CN103453940A - Optical fiber sensor based on multi-mode structure - Google Patents
Optical fiber sensor based on multi-mode structure Download PDFInfo
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- CN103453940A CN103453940A CN2013104166232A CN201310416623A CN103453940A CN 103453940 A CN103453940 A CN 103453940A CN 2013104166232 A CN2013104166232 A CN 2013104166232A CN 201310416623 A CN201310416623 A CN 201310416623A CN 103453940 A CN103453940 A CN 103453940A
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Abstract
The invention provides an optical fiber sensor based on a multi-mode structure. The core diameter of one of multi-mode optical fibers at the two ends of the optical fiber sensor is 105 micrometers, the length of each multi-mode optical fiber is 5mm, and the multi-mode optical fibers are used as mode couplers. The core diameter of a multi-mode optical fiber in the middle section of the optical fiber sensor is 50 micrometers, the length of the multi-mode optical fiber is 30mm, and the multi-mode optical fiber is used as a sensing area. Two modes of interference crests, namely, the fiber core-fiber core mode interference crest and the fiber core-blanket mode interference crest, exist in an optical fiber sensor output signal of the optical fiber sensor, and the temperature and the refractive index can be simultaneously measured according to the different sensitivity of the two modes of interference crests to the temperature and the refractive index. The optical fiber sensor is simple in structure, easy and convenient to operate and low in cost, the problems that an existing interference type optical fiber sensor can hardly eliminate cross sensitivity and is simplex in measurement parameter at the same time are solved, and the optical fiber sensor is suitable for the national defense field, the industrial production field and the civilian field.
Description
Technical field
The invention belongs to technical field of optical fiber sensing, particularly relate to two parameter (temperature, refractive index) optical fibre interferometric sensors.
Background technology
In the new science and technology epoch of current high speed development, three large pillars (sensing technology, the communication technology and computer technology) of modern information technologies, goed deep into every field, and played the part of and important role.In field of sensing technologies, optical fiber sensing technology is with the fastest developing speed, is leading the developing direction of new generation sensor.Fibre Optical Sensor has many unique advantages: simple in structure, easy and simple to handle, high sensitivity, anti-electromagnetic interference (EMI), be convenient to networking etc.Recent study scholar is furtherd investigate it, and obtained many Experiment Results, and come into operation, such as: temperature sensor, strain transducer, index sensor and humidity sensor etc.
Interferometric optical fiber sensor is compared with the conventional optical fibers sensor, and highly sensitive high with resolution, responding range is large, and cost is low.
Temperature and refractive index are most important in commercial measurement, it is also the study hotspot in sensory field of optic fibre, but being present in temperature and refractive index cross sensitivity problem in Fibre Optical Sensor can not be ignored, in experiment, generally to avoid the impact of extraneous parameter, the accurate measurement of realization to temperature (refractive index), common way is to add the fiber grating cascade to use, but this method cost is higher.
Summary of the invention
The present invention seeks to solve the existing fiber sensor and have temperature and refractive index cross sensitivity problem, a kind of interferometric optical fiber sensor of simple in structure and easy making is provided, this Fibre Optical Sensor is based on the multimode optical fiber structure, there is the interference peaks of two quasi-modes in output signal, different susceptibility according to it to temperature and refractive index, measure when can realize temperature and refractive index.
Fibre Optical Sensor based on multi-mode structure provided by the invention comprises: incident end single-mode fiber (1), first paragraph multimode optical fiber (2), second segment multimode optical fiber (3), the 3rd section multimode optical fiber (4), exit end single-mode fiber (5); The annexation of described Fibre Optical Sensor is: transmission light accesses first paragraph multimode optical fiber (2), second segment multimode optical fiber (3) and the 3rd section multimode optical fiber (4) successively through incident end single-mode fiber (1), through output terminal single-mode fiber (6), exports afterwards.
First paragraph multimode optical fiber of the present invention (2) is identical with the 3rd section multimode optical fiber (4) core diameter, span can be 65 ~ 110 μ m, the length span can be 1 ~ 8mm(core diameter and is preferably 105 μ m, length 5mm), as mode coupler, middle second segment multimode optical fiber (3) core diameter span can be 10 ~ 65 μ m, and the length span can be preferably 50 μ m of 20 ~ 40mm(core diameter, length 30mm), as sensitive zones.Wherein, the core diameter of second segment multimode optical fiber (3) is less than the core diameter of first paragraph multimode optical fiber (2) and the 3rd section multimode optical fiber (4).The interference peaks that output signal comprises fibre core-fibre core and fibre core-covering two quasi-modes, known according to the fiber optic interferometric theory, fibre core-the fibre core interference peaks is to responsive to temperature, and refractive index is insensitive; Fibre core-covering interference peaks is all responsive to temperature and refractive index, utilizes them can realize measuring to the different sensitivity of temperature and refractive index simultaneously.
According to the drift value of fibre core-fibre core interference peaks wavelength and fibre core-covering interference peaks wavelength, then in conjunction with the sensitive matrix equation
, can obtain the variable quantity of temperature and refractive index, wherein, Δ
λ co-co and Δ
λ co-cl be respectively the characteristic wavelength of fibre core-fibre core interference peaks and fibre core-covering interference peaks, Δ
Τand Δ
rIbe respectively the variable quantity of temperature and refractive index,
,
with
,
respectively temperature and the refractive index sensitivity of fibre core-fibre core interference peaks and fibre core-covering interference peaks characteristic wavelength.
advantage of the present invention and beneficial effect:
The present invention proposes a kind of interferometric optical fiber sensor, simple in structure and easy making, only need to carry out according to a certain percentage welding and get final product to the multimode optical fiber of different core diameters.The interference peaks that in this sensor, output signal comprises fibre core-fibre core and fibre core-covering two quasi-modes, the different susceptibility according to it to temperature and refractive index, measure when can realize temperature and refractive index.The interferometric sensor of this invention, cost is low, Stability Analysis of Structures, measuring accuracy is high, thereby is more suitable for actual application.
Below in conjunction with drawings and Examples, the present invention is further described.
The accompanying drawing explanation
Fig. 1 is this optic interferometric sensor principle schematic.
Fig. 2 is this optical fibre sensor structure schematic diagram.
The output spectrum that Fig. 3 is this Fibre Optical Sensor.
In figure: 1. incident end single-mode fiber, 2. first paragraph multimode optical fiber, 3. second segment multimode optical fiber, 4. the 3rd section multimode optical fiber, 5. exit end multimode optical fiber, 6. wideband light source, 7. spectroanalysis instrument.
Embodiment
Embodiment
A kind of Fibre Optical Sensor based on multi-mode structure, as shown in Figure 1 and Figure 2, adopt multimode-multimode-multimode optical fiber structure, by incident end single-mode fiber (1), first paragraph multimode optical fiber (2), second segment multimode optical fiber (3), the 3rd section multimode optical fiber (4), exit end single-mode fiber (5), wideband light source (6) and spectroanalysis instrument (7) form.Wideband light source (6) accesses first paragraph multimode optical fiber (2), second segment multimode optical fiber (3) and the 3rd section multimode optical fiber (4) successively through incident end single-mode fiber (1), is linked into spectroanalysis instrument (7) through output terminal single-mode fiber (5) afterwards.
Described first paragraph multimode optical fiber (2) is identical with the 3rd section multimode optical fiber (4) core diameter, chooses 105 μ m, length 5mm, and as mode coupler, second segment multimode optical fiber (3) core diameter is chosen 50 μ m, and length 30mm, as sensitive zones.Wherein, the core diameter of second segment multimode optical fiber (3) is less than the core diameter of first paragraph multimode optical fiber (2) and the 3rd section multimode optical fiber (4).
As shown in Figure 1 and Figure 2, optic path when the present invention carries out sensing to temperature and refractive index at the same time is: the light of wideband light source (6) enters first paragraph multimode optical fiber (2) through incident end single-mode fiber (1), its basic mode and each rank higher order mode have been encouraged, cause the redistribution of light field, then be coupled to second segment multimode optical fiber (3), due to fiber core mismatch, fibre core in second segment multimode optical fiber (3) and the various patterns of covering have been encouraged.The pattern that meets phase-matching condition interferes, and comprising fibre core-fibre core and fibre core-covering two quasi-modes, interferes, and interference signal is coupled in output terminal single-mode fiber (5) and is exported through the 3rd section multimode optical fiber (4).Can observe the variation of the characteristic wavelength of fibre core-fibre core interference peaks and fibre core-covering interference peaks with temperature, refractive index according to spectroanalysis instrument (7).The output spectrum of this Fibre Optical Sensor shown in Fig. 3.
The function that below will realize each device in this Fibre Optical Sensor is described in detail:
1) incident end single-mode fiber 1
Incident end single-mode fiber 2 is mainly that the light of wideband light source is accessed in designed sensor-based system.
2) the first paragraph multimode optical fiber 2
First paragraph 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, by redistributed power couple light to second segment multimode optical fiber (3), thereby encouraged the various patterns of core mode and the cladding mode of second segment multimode optical fiber (3).What in this experiment, adopt is multimode stepped-index optical fiber, and its model is SI 105/125-22/250, and length is 5 mm.
3) the second segment multimode optical fiber 3
The core mode and the cladding mode that in second segment multimode optical fiber (3), have been energized have different effective refractive indexs, therefore, after transmitting identical distance, can produce phase differential, when meeting phase-matching condition, interfere.What in this experiment, adopt is multimode stepped-index optical fiber, and its model is SI 150/125-22/250, and length is 30 mm.
4) the 3rd section multimode optical fiber 4
The 3rd section multimode optical fiber (4) plays the effect of coupling mechanism, and interference light is coupled in output terminal single-mode fiber (6) and is exported.What in this experiment, adopt is multimode stepped-index optical fiber, and its model is SI 105/125-22/250, and length is 5 mm.
5) the output terminal single-mode fiber 5
Interference light is exported to access spectroanalysis instrument (7) observation analysis.
6) wideband light source 6
Wideband light source (6) can provide suitable light signal for temperature, strain and refractive index sensing, and the wideband light source adopted in this experiment is the ASE light sourse(C+L BAND that Lightcomm produces).
7) spectroanalysis instrument 7
Spectroanalysis instrument (7) is used for observing spectral characteristic and the variation thereof of output optical signal.What in this experiment, adopt is MS9710B type spectroanalysis instrument, and wavelength resolution is 0.07 nm.
This interferometric optical fiber sensor that the present invention proposes, only the multimode optical fiber of single-mode fiber and different core diameters is carried out to welding according to a certain percentage, constructed a kind of Fibre Optical Sensor, just can learn the value of temperature and refractive index according to the drift value of interference peaks wavelength in the transmission spectrogram, when having realized temperature and refractive index, measure, and improved sensing sensitivity, it is little that this sensor has a volume, simple in structure, make easily, low cost and other advantages, can be widely used in the sensory fields such as national defence, commercial production and civil area, biological chemistry.
Claims (6)
1. the Fibre Optical Sensor based on multi-mode structure, is characterized in that this sensor comprises: incident end single-mode fiber (1), first paragraph multimode optical fiber (2), second segment multimode optical fiber (3), the 3rd section multimode optical fiber (4), exit end single-mode fiber (5);
The annexation of described optical fiber structure is: transmission light accesses first paragraph multimode optical fiber (2), second segment multimode optical fiber (3) and the 3rd section multimode optical fiber (4) successively through incident end single-mode fiber (1), through output terminal single-mode fiber (6), exports afterwards.
2. Fibre Optical Sensor according to claim 1, it is characterized in that: described first paragraph multimode optical fiber (2) is identical with the 3rd section multimode optical fiber (4) core diameter, span can be 65 ~ 110 μ m, the length span can be 1 ~ 8mm, as mode coupler, second segment multimode optical fiber (3) core diameter span can be 10 ~ 65 μ m, and the length span can be 20 ~ 40mm, as sensitive zones.
3. Fibre Optical Sensor according to claim 2, it is characterized in that: described first paragraph multimode optical fiber (2) and the 3rd section multimode optical fiber (4) preferably core diameter are 105 μ m, length 5mm, second segment multimode optical fiber (3) preferably core diameter is 50 μ m, length 30mm.
4. Fibre Optical Sensor according to claim 1 and 2, it is characterized in that: the interference peaks that output signal comprises fibre core-fibre core and fibre core-covering two quasi-modes, known according to the fiber optic interferometric theory, fibre core-the fibre core interference peaks is to responsive to temperature, and refractive index is insensitive; Fibre core-covering interference peaks is all responsive to temperature and refractive index, utilizes them can realize measuring to the different sensitivity of temperature and refractive index simultaneously.
5. Fibre Optical Sensor according to claim 3, is characterized in that: the light signal after the light signal of exit end single-mode fiber (5) output is fibre core-fibre core interference peaks and fibre core-covering interference peaks stack.
6. according to claim 1,2,4 or 5 described Fibre Optical Sensors, it is characterized in that: according to the drift value of fibre core-fibre core interference peaks wavelength and fibre core-covering interference peaks wavelength, then in conjunction with the sensitive matrix equation
, can obtain the variable quantity of temperature and refractive index, wherein, Δ
λ co-co and Δ
λ co-cl be respectively the characteristic wavelength of fibre core-fibre core interference peaks and fibre core-covering interference peaks, Δ
Τand Δ
rIbe respectively the variable quantity of temperature and refractive index,
,
with
,
respectively temperature and the refractive index sensitivity of fibre core-fibre core interference peaks and fibre core-covering interference peaks characteristic wavelength.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104297208A (en) * | 2014-10-21 | 2015-01-21 | 天津理工大学 | Interferometric optical fiber sensor based on pohotonic crystal optical fiber |
| CN109297519A (en) * | 2018-11-01 | 2019-02-01 | 中国计量大学 | A kind of temperature and strain based on cascade optical fiber and interior micro-cavity structure detection system simultaneously |
| CN109470309A (en) * | 2018-12-05 | 2019-03-15 | 华南师范大学 | A kind of full-fiber sensor and its measurement method of refractive index and temperature simultaneously measuring |
| CN110558958A (en) * | 2019-08-21 | 2019-12-13 | 武汉凯锐普信息技术有限公司 | vital sign monitoring devices based on light wave mode selection |
| CN110596814A (en) * | 2018-06-12 | 2019-12-20 | 中国计量大学 | Optical fiber corrosion groove type echo wall resonator based on microspheres |
| CN112067843A (en) * | 2020-09-07 | 2020-12-11 | 桂林电子科技大学 | Optical fiber acceleration measuring device based on fiber core mismatch |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104297208A (en) * | 2014-10-21 | 2015-01-21 | 天津理工大学 | Interferometric optical fiber sensor based on pohotonic crystal optical fiber |
| CN110596814A (en) * | 2018-06-12 | 2019-12-20 | 中国计量大学 | Optical fiber corrosion groove type echo wall resonator based on microspheres |
| CN110596814B (en) * | 2018-06-12 | 2021-06-15 | 中国计量大学 | Optical fiber corrosion groove type echo wall resonator based on microspheres |
| CN109297519A (en) * | 2018-11-01 | 2019-02-01 | 中国计量大学 | A kind of temperature and strain based on cascade optical fiber and interior micro-cavity structure detection system simultaneously |
| CN109470309A (en) * | 2018-12-05 | 2019-03-15 | 华南师范大学 | A kind of full-fiber sensor and its measurement method of refractive index and temperature simultaneously measuring |
| CN110558958A (en) * | 2019-08-21 | 2019-12-13 | 武汉凯锐普信息技术有限公司 | vital sign monitoring devices based on light wave mode selection |
| CN112067843A (en) * | 2020-09-07 | 2020-12-11 | 桂林电子科技大学 | Optical fiber acceleration measuring device based on fiber core mismatch |
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Application publication date: 20131218 |