CN203657934U - Reflection-type temperature/refractive index two-parameter sensing device employing long-period FBG based on Sagnac ring - Google Patents
Reflection-type temperature/refractive index two-parameter sensing device employing long-period FBG based on Sagnac ring Download PDFInfo
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- CN203657934U CN203657934U CN201420030827.2U CN201420030827U CN203657934U CN 203657934 U CN203657934 U CN 203657934U CN 201420030827 U CN201420030827 U CN 201420030827U CN 203657934 U CN203657934 U CN 203657934U
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Abstract
The utility model relates to a reflection-type temperature/refractive index two-parameter sensing device employing a long-period FBG based on a Sagnac ring. In order to realize reflection-type measurement and to solve a problem of crosstalk, a polarization maintaining optical fiber Sagnac ring is connected to the rear part of the long-period FBG according to the utility model. Since the polarization maintaining optical fiber Sagnac ring only response to medium temperature, synchronous measurement of temperature and refractive index is realized. The reflection-type temperature/refractive index two-parameter sensing device includes a broadband light source, an optical fiber circulator, the long-period FBG, a coupler, a polarization maintaining optical fiber and an fiber optic spectrometer. According to the utility model, synchronous measurement of refractive index and temperature is realized. And the reflection-type temperature/refractive index two-parameter sensing device can be applied to remote measurement and has advantages of being simple, convenient and quick in measurement; high in flexibility; high in practicability; and the like.
Description
Technical field
The utility model belongs to technical field of optical fiber sensing, relates to reflection-type long period fiber grating temperature and the two-parameter sensing device of refractive index based on Sagnac ring.
Background technology
Refractive index is the important parameter that characterizes material physics and chemistry character, and refractometry has application extremely widely at key areas such as food analysis, quality monitoring, contamination analysis.
Long period fiber grating is due to advantages such as its electrical isolation, corrosion-resistant, anti-electromagnetic interference (EMI), the resonance wavelength of long period fiber grating and the amplitude to external world variation of environment are very responsive, and can be used for accurately measuring other physical quantitys such as temperature, stress, refractive index, attract the application of people in the field such as chemical, biological, had wide application background in fields such as optical fiber communication, Fibre Optical Sensor and optical information processing.But most of apparatus for measuring refractive index is the variation that detects transmission spectrum, has significant limitation in many application scenarios.Reflectance spectrum detect have device layout simple, be easy to detect, low cost and other advantages, can be for long apart from monitoring system.
Generally, the refractive index of medium has certain response relation to temperature, makes temperature and refractive index cross sensitivity.Therefore, a lot of Fibre Optical Sensors are in surveying refractive index, and the impact that need to produce temperature compensates, and accurately measures required data.Now, although the method for plated film can address this problem on optical fiber, coating technique relative complex and easily damage optical fiber.Plated film in long period fiber grating, is not easy to keep, and is difficult to recycling.It is an insoluble problem that temperature and refractive index are crosstalked in actual measurement always, particularly in long-period fiber grating sensor.
Summary of the invention
The purpose of this utility model is exactly to overcome the impact that shortcoming that transmission spectrum detects and medium temperature and refractive index are crosstalked, and proposes reflection-type long period fiber grating temperature and the two-parameter sensing device of refractive index based on Sagnac ring.
The technical scheme that the utility model is taked for technical solution problem:
Based on reflection-type long period fiber grating temperature and the two-parameter sensing device of refractive index of Sagnac ring, comprise wideband light source, optical fiber circulator, long period fiber grating, Sagnac ring and fiber spectrometer.
The output terminal of wideband light source is connected with the input port of optical fiber circulator, the first output port of optical fiber circulator is connected with one end of long period fiber grating, the second output port of optical fiber circulator is connected with fiber spectrometer, and the other end of long period fiber grating is connected with Sagnac ring; Sagnac ring is made up of coupling mechanism and polarization maintaining optical fibre; The position at a peak of the interference peaks of the harmonic peak of long period fiber grating and Sagnac ring aligns.
The useful benefit that the utility model has is: utilize the design feature that connects Sagnac ring after long period fiber grating, realized reflection-type detection; Utilize long period fiber grating and polarization maintaining optical fibre Sagnac ring refractive index and temperature to have different response functions, solved smoothly the problem of crosstalking between temperature and refractive index, realized and having measured the temperature of a liquid and refractive index simultaneously.Applicable to the remote measurement in the field such as biological, chemical, measure simple, convenient, fast, sensitivity is high, practicality is high.
Accompanying drawing explanation
Fig. 1 is the structural representation of humidity sensor of the present utility model;
Wherein: 1. wideband light source, 2. optical fiber circulator, 3. long period fiber grating, 4. coupling mechanism, 5. polarization maintaining optical fibre, 6. fiber spectrometer.
Embodiment
Below in conjunction with accompanying drawing, the technical solution of the utility model is described further.
With reference to Fig. 1, a kind of reflection-type long period fiber grating temperature and two-parameter sensing device of refractive index based on Sagnac ring comprises wideband light source 1, optical fiber circulator 2, long period fiber grating 3, coupling mechanism 4, polarization maintaining optical fibre 5 and fiber spectrometer 6.Wherein wideband light source 1 is connected with the first input end of optical fiber circulator 2, the second output terminal of optical fiber circulator 2 is connected with long period fiber grating 3, the 3rd output terminal of optical fiber circulator 2 is connected with fiber spectrometer 6, a port of the input end of long period fiber grating 3 butt coupling devices 4, two ports of output terminal of coupling mechanism 4 connect respectively the two ends of polarization maintaining optical fibre 5.
Principle of work of the present utility model is:
The flashlight that wideband light source 1 sends first, by circulator 2 process long period fiber grating 3, by the modulation of long period fiber grating 3, can produce an absorption peak, thereby produce Yi Ge center resonance wavelength.The variation of long period light grating resonance wavelength is with temperature and the linear relation of variations in refractive index:
Δλ
LPFG=K
L，TΔT+K
L，nΔn (1)
K
l, Trepresent the temperature variant variation factor of harmonic peak wavelength of long period fiber grating, K
l, nrepresent that the harmonic peak wavelength of long period fiber grating is with the variation factor of variations in refractive index, Δ λ
lPGthe drift value that represents harmonic peak centre wavelength, Δ T and Δ n represent respectively the change amount of temperature and refractive index.
Coupling mechanism 4 and polarization maintaining optical fibre 5 can form polarization maintaining optical fibre Sagnac ring, and the optical path difference producing through polarization maintaining optical fibre Sagnac ring from long period fiber grating 3 light out, can interfere.The interference peaks producing can produce drift along with the variation of temperature:
Δλ
SFLM=K
S，TΔT (2)
K
s, Trepresent the temperature variant variation factor of interference peaks drift value of Sagnac ring, Δ λ
sFLMthe interference peaks drift value of Sagnac ring.
The 3rd port at optical fiber circulator 3 connects fiber spectrometer, records the drift value Δ λ of long period fiber grating harmonic peak
lPGdrift value λ with Sagnac ring generation interference peaks
sFLM, just can obtain each coefficient by formula (1) and (2).
The gordian technique that this device can be realized reflection-type measurement temperature and refractive index sensing is: by connect a Sagnac ring after long period fiber grating, utilize the annular characteristics of optical path of Sagnac ring, realize reflection-type and detect; Utilize long period fiber grating and protect inclined to one side Sagnac ring to temperature individual features different from refractive index, realization is measured temperature and refractive index biparametric simultaneously; The aligned in position of some peak values of the position of long period fiber grating harmonic peak and Sagnac ring interference peaks, in temperature and refraction index changing, can know respectively the position of the interference peaks of long period fiber grating harmonic peak and Sagnac generation.
In the present embodiment, the grating cycle of long period fiber grating is 420um, and periodicity is 40, and grid region length is 1.7cm, and resonance wavelength is 1500nm, and resonance wave strong point attenuation amplitude is 30dB; Polarization maintaining optical fibre length used is 4cm, and two-fold rate is 5.74e-4, and clapping long is 2.7mm; The loss of the Sagnac ring of coupling mechanism and polarization maintaining optical fibre composition is 6.8dB; The Sagnac aligning with long period fiber grating harmonic peak encircles the interference peaks position producing at 1499nm place.
Claims (1)
1. reflection-type long period fiber grating temperature and the two-parameter sensing device of refractive index based on Sagnac ring, comprise optical fiber circulator, long period fiber grating, Sagnac ring and fiber spectrometer, it is characterized in that: the output terminal of wideband light source is connected with the input port of optical fiber circulator, the first output port of optical fiber circulator is connected with one end of long period fiber grating, the second output port of optical fiber circulator is connected with fiber spectrometer, and the other end of long period fiber grating is connected with Sagnac ring; Sagnac ring is made up of coupling mechanism and one section of polarization maintaining optical fibre; The harmonic peak of long period fiber grating is relative with the position at a peak of the interference peaks of Sagnac ring.
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| CN201420030827.2U CN203657934U (en) | 2014-01-17 | 2014-01-17 | Reflection-type temperature/refractive index two-parameter sensing device employing long-period FBG based on Sagnac ring |
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| CN201420030827.2U CN203657934U (en) | 2014-01-17 | 2014-01-17 | Reflection-type temperature/refractive index two-parameter sensing device employing long-period FBG based on Sagnac ring |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104101370A (en) * | 2014-07-18 | 2014-10-15 | 中国计量学院 | Zigbee technology based distributed refractive index sensing network |
| CN105783996A (en) * | 2016-03-31 | 2016-07-20 | 华中科技大学 | Optical fiber sensor capable of measuring acoustic wave and pressure simultaneously |
| CN105784641A (en) * | 2016-03-16 | 2016-07-20 | 北京信息科技大学 | Method for measuring refractive index based on cascade Sagnac interferometer |
| CN107271077A (en) * | 2017-07-13 | 2017-10-20 | 燕山大学 | A kind of insensitive temperature sensor of pulling force based on Sagnac principle |
| CN108106752A (en) * | 2017-12-22 | 2018-06-01 | 北京信息科技大学 | Fiber F-P temperature and the two-parameter sensing device of strain based on Sagnac rings |
| CN108279039A (en) * | 2018-01-08 | 2018-07-13 | 东北大学 | A kind of two-parameter sensing device of temperature and refractive index based on optical fiber misconstruction and Sagnac rings |
-
2014
- 2014-01-17 CN CN201420030827.2U patent/CN203657934U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104101370A (en) * | 2014-07-18 | 2014-10-15 | 中国计量学院 | Zigbee technology based distributed refractive index sensing network |
| CN105784641A (en) * | 2016-03-16 | 2016-07-20 | 北京信息科技大学 | Method for measuring refractive index based on cascade Sagnac interferometer |
| CN105784641B (en) * | 2016-03-16 | 2019-01-18 | 北京信息科技大学 | A kind of refractive index measurement method based on cascade Sagnac interferometer |
| CN105783996A (en) * | 2016-03-31 | 2016-07-20 | 华中科技大学 | Optical fiber sensor capable of measuring acoustic wave and pressure simultaneously |
| CN107271077A (en) * | 2017-07-13 | 2017-10-20 | 燕山大学 | A kind of insensitive temperature sensor of pulling force based on Sagnac principle |
| CN108106752A (en) * | 2017-12-22 | 2018-06-01 | 北京信息科技大学 | Fiber F-P temperature and the two-parameter sensing device of strain based on Sagnac rings |
| CN108279039A (en) * | 2018-01-08 | 2018-07-13 | 东北大学 | A kind of two-parameter sensing device of temperature and refractive index based on optical fiber misconstruction and Sagnac rings |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140618 Termination date: 20160117 |
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| EXPY | Termination of patent right or utility model |