CN106248247B - A kind of sensing device based on the brillouin distributed temperature of Raman-, the double Parametric Detections of stress - Google Patents
A kind of sensing device based on the brillouin distributed temperature of Raman-, the double Parametric Detections of stress Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/322—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres using Brillouin scattering
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/324—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres using Raman scattering
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
- G01L1/246—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre using integrated gratings, e.g. Bragg gratings
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- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
The invention discloses a kind of sensing device based on the brillouin distributed temperature of Raman, the double Parametric Detections of stress, including：Laser, first coupler, Polarization Controller, impulse generator, semiconductor optical amplifier, erbium-doped fiber amplifier, bandpass filter, second coupler, optical attenuator, first annular device, third coupler, multi-core optical fiber, second circulator, Raman filter, first photodetector, second photodetector, oscillograph, Polarization Controller, modulator, microwave generator, polarization switch, 4th coupler, third photodetector, electric spectrum analysis instrument and data processing module.Due to constituting SDM system using single mode multi-core optical fiber in the present invention, there is no the unmatched problems of power of the Mode Coupling and wavelength-division multiplex system of mode division multiplexing system, can reach effect that is accurate and obtaining the double parameters of temperature stress simultaneously.
Description
Technical field
The invention belongs to technical field of optical fiber sensing, and the brillouin distributed temperature of Raman-is based on more particularly, to one kind
The sensing device of the double Parametric Detections of degree, stress.
Background technology
Fibre optical sensor has small, bandwidth, high sensitivity resistance to not by electromagnetic interference relative to traditional sensors
The advantages that corroding, high temperature resistant, anti-high pressure, adapting to adverse circumstances.Exactly because these features, Fibre Optical Sensor are constantly subjected to various countries
The great attention of related academia and research institution.So far from last century, over one hundred kind of fibre optical sensor is had now been developed.Mesh
It is preceding it has been proved that fibre optical sensor can be realized to strain, displacement, pressure, speed, acceleration, torque, angular speed, temperature, electricity
The detection of more than the 70 kinds of physical quantity such as stream, voltage, concentration, flow, flow velocity and magnetic, sound, light, ray.Its application penetrates into
The fields such as medicine and biology, workers and peasants' mining industry, energy environment protection, national defense and military, intelligence structure.
Distributed optical fiber sensing system can be defined as：It can be on entire continuous fiber lengths, with the continuous letter of distance
Several forms senses out the instrument or system that measured parameter changes with fiber length.Distributed temperature, stress sensing system
System is typically that optical fiber is arranged along temperature field, stress field, measures the carrying temperature generated when light transmits in a fiber, stress information
Scattering light, while use OTDR (Optical Time Domain Reflectometer) technology, so that it may with to being passed along optical fiber
The information that temperature, stress-space on defeated path are distributed and change over time is measured and is monitored.
When light enters in optical fiber, photon causes light to change the direction i.e. scattering of light with fiber medium interaction,
When the silicon dioxide molecules in photon and optical fiber interact, it may occur that two kinds of situations have energy exchange and handed over without energy
Change two kinds.When inelastic collision occurs for photon and fiber medium and has energy exchange, this process to be thus referred to as Brillouin
(Brillouin) scattering, Raman (Raman) scattering.
Distributed optical fiber temperature sensor based on Raman scattering is the product of external commercialization at first, while it has
Most possible practical technology at present.It focuses mostly in the distribution type fiber-optic based on optical time domain Raman scattering reflectometer (ROTDR)
Temperature sensor, then it measures the Raman light of backscattering, the optical signal is just by sending a short laser pulse to optical fiber
Contain the loss along optical fiber and temperature distribution information.
Distributed sensor based on Brillouin scattering be it is most widely used, including Brillouin optical time-domain reflectometer/point
Analyzer (BOTDR/A) and Brillouin's domain of dependence reflectometer/analyzer (BOCDR/A), etc..
BOTDR/A is the time-domain information based on light pulse to realize positioning, and to be measured can pass through measures brillouin frequency
In-migration is known.There are one frequency displacements, referred to as Brillouin shift relative to pump light for Brillouin scattering in optical fiber, are given by following formula
Go out：
Wherein, νBIt is Brillouin shift, n is fiber core refractive index, νAFor the velocity of sound in optical fiber, λ is the wavelength of pump light.When
The temperature change of optical fiber local environment or when being stressed effect, can cause Brillouin shift amount to change, so passing through survey
The frequency shift amount of amount Brillouin scattering can know the temperature of the point and the variable quantity of stress.In addition, for multi-core optical fiber
Situation, when bending, eccentric fibre core can be compressed or be stretched, the stress in tangential direction generated due to bending
Component can equally cause Brillouin's offset to change, and the Brillouin shift for showing as eccentric fibre core is sensitive to bending.
BOCDR/A is again based on the distributed measurement of Brillouin scattering realization, and difference is in BOCDR/A, pumps
Pu light and detection light are all the continuous light of same frequency modulation, in a fiber only when the difference on the frequency of pump light and detection light is Brillouin
It just will produce stimulated Brillouin scattering when frequency displacement, brillouin gain relevant peaks occur, by changing modulating frequency, thus it is possible to vary phase
The position of Guan Feng is achieved in positioning and information extraction to space, achievees the purpose that distributed measurement.
In the past, most brillouin distributed sensor-based systems were using common single mode optical fiber, in recent years, also someone
Have studied the brillouin distributed sensor-based system based on special optical fibers such as photonic crystal fiber, polarization maintaining optical fibre, less fundamental mode optical fibres.Due to
Brillouin sensing system to temperature and stress cross sensitivity, survey by traditional technical solution temperature all relatively difficult to achieve and stress while
Amount.Although there are some solutions, for example many reference amounts of the Brillouin sensing technology based on less fundamental mode optical fibre mode division multiplexing measure
With the multi-parameter measurement system of Raman-Brillouin sensing based on single mode optical fiber wavelength-division multiplex technique, but the former have it is real-time
The shortcomings that property is poor, Mode Coupling, and then there is system source power limited in the latter：One side spontaneous Raman scattering light is non-
It is often weak, it is therefore desirable to launched power is improved, and on the other hand since the threshold value of stimulated Brillouin scattering in optical fiber is relatively low, simply
Serious nonlinear effect, including stimulated Brillouin scattering and modulational instability etc. can be caused by improving launched power.
Invention content
In view of the drawbacks of the prior art, the purpose of the present invention is to provide one kind based on the brillouin distributed temperature of Raman-,
The sensing device of the double Parametric Detections of stress, it is intended to which the double parameters of temperature stress can not be obtained simultaneously and precisely by solving Brillouin's system
Problem.
The present invention provides a kind of sensing device based on the brillouin distributed temperature of Raman-, the double Parametric Detections of stress, packet
It includes：Laser, the first coupler, the first Polarization Controller, impulse generator, semiconductor optical amplifier, erbium-doped fiber amplifier,
Bandpass filter, the second coupler, optical attenuator, first annular device, third coupler, multi-core optical fiber, the second circulator, Raman
Filter, the first photodetector, the second photodetector, oscillograph, the second Polarization Controller, modulator, microwave generator,
Polarization switch, the 4th coupler, third photodetector, electric spectrum analysis instrument and data processing module；First coupler
Input terminal connects the laser, and the input terminal of first Polarization Controller is connected to the first output of first coupler
End, the light input end of the semiconductor optical amplifier are connected to the output end of first Polarization Controller, the semiconductor light
The electrical input of amplifier connects the impulse generator；The input terminal of the erbium-doped fiber amplifier is connected to the semiconductor
The output end of image intensifer, the input terminal of the bandpass filter is connected to the output end of the erbium-doped fiber amplifier, described
The input terminal of second coupler is connected to the output end of the bandpass filter, and the first port of second circulator is connected to
First output end of second coupler, the input terminal of the Raman filter are connected to the third end of second circulator
Mouthful, the input terminal of the input terminal of first photodetector and second photodetector is respectively connected to the Raman filter
The defeated place end of two output ends of wave device, the output end of first photodetector and second photodetector is all connected with institute
State oscillograph；The input terminal of the optical attenuator is connected to the second output terminal of second coupler, the first annular device
First port be connected to the output end of the optical attenuator, the first input end of the third coupler is connected to described second
The second port of circulator, the second input terminal of the third coupler are connected to the second port of the first annular device；Institute
The output end for stating third coupler connects the multi-core optical fiber；The input terminal of second Polarization Controller is connected to described first
The second output terminal of coupler, the optical signal input of the modulator are connected to the output end of second Polarization Controller,
The electric signal input end of the modulator connects microwave generator；The input terminal of the polarization switch is connected to the modulator
The first input end of output end, the 4th coupler is connected to the third port of the first annular device, the 4th coupling
Second input terminal of device is connected to the output end of the polarization switch, and the input terminal of the third photodetector is connected to described
The input terminal of the output end of 4th coupler, the electricity spectrum analysis instrument is connected to the output end of the third photodetector, institute
The output end for stating electric spectrum analysis instrument connects the data processing module.
The system that the present invention is combined using Raman-Brillouin, Raman system are respectively adopted more with Brillouin's system
The different fibre cores of core fibre constitute SDM system.Used technology includes but are not limited to Raman time-domain reflectomer
(ROTDR)-Brillouin optical time-domain reflectometer/analyzer (BOTDR/A) is related to Raman time-domain reflectomer (ROTDR)-Brillouin
Domain reflectometer/analyzer (BOCDR/A) etc..
Further, when work, the light of laser output is divided into first via light and the second road light through the first coupler；The
Light generates after passing sequentially through the first Polarization Controller, semiconductor optical amplifier, erbium-doped fiber amplifier and bandpass filter all the way
Detect light；The detection light is divided into third road light and the 4th road light after the second coupler；The second circulators of third Lu Guangjing,
The outer layer core for entering multi-core optical fiber after fan-in third coupler, is used for Raman scattering light detection temperature；Raman rear orientation light passes through
The stokes light detected and anti-Stokes light are sent into the first photoelectricity respectively by Raman filter after third coupler
Detector and the second photodetector and by oscilloscope display；4th road light is successively through optical attenuator, first annular device, fan-in
Three couplers enter the intermediate core of multi-core optical fiber, are used for Brillouin scattering light detection stress；Second road light is successively through the second polarization
Controller, modulator, polarization switch enter the 4th coupler, and enter the after the relevant effect of intermediate core Brillouin's rear orientation light
It is shown by electric spectrum analysis instrument after three photodetectors, data acquisition and procession is finally carried out by data processing module.
Further, the splitting ratio of first coupler, second coupler and the 4th coupler is
50:50。
Further, the third coupler is multicore coupler, multiport input, single port output；Input terminal connects
Order mode fiber, each input terminal is independent of one another, no coupling；Output port connects multi-core optical fiber.
Further, the operation wavelength of the bandpass filter is corresponding with light source, and the bandwidth of the bandpass filter is small
In 1nm.
Further, the multi-core optical fiber is the optical fiber for containing two or more fibre cores in same covering.
Contemplated above technical scheme through the invention, compared with prior art, due to using single mode multi-core optical fiber structure
At SDM system, ask there is no the power of the Mode Coupling of mode division multiplexing system and wavelength-division multiplex system is unmatched
Topic can reach effect that is accurate and obtaining the double parameters of temperature stress simultaneously.
Description of the drawings
Fig. 1 is the structural schematic diagram of multi-core optical fiber used provided in an embodiment of the present invention, wherein (a) is viewgraph of cross-section,
(b) it is lateral plan；
Fig. 2 is the structural schematic diagram of the ROTDR-BOTDR systems provided in an embodiment of the present invention based on multi-core optical fiber.
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 the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
The present invention detects Raman scattering signal using the outer layer core of multi-core optical fiber, and (anti-Stokes light) is only quick to temperature
Sense, while brillouin scattering signal is detected using intermediate core, frequency displacement is all sensitive with stress to temperature.Utilize this hair of this characteristic
It the double parameters of the brillouin distributed temperature of the bright Raman-realized based on multi-core optical fiber, stress while sensing.This invention solves
Wavelength-division multiplex system is directed to Brillouin's this problem different from incident optical power needed for Raman under conventional single mode fiber, utilizes multicore
Optical fiber forms SDM system, can real-time high-efficiency simultaneously and detection can be distinguished to the double parameters of temperature stress, it is contemplated that its
Related field will be widely used.
The present invention relates to a kind of brillouin distributed temperature of Raman-based on multi-core optical fiber, strain gauges.In optical fiber
Brillouin shift is and corresponding in a linear relationship to temperature, stress sensitive.And in multi-core optical fiber, the brillouin frequency of eccentric fibre core
Move also sensitive to bending, but intermediate core is due to being on the geometry neutral axis of optical fiber, to bend-insensitive；On the other hand, light
Spontaneous Raman scattering in fibre is only temperature sensitive, to stress and is bent all insensitive.Therefore, in the different fibre cores of multi-core optical fiber
In can build Raman and brillouin distributed sensor-based system respectively, specially intermediate core implements brillouin distributed sensing, obtains
Distributed temperature, stress information；Eccentric fibre core implements Raman distributed sensing, obtains distributed temperature information.Due to more
Uniform, the compact fibre core spatial distribution structure of core fibre, as intermediate core with temperature suffered by eccentric core is, therefore using this
The brillouin distributed sensor-based system of Raman-of space division multiplexing may be implemented the double parameters of temperature, stress simultaneously and can discriminating measurement；And
And system is efficiently solved in multi-core optical fiber and is used merely present in brillouin distributed sensor-based system to bend-insensitive
The problem sensitive and indistinguishable to temperature, stress, bending.The invention belongs to technical field of optical fiber sensing.
Brillouin shift is to temperature and stress cross sensitivity, because temperature and stress variation can all cause optical fiber to reflect
The variation of rate and phonon rate, by the formula (1) of Brillouin shift it is found that at this moment accordingly Brillouin shift will also become
Change, this is Brillouin's thermometric and surveys the principle of strain, and in addition in multi-core optical fiber, eccentric fibre core is also sensitive to bending.For simultaneously
Two temperature, stress parameters are demodulated, only thermally sensitive Raman scattering is introduced.And in order to avoid by the shadow being bent
It rings, is measured it is proposed that implementing distributed Brillouin in intermediate core, implement distributed Raman measurement in eccentric fibre core.
Related scholar utilizes wavelength-division multiplex system, and subrane extracts Raman and Brillouin signal from single mode optical fiber.But
Raman scattering intensities are very weak, so system needs very high incident optical power；And on the other hand due to being excited in cloth in optical fiber
The threshold value of deep pool scattering is relatively low, and raising launched power simply can cause serious nonlinear effect, including stimulated Brillouin scattering
With modulational instability etc..
The present invention proposes to implement the brillouin distributed sensing technology of Raman-in multi-core optical fiber with experimental verification, make
On the basis of a light source, temperature detection, the Brillouin shift of intermediate core are carried out using the Raman scattering intensities of its outer layer core
Into trip temperature, stress mornitoring, realize based on the brillouin distributed sensor of the Raman-containing multi-core optical fiber.The system can be efficient
While in real time to temperature, stress double parameter and can discriminating measurement, effectively solve incident optical power needed for Brillouin and Raman not
Same problem.
The present invention proposes that used technology includes based on the brillouin distributed sensor of the Raman-containing multi-core optical fiber
But it is not limited only to Raman time-domain reflectomer (ROTDR)-Brillouin optical time-domain reflectometer/analyzer (BOTDR/A) and Raman time domain
Reflectometer (ROTDR)-Brillouin's domain of dependence reflectometer/analyzer (BOCDR/A) etc..
It is a kind of seven core fibres of central symmetry distribution that Fig. 1, which is shown used in embodiment,.It is to be noted that of the invention
Required rights protection scope further includes any multi-core optical fiber structure containing eccentric fibre core using other core structures, quantity
The brillouin distributed temperature of Raman-, the stress sensing technology made.
Fig. 2 gives a kind of ROTDR-BOTDR system construction drawings based on multi-core optical fiber used by embodiment.Embodiment
In only used 2 cores (channel) in multi-core optical fiber：1 intermediate core and 1 outer layer core.Intermediate core is examined based on Brillouin shift
Stress and temperature are surveyed, outer layer core is based on Raman scattering intensities and detects temperature.Since Brillouin shift is intersected to temperature and stress
Sensitive, and Raman scattering intensities are only temperature sensitive.It is responded by outer layer core Raman thermometric, demodulates temperature value, make simultaneously
For the temperature-compensating in Brillouin shift measurement result, you can demodulate stress.
It should be noted that changing the usage quantity of fibre core, sequence, direction in multi-core optical fiber, or drawn using other
Graceful-Brillouin sensing technology, such as ROTDR-BOTDR, ROTDR-BOCDR, ROTDR-BOCDA etc. also the present invention claims right
In protection domain, all system construction drawings are not drawn herein.
Fig. 2 shows provided in an embodiment of the present invention a kind of based on the brillouin distributed temperature of Raman-, the double parameter inspections of stress
The structure of the sensing device of survey, for convenience of description, illustrate only with the relevant part of the embodiment of the present invention, details are as follows：
Sensing device includes：The laser 1 of narrow linewidth, Polarization Controller 3, impulse generator 4, is partly led at the first coupler 2
Body image intensifer 5, erbium-doped fiber amplifier 6, bandpass filter 7, the second coupler 8, optical attenuator 9, first annular device 10,
Three couplers 11, multi-core optical fiber 12, the second circulator 13, Raman filter 14, the first photodetector 15, the second photodetection
Device 16, oscillograph 17, Polarization Controller 18, modulator 19, microwave generator 20, polarization switch 21, the 4th coupler 22, third
Photodetector 23, electric spectrum analysis instrument 24 and data processing module 25；The delivery outlet of laser 1 connects coupler 2, coupler 2
Delivery outlet be divided into two-way, connect 5 light input end of semiconductor optical amplifier, the wherein output end of impulser 4 and half all the way
The electrical input of conductor image intensifer 5 is connected.The light input end phase of the light output end of semiconductor amplifier and erbium-based amplifier 6
Even, the light output end of erbium-based amplifier 6 is connect with the light input end of bandpass filter 7, the transmission light output end of bandpass filter 7
The input terminal of coupler 8 is connected, the output end of coupler 8 is divided into two-way, is connected all the way with optical attenuator 9,9 output end and the
1 port of one circulator 10 is connected, and 2 ports of first annular device 10 are connected with the input port of third coupler 11, circulator
3 ports and the two-way input terminal of the 4th coupler 22 connect all the way；Multi-core optical fiber 12 uses welding with third coupler 11
Mode links together；Another output end of second coupler 8 is connect with the input terminal of Raman filter 14, Raman filter 14
Two-way output end be separately connected the first photodetector 15 and the second photodetector 16, the output end difference of two detectors
It is linked into oscillograph 17.
The light of the output end connection modulator 19 of another output end connection Polarization Controller 18,18 of first coupler 2 is defeated
Enter end, 20 output end of microwave generator connects the electrical input of modulator 19, and the light output end of modulator 19 and polarization open the light 21
Input terminal connection.The output end of polarization switch 21 is attached all the way with the two-way input terminal of the 4th coupler 22, coupling
The two-way output end of device 22 only selects to connect with photodetector 23 all the way, the electricity output mouth of photodetector 23 and electric spectrometer 24
Connection, is finally connected with data collecting system 25.
The Distributed Feedback Laser of the laser of narrow linewidth, that is, common；The splitting ratio of coupler is all 50:50；Bandpass filtering
Device operation wavelength is corresponding with light source, bandwidth 1nm or less.
The optical fiber containing two or more fibre cores can all be classified as multi-core optical fiber in same covering.
The light that the laser 1 of narrow linewidth exports is divided into two-way through the first coupler 2：Pass sequentially through Polarization Control all the way above
Device 3, semiconductor optical amplifier 5 and by the control of impulse generator 4, erbium-doped fiber amplifier 6, bandpass filter 7 etc., for generating
Detect light；Light beam is divided into two-way again through the second coupler 8, above all the way through the second circulator 13, fan-in third coupler
11 enter the outer layer core of multi-core optical fiber 12, are used for Raman scattering light detection temperature.Raman rear orientation light is through third coupler 11
Afterwards by Raman filter 14 respectively by the stokes light detected and anti-Stokes light be sent into the first photodetector 15,
It 16 and is shown by oscillograph 17.Below after the second coupler 8 all the way light successively through optical attenuator 9, first annular device 10, fan
Enter the intermediate core that third coupler 11 enters multi-core optical fiber 12, is used for Brillouin scattering light detection stress.Light source 1 is through the first coupling
Light enters through Polarization Controller 18, modulator 19 (being controlled by microwave generator 20), polarization switch 21 successively all the way below after device 2
Enter after 4th coupler 22, with the relevant effect of intermediate core Brillouin's rear orientation light after third photodetector 23 by electricity spectrum point
Analyzer 24 is shown, finally carries out data acquisition and procession by data processing module 25.
The Raman scattering temperature-measurement principle of outer layer core：Anti-Stokes Raman scatters light and scatters the strong of light with Stokes Raman
Degree is than I (T), as shown by：
Wherein, φa, φsIt is that anti-Stokes Raman scattering light and the intensity of Stokes Raman scattering light pass through opto-electronic conversion
Level value afterwards；νa, νsIt is the frequency of anti-Stokes Raman scattered photon and Stokes Raman scattered photon respectively；H is wave
Lang Ke (Planck) constant, Δ νrIt is Phonon frequency (the Δ ν of optical fiber moleculer=13.2THz), K is Boltzmann constant, and T is out
Er Wen (Kelvin) absolute temperature.By the intensity ratio of the two, the temperature information of each section of optical fiber is obtained.
The Brillouin shift detection stress principle of intermediate core is given by：
ΔνB=Cνε·Δε+CνT·ΔT……(3)；
WhereinΔνBFor the variable quantity of Brillouin shift, Cνε, CνTFor the coefficient of strain and temperature coefficient of Brillouin shift.Pass through survey
Measure the stress that the temperature detected by frequency displacement and Raman scattering of the optical fiber backwards to Brillouin line is worth to each section on optical fiber
Variable quantity.
It is important to note that the system may have many mutation, can not one by one it be enumerated in this specification, as long as being
Using the brillouin distributed temperature of Raman-of the multi-core optical fiber realization containing eccentric fibre core, stress sensing scheme all in the present invention
It is required that protection domain in, it is meant that the size of used optical fiber, shape, fibre core quantity, position, the space of eccentric fibre core are multiple
Light path system, sequence, direction, the brillouin distributed sensing technology of Raman-used (including but not only limit ROTDR-
BOTDR/A, ROTDR-BOCDR/A etc.) etc. it is different from the present embodiment when, also in scope of the present invention.More
Further, " the brillouin distributed sensing technology of Raman-used " includes various real based on Raman in optical fiber-Brillouin scattering
Existing sensing technology does not jump out scope of the present invention with the difference of the realization method of specific system.Such as not
It can say by doing some variations to system, such as use more or use less certain instruments, or using another different from embodiment
Raman-Brillouin sensing technology achieve the purpose that jump out scope of the present invention.
Brillouin shift is to temperature, stress cross sensitivity, and what usual detector was detected is temperature and Stress superposition
Frequency shift amount.To obtain temperature, stress simultaneously, introducing Raman scattering carries out temperature detection, and Brillouin shift need to only demodulate
Stress value.
The brillouin distributed sensor-based system of traditional Raman-, is built upon on the basis of single mode optical fiber, passes through wavelength-division multiplex
System filters out Raman diffused light and Brillouin scattering respectively.But such system has what light source power was limited：On the one hand
Spontaneous Raman scattering light is very weak, it is therefore desirable to launched power is improved, and on the other hand due to stimulated Brillouin scattering in optical fiber
Threshold value it is relatively low, raising launched power simply can cause serious nonlinear effect, including stimulated Brillouin scattering and modulation
Unstability etc..
The present invention proposes simultaneously experimental verification based on the brillouin distributed sensor-based system of the Raman-containing multi-core optical fiber
In (including but not only limit ROTDR-BOTDR/A, ROTDR-BOCDR/A etc.), in conjunction with SDM system, using multi-core optical fiber outside
The Raman scattering of layer core realizes the double ginsengs of distributed temperature, stress to temperature detection, the Brillouin shift of intermediate core to stress mornitoring
Amount ga s safety degree detection simultaneously.
Technical solution proposed by the invention will find huge application prospect in actual commercial Application.Firstly the need of
It illustrates, there are many mutation for technical scheme of the present invention, can not list one by one, as long as being using containing the more of eccentric fibre core
Core fibre (includes but are not limited to ROTDR-BOTDR/A, ROTDR- based on the brillouin distributed sensing technology of various Ramans-
BOCDR/A) distributed temperature of realization, stress measurement are all in protection domain of the presently claimed invention.
The specific implementation mode of the present invention is as follows：
(1) as needed, sensing technology appropriate is reasonably selected, including but not only limits ROTDR-BOTDR/A, ROTDR-
BOCDR/A etc. builds corresponding system according to used technology.Embodiment is using ROTDR-BOTDR.Embodiment uses
Be seven core fibres containing 6 eccentric fibre cores.
(2) embodiment system as shown in Figure 2 is built.The light that the laser 1 of narrow linewidth exports is divided into through the first coupler 2
Two-way：It passes sequentially through Polarization Controller 3, semiconductor optical amplifier 5 all the way above and is controlled by impulse generator 4, Er-doped fiber
Amplifier 6, bandpass filter 7 etc., for generating detection light；Light beam is divided into two-way again through the second coupler 8, above all the way
The outer layer core for entering multi-core optical 12 through the second circulator 13, fan-in third coupler 11, is used for Raman scattering light detection temperature.It draws
Graceful rear orientation light is after third coupler 11 by Raman filter 14 respectively by the stokes light detected and this anti-support
Ke Si light is sent into the first photodetector 15,16 and is shown by oscillograph 17.Light is successively all the way below after the second coupler 8
The intermediate core for entering multi-core optical 12 through optical attenuator 9, first annular device 10, fan-in third coupler 11, is used for Brillouin scattering
Light detection stress.Wherein optical attenuator 9 can be by optical power adjustment in spontaneous radiation Brillouin threshold.Light source 1 is through the first coupling
Light enters the 4th coupler 22 through Polarization Controller 18, modulator 19, polarization switch 21 successively all the way below after device 2, with centre
It is shown by electric spectrum analysis instrument 24 after entering third photodetector 23 after the relevant effect of core Brillouin's rear orientation light, finally by counting
Data acquisition and procession is carried out according to processing module 25.
(3) in calibration formula (3) Brillouin shift coefficient of strain CνεWith temperature coefficient CνT.Due to the C of different optical fiberνε,
CνTMay be different, so needing to be demarcated before Experimental Research.Under the premise of stress is constant, changes temperature, detect corresponding cloth
In deep frequency shift amount carry out linear fit and can be obtained the temperature coefficient C in formula (3)νT；Similarly, under the premise of temperature-resistant,
Change stress, detects corresponding Brillouin shift amount and carry out linear fit and can be obtained stress coefficient C in formula (3)νε。
(4) temperature variation is demodulated.In temperature T0, according to the first photodetector 15 and the second photodetector 16 when T
Detect that voltage value finds out corresponding I (T0), I (T).By I (T0), I (T) substitutes into formula and (2) and does ratio proccessing i.e. such as following formula institute
Show：
And then temperature variation Δ T can be acquired.
(5) stress variation is demodulated.According to formula (3) and electric 24 gained frequency displacement variable quantity of spectrum analysis instrument, temperature change
Amount has been found out at this time, so can get system stress variable quantity.
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, all within the spirits and principles of the present invention made by all any modification, equivalent and improvement etc., should all include
Within protection scope of the present invention.
Claims (6)
1. a kind of sensing device based on the brillouin distributed temperature of Raman-, the double Parametric Detections of stress, which is characterized in that including：
Laser (1), the first Polarization Controller (3), impulse generator (4), semiconductor optical amplifier (5), is mixed the first coupler (2)
Doped fiber amplifier (6), bandpass filter (7), the second coupler (8), optical attenuator (9), first annular device (10), third coupling
Clutch (11), multi-core optical fiber (12), the second circulator (13), Raman filter (14), the first photodetector (15), the second light
Electric explorer (16), oscillograph (17), the second Polarization Controller (18), modulator (19), microwave generator (20), polarization switch
(21), the 4th coupler (22), third photodetector (23), electric spectrum analysis instrument (24) and data processing module (25)；
The input terminal of first coupler (2) connects the laser (1), the input terminal of first Polarization Controller (3)
It is connected to the first output end of first coupler (2),
The light input end of the semiconductor optical amplifier (5) is connected to the output end of first Polarization Controller (3), and described half
The electrical input of conductor image intensifer (5) connects the impulse generator (4)；
The input terminal of the erbium-doped fiber amplifier (6) is connected to the output end of the semiconductor optical amplifier (5), the band logical
The input terminal of filter (7) is connected to the output end of the erbium-doped fiber amplifier (6), the input of second coupler (8)
End is connected to the output end of the bandpass filter (7),
The first port of second circulator (13) is connected to the first output end of second coupler (8), the Raman
The input terminal of filter (14) is connected to the third port of second circulator (13), first photodetector (15)
The input terminal of input terminal and second photodetector (16) is respectively connected to two output ends of the Raman filter (14),
The output end of first photodetector (15) and the output end of second photodetector (16) are all connected with the oscillography
Device (17)；
The input terminal of the optical attenuator (9) is connected to the second output terminal of second coupler (8), the first annular device
(10) first port is connected to the output end of the optical attenuator (9), and the first input end of the third coupler (11) connects
It is connected to the second port of second circulator (13), the second input terminal of the third coupler (11) is connected to described first
The second port of circulator (10)；The output end of the third coupler (11) connects the multi-core optical fiber (12)；
The input terminal of second Polarization Controller (18) is connected to the second output terminal of first coupler (2), the tune
The optical signal input of device (19) processed is connected to the output end of second Polarization Controller (18), the electricity of the modulator (19)
Signal input part connects microwave generator (20)；The input terminal of the polarization switch (21) is connected to the defeated of the modulator (19)
Outlet,
The first input end of 4th coupler (22) is connected to the third port of the first annular device (10), and the described 4th
Second input terminal of coupler (22) is connected to the output end of the polarization switch (21),
The input terminal of the third photodetector (23) is connected to the output end of the 4th coupler (22), the electricity spectrum point
The input terminal of analyzer (24) is connected to the output end of the third photodetector (23), the output of the electricity spectrum analysis instrument (24)
End connects the data processing module (25).
2. sensing device as described in claim 1, which is characterized in that when work, the light of laser (1) output is through the first coupling
Device (2) is divided into first via light and the second road light；
First via light passes sequentially through the first Polarization Controller (3), semiconductor optical amplifier (5), erbium-doped fiber amplifier (6) and band
Bandpass filter (7) generates detection light afterwards；The detection light is divided into third road light and the 4th road light after the second coupler (8)；
The second circulators of third Lu Guangjing (13), fan-in third coupler (11) enter the outer layer core of multi-core optical fiber (12) afterwards, use
In Raman scattering light detection temperature；Raman rear orientation light respectively will after third coupler (11) by Raman filter (14)
The stokes light detected is sent into the first photodetector (15) and the second photodetector (16) simultaneously with anti-Stokes light
It is shown by oscillograph (17)；
4th road light enters multi-core optical fiber through optical attenuator (9), first annular device (10), fan-in third coupler (11) successively
(12) intermediate core is used for Brillouin scattering light detection stress；
Second road light enters the 4th coupler through the second Polarization Controller (18), modulator (19), polarization switch (21) successively
(22), enter after third photodetector (23) by electric spectrum analysis instrument with after the relevant effect of intermediate core Brillouin's rear orientation light
(24) it shows, data acquisition and procession is finally carried out by data processing module (25).
3. sensing device as claimed in claim 1 or 2, which is characterized in that first coupler (2), second coupling
Device (8) and the splitting ratio of the 4th coupler (22) are 50:50.
4. sensing device as claimed in claim 1 or 2, which is characterized in that the third coupler (11) is multicore coupler,
Multiport inputs, single port output；Input terminal connects single mode optical fiber, and each input terminal is independent of one another, no coupling；Output port connects
Multi-core optical fiber.
5. sensing device as claimed in claim 1 or 2, which is characterized in that the operation wavelength and light of the bandpass filter (7)
Source corresponds to, and the bandwidth of the bandpass filter (7) is less than 1nm.
6. sensing device as claimed in claim 1 or 2, which is characterized in that the multi-core optical fiber (12) is in same covering
Optical fiber containing two or more fibre cores.
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| 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 |
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| CN108020250A (en) * | 2017-12-28 | 2018-05-11 | 浙江杰昆科技有限公司 | A kind of distributed fiber optic temperature and strain sensing device |
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| CN110388948A (en) * | 2019-08-05 | 2019-10-29 | 长飞光纤光缆股份有限公司 | Distributed temperature, vibration while detection sensor based on multi-core optical fiber |
| CN110631735A (en) * | 2019-10-22 | 2019-12-31 | 武汉理工光科股份有限公司 | Pipeline temperature measurement system and method based on distributed sensing optical fiber |
| CN111664881A (en) * | 2020-07-24 | 2020-09-15 | 南京信息工程大学 | Bidirectional distributed sensing system and method based on multi-core few-mode optical fiber |
| CN112129426B (en) * | 2020-09-23 | 2022-07-05 | 长飞光纤光缆股份有限公司 | Raman sensing temperature measurement system and method with single end injected with multi-core optical fiber |
| CN112291007B (en) * | 2020-10-29 | 2022-02-22 | 国网辽宁省电力有限公司信息通信分公司 | Distributed optical fiber automatic monitoring system |
| CN114485903B (en) * | 2022-01-17 | 2023-09-15 | 武汉地震工程研究院有限公司 | System and method for measuring long-distance distributed optical fiber high-frequency vibration |
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| CN201104243Y (en) * | 2007-11-15 | 2008-08-20 | 中国计量学院 | Ultra-long range distributed optical fiber Raman and Brillouin photon sensor |
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| CN102313568B (en) * | 2011-08-30 | 2016-08-24 | 武汉康特圣思光电技术有限公司 | The distribution type optical fiber sensing equipment that a kind of Brillouin and Raman detect simultaneously |
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