CN103698049B - Distributed Measurement System based on Brillouin scattering and method - Google Patents
Distributed Measurement System based on Brillouin scattering and method Download PDFInfo
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- CN103698049B CN103698049B CN201310699063.6A CN201310699063A CN103698049B CN 103698049 B CN103698049 B CN 103698049B CN 201310699063 A CN201310699063 A CN 201310699063A CN 103698049 B CN103698049 B CN 103698049B
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Abstract
A kind of Distributed Measurement System based on Brillouin scattering, including can be local oscillator light with the first laser cell of pump light, can Laser Modulation be become can be as the second laser cell of OFDM optical signal, non-coaxial multi-core fiber and the Fibre Optical Sensor unit of detection light by laser beam splitter, non-coaxial multi-core fiber one end receives the pump light of the first laser cell, the other end receives OFDM optical signal, and Fibre Optical Sensor unit is connected with the first laser cell and the second laser cell respectively.Above-mentioned Distributed Measurement System based on Brillouin scattering, uses non-coaxial multi-core fiber replacement single mode single-core fiber as sensor fibre, can distinguish temperature and stress cross sensitivity problem.Use OFDM optical signal replacement single beam laser as the detection light in system, scanning speed can be increased, disposably complete the scanning of multiple frequency, improve detection response time.Additionally provide a kind of distributed measurement method based on Brillouin scattering.
Description
Technical field
The present invention relates to technical field of optical fiber sensing, particularly relate to a kind of based on Brillouin scattering distributed
Measure system and method.
Background technology
In power system, cable, wind power equipment etc. are chronically exposed in air, are easily subject to external force and the external world
The impact of environmental change.Equipment will be made to deform upon generation sag such as strong wind, earthquake and ice damage etc., thus lead
Causing to produce ess-strain, equipment intensity declines, and causes line interruption fault.And equipment is affected not by stress
Can intuitively show, once stress accumulation is to a certain extent, causes equipment operating interruptions, can have a strong impact on
The safety of the defeated power supply of power system.On the other hand, in power system, high temperature, fire are also to affect electric power
The Common Accidents of system safety operation, so the quality of on-line temperature monitoring is equally to safe operation of power system
Very important.Therefore, monitoring in time and grasp equipment ess-strain and temperature variations, and find in time
Fault and he takes preventive measure effectively, to improving the reliability of power system and safety is most important.
Brillouin scattering is light wave to interact when propagating in a fiber with sound wave and the light scattering process that produces,
There is between Brillouin scattering and incident illumination certain frequency difference, have good between this frequency difference and temperature and strain
Linear relationship, simultaneously with power and the proportional relation of temperature.Optical fiber as sensor information, have volume little,
Lightweight, electromagnetism interference and be prone to the advantages such as networking.Permissible by measuring the Brillouin's frequency spectrum in optical fiber
Realize temperature and the distributed sensing of strain in environment, distributed sensing technology based on optical fiber Brillouin scattering
Apply and give birth to.
But, due to the most strained impact with temperature of Brillouin shift in optical fiber, only by single background of cloth
It is by strain or to be caused by temperature that deep pool frequency displacement cannot tell this frequency displacement so that the practicality of this sensing technology
Occasion is greatly limited, this phenomenon, referred to as " cross sensitivity " of Brillouin scattering Fibre Optical Sensor
Problem.
In order to solve this problem, it is proposed that multiple solution.Such as, non-by research large effective area
The Brillouin spectrum of zero dispersion shift fiber and strain and the relation of temperature, thus the solution Brillouin proposed
The scheme of scattered light fiber sensor cross sensitivity problem.The method of temperature-compensating is used additionally, also proposed
Solve cross sensitivity problem.But, the use of large effective area non-zero scattering optical fiber, system cost increases,
And cannot merge with the optical cable laid, and detection response time is long, certainty of measurement is the highest.Employing temperature is mended
Repaying method, certainty of measurement is the highest, and detection response time is long.
Summary of the invention
Based on this, it is necessary to for response time length, problem that certainty of measurement is the highest, it is provided that a kind of based on cloth
In deep pool scattering Distributed Measurement System and method.
A kind of Distributed Measurement System based on Brillouin scattering, including:
Can be by the first laser cell that laser beam splitter is local oscillator light and pump light；
Can Laser Modulation be become can be as the second laser cell of the OFDM optical signal of detection light；
Non-coaxial multi-core fiber, one end receives the pump light of described first laser cell, and the other end receives described
OFDM optical signal；
The Fibre Optical Sensor unit of available described non-coaxial multi-core fiber fibre core Brillouin shift, respectively with described
First laser cell and the second laser cell connect, and described local oscillator light and detection light all input described Fibre Optical Sensor
Unit.
Wherein in an embodiment, described first laser cell includes pump laser, by the of laser beam splitter
One photo-coupler, carry out pulse or random sequence modulation the first electrooptic modulator, the first fiber amplifier,
Optical circulator, described pump laser is connected with described first bonder, swashing of described pump laser output
Light a branch of input optical fibre sensing unit, another bundle passes sequentially through the first electrooptic modulator, the first fiber amplifier
Inputting described non-coaxial multi-core fiber with optical circulator, described optical circulator is connected with described Fibre Optical Sensor unit.
Wherein in an embodiment, described optical circulator includes the first port, the second port and the 3rd port,
Described first fiber amplifier is connected with described optical circulator by the first port, described non-coaxial multi-core fiber
One end is connected with described second port, and described Fibre Optical Sensor unit is by the 3rd port with described optical circulator even
Connect.
Wherein in an embodiment, described first laser cell also includes optical filter, described optical filter
One end is connected with described optical circulator, and the other end is connected with described Fibre Optical Sensor unit.
Wherein in an embodiment, described second laser cell include detect light laser, can be by Laser Modulation
Be orthogonal the second electrooptic modulator of frequency division multiplexing optical signal, the second fiber amplifier, described detection ray laser
The laser of device output passes sequentially through the second electrooptic modulator, the second fiber amplifier inputs non-coaxial multi-core fiber.
Wherein in an embodiment, described second electrooptic modulator include OFDM optical signal generator,
Digital to analog converter, driver and electro-optic modulation arrangement, described OFDM optical signal generator, digital-to-analogue
Transducer, driver and electro-optic modulation arrangement are sequentially connected with, described detection light laser and described Electro-optical Modulation
Device connects, and described second fiber amplifier is connected with described electro-optic modulation arrangement.
Wherein in an embodiment, described Fibre Optical Sensor unit includes that opto-electronic receiver detects device, analog digital conversion
Device, channel estimating apparatus and master control display device, described opto-electronic receiver detection device swashs with described first respectively
Light unit and the second laser cell connect, and described analog-digital converter is connected with described opto-electronic receiver detection device,
Described channel estimating apparatus is connected with described analog-digital converter, and described master control display device is estimated with described channel
Device connects and the first laser cell connects.
Wherein in an embodiment, described opto-electronic receiver detection device includes the second photo-coupler and Photoelectric Detection
Device, described second photo-coupler is connected with the first laser cell and the second laser cell respectively, described smooth electric-examination
Surveying device to be connected with described second photo-coupler, described analog-digital converter is connected with described photoelectric detector.
A kind of distributed measurement method based on Brillouin scattering, comprises the following steps:
Lay non-coaxial multi-core fiber；
Produce local oscillator light, pump light and can as detection light OFDM optical signal, modulated pumping light
With can be as the OFDM optical signal of detection light, respectively input pumping light and can as detection light just
Hand over frequency division multiplexing optical signal in described non-coaxial multi-core fiber two ends；
Receive and detect described local oscillator light and carry described non-coaxial multi-core fiber generation Brillouin scattering optical signal
OFDM optical signal；
The OFDM optical signal detected is modulated demodulation, draws described non-coaxial multi-core fiber
The brillouin gain spectrum of each fibre core, and determine the Brillouin shift of each fibre core；
The Brillouin shift caused by temperature and STRESS VARIATION determines temperature and stress value.
Wherein in an embodiment, the described OFDM optical signal to detecting is modulated demodulation,
Draw the brillouin gain spectrum of the described each fibre core of non-coaxial multi-core fiber, and determine the Brillouin of each fibre core
The step of frequency displacement, specifically includes following steps:
The OFDM optical signal detected is carried out analog digital conversion；
The OFDM signal of telecommunication is carried out serioparallel exchange；
The OFDM signal of telecommunication of serioparallel exchange is removed Cyclic Prefix；
The OFDM signal of telecommunication removing Cyclic Prefix is carried out fast Fourier transform；
The OFDM signal of telecommunication of fast Fourier change is carried out channel estimation, and draws the background of cloth of fibre core
Deep pool frequency displacement.
Above-mentioned Distributed Measurement System based on Brillouin scattering and method, use non-coaxial multi-core fiber conduct
Sensor fibre, receives and detects optical signal, and optical signal includes local oscillator light and carries described non-coaxial multi-core fiber
There is the OFDM Detecting light of the optical signal of Brillouin scattering, then the optical signal detected is carried out
Modulation /demodulation, draws the brillouin gain spectrum of the described each fibre core of non-coaxial multi-core fiber, and determines each fibre
The Brillouin shift of core, the Brillouin shift caused by temperature and STRESS VARIATION determines temperature and stress value.
So, use non-coaxial multi-core fiber replacement single mode single-core fiber as sensor fibre, temperature can be distinguished
Degree and stress cross sensitivity problem.OFDM optical signal is used to replace single beam laser as in system
Detection light, can be greatly increased scanning speed, disposably complete the scanning of multiple frequency, improves detection response
Time.Use through ovennodulation OFDM optical signal as detection light, through OFDM solution
Adjust, draw the Brillouin shift of each fibre core of non-coaxial multi-core fiber, reduce system-computed complexity, letter
Change the averaging process in traditional approach, decrease the detection time.Additionally, OFDM optical signal transmission
Can long range propagation, transmit precision high, improve certainty of measurement.
Accompanying drawing explanation
Fig. 1 is the structural representation of the Distributed Measurement System based on Brillouin scattering of an embodiment；
Fig. 2 is the structural representation of the Distributed Measurement System based on Brillouin scattering of another embodiment；
Fig. 3 is the second electrooptic modulator of the Distributed Measurement System based on Brillouin scattering of an embodiment
Structural representation；
Fig. 4 is the schematic flow sheet of the distributed measurement method based on Brillouin scattering of an embodiment；
Fig. 5 is the distributed measurement method OFDM telecommunications based on Brillouin scattering of an embodiment
Number modulation /demodulation schematic flow sheet.
Detailed description of the invention
For the ease of understanding the present invention, below with reference to relevant drawings, the present invention is described more fully.
Accompanying drawing gives the preferred embodiment of the present invention.But, the present invention can come in many different forms
Realize, however it is not limited to embodiment described herein.On the contrary, provide the purpose of these embodiments be make right
The understanding of the disclosure is more thorough comprehensively.
It should be noted that when element is referred to as " being fixed on " another element, and it can be directly at another
On individual element or element placed in the middle can also be there is.When an element is considered as " connection " another yuan
Part, it can be directly to another element or may be simultaneously present centering elements.Used herein
Term " vertical ", " level ", "left", "right" and similar statement simply to illustrate that mesh
's.
Unless otherwise defined, all of technology used herein and scientific terminology and the technology belonging to the present invention
The implication that the technical staff in field is generally understood that is identical.The art used the most in the description of the invention
Language is intended merely to describe the purpose of specific embodiment, it is not intended that in limiting the present invention.Used herein
Term " and/or " include the arbitrary and all of combination of one or more relevant Listed Items.
As it is shown in figure 1, a kind of Distributed Measurement System based on Brillouin scattering, including laser being divided into
Two bundle the first laser cells 110, can using Laser Modulation become can as detection light OFDM optical signal
The second laser cell 120, non-coaxial multi-core fiber 130 and available non-coaxial multi-core fiber 130 fibre core cloth
In deep pool frequency displacement Fibre Optical Sensor unit 140.Laser can be divided into two bundles by the first laser cell 110, and a branch of is this
Shake light, and another bundle is pump light, and non-coaxial multi-core fiber 130 one end receives the pump of the first laser cell 110
Pu light, the other end receives can be as the OFDM optical signal of detection light.First laser cell 110 He
Second laser cell 120 is all connected with Fibre Optical Sensor unit 140, and local oscillator light and the detection equal input optical fibre of light pass
Sense unit 140.
In the present embodiment, use non-coaxial multi-core fiber 130 as sensor fibre, non-coaxial multi-core fiber
130 is a kind of to share surrounding layer, is contained within many fibre cores, and every fibre core has again the optical fiber of the inner cladding of oneself.
Non-coaxial multi-core fiber 130 can improve the integration density of stranding, also can reduce construction cost simultaneously.
Owing to non-coaxial multi-core fiber 130 core interval is big, the most there is not wet-out phenomenon, by temperature shadow
When ringing, the Brillouin shift change of each fibre core is identical, and each fibre core position is different, is stressed impact
Time Brillouin shift change difference.Therefore, it can tell Brillouin shift is by temperature or owing to answering
Power change causes, thus solves the cross sensitivity problem of Brillouin scattering sensing.
Laser can be divided into two bundles by the first laser cell 110, a branch of can be as local oscillator light, another bundle can be as pump
Pu light.Wherein in an embodiment, the first laser cell 110 can include pump laser the 112, first light
Bonder the 114, first electrooptic modulator the 116, first fiber amplifier 118 and optical circulator 119.Pumping
The laser that laser instrument 112 is launched can be as pump light source, and laser can be divided into two bundles by the first photo-coupler 114,
First electrooptic modulator 116 can carry out pulse or random sequence modulation, the first fiber amplifier 118 to pump light
Being amplified pump light, optical circulator 119 Single port is connected with non-coaxial multi-core fiber 130, the other end
Mouth is connected with Fibre Optical Sensor unit 140.
Wherein, the laser of pump laser 112 output is divided into two bundles, a branch of conduct through the first bonder 114
Pump light inputs the first fiber amplifier 118 after the first electrooptic modulator 116 pulse or random sequence are modulated
Amplify, enter back into optical circulator 119 thus be input to non-coaxial multi-core fiber 130 and produce Brillouin scattering,
Another beam of laser is as local oscillator light input optical fibre sensing unit 140.
Optical circulator 119 is a kind of nonreciprocal optics of multiport, has N number of port, and wherein N is more than
Equal to 3, N number of port forms a continuous print passage, can complete the separation of forward and reverse transmission light.In this reality
Executing in example, optical circulator 119 includes 3 ports, and the first fiber amplifier 118 is by the first port 1192
Being connected with optical circulator 119, one end of non-coaxial multi-core fiber 130 is connected with the second port 1194, optical fiber
Sensing unit 140 is connected with the 3rd port 1196.So, enter from the first fiber amplifier 118 when pump light
Enter the first port 1192 of optical circulator 119, can the most break-even be entered non-coaxial many by the second port 1194
Core fibre 130, due to the characteristics of non-reciprocity of optical circulator 119, the 3rd port 1196 not light output.
First photo-coupler 114 is ordinary optic fibre bonder, it is to be understood that in other embodiments, the
The coupling ratio of one photo-coupler 114 can select according to the needs of practical laser condition and output, only
The purpose of system stability to be realized work.Pump laser 112 can be end-face pump solid laser,
Can also be side pumped solid laser device, as long as realizing low-power consumption, dependable performance, life-span length, output light
The measured purpose of matter.In the present embodiment, pump laser 112 uses distributed feedback laser
(Distributed Feedback Laser, DFB).First fiber amplifier 118 mixes ear amplifier for being
(Erbium-doped Optical Fiber Amplifier, EDFA).
Laser Modulation can be become by the second laser cell 120 can be as the OFDM optical signal of detection light.
Wherein in an embodiment, the second laser cell 120 includes detecting light laser the 122, second electric light
Manipulator the 124, second fiber amplifier 126, by the after detection optical signals detecting laser 122 output
Two electrooptic modulator the 124, second fiber amplifiers 126 input non-coaxial multi-core fiber 130 other end.
Detection light laser 122 has certain frequency compared with the pump laser 112 of the first laser cell 110
Difference, as coherent source, the brillouin frequency that common quartzy non-coaxial multi-core fiber produces when room temperature is without strain
Move and be about 11GHz, therefore in the present embodiment, frequency difference is 11GHz, when temperature and strain variation, according to
The relation of Brillouin shift and temperature and strain can draw the change information of temperature and strain.
Second electrooptic modulator 124 can will produce OFDM (Orthogonal Frequency Division
Multiplexing, OFDM) analogue signal, and carry out OFDM with the laser detecting light laser 122 output
Modulation, is OFDM optical signal by Laser Modulation, and inputs non-coaxial many through the second fiber amplifier 126
The other end of core fibre 130, experiences brillouin gain.Second fiber amplifier 126 can be to mix ear amplifier.
It should be noted that OFDM is a kind of multi-carrier modulation technology, it transmits on multiple orthogonal subcarriers
Different information symbols, such as 4 qam symbols, frequency resolution is subcarrier spacing.
In the present embodiment, the second electrooptic modulator 124 can use MZ Mach-Zehnder
(Mach-Zehnder Modulator, MZM), input light is divided into the letter that two-way is equal by MZM modulator
Number respectively enteing two branch roads of manipulator, the material that the two light branch road uses is arc material, its folding
Signal of telecommunication size that rate of penetrating applies with outside and change.Owing to the variations in refractive index of light branch road can cause signal phase
The change of position, when two tributary signal manipulator outfans are bound together again, the optical signal of cooperation will
It is the interference signal of an intensity size variation, is equivalent to the change of the signal of telecommunication to be converted to the change of optical signal
Change, it is achieved that the modulation of light intensity.
So, it is OFDM optical signal by OFDM analogue signal and detection light modulation, and recently enters non-same
Axle multi-core fiber 130 experiences brillouin gain.Employing OFDM optical signal, can as the detection light in system
It is greatly increased scanning speed, disposably completes the scanning of multiple frequency, reduce the detection time.Additionally, use
OFDM technology can be effective against the interference of signal waveform, it is adaptable to the high speed in multi-path environment and fading channel
Data are transmitted, and have the strongest anti-fading ability by the combined coding of each subcarrier, are applicable to distance
Distributing optical fiber sensing.
It is understood that the second electrooptic modulator 124 may be used without other electrooptic modulators, as long as realizing
The purpose of OFDM optical signal modulation.Second fiber amplifier 126 may be used without other fiber amplifier
Device, as long as realizing OFDM optical signal amplification.
Fibre Optical Sensor unit 140 can get the Brillouin shift of non-coaxial multi-core fiber 130 fibre core, respectively with
First laser cell 110 and the second laser cell 120 connect, local oscillator light and detection light equal input optical fibre sensing
Unit 140.
Wherein in an embodiment, Fibre Optical Sensor unit 140 can include that opto-electronic receiver detects device 142, mould
Number converter 144, channel estimating apparatus 146 and master control display device 148, opto-electronic receiver detection device 142
It is connected with the first laser cell 110 and the second laser cell 120 respectively, analog-digital converter 144 and light electric-examination
Survey device connects, and channel estimating apparatus 146 is connected with analog-digital converter 144, master control display device 148 and
Channel estimating apparatus 146 connects, and is also connected with the first laser cell 110.
Referring to Fig. 2, wherein in an embodiment, opto-electronic receiver detection device 142 includes the second photo-coupler
1422 and photoelectric detector 1424, the second photo-coupler 1422 respectively with the first laser cell 110 and second
Laser cell 120 connects, and photoelectric detector 1424 is connected with the second photo-coupler 1422.First laser list
Unit's 110 laser are divided into two bundles, as a branch of input second photo-coupler 1422 of local oscillator light, the second laser list
Unit 120 is connected with the second photo-coupler 1422 by optical circulator 119, analog-digital converter 144 and light electric-examination
Survey device 1424 to connect.
First laser cell 110 pump light inputs non-coaxial multi-core fiber 130, produces Brillouin scattering, works as pump
Pu light is with the frequency difference detecting light with when in optical fiber, the Brillouin shift in certain region is equal, and this region will produce cloth
In deep pool enlarge-effect, i.e. brillouin gain, pump light and detection light between occur energy transfer.OFDM light
Signal inputs non-coaxial multi-core fiber 130 as detection light and experiences brillouin gain, owing to Brillouin scattering is believed
Number contrary with pump direction, OFDM optical signal carry brillouin scattering signal through optical circulator 119 with
Local oscillator light is coupled into photoelectric detector 1424 at the second photo-coupler 1422.
Wherein, channel estimating apparatus 146 has carried out OFDM solution to the OFDM optical signal through analog digital conversion
Adjust, in order to the data of brillouin scattering signal process.It should be noted that demodulation is from having carried message
Adjusting the process recovering message in signal, carrier wave is modulated by the message that transmitting terminal to be transmitted, and generation is taken
With the signal of this message, the message that receiving terminal recovers to be transmitted just can be used.Above-mentioned detection method is adopted
By direct Detection Method, carry brillouin scattering signal by OFDM optical signal, then convert optical signals to
The signal of telecommunication, demodulator circuit detection information, direct detection algorithm makes cost be substantially reduced.
It is understood that opto-electronic receiver detection device 142 can also be coherent receiver 1426, first swashs
The local oscillator light input coherent receiver 1426 of light unit 110, the OFDM optical signal of the second laser cell 120
Carry brillouin scattering signal and input coherent receiver 1426 through optical circulator 119.So, as long as realizing
Receive and detect local oscillator light and carry the OFDM optical signal of brillouin scattering signal, and to OFDM light
The purpose that signal is demodulated.Above-mentioned detection scheme uses coherent detection scheme, utilizes the coherence of light
Information signal entrained by light carrier is detected and processed, and compared with directly detection, relevant detection is more held
Easily obtaining big signal to noise ratio, recoverable signal kinds is many, and frequency selectivity is preferable, is more suitable for intensive
Wavelength-division multiplex system, therefore, in transmitting procedure, error is little, improves degree of accuracy.Additionally, coherent receiver
1426 highly sensitive, add the unrepeatered transmission distance of optical signal, thus add measurement distance.
Analog-digital converter 144 is connected with photoelectric detection system 142, channel estimating apparatus 146 and analog digital conversion
Device 144 connects, and master control display device 148 is connected with channel estimating apparatus 146, also with the first laser cell
110 connect.So, OFDM optical signal can be converted to the OFDM signal of telecommunication by analog-digital converter 144, letter
Road estimation unit 146 is by channel estimation technique thus obtains the brillouin gain spectrum of each fibre core, and master control shows
Showing device 148 thus process through data and draw the Brillouin shift of each fibre core, draw temperature and stress value.
Wherein, master control display device 148 is also connected with the first electrooptic modulator 116, thus controls the first electric light and adjust
The pulse of device 116 processed or random sequence modulation.
Above-mentioned Distributed Measurement System based on Brillouin scattering, including laser beam splitter can become local oscillator light and pump
First laser cell 110 of Pu light, can Laser Modulation be become can be as the OFDM optical signal of detection light
The second laser cell 120, one end receives the first laser cell 110 pump light, and the other end receives orthogonal frequency
The non-coaxial multi-core fiber 130 of multiplexing optical signal, and available non-coaxial multi-core fiber 130 fibre core Brillouin
The Fibre Optical Sensor unit 140 of frequency displacement.Fibre Optical Sensor unit 140 swashs with the first laser cell 110 and second respectively
Light unit 120 connects, local oscillator light and detection light equal input optical fibre sensing unit 140.
So, laser beam splitter is local oscillator light and pump light by the first laser cell 110, the second laser cell 120
Be orthogonal frequency division multiplexing optical signal by Laser Modulation, and the pump light input that the first laser cell 110 beam splitting goes out is non-
One end of coaxial multi-barrel optical fiber 130, produces Brillouin scattering, and the second laser cell 120 is by orthogonal frequency division multiplexing
Input the other end of non-coaxial multi-core fiber 130 with optical signal, and experience brillouin gain.Due to Brillouin
The direction of scattered signal is in opposite direction with pump light, and OFDM optical signal carries Brillouin scattering letter
Number input optical fibre sensing unit 140.The local oscillator light also input optical fibre sensing unit of the first laser cell 110 beam splitting
140, by the detection detection of Fibre Optical Sensor unit 140, OFDM demodulation, channel estimation etc., finally give
The brillouin gain spectrum of each fibre core, obtains the Brillouin shift of each fibre core after finding peak value.According to temperature
The Brillouin shift that change causes is identical in each fibre core, and the Brillouin shift that STRESS VARIATION causes
Each fibre core is different distinguish temperature and stress value, thus solves cross sensitivity problem.Additionally,
Distributed Measurement System is used to be applicable to the measurement of distance.
Use non-coaxial multi-core fiber 130 replacement single mode single-core fiber as sensor fibre, temperature can be distinguished
With stress cross sensitivity problem.Non-coaxial multi-core fiber 130 also can improve the integration density of stranding, the most also
Construction cost can be reduced.Employing OFDM optical signal replacement single beam laser, can be big as the detection light in system
Increase greatly scanning speed, disposably complete the scanning of multiple frequency, improve detection response time, also improve
Measurement dynamic range.Additionally, use OFDM technology can be effective against the interference of signal waveform, it is adaptable to
High speed data transfer in multi-path environment and fading channel, has the strongest by the combined coding of each subcarrier
Anti-fading ability, is applicable to long-distance distributed optical fiber sensing, significantly increases measurement distance, also improve
Certainty of measurement.
Referring to Fig. 1, wherein in an embodiment, the first laser cell 110 also includes optical filter 115,
One end of optical filter 115 is connected with optical circulator 119, and the other end is connected with Fibre Optical Sensor unit 140.
Signal producing, conversion, lopsided due to environment and the existence of interference in transmitting procedure, to such an extent as to signal and
Its entrained information is by noise jamming, thus forms OFDM inter-sub-carrier interference (inter-carrier
Interference, ICI), so, wave filter is greatly improved the transmission precision of OFDM, thus ensure that
Accuracy of detection.Filter additionally, the Ruili in signal is also scattered by wave filter with the end face reflection light in system,
Improve the accuracy of detection of system.
Referring to Fig. 3, wherein in an embodiment, the second electrooptic modulator 124 includes that orthogonal frequency division multiplexing is used up
Signal generator 1242, digital to analog converter 1244, driver 1246 and electro-optic modulation arrangement 1248, orthogonal
Frequency division multiplexing optical signal generator 1242, digital to analog converter 1244, driver 1246 and electro-optic modulation arrangement
1248 are sequentially connected with, and detection light laser 122 is connected with electro-optic modulation arrangement 1248, the second fiber amplifier
126 are connected with electro-optic modulation arrangement 1248.Orthogonal multiplex optical signal generator output OFDM signal, digital-to-analogue
Ofdm signal is converted into analogue signal by transducer 1244, and driver 1246 drives electro-optic modulation arrangement 1248
The Laser Modulation that OFDM analogue signal exports with detection light laser 122 is become OFDM optical signal, more defeated
Enter the second fiber amplifier 126 and be amplified into non-coaxial multi-core fiber 130.So, to realize orthogonal frequency
Multiplex technique is transmitted, and improves scanning speed, decreases the detection time.
As shown in Figure 4, a kind of distributed measurement method based on Brillouin scattering, comprise the following steps:
Step S110, lays non-coaxial multi-core fiber 130；
Step S120, produce local oscillator light, pump light and can as detection light OFDM optical signal,
Modulated pumping light and can be as the OFDM optical signal of detection light, respectively input pumping light and can conduct
The OFDM optical signal of detection light is in described non-coaxial multi-core fiber 130 two ends；
Step S130, receives and detects described local oscillator light and carry described non-coaxial multi-core fiber 130 cloth occurs
In deep pool scattered light signal OFDM optical signal；
Step S140, is modulated demodulation to the OFDM optical signal detected, draws described non-same
The brillouin gain spectrum of each fibre core of axle multi-core fiber 130, and determine the Brillouin shift of each fibre core；
Step S150, the Brillouin shift caused by temperature and STRESS VARIATION calculates temperature and stress value.
Above-mentioned distributed measurement method based on Brillouin scattering, lays non-coaxial multi-core fiber 130, produces this
Shake light, pump light and can be as the OFDM optical signal of detection light, input pumping light and can making respectively
For detecting the OFDM optical signal of light in described non-coaxial multi-core fiber 130 two ends.Receive and detect
Described local oscillator light and carry described non-coaxial multi-core fiber 130 orthogonal frequency of Brillouin scattering optical signal occurs
Multiplexing optical signal.The OFDM optical signal detected is modulated demodulation, draws described non-coaxial
The brillouin gain spectrum of each fibre core of multi-core fiber 130, and determine the Brillouin shift of each fibre core；, then root
The Brillouin shift caused according to temperature and STRESS VARIATION determines temperature and stress value.
So, use non-coaxial multi-core fiber 130 replacement single mode single-core fiber as sensor fibre, can be with district
Divide temperature and stress cross sensitivity problem.Non-coaxial multi-core fiber 130 also can improve the integration density of stranding,
Also can reduce construction cost simultaneously.Use OFDM optical signal replace single beam laser as the detection light in system,
Scanning speed can be greatly increased, disposably complete the scanning of multiple frequency, improve detection response time.
Use through ovennodulation OFDM as detection light, through OFDM demodulation, draw non-coaxial multi-core optical
The Brillouin shift of fine 130 each fibre cores, it is possible to decrease system-computed complexity, it is to avoid need to adjust through electric light
The processes such as system, Polarization Control, signal averaging, simplify the averaging process in traditional approach, when decreasing detection
Between.OFDM optical signal transmission can long range propagation, transmit precision high, improve certainty of measurement.
Referring to Fig. 5, wherein in an embodiment, the orthogonal frequency division multiplexing detected is used up letter by step S140
Number it is modulated demodulation, draws the brillouin gain spectrum of the described each fibre core of non-coaxial multi-core fiber, and determine
The step of the Brillouin shift of each fibre core, specifically includes following steps:
Step S141, carries out analog digital conversion to the OFDM optical signal detected；
Step S142, carries out serioparallel exchange to the OFDM signal of telecommunication；
Step S144, removes Cyclic Prefix to the OFDM signal of telecommunication of serioparallel exchange；
Step S146, carries out fast Fourier transform to the OFDM signal of telecommunication removing Cyclic Prefix；
Step S148, carries out channel estimation to the OFDM signal of telecommunication of fast Fourier change, and draws
The Brillouin shift of fibre core.
So, OFDM signal of telecommunication modulation /demodulation quickly and accurately can be calculated the Brillouin of each fibre core
Frequency displacement, can reduce system-computed complexity through steps such as OFDM demodulation, analog to digital conversion and channel estimations,
Simplify the averaging process in traditional approach, decrease the detection time.
Wherein in an embodiment, the OFDM signal of telecommunication that fast Fourier is changed by step S148 is carried out
Channel estimate particularly as follows:
If the symbol on kth subcarrier is X on OFDM detection optical signalk, detect device at opto-electronic receiver
The symbol on this subcarrier received when processing ofdm signal in 142 is Yk, then the signal of this subcarrier
Relative intensity is
According to relative intensity Hk, the frequency of the subcarrier trying to achieve its maximum is Brillouin shift υB(T) or
υB(ε).Then formula is utilized:
T=Tr+[υB(T)/υB(Tr)-1]/CrT
ε=εr+[υB(ε)/υB(εr)-1]/Crε
Temperature value T or stress value ε can be drawn.T in its Chinese styler、εrFor reference temperature and Reference Stress, CrT、
CrεFor temperature control coefficient and stress sensitivity coefficient, υB(Tr) it is reference temperature TrUnder Brillouin shift,
υB(εr) it is Reference Stress εrUnder Brillouin shift.
So, by can be calculated the Brillouin shift of each fibre core, so that it is determined that temperature and stress point
Cloth, it is achieved accurately measure.
Embodiment described above only have expressed the several embodiments of the present invention, and it describes more concrete and detailed,
But therefore can not be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that, for this area
Those of ordinary skill for, without departing from the inventive concept of the premise, it is also possible to make some deformation and
Improving, these broadly fall into protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be with appended
Claim is as the criterion.
Claims (7)
1. a Distributed Measurement System based on Brillouin scattering, it is characterised in that including:
Can be by the first laser cell that laser beam splitter is local oscillator light and pump light；
Can Laser Modulation be become can be as the second laser cell of the OFDM optical signal of detection light；
Non-coaxial multi-core fiber, one end receives the pump light of described first laser cell, and the other end receives described
OFDM optical signal；
The Fibre Optical Sensor unit of available described non-coaxial multi-core fiber fibre core Brillouin shift, respectively with described
First laser cell and the second laser cell connect, and described local oscillator light and detection light all input described Fibre Optical Sensor
Unit；
Described first laser cell include pump laser, by the first photo-coupler of laser beam splitter, carry out arteries and veins
Punching or the first electrooptic modulator of random sequence modulation, the first fiber amplifier, optical circulator, described pumping
Laser instrument is connected with described first photo-coupler, and the laser of described pump laser output is through described first light
Bonder is divided into two bundles, a branch of input optical fibre sensing unit, another bundle pass sequentially through the first electrooptic modulator,
First fiber amplifier and optical circulator input described non-coaxial multi-core fiber, described optical circulator and described light
Fine sensing unit connects；
Described second laser cell includes detecting light laser, the frequency division multiplexing light that can Laser Modulation be orthogonal letter
Number the second electrooptic modulator, the second fiber amplifier, described detection light laser output laser lead to successively
Cross the second electrooptic modulator, the second fiber amplifier inputs non-coaxial multi-core fiber.
Distributed Measurement System based on Brillouin scattering the most according to claim 1, it is characterised in that
Described optical circulator includes that the first port, the second port and the 3rd port, described first fiber amplifier pass through
First port is connected with described optical circulator, and described non-coaxial multi-core fiber one end is connected with described second port,
Described Fibre Optical Sensor unit is connected with described optical circulator by the 3rd port.
Distributed Measurement System based on Brillouin scattering the most according to claim 1, it is characterised in that
Described first laser cell also includes that optical filter, one end of described optical filter are connected with described optical circulator,
The other end is connected with described Fibre Optical Sensor unit.
Distributed Measurement System based on Brillouin scattering the most according to claim 1, it is characterised in that
Described second electrooptic modulator include OFDM optical signal generator, digital to analog converter, driver and
Electro-optic modulation arrangement, described OFDM optical signal generator, digital to analog converter, driver and electric light
Modulating device is sequentially connected with, and described detection light laser is connected with described electro-optic modulation arrangement, described second light
Fiber amplifier is connected with described electro-optic modulation arrangement.
Distributed Measurement System based on Brillouin scattering the most according to claim 1, it is characterised in that
Described Fibre Optical Sensor unit includes opto-electronic receiver detection device, analog-digital converter, channel estimating apparatus and master control
Display device, described opto-electronic receiver detection device connects with described first laser cell and the second laser cell respectively
Connecing, described analog-digital converter is connected with described opto-electronic receiver detection device, and described channel estimating apparatus is with described
Analog-digital converter connects, and described master control display device is connected with described channel estimating apparatus and the first laser cell
Connect.
Distributed Measurement System based on Brillouin scattering the most according to claim 5, it is characterised in that
Described opto-electronic receiver detection device includes that the second photo-coupler and photoelectric detector, described second photo-coupler divide
It is not connected with the first laser cell and the second laser cell, described photoelectric detector and described second photo-coupler
Connecting, described analog-digital converter is connected with described photoelectric detector.
7. a distributed measurement method based on Brillouin scattering, it is characterised in that comprise the following steps:
Lay non-coaxial multi-core fiber；
Produce local oscillator light, pump light and can as detection light OFDM optical signal, modulated pumping light
With can be as the OFDM optical signal of detection light, respectively input pumping light and can as detection light just
Hand over frequency division multiplexing optical signal in described non-coaxial multi-core fiber two ends；
Receive and detect described local oscillator light and carry described non-coaxial multi-core fiber generation Brillouin scattering optical signal
OFDM optical signal；
The OFDM optical signal detected is modulated demodulation, draws described non-coaxial multi-core fiber
The brillouin gain spectrum of each fibre core, and determine the Brillouin shift of each fibre core；
The Brillouin shift caused by temperature and STRESS VARIATION determines temperature and stress value；
The described OFDM optical signal to detecting is modulated demodulation, draws described non-coaxial multicore
The brillouin gain spectrum of each fibre core of optical fiber, and determine the step of the Brillouin shift of each fibre core, specifically wrap
Include following steps:
The OFDM optical signal detected is carried out analog digital conversion；
The OFDM signal of telecommunication is carried out serioparallel exchange；
The OFDM signal of telecommunication of serioparallel exchange is removed Cyclic Prefix；
The OFDM signal of telecommunication removing Cyclic Prefix is carried out fast Fourier transform；
The OFDM signal of telecommunication of fast Fourier change is carried out channel estimation, and draws the background of cloth of fibre core
Deep pool frequency displacement.
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| CN105004459B (en) * | 2015-07-22 | 2017-06-20 | 哈尔滨工业大学 | The distributed transverse pressure sensor of high sensitivity and the method that transverse pressure is measured using the sensor |
| CN105371785B (en) * | 2015-11-13 | 2018-04-17 | 华中科技大学 | A kind of curvature measurement method |
| FR3066280B1 (en) * | 2017-05-11 | 2019-09-13 | Febus Optics | OPTOELECTRONIC MEASURING DEVICE DISTRIBUTED BY OPTICAL FIBER |
| CN107588873B (en) * | 2017-07-20 | 2020-02-07 | 全球能源互联网研究院 | Optical fiber sensing device with electromagnetic environment monitoring function |
| CN109000157B (en) * | 2018-10-01 | 2024-03-29 | 江苏亨通光纤科技有限公司 | Online monitoring device and method for pipeline |
| CN110441651B (en) * | 2019-07-25 | 2021-07-30 | 武汉钜风科技有限公司 | Transmission line state detection method and system based on OPGW |
| CN110440841A (en) * | 2019-07-25 | 2019-11-12 | 武汉钜风科技有限公司 | A kind of Brillouin optical time domain analysis instrument |
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