CN202041465U - Capillary tube optical fiber refracting index sensor - Google Patents
Capillary tube optical fiber refracting index sensor Download PDFInfo
- Publication number
- CN202041465U CN202041465U CN201120139533XU CN201120139533U CN202041465U CN 202041465 U CN202041465 U CN 202041465U CN 201120139533X U CN201120139533X U CN 201120139533XU CN 201120139533 U CN201120139533 U CN 201120139533U CN 202041465 U CN202041465 U CN 202041465U
- Authority
- CN
- China
- Prior art keywords
- fiber
- optical fiber
- capillary
- capillary tube
- light source
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
The utility model belongs to the field of liquid temperature and refracting index measurement, and particularly relates to a capillary tube optical fiber refracting index sensor which can measure liquid temperature and refracting index simultaneously. The sensor adopts the structure that a light source is connected with an input optical fiber; the input optical fiber is connected with a sensing head part; the sensing head part is connected with an output optical fiber; and the output optical fiber is connected with a wavelength demodulating instrument, and is characterized in that the sensing head part is formed through connecting a single mode fiber with a Bragg fiber grating written in and a capillary tube optical fiber with a Bragg fiber grating written in a waveguide layer; the capillary tube optical fiber adopts a single-cladding capillary tube optical fiber or a double-cladding capillary tube optical fiber; both the input optical fiber and the output optical fiber are single mode fibers; and the incident light source is a wide-band light source. The capillary tube optical fiber refracting index sensor has the advantages of simple and compact structure, convenience in measurement, and high sensitivity.
Description
Technical field
The utility model belongs to fluid temperature, refractometry field, is specially a kind of can measuring the temperature of a liquid simultaneously and the capillary fiber index sensor of refractive index.
Background technology
Refractive index is the fluid media (medium) important physical parameter.The many character of fluid media (medium) can obtain reflection as strength of fluid, potpourri composition, proportion and pH value etc. on its refractive index.Therefore, people just can understand its physics and chemical property by measuring liquid refractive index.So the measurement of refractive index is a kind of effective means of analyzing and studying the various character of liquid, also be simultaneously the important method that various courses of reaction detect and control in the commercial production.The method of refractometry has multiple, and refractometry instrument commonly used is the Abbe measuring instrument.This method need be extracted a certain amount of measured matter and put into instrument and measure, and reads measured value by operating personnel, can't realize online detection and measure robotization.Along with the fast development of optical fiber sensing technology, receive publicity based on refractometry method, technology and the sensor of optical fiber technology.Especially the generation of fiber grating and superior performance thereof make fiber grating become the outstanding person of sensory field.It has not only that anti-electromagnetic interference (EMI), high sensitivity, response speed are fast, wide dynamic range, in light weight, compact conformation, use flexibly, be applicable to advantages such as corrosivity or risk environment, also have Wavelength-encoding simultaneously, be convenient to advantages such as multiplexing formation optical fiber sensing network.At aspects such as biochemical sensor or bioprobes, has very big application future based on the refractive index sensing of fiber grating.
Fiber grating is the light sensitive characteristic that utilizes fiber optic materials, forms periodic structure at fiber core or ducting layer, and its principle of work is at the wavelength place that satisfies phase-matching condition the intermode resonance coupling to take place.When physical quantitys such as the temperature of fiber grating environment of living in, refractive index change, usually should variation can cause that the cycle of grating or effective refractive index changed, thereby make the resonant wavelength of grating change, just can obtain the situation of change of measured physical quantity by measuring the variation of resonant wavelength.
The Bragg wavelength X of bragg grating
BCan determine by following formula:
λ
B＝2n
effΛ
In the formula, n
EffBe the fibre core effective refractive index, Λ is the grating cycle.The cycle of FBG is generally the hundreds of nanometer, and it is the reverse coupled to the basic mode that is transmitted in fibre core.Therefore can be used as stress, the reflection sensor of temperature etc.But traditional FBG is insensitive for the environment refractive index, can not be used to make biochemical sensor or bioprobe.
In order to improve the performance of fiber-optic grating sensor, people have proposed various sensor construction based on bragg grating.Bragg grating sensor device commonly used is that the end with the Bragg fiber grating is connected with light source, and the other end connects spectroanalysis instrument, by observation spectrum the variation variation that comes testing environment.Li Enbang proposes to utilize fiber grating and coreless fiber to realize measuring the temperature of a liquid simultaneously and refractive index in the patent of the application number 200610129439.x fibre-optical sensing device of refractive index " measure the temperature of a liquid simultaneously and "; The long period fiber grating biology sensor of side polishing has been proposed among the article Sensitive DNA biosensor based on a long-period grating formed on the side-polished fiber surface that people such as Hyun Soo Jang delivered in 2009 17 phases of Opt.Express; In the same year, the Use of a single-multiple-single-mode fiber filter for interrogating fiber Bragg grating strain sensors with dynamic temperature compensation that people such as Qing Wu delivered in the 48th phase of Appl.Opt has set forth and has utilized FBG and SMS structure to realize the pressure transducer of temperature compensation.
But because the refractive index of medium changes with the difference of temperature, these sensors have only the refractive index that records at a certain temperature just meaningful, therefore we are necessary to carry out temperature compensation when carrying out measuring refractive indexes of liquid, to improve the precision of refractometry.
Summary of the invention
The purpose of this utility model is the capillary fiber index sensor that proposes that a kind of structure is simpler, sensitivity is higher, has temperature compensation.
The purpose of this utility model is achieved in that
The utility model is that a kind of capillary fiber index sensor connects input optical fibre by light source, input optical fibre connects the sensing head part, sensing head partly connects output optical fibre, output optical fibre connects wavelength demodulation device, it is characterized in that: the sensing head part connects ducting layer by the single-mode fiber with the Bragg fiber grating and forms with the capillary fiber of Bragg fiber grating.Capillary fiber adopts single covering capillary fiber or double clad capillary fiber.Input optical fibre and output optical fibre are single-mode fiber.Incident light source is a wide spectrum light source.
The beneficial effects of the utility model are: what the utility model provided is a kind of based on the capillary fiber index sensor, by of the measurement of FBG single-mode fiber section to temperature, thereby realization temperature compensation, make the precision of refractometry that bigger raising arranged, simplify the structure of sensor and dwindled sensor bulk, the liquid measure kind obtains enlarging, and the spectrum peak of reflectance spectrum has independently been avoided the influence of interfering separately.
Description of drawings
Fig. 1 list covering capillary fiber structural representation;
Fig. 2 double clad capillary fiber structural representation;
Fig. 3 capillary fiber index sensor sensing head structural representation;
Fig. 4 is through the capillary fiber index sensor sensing head structural representation of encapsulation.
Embodiment
Below the technical solution of the utility model is described further:
This capillary fiber sensor senses head part that measures the temperature of a liquid simultaneously and reflect is by forming with the single-mode fiber 8 of Bragg fiber grating 9 with capillary fiber 11 fusion weld of Bragg fiber grating 10, the single-mode fiber section is used for the thermometric degree, and the capillary fiber section is used for thermometric degree and refractive index.Wherein capillary fiber 11 mainly is divided into two kinds of single covering capillary fiber (as Fig. 1) and double clad capillary fibers (as Fig. 2).
In the such scheme, described single-mode fiber is identical with the capillary fiber diameter, is 125 μ m; During welding, both axle center are on same straight line; Length after the welding is optimum in 10cm.Described capillary fiber all has the very thin ducting layer of one deck, and the Bragg fiber grating writes on this thin-film guide layer exactly.Consider that crooked meeting bring bigger influence to sensor, sensing head must be just available through encapsulation.Encapsulation process is: get the glass capillary that a diameter is 1mm, long 15cm, sensing head is inserted wherein, and guarantee that the capillary fiber terminal surface is parallel with the capillary end face, with AB glue the sensing head two ends of stretching naturally are fixed on the capillary tube inner wall.Be connected with wavelength demodulation device with wide spectrum light source respectively by one 2 * 2 coupling mechanisms by the input single-mode fiber, thus the modulation and demodulation of the system of realization.
The utility model realizes that to liquid temperature and the simultaneously-measured principle of refractive index and process are: the basic mode light that is transmitted by the input single-mode fiber satisfies phase-matching condition λ during through single-mode fiber Bragg fiber grating
B=2n
EffThe light of Λ is reflected back, wherein n
EffBe single-mode fiber fibre core effective refractive index, Λ is the grating cycle.Bragg resonance wavelength herein
BOnly vary with temperature and change, so single-mode fiber section Bragg fiber grating is used for the testing environment temperature.The light that is not reflected back continues to propagate forward along single-mode fiber, when arriving capillary fiber, will form a plurality of higher order modes in the ducting layer of capillary fiber, and the fibre core pattern is scattered.The single-mode fiber basic mode is determined by the basic mode mould field of single-mode fiber and the overlap integral of these high order guided modes mould fields to the coupling coefficient of these high order guided modes.These high order guided modes are propagated forward along capillary fiber, the corresponding longitudinal propagation constant β of each high order guided modes
i(β
i=k
0n
Effi), k
0n
2＜β
i＜k
0n
1, for single covering capillary fiber, n
1, n
2Be respectively ducting layer refractive index and fluid to be measured refractive index; And for the double clad capillary fiber, n
1, n
2Be respectively ducting layer refractive index and inner cladding effective refractive index.When these high order guided modes processes Bragg fiber grating, satisfy phase-matching condition λ
Bi=2n
EffiThe light of Λ is reflected back.In case the extraneous temperature or the refractive index of fluid to be measured change effective refractive index n
EffiChange, then the Bragg resonance wavelength
BiAlso can change thereupon.Therefore by detecting the Bragg resonance wavelength
BiDrift, just can obtain the temperature that need to detect and the dynamic-change information of refractive index.
Change because wavelengt demodulator is measured the resonance wavelength of two fiber gratings simultaneously, and each resonance wavelength is separate, therefore above-mentioned can carry out simultaneously to fluid temperature measurement and refractometry.
A kind of capillary fiber index sensor that the utility model provides, because the propagation of no fibre core guided mode in the capillary fiber, thereby the pattern that two bragg gratings reflect can not interfere, the spectrum peak of its reflectance spectrum is independence separately; The main body of sensor is a capillary fiber, adopts the single covering capillary fiber with fiber grating, can detect the liquid refractive index of refractive index less than ducting layer, as glucose, alcohol etc.; Employing then can detect the liquid refractive index of refractive index greater than ducting layer with the double clad capillary fiber of fiber grating, such as oil, benzene type organic etc.; By of the measurement of FBG single-mode fiber section, thereby realize temperature compensation, not only make the precision of refractometry that bigger raising has been arranged, also simplified the volume of sensor temperature.
Embodiment:
As shown in Figure 1, Fig. 1 is the capillary fiber structural representation of no inner cladding in the index sensor of the utility model capillary fiber.This capillary fiber comprises thin-film guide layer 1, and bragg grating writes on this thin-film guide layer 1 exactly; Airport core 2, the different refractivity sample can enter in the airport core 2 by capillarity; And covering 3, this capillary fiber only is fit to the little sample test of refractive index ratio ducting layer refractive index, and higher sensitivity is arranged.
As shown in Figure 2, Fig. 2 is for there being the capillary fiber structural representation of inner cladding in the index sensor of the utility model capillary fiber.This capillary fiber comprises thin-film guide layer 7, and bragg grating writes on this thin-film guide layer 7; Inner cladding 5 and surrounding layer 4 play a part transmission light in the constraint thin-film guide layer 7, therefore can be used for detecting the sample of high index of refraction, and to the low-refraction sample solution, sensitivity are relatively low; Airport core 6, liquid enters wherein by capillarity.
As shown in Figure 3, Fig. 3 is the index sensor sensing head structural representation of the utility model capillary fiber.This sensing head is mainly by forming with the capillary fiber 11 of Bragg grating 10 with single-mode fiber 8 weldings of Bragg grating 9, the Bragg grating utilizes position phase mask technique to write, single-mode fiber 8 has identical surrounding layer diameter with capillary fiber 11, and both axle center are on same straight line.Single-mode fiber 9 adopts standard single-mode fiber (G652), and its core diameter is 8.2 μ m, cladding diameter 125 μ m, numerical aperture 0.14.At first it is removed coat, use fiber cut cutter cutting end face then, make its end face vertical with shaft axis of optic fibre.The external diameter of capillary fiber 11 is 125 μ m, uses the fiber cut cutter to cut its end face, make its end face also with its axis normal.Single-mode fiber 9 and capillary fiber 11 after then end face being handled are put into the optical fiber bonding machine with two fused fiber splices, and guarantee that two optical fiber axle center are on same straight line.Capillary fiber 11 only keeps the length about 5cm as required, and removes coat.Then, with ultraviolet light incident, utilize the phase mask technology to write the Bragg fiber grating at single-mode fiber 9 and capillary fiber 11.The periods lambda of two Bragg fiber gratings has difference slightly, and is identical as far as possible with the temperature-responsive sensitivity that guarantees them, thereby realizes the purpose of temperature compensation.The index sensor sensor head construction is finished like this, and whole sensing head part length is in 10cm.
As shown in Figure 4, Fig. 4 is the index sensor sensing head synoptic diagram of the capillary fiber after encapsulation.Entangle optical fiber grating sensing head 13 with the about 1mm of diameter, the glass capillary 12 that is about 10cm, terminal concordant at glass capillary 12 with sensing head 13, and sensing head 13 natural straight configurations are fixed on sensing head 13 on the inwall 14 of glass capillary 12 with AB glue down, thereby the assurance sensing head is not by bending and stress influence.Tail optical fiber 15 among the figure is used for the transmission of signal.
The light of wideband light source outgoing enters first port of optical circulator by the input single-mode fiber, come out from second port through optical circulator, enter on the single-mode fiber of Bragg fiber grating, run into the Bragg fiber grating in communication process after, the light that meets the resonant wavelength coupling is reflected back.Except other light in resonant wavelength zone continues to propagate along fiber core, run into capillary fiber after, core mode is scattered, and the high-order mode that has encouraged at welding point place.These high-order modes enter the capillary fiber ducting layer and continue to propagate, and during Bragg fiber grating in running into ducting layer, that part of light that meets the resonant wavelength coupling is reflected back.That part of light in the resonant wavelength zone that is reflected back for twice reenters second port of optical circulator along optical fiber, comes out from the 3rd port through behind the optical circulator, connects by optical fiber to enter into spectroanalysis instrument.By Bragg fiber grating resonant wavelength formula λ
Bi=2n
EffΛ as can be known, when the environmental factor that acts on grating changes and when causing that refractive index around the grating changes, can cause that corresponding the change taken place for fiber core and cladding mode effective refractive index, finally can cause the variation of resonant wavelength.By detecting the drift of grating resonant wavelength, need just can obtain the temperature of detection and the dynamic-change information of refractive index.
Claims (5)
1. capillary fiber index sensor, connect input optical fibre by light source, input optical fibre connects the sensing head part, sensing head partly connects output optical fibre, output optical fibre connects wavelength demodulation device, it is characterized in that: the sensing head part connects ducting layer by the single-mode fiber with the Bragg fiber grating and forms with the capillary fiber of Bragg fiber grating.
2. capillary fiber index sensor according to claim 1 is characterized in that: described capillary fiber adopts single covering capillary fiber or double clad capillary fiber.
3. capillary fiber index sensor according to claim 1 and 2 is characterized in that: described input optical fibre and output optical fibre are single-mode fiber.
4. capillary fiber index sensor according to claim 1 and 2 is characterized in that: incident light source is a wide spectrum light source.
5. capillary fiber index sensor according to claim 3 is characterized in that: incident light source is a wide spectrum light source.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120139533XU CN202041465U (en) | 2011-05-05 | 2011-05-05 | Capillary tube optical fiber refracting index sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120139533XU CN202041465U (en) | 2011-05-05 | 2011-05-05 | Capillary tube optical fiber refracting index sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202041465U true CN202041465U (en) | 2011-11-16 |
Family
ID=44968903
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201120139533XU Expired - Lifetime CN202041465U (en) | 2011-05-05 | 2011-05-05 | Capillary tube optical fiber refracting index sensor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202041465U (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102269700A (en) * | 2011-05-05 | 2011-12-07 | 哈尔滨工程大学 | Capillary fiber refractive index sensor |
| WO2013139783A1 (en) | 2012-03-22 | 2013-09-26 | University Of Limerick | A sensor for combined temperature, pressure, and refractive index detection |
| CN103439293A (en) * | 2013-08-15 | 2013-12-11 | 吉林大学 | Tapering area micropore structure based single mode glass optical fiber liquid refractive index sensor |
| CN104237165A (en) * | 2014-08-29 | 2014-12-24 | 宁波大学 | Portable flowing water refractive index measuring device |
| CN104655590A (en) * | 2015-02-10 | 2015-05-27 | 天津大学 | All-fiber refractive index and temperature sensor and measuring method |
| CN110006846A (en) * | 2019-04-19 | 2019-07-12 | 哈尔滨工程大学 | A kind of the trace quantity liquid refractivity measuring device and preparation method of V-type special optical fiber |
-
2011
- 2011-05-05 CN CN201120139533XU patent/CN202041465U/en not_active Expired - Lifetime
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102269700A (en) * | 2011-05-05 | 2011-12-07 | 哈尔滨工程大学 | Capillary fiber refractive index sensor |
| CN102269700B (en) * | 2011-05-05 | 2013-06-05 | 哈尔滨工程大学 | Capillary fiber refractive index sensor |
| WO2013139783A1 (en) | 2012-03-22 | 2013-09-26 | University Of Limerick | A sensor for combined temperature, pressure, and refractive index detection |
| CN103439293A (en) * | 2013-08-15 | 2013-12-11 | 吉林大学 | Tapering area micropore structure based single mode glass optical fiber liquid refractive index sensor |
| CN103439293B (en) * | 2013-08-15 | 2016-02-03 | 吉林大学 | A kind of cone district micropore single mode glass fibre liquid refractive index sensor |
| CN104237165A (en) * | 2014-08-29 | 2014-12-24 | 宁波大学 | Portable flowing water refractive index measuring device |
| CN104655590A (en) * | 2015-02-10 | 2015-05-27 | 天津大学 | All-fiber refractive index and temperature sensor and measuring method |
| CN110006846A (en) * | 2019-04-19 | 2019-07-12 | 哈尔滨工程大学 | A kind of the trace quantity liquid refractivity measuring device and preparation method of V-type special optical fiber |
| CN110006846B (en) * | 2019-04-19 | 2021-11-23 | 哈尔滨工程大学 | Trace liquid refractive index measuring device of V-shaped special optical fiber and preparation method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102269700B (en) | Capillary fiber refractive index sensor | |
| CN100437036C (en) | Fibre optic sensor for measuring temperature and refractive index of liquid contemporarily | |
| CN102226725B (en) | Inner-wall waveguide long-time cycle fiber grating sensor | |
| CN202041465U (en) | Capillary tube optical fiber refracting index sensor | |
| CN101957227B (en) | Photonic crystal fiber optic liquid level sensor and sensing system formed by same | |
| EP1766369B1 (en) | Optical sensors | |
| Gao et al. | Fiber modal interferometer with embedded fiber Bragg grating for simultaneous measurements of refractive index and temperature | |
| US7668419B2 (en) | Evanescent sensor using a hollow-core ring mode waveguide | |
| CN100367016C (en) | Fibre-optical temperature measuring device and measurement thereof | |
| CN202041222U (en) | In-wall waveguide long-period fiber grating sensor | |
| CN203894161U (en) | All-fiber refractometer based on michelson interferometer and system | |
| CN103940455B (en) | A kind of all -fiber high-precision sensor and its application based on optical fiber multiple-mode interfence | |
| CN101545851B (en) | Long period fiber grating-based reflection-type optical fiber biochemical sensor and manufacturing method thereof | |
| CN103900994A (en) | All-fiber refractive index meter based on michelson interferometer, manufacturing method and system | |
| Li et al. | Temperature-independent refractometer based on fiber-optic Fabry–Perot interferometer | |
| Zhang et al. | 3D printing optofluidic Mach-Zehnder interferometer on a fiber tip for refractive index sensing | |
| CN101710065A (en) | Thin core optical fiber mode interferometer sensor | |
| CN101377527A (en) | Optical fiber voltage measuring instrument | |
| CN103134776B (en) | Liquid refractive index absolute measurement sensor based on D-type polarization maintaining optical fibre | |
| CN102147362B (en) | Temperature self-compensation FBG (Fiber Bragg Grating) refractive index sensor based on conical corrosion | |
| CN202024961U (en) | Temperature self compensation fiber bragg grating (FBG) refraction index sensor based on conical corrosion | |
| May-Arrioja et al. | Fiber optic sensors based on multicore structures | |
| CN206648950U (en) | Device based on SNS dislocation optical fiber combination FRM measurement strength of fluids | |
| CN203259472U (en) | Refractive index sensor based on fibre Bragg grating demodulated photonic crystal fibre | |
| Yan et al. | Design and simulation of a cascaded-coated LPG–FBG sensor structure for simultaneous monitoring of CTD in ocean |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20111116 Effective date of abandoning: 20130605 |
|
| AV01 | Patent right actively abandoned |
Granted publication date: 20111116 Effective date of abandoning: 20130605 |
|
| RGAV | Abandon patent right to avoid regrant |