin effect, while realizing ideal point
The key technical indexes of cloth Brillouin's temperature sensor, comprising: high spatial resolution, high frequency resolution, long range measurements
And normal time of measuring has higher detection efficiency simultaneously as the present invention only detects the relative quantity of temperature change
And temperature resolution, there is very big impetus for Brillouin's temperature or strain gauge investment actual use.
The above embodiments are only used to illustrate the present invention, and not limitation of the present invention, in relation to the common of technical field
Technical staff can also make a variety of changes and modification without departing from the spirit and scope of the present invention, therefore all
Equivalent technical solution also belongs to scope of the invention, and scope of patent protection of the invention should be defined by the claims.
Claims (9)
1. a kind of differential type temperature sensor based on stimulated Brillouin effect characterized by comprising
Unit, the first modulation amplifying unit, the second modulation amplifying unit, filtering are generated for generating pump light and detecting the light of light
Device, time delay optical fiber, three-dB coupler, the polarizer, third modulation amplifying unit, scrambler, isolator, sensor fibre, circulator with
And photodetector；
The light generates the pump light that unit generates
Then the signal of stokes light and anti-Stokes light carries out phase-modulation by the second modulation amplifying unit, obtains phase
Modulated signal, the phase modulated signal filter out stokes light and anti-Stokes light, this described support by the filter
Ke Si light is after the time delay optical fiber and the anti-Stokes light after three-dB coupler synthesis all the way optical signal by passing through
The extraction that the polarizer carries out polarised light is crossed, the polarised light extracted is modulated amplifying unit by the third and preset by force
The modulation and amplification of degree obtain pumping pulse light, and the pumping pulse light is injected to the first end of the sensor fibre；
The light generates the detection light that unit generates and injects the sensor fibre by the isolator after the scrambler
The other end, passed after excited Brillouin effect occurs with the pumping pulse light in the sensor fibre by the circulator
It is defeated to arrive the photodetector, electric signal is converted by the photodetector.
2. the differential type temperature sensor according to claim 1 based on stimulated Brillouin effect, which is characterized in that also wrap
Oscillograph is included, is connect with the output end of the photodetector, the electric signal for being formed to the photodetector carries out defeated
It shows out.
3. the differential type temperature sensor according to claim 1 or 2 based on stimulated Brillouin effect, which is characterized in that
It includes sequentially connected laser and fiber coupler that the light, which generates unit, and the laser is for launch wavelength
1550nm, power are the laser of 15.5dBm, and the fiber coupler is used to the laser that the laser emits being divided into pump light
With detection light.
4. the differential type temperature sensor according to claim 3 based on stimulated Brillouin effect, which is characterized in that described
The splitting ratio of fiber coupler is 10:90.
5. the differential type temperature sensor according to claim 1 or 2 based on stimulated Brillouin effect, which is characterized in that
The first modulation amplifying unit includes sequentially connected first electrooptic modulator and the first fiber amplifier；
First electrooptic modulator is used to pump light being modulated to suppressed-carrier double side band signal, the double-sideband signal packet
Containing stokes light and anti-Stokes light, the double-sideband signal carries out signal amplification by first fiber amplifier.
6. the differential type temperature sensor according to claim 1 or 2 based on stimulated Brillouin effect, which is characterized in that
The second modulation amplifying unit includes sequentially connected second electrooptic modulator and the second fiber amplifier；
Second electrooptic modulator is used to carry out phase-modulation to the double-sideband signal of the first modulation amplifying unit output,
Signal after phase-modulation carries out signal amplification by second fiber amplifier.
7. the differential type temperature sensor according to claim 1 or 2 based on stimulated Brillouin effect, which is characterized in that
The third modulation amplifying unit includes sequentially connected third electrooptic modulator and third fiber amplifier；
The polarised light that the third electrooptic modulator is used to extract the polarizer carries out the intensity modulated that width is 60ns, obtains
To pumping pulse light, the pumping pulse light is amplified by third fiber amplifier.
8. the differential type temperature sensor according to claim 7 based on stimulated Brillouin effect, which is characterized in that also wrap
Several Polarization Controllers are included, several described Polarization Controllers are protected for controlling the stokes light and anti-Stokes light
It holds identical peak power and polarization state enters the third electrooptic modulator.
9. the differential type temperature sensor according to claim 1 or 2 based on stimulated Brillouin effect, which is characterized in that
The sensor fibre is single mode optical fiber.
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| CN106225949A (en) * | 2016-08-04 | 2016-12-14 | 电子科技大学 | Wavelength-division multiplex dual-wavelength optical-fiber delay temperature sensor |
| CN106959167B (en) * | 2017-05-12 | 2019-03-08 | 暨南大学 | Measuring device, Brillouin optical time-domain reflectometer and brillouin frequency shift measurement system |
| CN108692766B (en) * | 2018-05-21 | 2019-09-06 | 北京邮电大学 | BFS measuring device, method and distributed fiber-optic sensor system |
| CN110445009B (en) * | 2019-07-29 | 2022-04-12 | 北京邮电大学 | Optical fiber Brillouin amplifier based on orthogonal double pumping |
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