CN102928002A - Multi-parameter optical fiber sensor based on optical fiber intermodal interference and polarization maintaining optical fiber grating - Google Patents
Multi-parameter optical fiber sensor based on optical fiber intermodal interference and polarization maintaining optical fiber grating Download PDFInfo
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- CN102928002A CN102928002A CN201210413040XA CN201210413040A CN102928002A CN 102928002 A CN102928002 A CN 102928002A CN 201210413040X A CN201210413040X A CN 201210413040XA CN 201210413040 A CN201210413040 A CN 201210413040A CN 102928002 A CN102928002 A CN 102928002A
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Abstract
The invention discloses a multi-parameter optical fiber sensor based on optical fiber intermodal interference and a polarization maintaining optical fiber grating, which is formed by connecting a multimode fiber-single mode fiber-multimode fiber structure with a polarization maintaining optical fiber grating in a cascaded manner. The multi-parameter optical fiber sensor comprises a broadband light source, a multimode fiber at an incidence end, a single mode fiber at a middle section, a multimode fiber at an emergent end, a polarization maintaining optical fiber grating and an optical spectrum analyzer, wherein the single mode tail fiber of the broadband light source is accessed to the a end of the multimode fiber at the incidence end; the b end of the multimode fiber at the incidence end is connected with the single mode fiber at the middle section, the multimode fiber at the emergent end and the polarization maintaining optical fiber grating in series; and the output end of the polarization maintaining optical fiber grating is connected with a spectrograph. The multi-parameter optical fiber sensor disclosed by the invention has the advantages of simultaneously measuring temperature, strain and refractive index according to interference light characteristic wavelength and different sensitivities of the polarization maintaining optical fiber grating to the temperature, strain and refractive index by combining the advantages of fiber interference and the polarization maintaining optical fiber grating, improving the sensing sensitivity, and is simple in structure, low in cost, and provided with extensive application prospects in such fields as chemistry, medicine, biology and the like.
Description
Technical field
The invention belongs to technical field of optical fiber sensing, be specifically related to a kind of many reference amounts Fibre Optical Sensor based on modal interference and polarization-maintaining fiber grating.
Background technology
Fibre Optical Sensor is compared with electric formula sensor, have advantages of that volume is little, quality is light, highly sensitive, anti-electromagnetic interference (EMI), anticorrosive etc. unique, be widely used in the fields such as oil, chemical industry, nuclear industry, bridge monitoring, medical science, space flight and aviation, boats and ships shipping.
Temperature, strain and refractive index are carried out the concern that simultaneously-measured research causes numerous scholars as the important parameter of chemistry, medicine and biologics to it.At present, proposed multiple with the simultaneously-measured method of temperature, strain and refractive index, harmonic peak such as play three different modes at the grating underexcitation by the corrosion Fiber Bragg Grating FBG utilizes its different sensitivity coefficients to these three parameters to realize temperature, strain and refractive index are measured simultaneously.But because fiber grating is original just very fragile, it is more easily broken after the corrosion, is unfavorable for measuring and uses and large batch of production.
Summary of the invention
The objective of the invention is for above-mentioned existing problems, a kind of many reference amounts Fibre Optical Sensor based on modal interference and polarization-maintaining fiber grating is provided, this sensor combines modal interference and polarization-maintaining fiber grating, realization is measured to temperature, strain and refractive index the time, improved the sensitivity of sensor, and simple in structure, cost is low, workable, have wide application prospects in fields such as safety monitorings.
Technical scheme of the present invention:
A kind of many reference amounts Fibre Optical Sensor based on modal interference and polarization-maintaining fiber grating, adopt multimode optical fiber-single-mode fiber-multimode optical fiber structure and polarization-maintaining fiber grating cascade, by wideband light source, incident end multimode optical fiber, the interlude single-mode fiber, the exit end multimode optical fiber, polarization-maintaining fiber grating and spectroanalysis instrument form, the a end of end multimode optical fiber is penetrated in the single-mode tail fiber access of wideband light source, the input end of the b termination interlude single-mode fiber of incident end multimode optical fiber, the output terminal of interlude single-mode fiber connects the c end of exit end multimode optical fiber, the input end of the d termination polarization-maintaining fiber grating of exit end multimode optical fiber, the output terminal of polarization-maintaining fiber grating is connected with spectroanalysis instrument.
Principle of work of the present invention:
This Fibre Optical Sensor adopts multimode optical fiber-single-mode fiber-multimode optical fiber (MSM) structure, core mode and cladding mode that its sensing principle is based in the single-mode fiber are interfered, when light enters single-mode fiber by the input end multimode optical fiber, encourage core mode and each rank cladding mode in the single-mode fiber, and in each rank cladding mode, always had a pattern to be in leading position.Because the effective refractive index of cladding mode and core mode there are differences, when being transferred to the fusion point of single-mode fiber and exit end multimode optical fiber, just produced phase differential between two kinds of patterns, so that cladding mode and core mode interfere in single-mode fiber, interference spectrum drifts about with the variation of temperature, strain and refractive index, be reflected in the drift that shows as characteristic wavelength on the transmitted spectrum, but thereby the variation of sense temperature, strain and refractive index.
Interference light is through behind the polarization-maintaining fiber grating, the light that satisfies polarization-maintaining fiber grating fast and slow axis centre wavelength is reflected, in spectrometer, can observe simultaneously two transmission peaks of interference peaks and polarization-maintaining fiber grating, the centre wavelength of polarization-maintaining fiber grating is not subjected to the impact of variations in refractive index, but is subjected to the impact of temperature and strain.Do simultaneously the time spent when temperature, strain, wavelength variable quantity can be expressed as
Wherein, i=x, y; Δ λ
Bx, Δ λ
ByRepresent respectively the center wavelength variation amount along quick shaft direction and slow-axis direction;
P
eBe respectively thermal expansivity, thermo-optical coeffecient, the valid round backscatter extinction logarithmic ratio of fibre core; Δ T, Δ ε are respectively temperature variation and strain variation amount.
According to the result who measures in the spectrometer, can obtain respectively the drift value of the centre wavelength of the characteristic wavelength of interference light and polarization-maintaining fiber grating, again by the sensitive matrix equation
Can obtain the variable quantity of temperature, strain and refractive index, wherein: Δ λ
MSM, Δ λ
x, Δ λ
yBe respectively the fast axle of variable quantity, polarization-maintaining fiber grating of MSM constructive interference light characteristic wavelength, the variable quantity of slow axis centre wavelength; Δ T, Δ ε and Δ n are respectively the variable quantity of temperature, strain and refractive index;
With
With
Be respectively temperature, strain and the refractive index sensitivity of MSM constructive interference light characteristic wavelength, the fast axle of polarization-maintaining fiber grating, slow axis centre wavelength.
Advantage of the present invention and beneficial effect:
This Fibre Optical Sensor combines the advantage of fiber optic interferometric and polarization-maintaining fiber grating, according to interference light characteristic wavelength and the polarization-maintaining fiber grating different sensitivity to temperature, strain and refractive index, measure when having realized temperature, strain and refractive index, improved the sensitivity of sensor, and simple in structure, cost is low, be not subjected to interference, the stable performance such as electromagnetism, be with a wide range of applications at chemistry, medicine and the field such as biological.
Description of drawings
Fig. 1 is this optical fibre sensor structure schematic diagram.
Fig. 2 is the local structure for amplifying schematic diagram of the interference portion of this Fibre Optical Sensor.
Fig. 3 is the output spectrum figure of this Fibre Optical Sensor.
Fig. 4 is the output spectrum partial enlarged drawing of this Fibre Optical Sensor.
Among the figure: 1. wideband light source 2. incident end multimode optical fibers 3. interlude single-mode fibers 4. exit end multimode optical fibers 5. polarization-maintaining fiber gratings 6. spectroanalysis instruments
Embodiment
Embodiment:
A kind of many reference amounts Fibre Optical Sensor based on modal interference and polarization-maintaining fiber grating, such as Fig. 1, shown in Figure 2, adopt multimode optical fiber-single-mode fiber-multimode optical fiber structure and polarization-maintaining fiber grating cascade, by wideband light source 1, incident end multimode optical fiber 2, interlude single-mode fiber 3, exit end multimode optical fiber 4, polarization-maintaining fiber grating 5 and spectroanalysis instrument 6 form, the a end of end multimode optical fiber 2 is penetrated in the single-mode tail fiber access of wideband light source 1, the input end of the b termination interlude single-mode fiber 3 of incident end multimode optical fiber 2, the output terminal of interlude single-mode fiber 3 connects the c end of exit end multimode optical fiber 4, the input end of the d termination polarization-maintaining fiber grating 5 of exit end multimode optical fiber 4, the output terminal of polarization-maintaining fiber grating 5 is connected with spectroanalysis instrument 6.
As shown in Figure 1 and Figure 2, the transmission light path of this sensor is:
After the light of wideband light source 1 enters incident end multimode optical fiber 2, encourage basic mode and each rank high order guided modes in the incident end multimode optical fiber 2, caused the redistribution of light field, then be coupled into the covering of interlude single-mode fiber 3.Because fiber core mismatch has encouraged core mode and each rank cladding mode in the interlude single-mode fiber 3.In each rank cladding mode, always there is a cladding mode to be in leading position.Because the effective refractive index of cladding mode and core mode there are differences, when being transferred to the fusion point of interlude single-mode fiber 3 and exit end multimode optical fiber 4, just produced phase differential between two kinds of patterns, so that cladding mode and core mode interfere in interlude single-mode fiber 3.Interference light is coupled into exit end multimode optical fiber 4 and transmits, through behind the polarization-maintaining fiber grating 5, the light that satisfies polarization-maintaining fiber grating 5 centre wavelengths is reflected, in the interference spectrum scope, form two transmission peaks, then enter spectroanalysis instrument 6 and observe the centre wavelength of the characteristic wavelength of interference lights and polarization-maintaining fiber grating 5 with the variation of temperature, strain and refractive index.
Fig. 3 is the output spectrum of this Fibre Optical Sensor, and Fig. 4 is the output spectrum partial enlarged drawing of this Fibre Optical Sensor.Show among the figure: because the fiber core mismatch principle, cladding mode and core mode interfere in the interlude single-mode fiber.Interference light is through behind the polarization-maintaining fiber grating, and the light that satisfies polarization-maintaining fiber grating fast and slow axis centre wavelength is reflected, and forms two transmission peaks in the interference spectrum scope.Owing to interference light characteristic wavelength and polarization-maintaining fiber grating fast and slow axis centre wavelength along with the variation of temperature, strain and refractive index is drifted about, and the response sensitivity to temperature, strain and refractive index is different, therefore two centre wavelengths that can be by interference light characteristic wavelength and polarization-maintaining fiber grating are with the drift situation of three parameters, and measure when utilizing sensitive matrix to realize temperature, strain and refractive index.
Below will the function that each device in this Fibre Optical Sensor is realized be described in detail:
1) wideband light source 1
Wideband light source 1 can provide light signal for temperature, strain and refractive index sensing, and the model of the wideband light source that adopts in this experiment is ASE Light Sourse(C+L Band).
2) incident end multimode optical fiber 2
Incident end multimode optical fiber 2 not only can make the single-mode optics of incident inspire the light of higher order mode, also can play coupling, with redistributed power couple light to single-mode fiber 3, thereby encouraged core mode and each rank cladding mode of single-mode fiber 3.What adopt in this experiment is multimode stepped-index optical fiber, and its model is SI105/125-22/250, and length is 6mm.
3) single-mode fiber 3
The core mode that has been energized in the single-mode fiber 3 has different effective refractive indexs with cladding mode, therefore after the identical distance of transmission, can produce phase differential, when satisfying phase-matching condition, interferes in single-mode fiber 3.What adopt in this experiment is step type single mode optical fiber, and its model is RDD 8/125-14/250, and length is 25mm.
4) the exit end multimode optical fiber 4
Exit end multimode optical fiber 4 plays the effect of coupling mechanism, interference light is coupled to polarization-maintaining fiber grating 5 relayings resumes defeated.What adopt in this experiment is multimode stepped-index optical fiber, and its model is SI 105/125-22/250, and length is 6mm.
5) polarization-maintaining fiber grating 5
Interference light is through behind the polarization-maintaining fiber grating 5, and the light that satisfies its fast and slow axis centre wavelength is reflected, and produces two transmission peaks in the interference spectrum scope.What adopt in this experiment is the polarization-maintaining fiber grating that fast and slow axis centre wavelength is respectively 1546.32nm and 1545.92nm.
6) spectroanalysis instrument 6
This Fibre Optical Sensor is measured fiber optic interferometric and polarization-maintaining fiber grating cascade, and has been improved transducer sensitivity when having realized temperature, strain and refractive index, has volume little, simple in structure, low cost and other advantages can be widely used in chemistry, medicine and the sensory field such as biological.
Claims (1)
1. many reference amounts Fibre Optical Sensor based on modal interference and polarization-maintaining fiber grating, it is characterized in that: adopt multimode optical fiber-single-mode fiber-multimode optical fiber structure and polarization-maintaining fiber grating cascade, by wideband light source, incident end multimode optical fiber, the interlude single-mode fiber, the exit end multimode optical fiber, polarization-maintaining fiber grating and spectroanalysis instrument form, the a end of end multimode optical fiber is penetrated in the single-mode tail fiber access of wideband light source, the input end of the b termination interlude single-mode fiber of incident end multimode optical fiber, the output terminal of interlude single-mode fiber connects the c end of exit end multimode optical fiber, the input end of the d termination polarization-maintaining fiber grating of exit end multimode optical fiber, the output terminal of polarization-maintaining fiber grating is connected with spectroanalysis instrument.
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Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103323058A (en) * | 2013-07-12 | 2013-09-25 | 华南师范大学 | Optical fiber refractive index and temperature sensor and measurement method thereof |
| CN103453940A (en) * | 2013-09-13 | 2013-12-18 | 天津理工大学 | Optical fiber sensor based on multi-mode structure |
| CN103940360A (en) * | 2014-04-23 | 2014-07-23 | 鲁东大学 | Strain monitoring device based on cascade chirped fiber gratings |
| CN104297208A (en) * | 2014-10-21 | 2015-01-21 | 天津理工大学 | Interferometric optical fiber sensor based on pohotonic crystal optical fiber |
| CN104316106A (en) * | 2014-10-28 | 2015-01-28 | 天津理工大学 | Optical fiber sensor based on Mach-Zehnder interference and fiber bragg grating |
| CN105890828A (en) * | 2014-10-23 | 2016-08-24 | 中国计量学院 | Polarization-dependent embedded fiber M-Z interference type transverse pressure transducer |
| CN105911023A (en) * | 2016-04-08 | 2016-08-31 | 北京信息科技大学 | Method for measuring refractive index based on raster deformation induced by ultrasonic pulses |
| CN106052731A (en) * | 2016-08-16 | 2016-10-26 | 广州科技职业技术学院 | Novel fiber sensing head and sensor |
| CN108036733A (en) * | 2017-12-25 | 2018-05-15 | 北京信息科技大学 | Temperature and strain while measurement sensor under II type-IR type polarization-maintaining FBG hot environments |
| CN108195483A (en) * | 2017-12-26 | 2018-06-22 | 北京信息科技大学 | A kind of fibre-optical F-P sensor production method for realizing temperature and strain measurement |
| CN109060169A (en) * | 2018-08-29 | 2018-12-21 | 厦门大学 | A kind of pyrostat based on thin fiber |
| CN109171683A (en) * | 2018-08-28 | 2019-01-11 | 盐城工学院 | A kind of live pig temperature and heart rate monitoring unit and method based on fiber-optic grating sensor |
| CN110595515A (en) * | 2019-09-17 | 2019-12-20 | 华中科技大学 | Double-parameter optical fiber sensor based on polarization maintaining optical fiber and FP (Fabry-Perot) cavity |
| CN110806233A (en) * | 2019-10-28 | 2020-02-18 | 中广核核电运营有限公司 | Fiber grating sensor device and detection device for pressure container |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101447637A (en) * | 2008-12-31 | 2009-06-03 | 华南理工大学 | Single longitudinal-mode optical fiber laser with low noise, narrow linewidth and high power |
| US20090260501A1 (en) * | 2008-04-18 | 2009-10-22 | Raman Kashyap | Multi-mode optical fiber sensor |
-
2012
- 2012-10-25 CN CN201210413040XA patent/CN102928002A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090260501A1 (en) * | 2008-04-18 | 2009-10-22 | Raman Kashyap | Multi-mode optical fiber sensor |
| CN101447637A (en) * | 2008-12-31 | 2009-06-03 | 华南理工大学 | Single longitudinal-mode optical fiber laser with low noise, narrow linewidth and high power |
Non-Patent Citations (3)
| Title |
|---|
| 童峥嵘等: "基于多模_单模_多模结构和光纤布拉格光栅同时测量温度和折射率", 《光学精密工程》 * |
| 赵金婷等: "保偏光纤布拉格光栅轴向应变传感特性的研究", 《南开大学学报（自然科学版）》 * |
| 魏颖等: "保偏光纤Bragg光栅传感特性的实验研究", 《红外与激光工程》 * |
Cited By (17)
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| CN103323058A (en) * | 2013-07-12 | 2013-09-25 | 华南师范大学 | Optical fiber refractive index and temperature sensor and measurement method thereof |
| CN103323058B (en) * | 2013-07-12 | 2015-10-28 | 华南师范大学 | A kind of optical fibre refractivity and temperature sensor and measuring method thereof |
| CN103453940A (en) * | 2013-09-13 | 2013-12-18 | 天津理工大学 | Optical fiber sensor based on multi-mode structure |
| CN103940360B (en) * | 2014-04-23 | 2016-10-05 | 鲁东大学 | A kind of strain monitoring device based on cascade chirped fiber grating |
| CN103940360A (en) * | 2014-04-23 | 2014-07-23 | 鲁东大学 | Strain monitoring device based on cascade chirped fiber gratings |
| CN104297208A (en) * | 2014-10-21 | 2015-01-21 | 天津理工大学 | Interferometric optical fiber sensor based on pohotonic crystal optical fiber |
| CN105890828A (en) * | 2014-10-23 | 2016-08-24 | 中国计量学院 | Polarization-dependent embedded fiber M-Z interference type transverse pressure transducer |
| CN104316106A (en) * | 2014-10-28 | 2015-01-28 | 天津理工大学 | Optical fiber sensor based on Mach-Zehnder interference and fiber bragg grating |
| CN105911023A (en) * | 2016-04-08 | 2016-08-31 | 北京信息科技大学 | Method for measuring refractive index based on raster deformation induced by ultrasonic pulses |
| CN105911023B (en) * | 2016-04-08 | 2018-09-07 | 北京信息科技大学 | A method of based on ultrasonic pulse induction grating deformation for measuring refractive index |
| CN106052731A (en) * | 2016-08-16 | 2016-10-26 | 广州科技职业技术学院 | Novel fiber sensing head and sensor |
| CN108036733A (en) * | 2017-12-25 | 2018-05-15 | 北京信息科技大学 | Temperature and strain while measurement sensor under II type-IR type polarization-maintaining FBG hot environments |
| CN108195483A (en) * | 2017-12-26 | 2018-06-22 | 北京信息科技大学 | A kind of fibre-optical F-P sensor production method for realizing temperature and strain measurement |
| CN109171683A (en) * | 2018-08-28 | 2019-01-11 | 盐城工学院 | A kind of live pig temperature and heart rate monitoring unit and method based on fiber-optic grating sensor |
| CN109060169A (en) * | 2018-08-29 | 2018-12-21 | 厦门大学 | A kind of pyrostat based on thin fiber |
| CN110595515A (en) * | 2019-09-17 | 2019-12-20 | 华中科技大学 | Double-parameter optical fiber sensor based on polarization maintaining optical fiber and FP (Fabry-Perot) cavity |
| CN110806233A (en) * | 2019-10-28 | 2020-02-18 | 中广核核电运营有限公司 | Fiber grating sensor device and detection device for pressure container |
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