CN206594060U - A kind of index sensor for the Michelson structure that CNT is modified based on thin-core fibers - Google Patents
A kind of index sensor for the Michelson structure that CNT is modified based on thin-core fibers Download PDFInfo
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- CN206594060U CN206594060U CN201720048951.5U CN201720048951U CN206594060U CN 206594060 U CN206594060 U CN 206594060U CN 201720048951 U CN201720048951 U CN 201720048951U CN 206594060 U CN206594060 U CN 206594060U
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Abstract
The utility model patent provides a kind of index sensor for the Michelson structure that CNT is modified based on thin-core fibers, is made up of single-mode fiber (1), thin-core fibers (2), differential of the arc top covering (3), CNT sedimentaries (4)；Single-mode fiber (1) is connected with thin-core fibers (2), differential of the arc top covering (3) is connected with thin-core fibers (2), CNT sedimentaries (4) parcel thin-core fibers (2), the surface of differential of the arc top covering (3)；The utility model sensitivity degree is high, structure is small, make simple, it can apply in all kinds of Practical Projects, the CNT of high index of refraction will increase the effective refractive index of covering, the effective refractive index difference of cladding mode and core mode will reduce so caused by the increase of external environment refractive index, so that the drift value of the sensor wavelength will be reduced compared with unmodified CNT sensor.Appropriate control CNT modification thickness will increase the drift value of sensor intensity, can reduce the influence to wavelength as far as possible, in the refractive index monitoring of real life.
Description
Technical field
One kind modifies the index sensor of CNT (Carbon Nanotube) Michelson structure based on thin-core fibers,
Belong to technical field of optical fiber sensing.
Background technology
A kind of important fibre optical sensor of optic fibre refractive index sensor, some common improve the method for transducer sensitivity
It is to carry out some special dissolvings to optical fiber or chemical treatment makes the refractive index of its environment to external world more sensitive, but these sides
Method reduces the pliability of optical fiber in itself while refractive index sensitivity is improved, and it is limited in actual applications by some
System.Most of index sensors can be drifted about with the increase wavelength of extraneous refractive index simultaneously, and therefore intensity will not be sent out
Raw regular or obvious fluctuating.Such sensor is easily limited by FSR (Free Spectral Rang), and not
Continuous monitoring in real time can be carried out in relatively wide ranges of indices of refraction.In the last few years, increasing people were in optical fiber table
Face deposits thin film to improve the sensing characteristicses of sensor.This kind of sensor has low cost, easy making, makes the folding of structure
The advantages of measurement range for penetrating rate changes with the change of external environment.
All -fiber Michelson's interferometer is a kind of important fibre optic interferometer, and its structure is divided to two kinds, and one kind is at one section
Welding goes out a structure in the middle of single-mode fiber, and the structure can inspire cladding mode, while the end face of optical fiber can plate high reflection
The silver of rate, the light that can be reflected back into the cladding mode inspired in fibre core with being transmitted in fibre core is interfered, or can be by optical fiber
End face welding goes out some special constructions, can excite the cladding mode of higher level time.Second of structure be by a section single-mould fiber with
Special optical fiber is welded together, and cladding mode is inspired using the unmatched principle of the core diameter of single-mode fiber and special optical fiber.
The structured refractive rate sensitivity is very high, can carry out wavelength and the bilingual tune of intensity.
CNT is a kind of material for having high absorptivity to light and having the black of high refractive index, another aspect CNT
Have good compatibility can be in silicon face formation film for silicon materials., can be with it is important that the sensing principle based on it
Make the measurement range increase of the refractive index of script structure, and as extraneous refraction index changing interferes the intensity change of wave spectrum to obtain
Improve.
Utility model content
The purpose of this utility model is to provide a kind of refractive index for the Michelson structure for modifying CNT based on thin-core fibers
Sensor.The installation cost is low, is easy to make, and can make the measurement range increase of the refractive index of script structure, and with outer
The intensity of boundary's refraction index changing interference wave spectrum, which changes, to be improved.
The utility model is realized by following technology：
A kind of index sensor for the Michelson structure that CNT is modified based on thin-core fibers, it is characterised in that：By single mode
Optical fiber (1), thin-core fibers (2), differential of the arc top covering (3), CNT sedimentaries (4) composition；Single-mode fiber (1) and thin-core fibers (2)
It is connected, differential of the arc top covering (3) is connected with thin-core fibers (2), CNT sedimentaries (4) parcel thin-core fibers (2), differential of the arc top bag
The surface of layer (3).
A kind of index sensor of described Michelson structure that CNT is modified based on thin-core fibers, it is characterised in that：
Single-mode fiber (1), thin-core fibers (2), differential of the arc top covering (3) can be using G.652 single-mode fibers, the fibre of thin-core fibers (2)
Core and cladding diameter are respectively 4 μm and 124.5 μm, and the length L of thin-core fibers (2) is 2mm, the length l of differential of the arc top covering (3)
For 45.08 μm.
A kind of index sensor of described Michelson structure that CNT is modified based on thin-core fibers, it is characterised in that：
CNT sedimentaries (5) are uniformly deposited on the surface of optical fiber using CNT.
Operation principle of the present utility model is：It is according to the interference formula of Michelson's interferometer：
Wherein E1And E2It is the size of basic mode and the cladding mode excited, Δ n=n respectively1-n2It is that the fibre core of cladding mode has
Imitate refringence, l1It is two times of L, λ is operation wavelength,It is initial phase.The change of the refractive index of external environment have impact on bag
The effective refractive index of layer model, so as to cause the change of phase.
This can explain the Michelson structure based on thin-core fibers with the change wavelength of external environment refractive index and strong
Degree all there occurs obvious change.Michelson structure after CNTs modifieds, as shown in Figure 2.Because CNTs is a kind of
The material of high index of refraction and high absorptivity, then high index of refraction characteristic causes the effective refractive index of cladding mode to change,
This will influence the intensity of the evanescent wave of the cladding mode on thin-core fibers surface, cause the wavelength and extinction ratio of drift value interfering crest and trough
Change.When the refractive index of external environment changes, the thin-core fibers that end face has modified CNTs also change, cladding mode
Formula can be used in formula evanescent wave reflected intensity：
Wherein a=4 π k/ λ are CNT layers of absorption coefficients,ncladAnd namIt is covering and external environment respectively
Refractive index.rX, yIt is the reflectance factor interfered in different layers.Corresponding four layers are fiber core respectively, covering, and carbon nanotube thin film is also
There is external environment.It can be seen that the change of external environment refractive index have impact on R change from formula.When external environment refractive index
Less than covering refractive index when, the increase of external environment refractive index will cause R reduction, it means that have seldom evanescent wave
Energy is reflected back toward fibre core and the basic mode of fibre core is interfered, so as to ultimately result in the reduction of extinction ratio.Wherein R change will be compared
The R of unmodified CNT sensor change is bigger, because for unmodified CNT sensing, the intensity of cladding mode is
Dependent on the Fresnel reflection between fibre cladding and external environment.Carbon nanotube thin film will improve the reflected intensity of cladding mode, therefore
With the change of external environment refractive index, bigger change will occur for the intensity of drift value interfering crest and trough.
The beneficial effects of the utility model are：A kind of simple and effective deposition process has been used to deposit CNTs in an experiment
In the end face of optical fiber.Sensing principle based on it, can make the measurement range increase of the refractive index of script structure, and with outer
The intensity of boundary's refraction index changing interference wave spectrum, which changes, to be improved.The thin-core fibers structure that so deposited CNTs overcomes FSR
Limitation.While basisThe CNT of high index of refraction will increase the effective refractive index of covering, then external environment is rolled over
Penetrating the effective refractive index difference of cladding mode caused by the increase of rate and core mode will reduce, thus the drift value of the sensor wavelength with
Unmodified CNT sensor is compared and will reduced.Appropriate control CNT modification thickness will increase the drift of sensor intensity
Amount, can reduce the influence to wavelength as far as possible.
Brief description of the drawings
Fig. 1 is the structure index sensor signal of the Michelson knot of the present utility model that CNT is modified based on thin-core fibers
Figure
Fig. 2 is the change lab diagram of interference spectrum before and after sensor modification CNT of the present utility model
Fig. 3 is sensor of the present utility model with the variation diagram of the change interference spectrum of external environment refractive index
Fig. 4 is the fitted figure of external environment refractive index of the present utility model and interference peaks wavelength
Fig. 5 is external environment refractive index of the present utility model and the fitted figure of interference peak intensity
Embodiment
The experimental provision of optic fibre refractive index sensor：
A kind of system of the index sensor for the Michelson structure that CNT is modified based on thin-core fibers includes a bandwidth
Light source, fiber coupler and spectrometer.Structure after the processing of Piranha solution is connected on spectrometer and light source during experiment.It is logical
Light deposition method is crossed, during fiber end face is deposited on, output energy is 95dB to wideband light source originally, is adjusted to
The end face of structure, extend into CNT solution continue 20min in this case by 120dB, about 20mW energy, photo-thermal amount
Temperature can slowly be increased, CNT is uniformly deposited on the surface of the optical fiber, it is small that structure then is immersed in the water into flushing two
When, the CNT of non-stably depositing is rinsed out.It is monitored to control CNT thickness using spectrometer in the process entirely deposited
Degree, to ensure that the structure after modification has good interference spectrum.
Below in conjunction with the accompanying drawings and embodiment is further described to the utility model：
Referring to accompanying drawing 1, a kind of index sensor for the Michelson structure that CNT is modified based on thin-core fibers, its feature
It is：It is made up of single-mode fiber (1), thin-core fibers (2), differential of the arc top covering (3), CNT sedimentaries (4)；Single-mode fiber (1) with
Thin-core fibers (2) are connected, and differential of the arc top covering (3) is connected with thin-core fibers (2), CNT sedimentaries (4) parcel thin-core fibers (2),
The surface of differential of the arc top covering (3).Single-mode fiber (1), thin-core fibers (2), differential of the arc top covering (3) can be using G.652 single
Mode fiber, the fibre core and cladding diameter of thin-core fibers (2) are respectively 4 μm and 124.5 μm, and the length L of thin-core fibers (2) is 2mm,
The length l of differential of the arc top covering (3) is 45.08 μm.CNT sedimentaries (4) are uniformly deposited on the surface of optical fiber using CNT.
Fig. 2 shows the aerial reflectance spectrum of thin-core fibers structure before and after modification.It can be seen that the structure after modification
Reflectance spectrum drifts about to long wave direction.CNT high index of refraction causes the change of the effective refractive index of cladding mode, so as to cause dry
Relate to wave spectrum and occur red shift.The sensor modified is carried out to the measurement of refractive index.
Fig. 3 shows the change of the change reflectance spectrum with extraneous refractive index.The unmodified folding based on thin-core fibers
Rate sensor refractive index scope is penetrated for 1.33RIU (Refractive Index) -1.38RIU, the sensitivity after Wavelength demodulation is
Sensitivity after 228.85nm/RIU, intensity demodulation is -158.75dB/RIU.The reflectance spectrum of sensor to depositing CNT is carried out
Demodulation finds that wave length shift is not changed significantly with unmodified, but the refractive index sensitivity after intensity drift increase demodulation
For -183.67dB/RIU,
Fig. 4 shows change of the extraneous refractive index with wavelength.
Fig. 5 shows change of the extraneous refractive index with intensity.
Claims (3)
1. a kind of index sensor for the Michelson structure that CNT is modified based on thin-core fibers, it is characterised in that：By single-mode optics
Fine (1), thin-core fibers (2), differential of the arc top covering (3), CNT sedimentaries (4) composition；Single-mode fiber (1) and thin-core fibers (2) phase
Even, differential of the arc top covering (3) is connected with thin-core fibers (2), CNT sedimentaries (4) parcel thin-core fibers (2), differential of the arc top covering
(3) surface.
2. a kind of index sensor of Michelson structure that CNT is modified based on thin-core fibers according to claim 1,
It is characterized in that：Single-mode fiber (1), thin-core fibers (2), differential of the arc top covering (3) can be using G.652 single-mode fibers, thin core
The fibre core and cladding diameter of optical fiber (2) are respectively 2 μm~5 μm and 120 μm~130 μm, the length L of thin-core fibers (2) for 2mm~
5mm, the length l of differential of the arc top covering (3) is 40 μm~50 μm.
3. a kind of index sensor of Michelson structure that CNT is modified based on thin-core fibers according to claim 1,
It is characterized in that：CNT sedimentaries (4) are uniformly deposited on the surface of optical fiber using CNT.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106525770A (en) * | 2017-01-12 | 2017-03-22 | 中国计量大学 | Refractive index sensor adopting Michelson structure based on CNT (carbon nanotube) modified thin core fiber |
| CN110389111A (en) * | 2019-07-10 | 2019-10-29 | 哈尔滨工程大学 | One kind being based on bimodulus core shift optical fiber interference type index sensor |
-
2017
- 2017-01-12 CN CN201720048951.5U patent/CN206594060U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106525770A (en) * | 2017-01-12 | 2017-03-22 | 中国计量大学 | Refractive index sensor adopting Michelson structure based on CNT (carbon nanotube) modified thin core fiber |
| CN110389111A (en) * | 2019-07-10 | 2019-10-29 | 哈尔滨工程大学 | One kind being based on bimodulus core shift optical fiber interference type index sensor |
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