CN100340846C - Temperature sensor of long period optical fiber grating - Google Patents
Temperature sensor of long period optical fiber grating Download PDFInfo
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- CN100340846C CN100340846C CNB2004100663909A CN200410066390A CN100340846C CN 100340846 C CN100340846 C CN 100340846C CN B2004100663909 A CNB2004100663909 A CN B2004100663909A CN 200410066390 A CN200410066390 A CN 200410066390A CN 100340846 C CN100340846 C CN 100340846C
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Abstract
The present invention discloses a temperature sensing device for long period optical fiber grating, belonging to the field of optical fiber communication and optical fiber sensing. Long period grating is wedged in a single mode fiber cladding via corrosion, and then low thermosensitive and high thermosensitive materials are plated on one side of optical fiber along axial direction. When outside temperature changes, grating can slightly bend since the outer plated film layer expands in high temperature and shrinks in low temperature, and thus, the resonant wavelength of long period optical fiber grating is changed. The sensing device has the advantages of high temperature sensitivity, simple structure, favorable stability and high temperature resistance, and the sensing device can be applied to high-temperature measurement, multi-point temperature measurement, etc.
Description
Technical field
The present invention relates to temperature sensing device, particularly a kind of temperature sensing device of long period fiber grating belongs to optical fiber communication and sensory field of optic fibre.
Background technology
The grating cycle of long period fiber grating (LPFG) is far longer than the general optical fiber grating, is generally tens microns to the hundreds of micron.From mode coupling theory, what long-period gratings was realized is optical fiber coupling between modes in the same way, i.e. coupling between guided mode and the cladding mode.The transport property of long period fiber grating can change because of the influence of ambient temperature, stress, bending etc.When extraneous factor changes, be different corresponding to the variation of the guided mode of a certain frequency and the transmission of cladding mode.When but ambient temperature was higher, the grating that writes fibre core by ultraviolet technology can be by floating, and the long period effect disappears.
Document [C.Y.Lin and L.A.Wang; " Loss-tunable Long Period FibreGrating Made From Etched Corrugation Structure "; Electron.Lett.; vol.35; no.21, pp.1872-1873,1999] introduced a kind of cutting LPFG; it is not plate the layer of metal floor outside the cutting district covering, and protection part covering is not corroded in the process of making LPFG and forms grooved LPFG.Here the effect of metal film only is used for etched diffraction grating.Because this long-period gratings is by being etched into, when ambient temperature was higher, the grating that writes can be by not floating so.But its degree of modulation is lower, and promptly temperature control is lower.
Document [Wang Yiping, Rao Yunjiang, Ceng Xiangkai.The mode coupling theory analysis of long period fiber grating flexural property, photon journal, 2002,31 (10): 1205-1208] analyzed the flexural property of long period fiber grating, drawn this characteristic conclusion relevant with order of model with the optical fiber normalized frequency.The etching long period fiber grating can be analogous to this situation.When it bends, the variation of the same pests occurrence rule of centre wavelength of its harmonic peak correspondence.
Summary of the invention
The objective of the invention is provides a kind of temperature sensing device of long period fiber grating in order to solve the deficiency of above-mentioned prior art, and it should have temperature control height, characteristics that resolution is high.
Technical solution of the present invention is:
A kind of temperature sensing device of long period fiber grating, the formation that it is characterized in that it is: writing on the single-mode fiber covering of long-period gratings, the side at fiber grating is coated with low heat expansion coefficient coatings and high coefficient of thermal expansion coatings from inside to outside vertically.
The cycle of described long-period gratings is 500-900 μ m, and cladding diameter is 65-85 μ m after the etching, and the grating total length is 40-60mm.
The central angle of described low heat expansion coefficient coatings and high coefficient of thermal expansion coatings correspondence is 60-120 °, and the thickness of described low heat expansion coefficient coatings is 20-30 μ m.
Ultimate principle of the present invention is:
The variations in refractive index that temperature is caused changes the variations in refractive index that bending causes into, makes that the coupling of fibre core pattern and cladding mode changes in the single-mode fiber.The Mode Coupling of long period fiber grating belongs to the coupling between modes of co-propagate, mainly is the cladding mode that the guided mode of forward-propagating is coupled to forward-propagating.When ambient temperature changed, the high coefficient of thermal expansion coatings that is plated in optical fiber one side was expanded with heat and contract with cold, and it is little curved that the grating fibers section is produced.Make optical fiber become curved waveguide on the one hand; Make each modulated refractive index xsect run-off the straight in the long-period gratings on the other hand, be equivalent to the inclination chirp grating, the grating fringe visibility is reduced, the average effective index modulation in each grating cycle reduces, and cross-couplings efficient reduces.Along with the increase of bending curvature, cause the covering average effective index modulation of equivalence to reduce gradually, thus the trend of the oriented shortwave direction drift of resonance wavelength of guided mode and the coupling of low order cladding mode.
The invention has the beneficial effects as follows that the thermal effect of coatings makes temperature modulation change the modulation of fiber grating flexibility into, realizes the adjusting of Resonant Wavelengths of Long Period Fiber Gratings, temperature control height of the present invention is not disturbed by extraneous factor, and is simple in structure, good stability.Under hot conditions, the grating of etching can be applicable to high temperature measurement by floating.
The present invention is further described below in conjunction with accompanying drawing.
Description of drawings
Fig. 1 is the longitudinal sectional view of plated film long period fiber grating.
Fig. 2 is the transverse sectional view at the former cladding diameter of plated film long period fiber grating place.
Fig. 3 is the transverse sectional view at cladding diameter place after the plated film long period fiber grating etching
Among the figure:
The 1st, fiber core, the 2nd, fibre cladding, the 3rd, high coefficient of thermal expansion coatings, the 4th, long period fiber grating cycle, the 5th, fibre cladding diameter after the etching, the 6th, long period fiber grating length, the 7th, the corresponding central angle of coatings, the 8th, low heat expansion coefficient coatings.
Embodiment
Embodiments of the invention as shown in Figure 1.As seen from the figure, the temperature sensing device of long period fiber grating of the present invention, its formation is: writing on the single-mode fiber covering 2 of long-period gratings, the side at fiber grating is coated with low heat expansion coefficient coatings 8 and high coefficient of thermal expansion coatings 3 from inside to outside vertically.The cycle 4 of described long-period gratings is 500-900 μ m, and cladding diameter is 65-85 μ m after the etching, and grating total length 6 is 40-60mm.The central angle of described low heat expansion coefficient coatings 8 and high coefficient of thermal expansion coatings 3 correspondences is 60-120 °, and the thickness of described low heat expansion coefficient coatings is 20-30 μ m.Long period fiber grating can realize that coatings can realize by mask and vacuum coating technology by photoetching and corroding method.When central angle less than 60 ° or during greater than 120 °, the deficient change of coatings 3 causes moisture sensitivity to reduce so that the grating section takes place obviously crookedly.Low heat expansion coefficient coatings 8 is too thin or too thick, all can reduce the effect of coatings 3 temperature deformation, makes the grating flexibility reduce, and moisture sensitivity reduces.
Its course of work is as follows:
Light enters single-mode fiber, and what propagate in fibre core 1 is guided mode, and what propagate in covering 2 is cladding mode.When ambient temperature changed, high coefficient of thermal expansion coatings 3 was expanded with heat and contract with cold, and low heat expansion coefficient coatings 8 is temperature influence hardly, causes optical fiber to bend, and caused that the coupling efficiency of guided mode and cladding mode changes, and made resonance wavelength that corresponding displacement take place.
The experiment proved that the present invention has the temperature control height, and is simple in structure, good stability, resistant to elevated temperatures characteristics can be applicable to high temperature measurement, multipoint mode temperature survey etc.
Claims (3)
1, a kind of temperature sensing device of long period fiber grating, the formation that it is characterized in that it is: writing on the single-mode fiber covering (2) of long-period gratings, the side at fiber grating is coated with low heat expansion coefficient coatings (8) and high coefficient of thermal expansion coatings (3) from inside to outside vertically.
2, the temperature sensing device of long period fiber grating according to claim 1 is characterized in that the cycle (4) of described long-period gratings is 500-900 μ m, and cladding diameter is 65-85 μ m after the etching, and grating total length (6) is 40-60mm.
3, the temperature sensing device of long period fiber grating according to claim 1, it is characterized in that the corresponding central angle of described low heat expansion coefficient coatings (8) and high coefficient of thermal expansion coatings (3) is 60-120 °, the thickness of described low heat expansion coefficient coatings is 20-30 μ m.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2004100663909A CN100340846C (en) | 2004-09-15 | 2004-09-15 | Temperature sensor of long period optical fiber grating |
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| CNB2004100663909A CN100340846C (en) | 2004-09-15 | 2004-09-15 | Temperature sensor of long period optical fiber grating |
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| CN1587935A CN1587935A (en) | 2005-03-02 |
| CN100340846C true CN100340846C (en) | 2007-10-03 |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100350220C (en) * | 2005-11-25 | 2007-11-21 | 浙江大学 | Double parameter measuring method basing on long period optical-fiber grating to sen sor |
| CN102466528A (en) * | 2010-11-11 | 2012-05-23 | 香港理工大学 | Method for measuring refractive index and temperature, optical fiber sensor and corresponding manufacturing method |
| CN105353458A (en) * | 2015-10-22 | 2016-02-24 | 重庆理工大学 | Linear-groove type optical fiber cladding surface Bragg grating |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003254838A (en) * | 2002-03-04 | 2003-09-10 | Furukawa Electric Co Ltd:The | Optical temperature sensor |
| CN1472552A (en) * | 2003-06-24 | 2004-02-04 | 重庆大学 | Singe lnog period optical fiber gratings based simultaneous temperature and load measuring method and sensor |
| CN2733328Y (en) * | 2004-09-15 | 2005-10-12 | 中国科学院上海光学精密机械研究所 | Temperature sensing device for long period optical fiber grating |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003254838A (en) * | 2002-03-04 | 2003-09-10 | Furukawa Electric Co Ltd:The | Optical temperature sensor |
| CN1472552A (en) * | 2003-06-24 | 2004-02-04 | 重庆大学 | Singe lnog period optical fiber gratings based simultaneous temperature and load measuring method and sensor |
| CN2733328Y (en) * | 2004-09-15 | 2005-10-12 | 中国科学院上海光学精密机械研究所 | Temperature sensing device for long period optical fiber grating |
Non-Patent Citations (1)
| Title |
|---|
| 基于长周期光纤光栅的高灵敏度温度传感方案 何万迅，施文康，叶爱伦，传感技术学报，第1期 2002 * |
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Owner name: SHANGHAI OPTICS AND PRECISION MECHANICS INSTITUTE Free format text: FORMER OWNER: SHANGHAI OPTICS AND PRECISION MECHANICS INSTITUTE, CHINESE ACADEMY OF SCIENCES Effective date: 20080912 |
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Effective date of registration: 20080912 Address after: Shanghai 800-211 post office mailbox: 201800 Co-patentee after: Shanghai Xinhui Shidai Optical Disk Technology Co., Ltd. Patentee after: Shanghai Institute of Optics and Fine Mechanics.CAS, Chinese Academy of Sciences Address before: Shanghai 800-211 post office mailbox: 201800 Patentee before: Shanghai Optical Precision Machinery Inst., Chinese Academy of Sciences |
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