CN206696180U - A kind of high index of refraction sensor based on mode excitation thin-core fibers - Google Patents
A kind of high index of refraction sensor based on mode excitation thin-core fibers Download PDFInfo
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- CN206696180U CN206696180U CN201621420919.7U CN201621420919U CN206696180U CN 206696180 U CN206696180 U CN 206696180U CN 201621420919 U CN201621420919 U CN 201621420919U CN 206696180 U CN206696180 U CN 206696180U
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Abstract
The utility model patent provides a kind of high index of refraction sensor based on mode excitation thin-core fibers, it is characterised in that：It is made up of single-mode fiber (1), thin-core fibers (2), differential of the arc region (3)；Single-mode fiber (1), thin-core fibers (2), differential of the arc region (3) are connected to form the Michelson's interferometer of all -fiber；The end face in differential of the arc region (3) is used for inspiring the cladding mode of higher level time.Beam splitting and the cladding mode of a part of thin-core fibers is inspired when the basic mode of transmission in single-mode fiber fibre core reaches first fusion point, when core mode and cladding mode are coupled in first fusion point, with certain phase delay, so as to realize the mode-interference of core mode and cladding mode.The utility model cost is low, easy making, the maximum sensitivity presented in the range of refractive index 1.3321RIU (Refractive Index Unit) to 1.3823RIU is 228.85nm/RIU and 158.75dB/RIU, and the sensor for temperature is insensitive, not only Wavelength demodulation can have been carried out but also intensity demodulation can be carried out, can be used in the refractive index monitoring of real life.
Description
Technical field
The utility model provides a kind of high index of refraction sensor based on mode excitation thin-core fibers, belongs to Fibre Optical Sensor
Technical field.
Background technology
Optic fibre refractive index sensor has attracted extensive attention as one kind of fibre optical sensor, because its structure is micro-
It is small, high sensitivity, the advantage such as easy to manufacture.In the last few years, optic fibre refractive index sensor was based on SPR (Surface Plasmon
Resonance), covering corrodes, thin wimble structure, and fiber grating etc. has been suggested, and is based in these different structure types
The sensor of thin-core fibers account for a part, such as etching corrosion thin-core fibers etc. on thin-core fibers.Although these methods are all
A certain degree of sensitivity for improving refractive index, but the defects of still have some aspects.Such as based on fiber grating
There is Temperature cross-over sensitivity temperature in structure, the Structural flexibility based on dislocation is very poor, also have some to need the place of chemical attack
Reason process, both increase the difficulty in manufacturing process.It is suggested to solve a kind of new high index of refraction sensor of problem above,
This sensor have cost it is low, it is easy make, to temperature-insensitive, can not only carry out Wavelength demodulation but also intensity solution can be carried out
The advantages that tune.
A kind of high index of refraction sensor based on mode excitation thin-core fibers can realize the pattern of core mode and cladding mode
Interference, and the interference spectrum of two level is not present in the sensor, it is not necessary to and computer carries out the filtering of data.When the use sensor pair
When external environment refractive index measures, can all interference fringe be set to drift about whenever extraneous refractive index is changed, reflectance spectrum
Wavelength and intensity also can accordingly change, and be demodulated by the wavelength to reflectance spectrum or intensity, it is possible to achieve refractive index
Measurement, ambient temperature increase to 90 DEG C from 25 DEG C, and the wavelength and intensity of reflectance spectrum do not have significant change, therefore the sensor is temperature
Spend insensitive index sensor.
Utility model content
The purpose of this utility model is to provide a kind of high index of refraction sensor based on mode excitation thin-core fibers.The dress
The wavelength that the variable quantity of refractive index to be measured can be changed into reflectance spectrum or the variable quantity of intensity are put, has cost low, easily makes
Make, can not only carry out Wavelength demodulation but also intensity demodulation can be carried out, and the features such as to temperature-insensitive.
The utility model is realized by following technology：
A kind of high index of refraction sensor based on mode excitation thin-core fibers, by single-mode fiber (1), thin-core fibers (2), micro-
Arc region (3) forms；The Michelson that single-mode fiber (1), thin-core fibers (2), differential of the arc region (3) are connected to form all -fiber is done
Interferometer.
A kind of described high index of refraction sensor based on mode excitation thin-core fibers, it is characterised in that：Single-mode fiber
(1), thin-core fibers (2) can use G.652 single-mode fiber, and the fibre core and cladding diameter of thin-core fibers (2) are respectively 4.00 μm
With 124.50 μm, the length L of thin-core fibers (2) is about 3.00mm, and the length l of differential of the arc region (3) is 45.08 μm.
Operation principle of the present utility model is：When the basic mode of transmission in single-mode fiber fibre core reaches first fusion point
Beam splitting and the cladding mode for inspiring a part of thin-core fibers, the end face of the differential of the arc inspire the cladding mode of higher level time, work as core mode
With cladding mode when first fusion point is coupled, there is certain phase delay, so as to realize core mode and cladding mode
Mode-interference.The interference formula of the Michelson's interferometer is：
Wherein E1And E2The size of cladding mode for being basic mode respectively and exciting, Δ n=n1-n2 is having for the fibre core of cladding mode
Imitate refringence, l1It is two times of L, λ is operation wavelength, and φ is initial phase.The change of the refractive index of external environment have impact on
The effective refractive index of cladding mode, so as to cause the change of phase.
In order to study the excitation process of cladding mode, end face discharge time different Michelson structure is produced.Experiment
As a result show：Interference peaks are not present when it is flat that end face, which does not have electric discharge,.It can be seen that the end face of the differential of the arc can inspire it is higher
The cladding mode of level is so as to realizing the interference of basic mode and cladding mode.It is considered that when end face is smooth, cladding mode with
Low-angle returns from fiber end face, the incident angle when end face of the differential of the arc adds the reflection of cladding mode and inspires higher level
Secondary cladding mode, so as to produce additional phase difference.With the increase of discharge time, fiber end face becomes more and more round.When
When discharge time is more than 15.000ms, fiber end face becomes very round, and most cladding mode will be scattered out can not be again
Fibre core is coupled into, it can be found that interference spectrum will reduce.
The beneficial effects of the utility model are：The Michelson's interferometer is made by one section of thin-core fibers and single mode
Optical fiber is connected, and electric discharge is carried out to the end faces of thin-core fibers makes its end face differential of the arc, and the end face of the differential of the arc can excite higher level time
Cladding mode, and the sensor cost it is low, it is easy make, to temperature-insensitive, can not only carry out Wavelength demodulation but also can carry out
Intensity demodulation, therefore the structure can be used for the refractive index monitoring of real life.
Brief description of the drawings
Fig. 1 is a kind of Michelson structural representation that high-order cladding mode is excited based on thin-core fibers end face
Fig. 2 is the reflectance spectrum lab diagram with the change of external environment refractive index
Fig. 3 is the change lab diagram of the wavelength of the change interference spectrum with external environment refractive index and temperature
Fig. 4 is the change lab diagram of the intensity of the change interference spectrum with external environment refractive index and temperature
Embodiment
The experimental provision of optic fibre refractive index sensor：
A kind of system of the high index of refraction sensor based on mode excitation thin-core fibers includes a bandwidth light source, optical fiber coupling
Clutch and spectrometer.Sensor construction is immersed in refraction index solution, the light of wideband light source enters sensor by circulator
Structure, the reflected light of sensor construction enter spectrometer by circulator and the sensor are completely immersed into different refractivity
In the refraction index solution of value, the situation of change of reflectance spectrum is observed by spectrometer, holding ambient temperature is in measurement process
Room temperature is constant.
Below in conjunction with the accompanying drawings and embodiment is further described to the utility model：
Fig. 1 is a kind of Michelson structure that high-order cladding mode is excited based on thin-core fibers end face, Fig. 2 show with
The situation of change of the change reflectance spectrum of external environment refractive index.Experimental result shows the increase peak 1 with external environment refractive index
Drifted about with peak 2 to long wave direction, when 2 π Δsneffl1When/λ=2m π are integer, interference peaks occur, when extraneous refractive index increase,
ΔneffIncrease, wavelength drift about.Simultaneously experimental result show with external environment refractive index increase reflectance spectrum intensity by
Decrescence small, because when external environment refractive index increase, reflected energy will reduce, the part evanescent wave energy in cladding mode will
It can be coupled out, so as to cause the reduction of interference spectrum extinction ratio.
Fig. 3 shows the change of the wavelength of the change interference spectrum with external environment refractive index and temperature.When the external world reflects
Rate increases to 1.3823RIU from 1.3321RIU (Refractive Index Unit), and sensor refractive index sensitivity is
228.85nm/RIU.The wavelength resolution of spectrometer is 0.01nm, therefore corresponding minimum Measurement Resolution 4.326*10-5RIU。
Fig. 4 shows the change of the intensity of the change interference spectrum with external environment refractive index and temperature.When the external world reflects
Rate from 1.3321RIU increase to 1.3823RIU when, the sensor refractive index sensitivity is -158.75dB/RIU.Spectrometer it is strong
Degree resolution ratio is 0.01dB, therefore corresponding minimum Measurement Resolution is 6.299*10-5RIU.In order to understand the sensor for temperature
Response condition, the sensor is put on hot plate.Fig. 3 and Fig. 4 is shown as ambient temperature from 25 DEG C increases to 90 DEG C, instead
Penetrating the wavelength of spectrum and intensity does not have significant change, therefore the sensor is the index sensor of temperature-insensitive.
Claims (2)
- A kind of 1. high index of refraction sensor based on mode excitation thin-core fibers, it is characterised in that：By single-mode fiber (1), thin core Optical fiber (2), differential of the arc region (3) composition；The both ends of thin-core fibers (2) are connected with single-mode fiber (1), differential of the arc region (3) respectively； Single-mode fiber (1), thin-core fibers (2), differential of the arc region (3) are connected to form the Michelson's interferometer of all -fiber.
- A kind of 2. high index of refraction sensor based on mode excitation thin-core fibers according to claim 1, it is characterised in that： Single-mode fiber (1), thin-core fibers (2), differential of the arc region (3) can use G.652 single-mode fiber, the fibre core of thin-core fibers (2) and Cladding diameter is respectively 2 μm~5 μm and 120 μm~130 μm, and the length L of thin-core fibers (2) is 2mm~5mm, differential of the arc region (3) Length l be 40 μm~50 μm.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621420919.7U CN206696180U (en) | 2016-12-21 | 2016-12-21 | A kind of high index of refraction sensor based on mode excitation thin-core fibers |
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| CN201621420919.7U CN206696180U (en) | 2016-12-21 | 2016-12-21 | A kind of high index of refraction sensor based on mode excitation thin-core fibers |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106770042A (en) * | 2016-12-21 | 2017-05-31 | 中国计量大学 | A kind of high index of refraction sensor based on mode excitation thin-core fibers |
| CN115355830A (en) * | 2022-10-18 | 2022-11-18 | 南京信息工程大学 | Optical fiber MI sensor with bending structure, manufacturing method and sensing system |
-
2016
- 2016-12-21 CN CN201621420919.7U patent/CN206696180U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106770042A (en) * | 2016-12-21 | 2017-05-31 | 中国计量大学 | A kind of high index of refraction sensor based on mode excitation thin-core fibers |
| CN115355830A (en) * | 2022-10-18 | 2022-11-18 | 南京信息工程大学 | Optical fiber MI sensor with bending structure, manufacturing method and sensing system |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20171201 Termination date: 20181221 |