CN102359830A - Multiple Raman scattering effect fused ultra remote fiber temperature measurement sensor - Google Patents
Multiple Raman scattering effect fused ultra remote fiber temperature measurement sensor Download PDFInfo
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- CN102359830A CN102359830A CN2011102643242A CN201110264324A CN102359830A CN 102359830 A CN102359830 A CN 102359830A CN 2011102643242 A CN2011102643242 A CN 2011102643242A CN 201110264324 A CN201110264324 A CN 201110264324A CN 102359830 A CN102359830 A CN 102359830A
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Abstract
The invention discloses a multiple Raman scattering effect fused ultra remote fiber temperature measurement sensor. By utilizing 1660 nm wave band wide spectrum laser generated by a Raman frequency shifter as a light source for system measurement, combined with a Raman amplification effect, and the system light source is amplified to increase a length of a sensing fiber capable of measuring temperature. Anti-Stokes light with temperature information generated in the sensing fiber is amplified by a Raman amplifier of a C wave band, through a coupled narrowband optical filter, Rayleigh scattering light is removed, and the temperature information on the sensing fiber is obtained after demodulation. The invention has the following advantages: after a 1660 nm system light source is subjected to Raman amplification, a temperature measurement length of the sensing fiber is raised, and after anti-Stokes Raman light with the temperature information is moved to a 1550 nm fiber low loss area, combined with the Raman amplifier of a C wave band, a signal to noise ratio of a system is raised. The system is applied to calamity forecasting and monitoring of a petrochemical pipeline, a tunnel and the like of an ultra remote distance of 100 kilometers or more.
Description
Technical field
The invention belongs to distributing optical fiber sensing thermometric field, relate to the very-long-range optical fiber temperature-measurement sensor that the graceful scattering effect of Duola merges.This system is suitable for long-range 100km and the real-time disaster monitoring occasion of above need.
Technical background
In recent years, utilize optical fibre distribution type sensor realize online real-time prediction field temperature and variation tendency thereof based on simple to operate, can be applicable to advantages such as rugged surroundings and obtained to pay close attention to widely and study.Effect that such sensor utilizes fiber raman scattering light to infer to receive temperature modulation and optical time domain reflection principle realize the monitoring of temperature, can be to petrochemical industry, and traffic bridge, tunnel etc. carry out the forecast and the monitoring of safety and Health monitoring and disaster.Zhang Zaixuan proposed " fully distributed fiber Rayleigh and Raman scattering photon strain, temperature sensor " patent of invention in 2009; Utilize the temperature information of acquisition recently of thermally sensitive anti Stokes scattering light intensity and Rayleigh scattering light intensity or stokes scattering light intensity; This method can overcome the measuring error that causes owing to light source fluctuation; But in being only applicable to, short distance 100m-15km on-line temperature monitoring, can not satisfy in recent years petroleum pipe line, transferring electric power cable etc. fully to active demand long-range, very-long-range distributed fiber Raman temperature probe.
The present invention adopt Raman frequency shift device based on the stimulated Raman scattering effect testing light source from traditional arrowband 1550nm wave band frequency displacement to wide range 1660nm wave band; When having suppressed coherent noise with the anti Stokes scattering light that has temperature information in the sensor fibre; Move on to the 1550nm low-loss band of optical fibers, improved the signal to noise ratio (S/N ratio) of system.Be fused to wide range 1660nm wave band to the Raman enlarge-effect, make system testing luminous energy highest-gain reach 17dB, be equal to and improved the about 40km of sensor fibre length.Merged the C-band fiber Raman amplifier, amplified the anti-Stokes Raman light of 1550nm wave band, highest-gain can reach 25dB, has improved system signal noise ratio, has reduced the difficulty of weak signal inspection.This temp measuring system possesses advantages such as far measuring distance, temperature measurement accuracy is high, system's demodulation is simple, is applicable to very-long-range 100km fully distributed fiber TEMP net, is used for preventing pipeline, various possible disasters such as tunnel.
Summary of the invention
The purpose of this invention is to provide the very-long-range optical fiber temperature-measurement sensor that the graceful scattering effect of a kind of Duola merges, can realize the very-long-range 100km distributed optical fiber temperature measurement function that signal to noise ratio (S/N ratio) is good, resolution is high.
Technical solution of the present invention is following:
The very-long-range optical fiber temperature-measurement sensor that the graceful scattering effect of Duola merges comprises fiber pulse laser, optical fiber splitter, the fiber Raman frequency shifter of being made up of single-mode fiber and fiber filter; Time delay optical fiber, optical fiber wave multiplexer, optical fibre wavelength division multiplexer; Fiber coupler, Raman laser, sensor fibre; Two fiber reflection light filters, photoelectricity receiver module, digital signal processor and industrial computer.The input port of optical fiber splitter links to each other with fiber pulse laser, and two output ports link to each other with single-mode fiber, time delay optical fiber respectively; Two input ports of optical fiber wave multiplexer link to each other with time delay optical fiber, fiber filter, and output port links to each other with the input port of optical fibre wavelength division multiplexer; Optical fibre wavelength division multiplexer has three output ports; COM output port and centre wavelength are that the fiber reflection light filter input port of 1450nm links to each other; The 1660nm output port links to each other with an input port of photoelectricity receiver module (22), and the output port of 1550nm and centre wavelength are that the input port of 1550nm fiber reflection light filter links to each other; Two input ports of fiber coupler and centre wavelength are that fiber reflection light filter, the Raman laser of 1450nm links to each other, and output port links to each other with sensor fibre.
Among the present invention, the centre wavelength of mentioned pulsed laser is 1550nm, and spectral width is 0.2nm, and laser pulse width is that 10-30ns is adjustable, and peak power is that 1-100W is adjustable, and repetition frequency is that 500-800Hz is adjustable; The branching ratio of mentioned optical fiber splitter is 80/20, and the branching ratio of optical fiber wave multiplexer is 60/40; Mentioned fiber Raman frequency shifter is made up of 800 meters single-mode fibers and fiber filter, and wherein the centre wavelength of light filter is 1660nm, spectral bandwidth 28nm, and transmitance 98% is to the isolation＞45dB of 1550nm laser; Mentioned time delay optical fiber length is the general single mode fiber of 805-820 rice; The centre wavelength of mentioned fiber reflection light filter (20) is 1450nm, and spectral width is 0.5nm, and reflectivity 95% is to the isolation＞45dB of 1450nm laser; The centre wavelength of fiber reflection light filter (21) is 1550nm, and spectral width is 0.5nm, and reflectivity 95% is to the isolation＞45dB of 1550nm laser.
Beneficial effect of the present invention is:
The very-long-range optical fiber temperature-measurement sensor that the graceful scattering effect of Duola of the present invention merges adopts the stimulated Raman scattering principle to realize the raman amplifier effect of Raman frequency shift device, two wave bands, adopts the spontaneous Raman scattering effect to realize the fully distributed fiber thermometric.The raman amplifier of different-waveband plays two effects: the one, amplified the energy of system source, and increased the thermometric fiber lengths; The 2nd, amplified the anti-Stokes light intensity, improved system signal noise ratio, reduced the difficulty of Testing of Feeble Signals.Compare with traditional optical fiber temperature-measurement sensor, this system's thermometric distance, measuring accuracy height, simple in structure.The present invention is applicable to that very-long-range needs the occasion of continuous temperature measurement, prevents pipeline, various possible disasters such as tunnel.
Description of drawings
Fig. 1 is the very-long-range optical fiber temperature-measurement sensor construction synoptic diagram that the graceful scattering effect of Duola merges.
Embodiment
Below in conjunction with accompanying drawing the present invention is further described.
Referring to shown in Figure 1, the very-long-range optical fiber temperature-measurement sensor that the graceful scattering effect of Duola merges comprises fiber pulse laser 10, optical fiber splitter 11; By the fiber Raman frequency shifter that single-mode fiber 12 and fiber filter 13 are formed, time delay optical fiber 14, optical fiber wave multiplexer 15, optical fibre wavelength division multiplexer 16; Fiber coupler 17, Raman laser 18, sensor fibre 19, fiber reflection light filter 20; Fiber reflection light filter 21, photoelectricity receiver module 22, digital signal processor 23 and industrial computer 24.
The input port of optical fiber splitter 11 links to each other with fiber pulse laser 10, and two output ports link to each other with single-mode fiber 12, time delay optical fiber 14 respectively; Two input ports of optical fiber wave multiplexer 15 link to each other with time delay optical fiber 14, fiber filter 13, and output port links to each other with the input port of optical fibre wavelength division multiplexer 16; Optical fibre wavelength division multiplexer 16 has three output ports; The COM output port links to each other with the input port of fiber reflection light filter 20; The 1660nm output port links to each other with an input port of photoelectricity receiver module 22, and the output port of 1550nm links to each other with the input port of fiber reflection light filter 21; Two input ports of fiber coupler 17 link to each other with fiber reflection light filter 20, Raman laser 18, and output port links to each other with sensor fibre 19.
The centre wavelength of above-mentioned pulsed laser is 1550nm, and spectral width is 0.2nm, and laser pulse width is that 10-30ns is adjustable, and peak power is that 1-100W is adjustable, and repetition frequency is that 500-800Hz is adjustable.
The branching ratio of above-mentioned optical fiber splitter is 80/20, and the branching ratio of optical fiber wave multiplexer is 60/40.
Above-mentioned fiber Raman frequency shifter, it is made up of 800 meters single-mode fibers and fiber filter.Wherein the centre wavelength of light filter is 1660nm, spectral bandwidth 28nm, and transmitance 98% is to the isolation＞45dB of 1550nm laser.
Above-mentioned time delay optical fiber length is the general single mode fiber of 805-820 rice.
The centre wavelength of above-mentioned fiber reflection light filter 20 is 1450nm, and spectral width is 0.5nm, and reflectivity 95% is to the isolation＞45dB of 1450nm laser; The centre wavelength of fiber reflection light filter 21 is 1550nm, and spectral width is 0.5nm, and reflectivity 95% is to the isolation＞45dB of 1550nm laser.
The present invention is based on following three principles:
(1) based on the principle of work of the fiber Raman frequency shifter of stimulated Raman scattering effect
The fiber Raman frequency shifter is made up of single-mode fiber and broadband 1660nm light filter.When a branch of 1550nm pulse laser incides single-mode fiber; Laser and optical fiber molecule generation nonlinear interaction; Incident photon is become another Stokes photon or anti-Stokes photon by an optical fiber molecular scattering, emits a phonon and is called the stokes scattering photon, in sensor fibre, has produced the 1660nm stokes light of frequency displacement 13.2THz; After the 1550nm of incident laser power reached certain threshold value, most of incident light was converted into stokes light (excited state).When another bundle 1550nm laser and 1660nm Stokes Raman light of being told by the incident laser source incide same sensor fibre; Two-beam produces nonlinear interaction at the place of meeting; Produce the stokes light (enlargement factor is relevant with the ratio of two-beam power) that amplifies, obtained to merge the wide range 1660nm wave band of laser of Raman enlarge-effect, as the system testing light source; Highest-gain can reach 17dB, is equivalent to prolong thermometric fiber lengths 40km.
(2) distributed optical fiber Raman amplifier principle of work
For fiber Raman amplifier; Pump power has only when surpassing a certain threshold value; Just might produce excited Raman to signal and amplify, the stokes wave in the optical fiber is increased in fiber medium fast, the power of most of pump light can convert stokes light to; Possess Raman amplification, the turn off gain of its amplification does
G
A＝exp(g
RP
0L
eff/A
eff) (1)
P wherein
0=I
0A
EffBe the pump light power input of amplifier, g
RBe Raman gain coefficienct A
EffBe the free area of optical fiber, L
EffEffective interaction length (having considered the absorption loss of optical fiber) for optical fiber to pumping.
Gain can suppress the loss of optical fiber, improves the signal to noise ratio (S/N ratio) of system, reduces the difficulty of weak signal check system.
(3) based on the fully distributed fiber temperature probe principle of spontaneous Raman scattering effect
When incident laser and optical fiber molecule generation nonlinear interaction, emit a phonon and be called the Stokes Raman scattering photon, absorb a phonon and be called the anti-Stokes Raman scattering photon.Boltzmann's law is obeyed in population heat distribution on the optical fiber molecular entergy level, and anti-Stokes Raman scattering light intensity dorsad does in optical fiber
I
a＝I
0·v
a 4R
a(T)exp[-(α
0+α
a)·L] (2)
It receives the modulation of fiber optic temperature, the temperature modulation function R
a
R
a(T)＝[exp(hΔv/kT)-1]
-1 (3)
H is the Bo Langke constant, and Δ v is the phonon frequency of an optical fiber molecule, is 13.2THz, and k is a Boltzmann constant, and T is a Kai Erwen absolute temperature.
Adopt the fiber Rayleigh passage to do reference signal in the present invention, come detected temperatures with the ratio of the sharp light intensity of anti-Stokes Raman diffused light and auspicious scattered light
By anti-Stokes Raman diffused light and the auspicious scattered light sharp light strength ratio of fiber Raman optical time domain reflection (OTDR) curve, obtain the temperature information of each section of optical fiber at the optical fiber check point.
Claims (6)
1. the very-long-range optical fiber temperature-measurement sensor of the graceful scattering effect fusion of Duola is characterized in that comprising fiber pulse laser (10), optical fiber splitter (11); By the fiber Raman frequency shifter that single-mode fiber (12) and fiber filter (13) are formed, time delay optical fiber (14), optical fiber wave multiplexer (15); Optical fibre wavelength division multiplexer (16), fiber coupler (17), Raman laser (18); Sensor fibre (19), fiber reflection light filter (20), fiber reflection light filter (21); Photoelectricity receiver module (22), digital signal processor (23) and industrial computer (24).The input port of optical fiber splitter (11) links to each other with fiber pulse laser (10), and two output ports link to each other with single-mode fiber (12), time delay optical fiber (14) respectively; Two input ports of optical fiber wave multiplexer (15) link to each other with time delay optical fiber (14), fiber filter (13), and output port links to each other with the input port of optical fibre wavelength division multiplexer (16); Optical fibre wavelength division multiplexer (16) has three output ports; The COM output port links to each other with the input port of fiber reflection light filter (20); The 1660nm output port links to each other with an input port of photoelectricity receiver module (22), and the output port of 1550nm links to each other with the input port of fiber reflection light filter (21); Two input ports of fiber coupler (17) link to each other with fiber reflection light filter (20), Raman laser (18), and output port links to each other with sensor fibre (19).
2. the very-long-range optical fiber temperature-measurement sensor that the graceful scattering effect of Duola according to claim 1 merges; The centre wavelength that it is characterized in that pulsed laser (10) is 1550nm; Spectral width is 0.2nm; Laser pulse width is that 10-30ns is adjustable, and peak power is that 1-100W is adjustable, and repetition frequency is that 500-800Hz is adjustable.
3. the very-long-range optical fiber temperature-measurement sensor that the graceful scattering effect of Duola according to claim 1 merges, the branching ratio that it is characterized in that optical fiber splitter (11) is 80/20, the branching ratio of optical fiber wave multiplexer (15) is 60/40.
4. the very-long-range optical fiber temperature-measurement sensor that the graceful scattering effect of Duola according to claim 1 merges; It is characterized in that the fiber Raman frequency shifter; It is characterized in that single-mode fiber (12) is 800 meters, the centre wavelength of fiber filter (13) is 1660nm, spectral bandwidth 28nm; Transmitance 98% is to the isolation＞45dB of 1550nm laser.
5. the very-long-range optical fiber temperature-measurement sensor that the graceful scattering effect of Duola according to claim 1 merges, the length that it is characterized in that time delay optical fiber (14) is the general single mode fiber of 805-820 rice.
6. the very-long-range optical fiber temperature-measurement sensor that the graceful scattering effect of Duola according to claim 1 merges; The centre wavelength that it is characterized in that fiber reflection light filter (20) is 1450nm; Spectral width is 0.5nm, and reflectivity 95% is to the isolation＞45dB of 1450nm laser; The centre wavelength of fiber reflection light filter (21) is 1550nm, and spectral width is 0.5nm, and reflectivity 95% is to the isolation＞45dB of 1550nm laser.
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| WO2013123655A1 (en) * | 2012-02-21 | 2013-08-29 | 中国计量学院 | Fused optical fiber raman frequency shifter and fully distributed optical fiber sensor for raman amplifier |
| WO2013123656A1 (en) * | 2012-02-21 | 2013-08-29 | 中国计量学院 | Fully distributed optical fiber sensor for optical fiber raman frequency shifter of fused raman amplification effect |
| CN105067146A (en) * | 2015-03-20 | 2015-11-18 | 深圳市迅捷光通科技有限公司 | Stimulated raman scattering suppression device, method and distributed optical fiber sensing system |
| CN106230960A (en) * | 2016-08-10 | 2016-12-14 | 合肥国盛电池科技有限公司 | Lithium battery group long-distance monitorng device |
| CN106645082A (en) * | 2016-11-03 | 2017-05-10 | 北京信息科技大学 | Gating optical fiber Raman spectrometer based on laser ranging automatic focusing |
| US11327226B2 (en) * | 2019-04-22 | 2022-05-10 | California Institute Of Technology | Integrated photonics long-distance sensing system |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2013123655A1 (en) * | 2012-02-21 | 2013-08-29 | 中国计量学院 | Fused optical fiber raman frequency shifter and fully distributed optical fiber sensor for raman amplifier |
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| CN105067146A (en) * | 2015-03-20 | 2015-11-18 | 深圳市迅捷光通科技有限公司 | Stimulated raman scattering suppression device, method and distributed optical fiber sensing system |
| CN106230960A (en) * | 2016-08-10 | 2016-12-14 | 合肥国盛电池科技有限公司 | Lithium battery group long-distance monitorng device |
| CN106645082A (en) * | 2016-11-03 | 2017-05-10 | 北京信息科技大学 | Gating optical fiber Raman spectrometer based on laser ranging automatic focusing |
| CN106645082B (en) * | 2016-11-03 | 2020-12-11 | 北京信息科技大学 | Gated fiber Raman spectrometer based on automatic focusing of laser ranging |
| US11327226B2 (en) * | 2019-04-22 | 2022-05-10 | California Institute Of Technology | Integrated photonics long-distance sensing system |
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