CN209495726U - A kind of full-fiber sensor of refractive index and temperature simultaneously measuring - Google Patents
A kind of full-fiber sensor of refractive index and temperature simultaneously measuring Download PDFInfo
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- CN209495726U CN209495726U CN201822034528.7U CN201822034528U CN209495726U CN 209495726 U CN209495726 U CN 209495726U CN 201822034528 U CN201822034528 U CN 201822034528U CN 209495726 U CN209495726 U CN 209495726U
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Abstract
The utility model provides the full-fiber sensor of a kind of refractive index and temperature simultaneously measuring.Full-fiber sensor includes broadband spectral light source, optical fiber sensor head and spectroanalysis instrument, and the input port of the optical fiber sensor head is connect with broadband spectral light source by optical fiber, and the output port of the optical fiber sensor head is connect with spectroanalysis instrument by optical fiber.Using the utility model, optical fiber sensor head is put into environment to be measured；The moving range of interference fringe valley wavelength is measured by spectroanalysis instrument and computer；Then the changing value that refractive index and temperature are obtained after mathematical method processing is utilized；The full-fiber sensor and its measurement method of a kind of refractive index and temperature simultaneously measuring of the utility model, when can eliminate refractometry there are potential Temperature cross-over sensitive question and can be improved measurement refractive index and temperature accuracy, have the advantages that structure is simple, at low cost, easy to operate and measurement range is big.
Description
Technical field
The utility model relates to fibre optical sensor fields, and in particular to one kind is based on Mach-Zehnder interferometer type refractive index
With the full-fiber sensor of temperature simultaneously measuring.
Background technique
Along with the fast development of high-tech industry, refractive index and temperature are most important parameters in these applications, are such as changed
, food industry and high-tech lab field.Therefore, real-time monitoring refractive index and temperature are extremely important.Optical fiber mach-Zeng De
Interferometer (Mach-Zehnder Interferometer, MZI) type sensor is widely studied due to its unique advantage,
It is highly sensitive such as electromagnetism interference, a possibility that potential low cost and long-distance distributed measurement.Early stage related refractive index
Work with the manufacturing method of temperature measurement is it has been reported that including punching optical fiber with femtosecond laser, being embedded in photon
Crystal optical fibre structure, cascaded optical fiber Bragg grating or long-period fiber grating or embedded special fiber.In general, this
It is relatively expensive that a little methods usually require complicated manufacturing process or price.Most importantly the studies above has ignored temperature birefringence
The influence of rate.Generally, due to thermo-optic effect and thermal expansion, Mach-Zehnder interferometer type sensor for temperature is also very sensitive.Cause
This, there are potential Temperature cross-over sensitive questions for refractometry.Meanwhile many researchs use improved optical fiber Bragg light
Grid (Fiber Bragg Grating, FBG) and long-period fiber grating (Long Period Fiber Grating, LPFG) are same
When detection refractive index and temperature, but this method is also very expensive, and its practical application is restricted.
Utility model content
In view of this, to solve above-mentioned the problems of the prior art, the utility model provides a kind of based on Mach-Zehnder
The refractive index of interferometer and the full-fiber sensor of temperature simultaneously measuring, there are potential temperature when can eliminate refractometry
Cross-sensitivity problem and the accuracy that measurement refractive index and temperature can be improved, simple, at low cost, the operation side with structure
Just and the big advantage of measurement range.
To achieve the above object, the technical solution of the utility model is as follows.
A kind of full-fiber sensor of refractive index and temperature simultaneously measuring comprising broadband spectral light source, optical fiber sensor head
And spectroanalysis instrument；The optical fiber sensor head includes input-output optical fiber part, light beam coupling part and transducing part, described defeated
Entering output optical fibre part includes input single mode optical fiber and output single mode optical fiber, and the light beam coupling part includes multimode fibre and thin
Core-single mode optical fiber fusion point, that is, thick wimble structure；Transducing part includes thin-core fibers, is located among optical fiber sensor head, the input
Output optical fibre part is connected with transducing part by light beam coupling part, and the first Coupling point is that multimode fibre is connect with single mode optical fiber
Point, since fiber core mismatch causes light wave to be propagated in the fibre core and covering in thin-core fibers, the second Coupling point is thin core-single-mode optics
The light wave that the fibre core in thin-core fibers and covering are propagated is coupled together again, is interfered, and enters single mode by fine welding structure
It is propagated in the fibre core of optical fiber；The input port of optical fiber sensor head is connect with broadband spectral light source by optical fiber, the Fibre Optical Sensor
The output port of head is connect with spectroanalysis instrument by optical fiber, by the multimode fibre (MMF), thin-core fibers in optical fiber sensor head
(TCF) and thin-core fibers and single mode optical fiber fusion point constitute Mach-Zehnder interferometer, the light beam inside Mach-Zehnder interferometer
It is interfered in transmission, is then transferred into spectroanalysis instrument.
It further, further include computer, the computer and spectroanalysis instrument output end communicate to connect；The computer
For receiving the output data of spectrometer and realizing refractive index and temperature simultaneously measuring using two-dimensional matrix.
Further, the mach-zehnder interferometer configuration is the thin-core fibers for removing coat.
Further, the broadband spectral light source is the fiber broadband spectroscopic light source of L-band 1570nm-1605nm, institute
Stating all transmission fibers is general single mode fiber.
A kind of measurement method of refractive index and temperature simultaneously measuring based on Mach-Zehnder interferometer, comprising the following steps:
Optical fiber sensor head is put into environment to be measured by step 1；
Step 2, the moving range that interference fringe valley wavelength is measured by spectroanalysis instrument and computer；
Then step 3 utilizes the changing value that refractive index and temperature are obtained after mathematical method processing.
Further, in step 3, coefficient matrix is formed such as to the sensitivity of temperature and response of refractive index using interference trough
Shown in following formula, two-parameter measurement is realized:
WhereinFor the sensitivity of different interference trough refractive index and temperature, Δ λm1、Δ
λm2For the offset of different trough wavelength, each amount is gone out by experimental calculation, then can be calculated simultaneously by matrix inverse transformation
The changing value Δ n of the refractive index and changing value Δ T of temperature.
Compared with the prior art, a kind of refractive index and temperature based on Mach-Zehnder interferometer of the utility model be simultaneously
The full-fiber sensor of measurement there are potential Temperature cross-over sensitive question and can mention when can eliminate refractometry
The accuracy of high measurement refractive index and temperature has the advantages that structure is simple, at low cost, easy to operate and measurement range is big.
Detailed description of the invention
Fig. 1 is a kind of full light of refractive index and temperature simultaneously measuring based on Mach-Zehnder interferometer of the utility model
The structural schematic diagram of fiber sensor.
Fig. 2 be Fibre Optical Sensor header structure and with solution mass interface schematic diagram to be measured.
Fig. 3 is transmitted light spectrogram when optical fiber sensor head is immersed in distilled water.
Fig. 4 is the corresponding transmission spectrum spectrogram of sodium chloride solution when refractive index 1.3105-1.3465 changes.
Fig. 5 is trough A (1581.74nm) and the offset and index of refraction relationship figure of trough B (1591.53nm).
Fig. 6 is transmitted light spectrogram of the optical fiber sensor head at 25 DEG C -50 DEG C.
Fig. 7 is the offset of trough A (1581.74nm) and trough B (1591.53nm) and the relational graph of temperature.
Specific embodiment
The specific implementation of the utility model is described further below in conjunction with attached drawing and specific embodiment.It needs to refer to
Out, the key of the utility model be to structure division propose technical solution, if following embodiment relate to need it is soft
What part was realized, it belongs to the follow-up data processing to the utility model and is that those skilled in the art can refer to prior art understanding
Or realize.
As shown in Figure 1 and Figure 2, simultaneously for a kind of refractive index and temperature based on Mach-Zehnder interferometer of the utility model
The structural schematic diagram of the full-fiber sensor of measurement comprising broadband spectral light source 1, optical fiber sensor head 2 and spectroanalysis instrument 3；
The optical fiber sensor head includes input-output optical fiber part, light beam coupling part and transducing part, the input-output optical fiber portion
Dividing includes input single mode optical fiber 201 and output single mode optical fiber 202, and the light beam coupling part includes that multimode fibre and thin core-are mono-
Mode fiber fusion point, that is, thick wimble structure；Transducing part 203 includes thin-core fibers (TCF), is located among optical fiber sensor head, described defeated
Enter output optical fibre part and connected with transducing part by light beam coupling part, the first Coupling point is multimode fibre (MMF) and single mode
Optical fiber (SMF) tie point, since fiber core mismatch causes light wave to be propagated in the fibre core and covering in thin-core fibers；Second Coupling point
For thin-core fibers-single mode optical fiber welding structure, the light wave that the fibre core in thin-core fibers and covering are propagated is coupled together again, hair
Interference is given birth to, and is propagated in the fibre core of entrance single mode optical fiber；The input port and broadband spectral light source of optical fiber sensor head pass through optical fiber
Connection, the output port of the optical fiber sensor head is connect with spectroanalysis instrument by optical fiber, by the multimode in optical fiber sensor head
Optical fiber (MMF), thin-core fibers (TCF) and thin-core fibers and single mode optical fiber fusion point constitute Mach-Zehnder interferometer, and Mach-was once
Light beam inside Deccan interferometer is interfered in transmission, is then transferred into spectroanalysis instrument.
The refractive index based on Mach-Zehnder interferometer of the present embodiment and temperature simultaneously measuring sensor its sensing arrangement base
In broadband spectral light source (BBS), optical fiber sensor head (Sensor Head), spectroanalysis instrument (OSA) and single mode optical fiber (SMF),
The input port of sensing head (Sensor Head) is connect with broadband spectral light source (BBS) by single mode optical fiber (SMF), and optical fiber passes
The output port of sense head (Sensor Head) connect (SMF), optical fiber sensor head by optical fiber with spectroanalysis instrument (OSA)
Light beam in (Sensor Head) inside Mach-Zehnder interferometer is interfered in transmission, is then transferred into spectrum analysis
Instrument (OSA).
It preferably, further include computer, the computer and spectroanalysis instrument output end communicate to connect；The computer is used
Refractive index and temperature simultaneously measuring are realized in the output data for receiving spectrometer and using two-dimensional matrix.
Preferably, the mach-zehnder interferometer configuration is the thin-core fibers for removing coat.
Preferably, the broadband spectral light source is the fiber broadband spectroscopic light source of L-band 1570nm-1605nm, described
All transmission fibers are general single mode fiber.
A kind of measurement method of refractive index and temperature simultaneously measuring based on Mach-Zehnder interferometer, comprising the following steps:
Optical fiber sensor head is put into environment to be measured by step 1；
Step 2, the moving range that interference fringe valley wavelength is measured by spectroanalysis instrument and computer；
Then step 3 utilizes the changing value that refractive index and temperature are obtained after mathematical method processing.
When measuring to sensor, fiber interference fringe trough becomes with the variation of the refractive index and temperature of solution
Change, basic principle is as follows:
Due to fiber core mismatch, Mach-Zehnder interferometer is constituted, so that the light beam transmitted in single mode optical fiber is divided into two
Divide and propagate, a part is transmitted in fibre core, and another part transmits in covering, because the effective refractive index of fibre core and covering is not
Together, so two parts light generates interference after transducing part, then interference cancellation trough is detected, by trough offsetWherein δ neffFor the difference Δ n of effective refractive indexeff kChanging value, by known to the formula when external physical quantity such as temperature,
Refractive index waits when changing, δ neffAlso change therewith, lead to that trough is interfered to move, so that transmitted spectrum also will appear
Offset.
As the phase difference Φ of core mode and the k rank cladding mode being excitedkWhen=(2n+1) π (n is integer), n-th order interference
Trough are as follows:
Wherein λ is lambda1-wavelength, and L is the length of thin-core fibers, Δ neff kFor effective folding of core mode and k rank cladding mode
It is poor to penetrate rate.
It is shown below using sensitivity composition coefficient matrix of the interference trough to temperature and response of refractive index, realizes double ginsengs
Number measurement
WhereinThe sensitivity of difference interference trough refractive index and temperature, Δ λm1、Δλm2
For the offset of different trough wavelength, above data can be calculated by testing, then can be same by matrix inverse transformation
When calculate the changing value Δ n of refractive index and the changing value Δ T of temperature.
As shown in figure 3, transmitted light spectrogram when being immersed in distilled water for optical fiber sensor head, sees that interference waveform is not advised at this time
Then, it is primarily due in optical fiber that not only prevailing cladding mode is interfered with core mode, weak cladding mode has also assisted in and fine
Core model generates interference, to reach experiment purpose, selects trough A (1581.74nm) and trough B (1594.53nm) as real here
Test measurement object.
Embodiment
As shown in figure 4, to penetrate the corresponding transmission spectrum spectrogram of sodium chloride solution when rate 1.3105-1.3465 variation.It is first
Refractometry is first carried out, sensing head is fixed on glass slide, is then placed in the sodium chloride solution at a temperature of keeping environment,
Then successively refractive index is that the sodium chloride solution of 1.3105-1.3465 measures, and is all rinsed with a large amount of water after having surveyed every time
And continue to test after automatic air-drying, it can be seen that interfere the wavelength of trough mobile to shortwave length direction with the increase of refractive index.
As shown in figure 5, for the offset and index of refraction relationship figure of trough A (1581.74nm) and trough B (1591.53nm),
To the data fitting result under the conditions of the different refractivity of solution to be measured with trough offset, the sensitivity difference of trough A and trough B
For -18.1764nm/RIU and -12.2197nm/RIU, in general scientific research range, this sensitivity can achieve to be wanted accordingly
It asks.
Further temperature is measured, the glass slide of fixed sensing head is put into 10% sodium chloride solution, this
Testing measurement range is 25 DEG C -50 DEG C, the response at interval of 5 DEG C of record primary transducers to temperature change.Fig. 4-7 is obtained at this time
The transmitted spectrum of shown different temperatures lower sensor, it can be seen that red shift occurs as temperature increases wavelength, had both interfered trough A
It is all mobile towards wavelength augment direction with trough B, as shown in Figure 6；It is similarly available such as Fig. 7 according to the relationship of offset and temperature
Fitted figure, can be respectively in the hope of the sensitivity of trough A and trough B, however as the raising of temperature, the folding of sodium chloride solution
The rate of penetrating gradually becomes smaller, therefore the temperature sensitivity measured is caused by temperature and sodium chloride refractive index while variation as a result, institute
It can be write as following expression with pure temperature sensitivity:
It is pure temperature sensitivity, RRI,For the thermo-optical coeffecient of sodium chloride solution, value is
-1.6065×10-4/ DEG C, by the temperature sensitivity and refractive index sensitivity band in the sodium chloride solution found out above
Enter, thus according to upper it can be concluded that the pure temperature sensitivity of trough A and trough B is
0.0733nm/ DEG C and 0.0330nm/ DEG C, available refractive index and temperature after then bringing two-dimensional matrix into and inverting
Changing value, by the offset Δ λ for bringing trough A Yu trough B intoA、ΔλB, to realize refraction
Rate and temperature simultaneously measuring, expression formula are as follows:
From experiment it is found that although transmission spectrum interference fringe valley wavelength changes at any time and at random, due to its with
Time change very little illustrates that this sensor stability is feasible.
In conclusion a kind of refractive index and temperature simultaneously measuring based on Mach-Zehnder interferometer of the utility model
Full-fiber sensor and its measurement method, when can eliminate refractometry there are potential Temperature cross-over sensitive question and
The accuracy that measurement refractive index and temperature can be improved, at low cost, easy to operate and measurement range simple with structure are big
Advantage.
Claims (5)
1. the full-fiber sensor of a kind of refractive index and temperature simultaneously measuring, it is characterised in that: including broadband spectral light source, optical fiber
Sensing head and spectroanalysis instrument；The optical fiber sensor head includes input-output optical fiber part, light beam coupling part and transducing part,
The input-output optical fiber part includes input single mode optical fiber and output single mode optical fiber, and the light beam coupling part includes multimode light
Fine and thin core-single mode optical fiber fusion point, that is, thick wimble structure；Transducing part includes thin-core fibers, is located among optical fiber sensor head, institute
It states input-output optical fiber part and is connected with transducing part by light beam coupling part, the first Coupling point is multimode fibre and single-mode optics
Fine tie point, since fiber core mismatch causes light wave to be propagated in the fibre core and covering in thin-core fibers, the second Coupling point is thin core-
The light wave that the fibre core in thin-core fibers and covering are propagated is coupled together again, interferes, go forward side by side by single mode optical fiber welding structure
Enter in the fibre core of single mode optical fiber and propagates；The input port of optical fiber sensor head is connect with broadband spectral light source by optical fiber, the light
The output port of fine sensing head is connect with spectroanalysis instrument by optical fiber, by the multimode fibre (MMF), thin in optical fiber sensor head
Core fibre (TCF) and thin-core fibers and single mode optical fiber fusion point constitute Mach-Zehnder interferometer, inside Mach-Zehnder interferometer
Light beam transmission when interfere, be then transferred into spectroanalysis instrument.
2. the full-fiber sensor of a kind of refractive index and temperature simultaneously measuring according to claim 1, it is characterised in that: also
Including computer, the computer and spectroanalysis instrument output end are communicated to connect；The computer is for receiving the defeated of spectrometer
Data and utilization two-dimensional matrix realization refractive index and temperature simultaneously measuring out.
3. the full-fiber sensor of a kind of refractive index and temperature simultaneously measuring according to claim 1, it is characterised in that: institute
Mach-Zehnder interferometer is stated to constitute using the thin-core fibers of removal coat.
4. the full-fiber sensor of a kind of refractive index and temperature simultaneously measuring according to claim 1, it is characterised in that: institute
The broadband spectral light source stated is the fiber broadband spectroscopic light source of L-band 1570nm-1605nm.
5. the full-fiber sensor of a kind of refractive index and temperature simultaneously measuring according to claim 1, it is characterised in that: should
All transmission fibers are general single mode fiber in full-fiber sensor.
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