CN104776871A - Optical fiber Brillouin distributed type measuring light path, device and method - Google Patents
Optical fiber Brillouin distributed type measuring light path, device and method Download PDFInfo
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Abstract
The embodiment of the invention relates to an optical fiber Brillouin distributed type measuring light path, device and method. The measuring light path comprises a first coupler, a second coupler, a third coupler, a first circulator, a first light channel, a second light channel, a sensing optical fiber, a third light path and a fourth light path, wherein pulse light is input into one end of the sensing optical fiber; continuous light is input into the other end of the sensing optical fiber so as to excite Brillouin scattering. Therefore, anti-Stokes components can be enhanced, if the anti-Stokes light is intense enough, the Stokes light is relatively weak in intensity, the Stokes light can be neglected, the conflict of the input light pulse luminosity and the spatial resolution can be avoided, and a high-precision light filter is not needed.
Description
Technical field
The invention belongs to technical field of optical fiber sensing, in particular a kind of optical fiber Brillouin distributed measurement light path, apparatus and method.
Background technology
Optical fiber sensing technology is a kind of novel sensing technology, have that measuring accuracy is high, the advantage such as electromagnetism interference and distributed measurement, have a extensive future in the industry heavy construction structural health on-line monitorings such as electric power, building, oil and water conservancy and localization of fault.At present, distributed optical fiber sensing system based on Brillouin scattering is mainly divided into three kinds scheme: based on Brillouin light Time Domain Reflectometry (Brillouin Optical TimeDomain Reflectometry, BOTDR) optical fiber sensing technology, based on Brillouin light frequency-domain analysis (Brillouin Optical FrequencyDomain Analysis, BOFDA) optical fiber sensing technology and the optical fiber sensing technology based on Brillouin optical time domain analysis (BrillouinOptical Time Domain Analysis, BOTDA).Wherein, BOTDR measure be spontaneous brillouin scattering signal, and due to spontaneous brillouin scattering signal relatively weak, so detection difficulty is larger.And in the measuring technique of BOFDA, there is required Measuring Time long, high to environmental requirement residing for measuring optical fiber, and the shortcomings such as signal detection apparatus costliness.
Summary of the invention
For the deficiencies in the prior art, the object of the present invention is to provide a kind of optical fiber Brillouin distributed measurement light path, apparatus and method, to solve the not high technological deficiency of existing fiber measuring accuracy.
For this reason, embodiment of the present invention provides a kind of optical fiber Brillouin distributed measurement light path, comprise the first coupling mechanism, the second coupling mechanism, the 3rd coupling mechanism, the first circulator, the first optical channel, the second optical channel, sensor fibre, the 3rd optical channel and the 4th optical channel
Two output ports of described first coupling mechanism are connected with the input end of described first optical channel and the input end of the second optical channel respectively, the output terminal of described first optical channel is connected with the input port of the second coupling mechanism, an output port of described second coupling mechanism is connected through the input port of the first Polarization Controller with described 3rd coupling mechanism, and another output port is connected with one end of described sensor fibre through described 3rd optical channel;
The output terminal of described second optical channel is connected with the first port of described first circulator, second port of described first circulator is connected with other one end of described sensor fibre, 3rd port of described first circulator is connected with grating, and the 4th port of described first circulator is connected with the input end of the 4th optical channel; The output terminal of described 4th optical channel is connected with an input port of described 3rd coupling mechanism.
As the preferred technical scheme of one, described first optical channel comprises the second Polarization Controller, phase type electrooptic modulator successively from input end to output terminal.
As the preferred technical scheme of one, described second optical channel comprises the 3rd Polarization Controller, intensity type electrooptic modulator, Erbium-Doped Fiber Amplifier (EDFA), the second circulator, optoisolator successively from input end to output terminal, first port of described second circulator is connected with the output terminal of described Erbium-Doped Fiber Amplifier (EDFA), second port is connected with grating, and the 3rd port is connected with the input port of described optoisolator.
As the preferred technical scheme of one, described 3rd optical channel comprises optical filter, optoisolator and scrambler from input end successively to output terminal.
As the preferred technical scheme of one, described 4th optical channel comprises Erbium-Doped Fiber Amplifier (EDFA), the 3rd circulator, dual-pass Mach-Zehnder interferometer successively from input end to output terminal, first port of described 3rd circulator is connected with the output terminal of described Erbium-Doped Fiber Amplifier (EDFA), second port is connected with grating, and the 3rd port is connected with the input port of described dual-pass Mach-Zehnder interferometer.
Embodiment of the present invention additionally provides a kind of optical fiber Brillouin distributed measurement device, comprise laser instrument, photoelectric detector and digital sampling and processing, also comprise above-mentioned optical fiber Brillouin distributed measurement light path, described laser instrument is connected with the input port of described first coupling mechanism, described photoelectric detector and described data acquisition and procession model calling, an output port of described 3rd coupling mechanism is connected with described photoelectric detector.
The embodiment of the present invention further provides a kind of optical fiber Brillouin distributed measurement method, comprising:
The laser sent by laser instrument is divided into two ways of optical signals, and wherein a road optical signal modulation becomes pulsed light, and an other road optical signal modulation becomes to have the continuous light of Brillouin shift frequency;
Described continuous light is divided into the first pulse continuous light signal and the second continuous light signal;
Described first continuous light signal and described pulsed light are produced stimulated Brillouin scattering in sensor fibre, produces Brillouin scattering;
Described Brillouin scattering and described second continuous light signal are interfered, after Data Analysis Services, obtains measurement result.
As the preferred technical scheme of one, described first pulsed light intensity accounts for 95% of described continuous light light intensity.
As the preferred technical scheme of one, the step of described " described Brillouin scattering and described second continuous light signal are interfered, obtain measurement result after Data Analysis Services " comprising:
Carry out result of interference according to described Brillouin scattering and described second continuous light signal, obtain Brillouin shift;
According to following formula accounting temperature:
ν
B(T,0)＝v
B(T
0,0)[1+1.18*10
-4ΔT]
Wherein: ν
bwhen (T, 0) represents that strain stress is 0 and remains unchanged, the temperature variant relational expression of Brillouin scattering optical frequency shift; T
0for reference temperature, generally get 20 DEG C; v
b(T
0, 0) and represent that temperature is 20 DEG C, the frequency shift amount of Brillouin scattering when strain stress is 0; Δ T=T-T
0for the temperature variation relative to reference temperature.
As the preferred technical scheme of one, the step of described " described Brillouin scattering and described second continuous light signal are interfered, obtain measurement result after Data Analysis Services " comprising:
Carry out result of interference according to described Brillouin scattering and described second continuous light signal, obtain Brillouin shift;
Strain is calculated according to following formula:
ν
B(T
0,ε)＝v
B(T
0,0)(1+4.48ε)
Wherein: ν
b(T
0, ε) and represent that temperature is reference temperature (T
0=20 DEG C) time, the relational expression that Brillouin shift changes with stress ε; v
b(T
0, 0) and represent that temperature is reference temperature (T
0=20 DEG C), the Brillouin shift amount of stress ε when being 0.
Compared with prior art, embodiment of the present invention has following beneficial effect:
1. this optical path, apparatus and method adopt single light source input, utilize double-width grinding laser to excite Brillouin scattering, make measuring system be simplified like this and measuring accuracy is higher;
2. utilize dual-pass Mach-Zehnder interferometer to realize being separated of stimulated Brillouin scattering and Rayleigh scattering, make separating effect better, improve measuring accuracy;
3. sensor fibre one end input pulse light, the other end input continuous light excite Brillouin scattering, strengthen anti Stokes components like this, if the intensity of anti-Stokes light is enough strong, the intensity of stokes light is then more weak so comparatively speaking, can be left in the basket, so both solve the contradiction of input optical pulse luminosity and spatial resolution, can avoid again using high-precision light filter;
4. embodiment of the present invention no longer needs the difference interference method of additional reference light to detect Brillouin shift, reference light carries out through electrooptic modulator modulating the continuous signal producing about 11GHZ, carry out difference interference with the detection light processed after filtering at photoelectric sensor, further simplify system.
Accompanying drawing explanation
Fig. 1 is the structural representation of the optical fiber Brillouin distributed measurement light path that embodiment of the present invention provides;
Fig. 2 is the structural drawing that Fig. 1 illustrates dual-pass Mach-Zehnder interferometer in embodiment;
Fig. 3 is the structural representation of the optical fiber Brillouin distributed measurement device that embodiment of the present invention provides;
Fig. 4 is the process flow diagram of the optical fiber Brillouin distributed measurement method that embodiment of the present invention provides;
Fig. 5 is Brillouin's backscatter intensity-frequency shift amount-Distance geometry temperature variation graph of a relation when not applying temperature and strain;
Fig. 6 is the graph of a relation of the excited Brillouin backscatter intensity-frequency shift amount-Distance geometry temperature when the 3000m distance of sensor fibre changes a temperature;
Fig. 7 is the graph of a relation of the excited Brillouin backscatter intensity-frequency shift amount-Distance geometry temperature when the 3000m distance of sensor fibre applies a microstress;
In figure:
100: optical fiber Brillouin distributed measurement light path; 111: the first coupling mechanisms; 112: the second coupling mechanisms; 113: the first Polarization Controllers; 114: the three coupling mechanisms; 115: the first circulators; 116: grating; 117: sensor fibre; 120: the first optical channels; 121: the second Polarization Controllers; 122: phase type electrooptic modulator; 130: the second optical channels; 131: the three Polarization Controllers; 132: intensity type electrooptic modulator; 133: Erbium-Doped Fiber Amplifier (EDFA); 134: the second circulators; 135: optoisolator; 140: the three optical channels; 141: optical filter; 142: optoisolator; 143: scrambler; 150: the four optical channels; 151: Erbium-Doped Fiber Amplifier (EDFA); 152: the three circulators; 153: dual-pass Mach-Zehnder interferometer; 1531: coupling mechanism; 1532: piezoelectric ceramics; 1533: coupling mechanism; 1534: optical fiber; 1535: optoisolator; 1536: DC voltage controller; 200: laser instrument; 300: photoelectric detector; 400: data acquisition and procession module.
Embodiment
Below in conjunction with accompanying drawing, embodiments of the present invention are described further.
See the structural representation that Fig. 1, Fig. 1 are the optical fiber Brillouin distributed measurement light paths that embodiment of the present invention provides.Optical fiber Brillouin distributed measurement light path 100 shown in Fig. 1 comprises the first coupling mechanism 111, second coupling mechanism 112, the 3rd coupling mechanism 114, first circulator 115, first optical channel 120, second optical channel 130, sensor fibre 117, the 3rd optical channel 140 and the 4th optical channel 150.
Wherein, two output ports of the first coupling mechanism 111 are connected with the input end of the first optical channel 120 and the input end of the second optical channel 130 respectively, and the output terminal of the first optical channel 120 is connected with the input port of the second coupling mechanism 112.An output port of the second coupling mechanism 112 is connected with an input port of the 3rd coupling mechanism 114 through the first Polarization Controller 113, and another output port is connected with one end of sensor fibre 117 through the 3rd optical channel 140.
The output terminal of the second optical channel 130 is connected with the first port of the first circulator 115, second port of the first circulator 115 is connected with other one end of sensor fibre 117,3rd port of the first circulator 115 is connected with grating, and the 4th port of the first circulator 115 is connected with the input end of the 4th optical channel 150.The output terminal of the 4th optical channel 150 is connected with an input port of the 3rd coupling mechanism 114.
Refer to Fig. 1, the first optical channel 120 comprises the second Polarization Controller 121, phase type electrooptic modulator 122 successively from input end to output terminal.Second optical channel 130 comprises the 3rd Polarization Controller 131, intensity type electrooptic modulator 132, Erbium-Doped Fiber Amplifier (EDFA) 133, second circulator 134, optoisolator 135 successively from input end to output terminal, first port of the second circulator 134 is connected with the output terminal of Erbium-Doped Fiber Amplifier (EDFA) 133, second port is connected with grating 116, and the 3rd port is connected with the input port of optoisolator 135.3rd optical channel 140 comprises optical filter 141, optoisolator 142 and scrambler 143 successively from input end to output terminal.4th optical channel 150 comprises Erbium-Doped Fiber Amplifier (EDFA) 151, the 3rd circulator 152, dual-pass Mach-Zehnder interferometer 153 successively from input end to output terminal, first port of the 3rd circulator 152 is connected with the output terminal of Erbium-Doped Fiber Amplifier (EDFA) 151, second port is connected with grating 116, and the 3rd port is connected with the input port of dual-pass Mach-Zehnder interferometer 153.
The structural drawing that Fig. 1 illustrates dual-pass Mach-Zehnder interferometer 153 in embodiment see Fig. 2, Fig. 2.In the embodiment shown in Fig. 2, dual-pass Mach-Zehnder interferometer 153 has two three-dB couplers 1531 and 1533, a cylindrical piezoelectric pottery (PZT) 1532 and an optoisolator 1535.In order to realize the adjustment interfering free path, by the optical fiber of dual-pass Mach-Zehnder interferometer 153 arm around on cylindrical shape PZT (piezoelectric ceramics 1532), regulate the DC voltage be added on PZT two electrode to realize the control of interferometer optical path difference by DC voltage controller 1536, thus realize being separated of stimulated Brillouin scattering and Rayleigh scattering.
The transition function of dual-pass Mach-Zehnder interferometer 153 is:
F(v)＝I
out/I
in＝[1+cos(2πv/FSR)]
2/4
At normal temperatures, when optical wavelength is 1550nm, optical fiber Brillouin frequency displacement is 10.85GHz, from above formula, as FSR=2vB=21.7GHz, can realize being separated of Brillouin scattering and Rayleigh scattering light.
In the embodiment shown in Fig. 1 and Fig. 2, the continuous light that laser instrument sends is equally divided into two bundles through the first coupling mechanism 111, wherein a branch ofly enters the first optical channel 120, a branch ofly in addition enters the second optical channel 130.Enter the laser of the first optical channel 120 after the second Polarization Controller 121 laggard applying aspect type electrooptic modulator 122, modulated generation is close to the continuous light of Brillouin shift frequency (about 11GHz).This continuous light, after the second coupling mechanism 112, is divided into two bundle laser.Wherein the laser beam of 5% intensity enters the 3rd coupling mechanism 114 by the first Polarization Controller 113; The laser beam of 95% then enters the 3rd optical channel 140.The laser beam entering the 3rd optical channel 140 enters sensor fibre 117 by after optical filter 141, optoisolator 142 and scrambler 143 successively.
In addition on the one hand, from the laser beam (namely entering the laser beam of the second optical channel 130) of the first coupling mechanism 111 another bundle 50% out through the 3rd Polarization Controller 131 laggard applying aspect type electrooptic modulator 132, pulsed light is modulated to.After this pulsed light is amplified by Erbium-Doped Fiber Amplifier (EDFA) 133 after the second circulator 134, enter the first port of the first circulator 115 through optoisolator 135, then out enter the other end of sensor fibre 117 from the second port of the first circulator 115.Like this, sensor fibre 117, stimulated Brillouin scattering is produced from the 3rd optical channel 140 and the second optical channel 130 two-beam out, the backward Brillouin scattering produced enters the second port of the first circulator 115 along the opposite direction of continuous light, after being amplified by Erbium-Doped Fiber Amplifier (EDFA) 151 after grating 116 filtering, again after grating 116 filtering, enter dual-pass Mach-Zehnder interferometer 153.
Rayleigh scattering light in back scattering is separated with Brillouin scattering by dual-pass Mach-Zehnder interferometer 153, thus obtain the less Brillouin scattering of noise, this Brillouin scattering with enter through the first polarizer 113 continuous light (i.e. reference light) inputted in the 3rd coupling mechanism 114 and interfere.
See the structural representation that Fig. 3, Fig. 3 are the optical fiber Brillouin distributed measurement devices that embodiment of the present invention provides.Optical fiber Brillouin distributed measurement device shown in Fig. 3 comprises laser instrument 200, photoelectric detector 300 and digital sampling and processing 400, and the optical fiber Brillouin distributed measurement light path 100 that above-mentioned embodiment relates to, laser instrument is connected with the input port of the first coupling mechanism 111, photoelectric detector 300 is connected with data acquisition and procession module 400, and an output port of the 3rd coupling mechanism 114 is connected with photoelectric detector 300.
In the embodiment illustrated in fig. 3, laser instrument 200 can be narrow linewidth laser.The laser that laser instrument 200 sends enters the first coupling mechanism 111 of the optical fiber Brillouin distributed measurement light path 100 shown in Fig. 1, after interfering in the optical fiber Brillouin distributed measurement light path 100 shown in Fig. 1, be radiated on photoelectric detector 300 through the 3rd coupling mechanism 114 and change electric signal into.The circuit of interference signal in data acquisition and procession module 400 carries out Acquire and process.Some preferred embodiment in, the signal of collection, after conciliation, is gathered into computing machine by NI data collecting card, by the LabVIEW routine call of computing machine.
See the process flow diagram that Fig. 4, Fig. 4 are the optical fiber Brillouin distributed measurement methods that embodiment of the present invention provides.Optical fiber Brillouin distributed measurement method shown in Fig. 4 comprises step S401-S404.
In step S401, the laser sent by laser instrument is divided into two ways of optical signals, and wherein a road optical signal modulation becomes pulsed light, and an other road optical signal modulation becomes to have the continuous light of Brillouin shift frequency.
In step S402, continuous light is divided into the first continuous light signal and the second continuous light signal.Some preferred embodiment in, the first continuous light intensity accounts for 95% of continuous light intensity.
In step S403, the first continuous light signal and pulsed light are produced stimulated Brillouin scattering in sensor fibre 117, produce Brillouin scattering.
In step s 404, Brillouin scattering and the second continuous light signal are interfered, after Data Analysis Services, obtains measurement result.
See Brillouin's backscatter intensity-frequency shift amount-Distance geometry temperature variation graph of a relation that Fig. 5, Fig. 5 are when not applying temperature and strain.In some embodiments, can according to the relation of Brillouin shift and sensor fibre 117 temperature variation, accounting temperature.Such as, carry out result of interference according to Brillouin scattering and the second continuous light signal, obtain Brillouin shift;
Then, according to following formula accounting temperature:
ν
B(T,0)＝v
B(T
0,0)[1+1.18*10
-4ΔT]
Wherein: ν
bwhen (T, 0) represents that strain stress is 0 and remains unchanged, the temperature variant relational expression of Brillouin scattering optical frequency shift; T
0for reference temperature, generally get 20 DEG C; v
b(T
0, 0) and represent that temperature is 20 DEG C, the frequency shift amount of Brillouin scattering when strain stress is 0; Δ T=T-T
0for the temperature variation relative to reference temperature.
The specific implementation process calculating sensor fibre 117 temperature variation according to Brillouin shift is as follows:
The first step: the change due to temperature can cause the thermal expansion effects in sensor fibre 117, thus affects density of optic fibre.The thermo-optic effect of sensor fibre 117 can cause optical fibre refractivity to change, and the free energy of sensor fibre 117 varies with temperature the change of the physical parameter such as Young modulus and Poisson ratio that also can cause sensor fibre 117.First suppose when accounting temperature affects that sensor fibre 117 is not strained, i.e. ε=0, utilize imfinitesimal method work as temperature variation less time, according to formula
By Taylor series expansion and the numerical value substituting into infinitesimal calculate.Here no longer do further to discuss to deriving in detail, make ε=0, finally obtaining Brillouin shift to the variation relation of temperature is:
ν
B(T,0)＝v
B(T,0)[1+(Δn
r+Δρ
r+ΔE
r+Δk
r)ΔT] (2)
In formula, T
0for reference temperature, refer generally to T
0=20 DEG C, temperature variation is Δ T.N
tit is thermal refractive index coefficient.ρ
tdensity of optic fibre temperature coefficient, E
tand k
tyoung modulus temperature coefficient and Poisson ratio temperature coefficient respectively.The parameters value of normal single mode quartz optical fiber and temperature correlation is:
By formula (2) generation to formula (3), by pushing over calculating, finally draw the relational expression of Brillouin shift and temperature variation:
ν
B(T,0)＝v
B(T,0)[1+1.18*10
-4ΔT] (4)
As T=20 DEG C, strain is 0, when lambda1-wavelength is 1550nm, the Brillouin shift of general single mode fiber is about 10.85GHz, by formula (4) known temperature and Brillouin shift linear, temperature often changes 1 DEG C, Brillouin shift change be about 1.2803MHz.
Second step: frequency deviation measurement.Frequency deviation measurement refers to by carrying out frequency modulation to the detection light of incidence system and pump light, make the frequency difference of two light sources stably be in stimulated Brillouin scattering magnification region, thus directly can obtain stimulated Brillouin scattering gain spectral by power detection thus detect Brillouin shift.Principle is as follows:
If the intensity of single-ended incident laser is:
The electric field intensity of microwave modulation signal is:
E
m＝A
mcos(2πf
mt) (6)
After ovennodulation, total intensity can be expressed as:
Above formula distortion is obtained:
Wherein f
mfor frequency displacement, m is amplitude modulation coefficient.The field intensity both sides, the center that is distributed as of incident laser its distribution of light intensity after frequency modulation are symmetrical two sideband carriers also.By regulating the modulating frequency of electrooptic modulator, make it drop on stimulated Brillouin scattering gain magnification region, light in transmitting procedure, rightmost side sideband f+f
mamplify center light f, energy is all transferred to center light place, and meanwhile, center light also will amplify leftmost side sideband f+f
m, make the distribution of light intensity of sideband carrier realize progressively shifting like this, finally all move on the sideband of the leftmost side.Finally, we only need measure the maximal value of output power corresponding to different modulating frequencies, just can realize the detection of stimulated Brillouin scattering gain spectral, and obtain now corresponding Brillouin shift.
3rd step: adopt the method for stepping type progressive mean to carry out rough handling to signal.
Generally one-dimensional signal model is:
f(t)＝s(t)+n(t) (9)
In formula, s (t) is useful signal, and n (t) is average is 0, variance is σ
2white Gaussian noise, open width degree signal to noise ratio (S/N ratio) is
For linear superposition on average, after m sub-sampling, the value of i-th is:
Because this is a kind of Batch processing algorithm, gather again by its mean value of computer calculate after m group data, so have the shortcomings such as calculated amount is large, occupying system resources is many.For this reason, we adopt stepping type progressive mean algorithm, change its accumulate mode to overcome the average shortcoming of linear superposition.
Order
represent m-1 data average result before moment m-1,
represent the average result of moment m, f
mrepresent the value of moment m, obtained by above formula:
Like this, whenever data arrive, namely the average result of available new data to last time upgrades, thus obtains new average result.
Can be obtained by formula (11):
As can be seen here, along with the increase of m, above formula Section 2 can be more and more less, and namely the effect of new data can be more and more less.After m acquires a certain degree, this goes to zero.Average result afterwards will be stablized constant.
4th step: wavelet transformation is carried out to signal.
Due to Brillouin signal can because optical fiber be subject to temperature, strain and other noises impact and make envelope not be a desirable smooth curve, signal envelope has some kicks.Therefore, seek one to suppress to some extent noise, can detect that again the signal processing method of the signal of these projections is very important, based on above analysis, wavelet transformation conventional in signal transacting field meets the requirements substantially, can solve the method for the final link of weak signal extraction in this application by the method.
The principle of wavelet transformation is:
Assuming that a given basic function
order
In formula, a and b is constant, if the value of a and b constantly changes, then can obtain gang's function
if square-integrable signal is x (t), then the wavelet transformation of x (t) is:
Wherein b is time shift, and a is scale factor, is the function of a and b by the wavelet transformation Wx (a, b) of signal x (t) known in formula.
become wavelet basis, morther wavelet
both can be real number, can be again complex function.
From formula, the effect of scale factor a is right
stretch, and b is used to the time location determining to analyze x (t), represent time centre.Therefore, by
become
explanation below can be had: as a>1, a is larger, then
time domain width than
become larger.Otherwise, as a<1, if a is less, then
width become narrower.Such a and b combines the center and time width that just can determine analyze x (t).
X (t) is made to be transformed to X (Ω) through fourier,
fourier be transformed to Ψ (Ω), then the character converted from fourier, the frequency-domain expression of wavelet transformation is:
From implementation procedure above, when a diminishes, the Time Domain Processing scope of x (t) is narrowed, but X (Ω) is broadened in the accessible scope of frequency, and its centre frequency moves to high frequency treatment.Otherwise when a becomes large, broaden to the Time Domain Processing scope of x (t), the accessible scope of frequency domain narrows, and its centre frequency moves to low frequency place.
The relation of the excited Brillouin backscatter intensity-frequency shift amount-Distance geometry temperature when 3000m distance that Fig. 6 shows sensor fibre 117 changes a temperature.
In other embodiment, carry out result of interference according to Brillouin scattering and the second continuous light signal, obtain Brillouin shift;
Strain is calculated according to following formula:
ν
B(T
0,ε)＝v
B(T
0,0)(1+4.48ε)
Wherein: ν
b(T
0, ε) and represent that temperature is reference temperature (T
0=20 DEG C) time, the relational expression that Brillouin shift changes with stress ε; v
b(T
0, 0) and represent that temperature is reference temperature (T
0=20 DEG C), the Brillouin shift amount of stress ε when being 0.
See the graph of a relation that Fig. 7, Fig. 7 are the excited Brillouin backscatter intensity-frequency shift amount-Distance geometry temperature when the 3000m distance of sensor fibre applies a microstress.The specific implementation process calculating sensor fibre 117 strain variation according to Brillouin shift is as follows:
Make temperature be under the condition of certain value, Brillouin's frequency drift can be caused to carry out theoretical analysis to strain, elasto-optical effect can occur in optical transmission process, and then result in the impact of strain on optical fibre refractivity, also cause the change of optical fiber Young modulus and Poisson ratio.Can obtain according to pushing over:
For small strain, in ε=0, pair formula (16) carries out Taylor series expansion, is accurate to the once item of ε, can derive the relation between strain and Brillouin shift:
ν
B(T,0)＝v
B(T,0)[1+(Δn
ε+Δρ
ε+ΔE
ε+Δk
ε)ε] (17)
Therefore, strain with the relational expression of Brillouin shift is:
ν
B(T
0,ε)＝v
B(T
0,0)(1+4.48ε) (19)
Δν
B(T
0,ε)-v
B(T
0,0)＝4.48v
B(T
0,0)ε (20)
At normal temperatures, general single mode fiber Brillouin shift in strainless situation is 10.85GHz, so the Brillouin shift changes delta v that each microstrain causes
bbe about 0.0486MHz.Wherein, frequency deviation measurement is similar to the embodiment that accounting temperature changes to signal transacting.
Should be appreciated that, the present invention is not limited to above-mentioned embodiment, every the spirit and scope of the present invention are not departed to various change of the present invention or modification, if these are changed and modification belongs within claim of the present invention and equivalent technologies scope, then the present invention also means that comprising these changes and modification.
Claims (10)
1. an optical fiber Brillouin distributed measurement light path, is characterized in that, comprises the first coupling mechanism, the second coupling mechanism, the 3rd coupling mechanism, the first circulator, the first optical channel, the second optical channel, sensor fibre, the 3rd optical channel and the 4th optical channel,
Two output ports of described first coupling mechanism are connected with the input end of described first optical channel and the input end of the second optical channel respectively, the output terminal of described first optical channel is connected with the input port of the second coupling mechanism, an output port of described second coupling mechanism is connected through the input port of the first Polarization Controller with described 3rd coupling mechanism, and another output port is connected with one end of described sensor fibre through described 3rd optical channel;
The output terminal of described second optical channel is connected with the first port of described first circulator, second port of described first circulator is connected with other one end of described sensor fibre, 3rd port of described first circulator is connected with grating, and the 4th port of described first circulator is connected with the input end of the 4th optical channel; The output terminal of described 4th optical channel is connected with an input port of described 3rd coupling mechanism.
2. optical fiber Brillouin distributed measurement light path as claimed in claim 1, it is characterized in that, described first optical channel comprises the second Polarization Controller, phase type electrooptic modulator successively from input end to output terminal.
3. optical fiber Brillouin distributed measurement light path as claimed in claim 2, it is characterized in that, described second optical channel comprises the 3rd Polarization Controller, intensity type electrooptic modulator, Erbium-Doped Fiber Amplifier (EDFA), the second circulator, optoisolator successively from input end to output terminal, first port of described second circulator is connected with the output terminal of described Erbium-Doped Fiber Amplifier (EDFA), second port is connected with grating, and the 3rd port is connected with the input port of described optoisolator.
4. as the optical fiber Brillouin distributed measurement light path that claim 3 is stated, it is characterized in that, described 3rd optical channel comprises optical filter, optoisolator and scrambler from input end successively to output terminal.
5. optical fiber Brillouin distributed measurement light path as claimed in claim 4, it is characterized in that, described 4th optical channel comprises Erbium-Doped Fiber Amplifier (EDFA), the 3rd circulator, dual-pass Mach-Zehnder interferometer successively from input end to output terminal, first port of described 3rd circulator is connected with the output terminal of described Erbium-Doped Fiber Amplifier (EDFA), second port is connected with grating, and the 3rd port is connected with the input port of described dual-pass Mach-Zehnder interferometer.
6. an optical fiber Brillouin distributed measurement device, it is characterized in that, comprise laser instrument, photoelectric detector and digital sampling and processing, also comprise the optical fiber Brillouin distributed measurement light path as described in any one of claim 1-5, described laser instrument is connected with the input port of described first coupling mechanism, described photoelectric detector and described data acquisition and procession model calling, an output port of described 3rd coupling mechanism is connected with described photoelectric detector.
7. an optical fiber Brillouin distributed measurement method, is characterized in that, comprising:
The laser sent by laser instrument is divided into two ways of optical signals, and wherein a road optical signal modulation becomes pulsed light, and an other road optical signal modulation becomes to have the continuous light of Brillouin shift frequency;
Described continuous light is divided into the first continuous light signal and the second continuous light signal;
Described first continuous light signal and described pulsed light are produced stimulated Brillouin scattering in sensor fibre, produces Brillouin scattering;
Described Brillouin scattering and described second continuous light signal are interfered, after Data Analysis Services, obtains measurement result.
8. optical fiber Brillouin distributed measurement method as claimed in claim 7, it is characterized in that, described first continuous light intensity accounts for 95% of described continuous light light intensity.
9. source distribution formula measuring method in optical fiber cloth as claimed in claim 7, it is characterized in that, the step of described " described Brillouin scattering and described second continuous light signal are interfered, obtain measurement result after Data Analysis Services " comprising:
Carry out result of interference according to described Brillouin scattering and described second continuous light signal, obtain Brillouin shift;
According to following formula accounting temperature:
ν
B(T,0)＝v
B(T
0,0)[1+1.18*10
-4ΔT]
Wherein: ν
bwhen (T, 0) represents that strain stress is 0 and remains unchanged, the temperature variant relational expression of Brillouin scattering optical frequency shift; T
0for reference temperature; v
b(T
0, 0) and represent that temperature is 20 DEG C, the frequency shift amount of Brillouin scattering when strain stress is 0; Δ T=T-T
0for the temperature variation relative to reference temperature.
10. source distribution formula measuring method in optical fiber cloth as claimed in claim 7, it is characterized in that, the step of described " described Brillouin scattering and described second continuous light signal are interfered, obtain measurement result after Data Analysis Services " comprising:
Carry out result of interference according to described Brillouin scattering and described second continuous light signal, obtain Brillouin shift;
Strain is calculated according to following formula:
ν
B(T
0,ε)＝v
B(T
0,0)(1+4.48ε)
Wherein: ν
b(T
0, ε) and represent that temperature is T
0when=20 DEG C, the relational expression that Brillouin shift changes with stress ε; v
b(T
0, 0) and expression temperature is T
0=20 DEG C, the Brillouin shift amount of stress ε when being 0.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105241390A (en) * | 2015-10-21 | 2016-01-13 | 吉林大学 | Rapid Brillouin optical-time domain analysis type strain measuring device and data processing method |
| CN105588587A (en) * | 2015-12-11 | 2016-05-18 | 中国电子科技集团公司第四十一研究所 | Automatic level control-based spontaneous Brillouin scattering signal extraction device and method |
| CN105910546A (en) * | 2016-04-20 | 2016-08-31 | 北京信息科技大学 | BOTDR system based on dual-channel Mach-Zehnder interferometer |
| CN105953724A (en) * | 2016-04-20 | 2016-09-21 | 北京信息科技大学 | Two-channel adjustable Mach-Zehnder interferometer |
| CN109084883A (en) * | 2018-08-09 | 2018-12-25 | 合肥工业大学 | Based on phase-BOTDR optical fiber distributed type Brillouin's vibrating sensing measurement method |
| CN114720780A (en) * | 2022-06-09 | 2022-07-08 | 杭州微纳智感光电科技有限公司 | High-power high-frequency microwave field intensity sensing method and device |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080068586A1 (en) * | 2004-06-25 | 2008-03-20 | Neubrex Co., Ltd | Distributed Optical Fiber Sensor |
| US20090008536A1 (en) * | 2007-07-03 | 2009-01-08 | Schlumberger Technology Corporation | Distributed sensing in an optical fiber using brillouin scattering |
| CN201885732U (en) * | 2010-11-26 | 2011-06-29 | 中国计量学院 | Distributed optical fiber Brillouin sensor integrating optical fiber Brillouin frequency shifter |
| CN102538985A (en) * | 2011-12-27 | 2012-07-04 | 中国计量学院 | Sensing signal detecting device and method based on fiber Brillouin ring laser |
| CN103323041A (en) * | 2013-06-26 | 2013-09-25 | 武汉华之洋光电系统有限责任公司 | Distributed Brillouin optical fiber sensing system based on coherent detection |
| CN104111086A (en) * | 2014-08-12 | 2014-10-22 | 盐城工学院 | Low-Brillouin scattering threshold sensing fiber-based optical time domain reflectometer device and method |
-
2015
- 2015-01-30 CN CN201510051778.XA patent/CN104776871B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080068586A1 (en) * | 2004-06-25 | 2008-03-20 | Neubrex Co., Ltd | Distributed Optical Fiber Sensor |
| US20090008536A1 (en) * | 2007-07-03 | 2009-01-08 | Schlumberger Technology Corporation | Distributed sensing in an optical fiber using brillouin scattering |
| CN201885732U (en) * | 2010-11-26 | 2011-06-29 | 中国计量学院 | Distributed optical fiber Brillouin sensor integrating optical fiber Brillouin frequency shifter |
| CN102538985A (en) * | 2011-12-27 | 2012-07-04 | 中国计量学院 | Sensing signal detecting device and method based on fiber Brillouin ring laser |
| CN103323041A (en) * | 2013-06-26 | 2013-09-25 | 武汉华之洋光电系统有限责任公司 | Distributed Brillouin optical fiber sensing system based on coherent detection |
| CN104111086A (en) * | 2014-08-12 | 2014-10-22 | 盐城工学院 | Low-Brillouin scattering threshold sensing fiber-based optical time domain reflectometer device and method |
Non-Patent Citations (2)
| Title |
|---|
| 何玉钧等: "《一种新型的基于全光纤Mach-Zehnder干涉仪BOTDR系统》", 《光子学报》 * |
| 王庭钧等: "《基于布里渊散射特性的光纤传感系统的设计》", 《光通信研究》 * |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105241390A (en) * | 2015-10-21 | 2016-01-13 | 吉林大学 | Rapid Brillouin optical-time domain analysis type strain measuring device and data processing method |
| CN105241390B (en) * | 2015-10-21 | 2018-05-15 | 吉林大学 | Quick Brillouin optical time domain analysis type strain gauge means and data processing method |
| CN105588587A (en) * | 2015-12-11 | 2016-05-18 | 中国电子科技集团公司第四十一研究所 | Automatic level control-based spontaneous Brillouin scattering signal extraction device and method |
| CN105588587B (en) * | 2015-12-11 | 2017-10-24 | 中国电子科技集团公司第四十一研究所 | Spontaneous brillouin scattering signal extracting device and method based on auto level control |
| CN105910546A (en) * | 2016-04-20 | 2016-08-31 | 北京信息科技大学 | BOTDR system based on dual-channel Mach-Zehnder interferometer |
| CN105953724A (en) * | 2016-04-20 | 2016-09-21 | 北京信息科技大学 | Two-channel adjustable Mach-Zehnder interferometer |
| CN109084883A (en) * | 2018-08-09 | 2018-12-25 | 合肥工业大学 | Based on phase-BOTDR optical fiber distributed type Brillouin's vibrating sensing measurement method |
| CN114720780A (en) * | 2022-06-09 | 2022-07-08 | 杭州微纳智感光电科技有限公司 | High-power high-frequency microwave field intensity sensing method and device |
| CN114720780B (en) * | 2022-06-09 | 2022-09-09 | 杭州微纳智感光电科技有限公司 | High-power high-frequency microwave field intensity sensing method and device |
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