CN111579534A - Optical fiber sensing detection device for detecting solution refractive index and refractive index detection method - Google Patents
Optical fiber sensing detection device for detecting solution refractive index and refractive index detection method Download PDFInfo
- Publication number
- CN111579534A CN111579534A CN202010478275.1A CN202010478275A CN111579534A CN 111579534 A CN111579534 A CN 111579534A CN 202010478275 A CN202010478275 A CN 202010478275A CN 111579534 A CN111579534 A CN 111579534A
- Authority
- CN
- China
- Prior art keywords
- optical fiber
- refractive index
- fiber
- solution
- thin
- 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.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/255—Details, e.g. use of specially adapted sources, lighting or optical systems
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/4133—Refractometers, e.g. differential
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/255—Splicing of light guides, e.g. by fusion or bonding
- G02B6/2551—Splicing of light guides, e.g. by fusion or bonding using thermal methods, e.g. fusion welding by arc discharge, laser beam, plasma torch
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
- G01N2021/458—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods using interferential sensor, e.g. sensor fibre, possibly on optical waveguide
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Plasma & Fusion (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Engineering & Computer Science (AREA)
- Optics & Photonics (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The invention discloses an optical fiber sensing detection device for detecting the refractive index of a solution, which comprises a broadband light source device, an optical fiber refractive index sensor and a spectrum analyzer, wherein the optical fiber refractive index sensor comprises a thin-core optical fiber, a coreless optical fiber and two single-mode optical fibers, the optical fiber refractive index sensor is sequentially welded to form a structure of the single-mode optical fiber-the thin-core optical fiber-the coreless optical fiber-the single-mode optical fiber, and two ends of the optical fiber refractive index sensor are respectively connected to the broadband light source device. The invention also discloses a detection method of the refractive index, which comprises the steps of immersing the thin-core optical fiber and the coreless optical fiber in the optical fiber refractive index sensor in the solution to obtain corresponding transmitted light spectrograms, selecting the central wavelength of the corresponding characteristic peak, and calculating the refractive index of the solution according to a formula. The optical fiber sensing detection device has the advantages of simple structure, low cost, high sensitivity to the refractive index detected by the solution and large detection range of the refractive index.
Description
Technical Field
The invention relates to the field of optical fiber sensing, in particular to an optical fiber sensing detection device and a refractive index detection method for detecting the refractive index of a solution.
Background
In recent years, optical fiber sensors have been widely used in the fields of physics, biology, chemistry, etc. because of their advantages of high flexibility, convenience in manufacture, electromagnetic interference resistance, high temperature resistance, and adaptability to harsh environments. Because of its unique advantages, fiber optic sensors have been widely used in the field of measurement of physical parameters. Such as refractive index, strain, temperature, humidity, curvature, etc. Among the above parameters, refractive index, strain and temperature are important parameters in many domestic applications. To date, a number of fiber optic sensing configurations have been proposed for measuring strain, temperature and refractive index. In 2008, a double-tapered single-mode fiber Mach-Zehnder interferometer was proposed by Tianmegan et al. It has the advantages of simple manufacture, low cost and the like. The refractive index of the measurement sensitivity is low. In the range of refractive index 1.315-1.3618, the refractive index sensitivity is only 17.1 nm/RIU; in 2012, Liuqi proposed that a tapered photonic crystal fiber Mach-Zehnder interferometer was fabricated by a chemical etching method, with a sensitivity of 199 nm/RIU. But the manufacturing process is complex and the mechanical strength is low; in 2013, shore sensitive et al designed a mach-zehnder interferometer based on a multimode optical fiber core sandwiched between two large-waist optical fiber cones for measuring refractive index sensing. But there is severe cross-temperature sensitivity; in 2018, Zhana et al propose a multi-parameter micro optical fiber refractive index sensor with the refractive index sensitivity of 131.93 nm/RIU. But the mechanical strength of the sensor is low and there is cross sensitivity with temperature. In the research, some sensors in the existing sensing technology are complex to manufacture, some sensors have low refractive index sensitivity, and some sensors have a small refractive index detection range, so that the application of the optical fiber sensor is limited.
Disclosure of Invention
Aiming at the defects of the prior art, the technical problems to be solved by the invention are as follows: how to provide a low cost, simple structure, refractive index sensitivity is high, the refractive index detection scope is great solution refractive index detection's optical fiber sensing detection device.
In order to solve the technical problems, the invention adopts the following technical scheme:
the utility model provides an optical fiber sensing detection device that solution refracting index detected, including broadband light source device, optic fibre refracting index sensor and spectral analysis appearance, optic fibre refracting index sensor includes thin core fiber, centreless fiber and two single mode fiber, the fibre core diameter of thin core fiber is less than single mode fiber's fibre core diameter, the one end of thin core fiber is in the same place with the one end butt fusion of centreless fiber, the one end butt fusion of one of them single mode fiber and thin core fiber and keep away from coreless fiber, the output of other end access broadband light source device, the one end of another single mode fiber and the one end butt fusion of coreless fiber and keeping away from thin core fiber, the input at the spectral analysis appearance is connected to the other end, thin core fiber is linear state with coreless fiber.
As an optimization, the optical fiber refractive index sensor is provided with an optical fiber fixing device at the positions of the thin core optical fiber and the coreless optical fiber, the optical fiber fixing device comprises a fixing base, the upper surface of the fixing base is separated and fixedly connected with two fixing rings which are arranged at the same central line, the central lines of the fixing rings are horizontally arranged, the optical fiber refractive index sensor penetrates through the two fixing rings, the welding positions of the thin core optical fiber, the coreless optical fiber, the thin core optical fiber and the coreless optical fiber and the single mode optical fiber are respectively positioned between the two fixing rings, the fixing base is respectively provided with an optical fiber support at the outer sides along the opposite directions of the two fixing rings, the top of the optical fiber support is relatively provided with two U-shaped supports positioned in the same horizontal direction, the planes of the U-shaped supports are arranged in parallel to each other, and the horizontal height of, the bottom fixedly connected with branch of U-shaped support just fixes on its place fiber support through branch, two single mode fiber wears respectively and places in on the interior bottom surface of U-shaped support inside two U-shaped supports on one side of its place and its fine body, single mode fiber and lie in with having hung on one's body between two U-shaped supports with the fine balancing weight that has connect in order to be right thin core fiber with coreless fiber straightens and provides the pulling force.
The invention also discloses a method for detecting the solution refractive index, which comprises the following steps:
(1) obtaining the optical fiber sensing detection device for detecting the solution refractive index, and configuring a plurality of solutions with different refractive indexes;
(2) placing an optical fiber refractive index sensor in a solution with one refractive index, wherein when the optical fiber refractive index sensor is placed in the solution, the thin-core optical fiber, the coreless optical fiber and the welding positions of the thin-core optical fiber and the coreless optical fiber in the optical fiber refractive index sensor and the single-mode optical fiber are all in the solution, the thin-core optical fiber and the coreless optical fiber are in a linear state, and recording a transmission spectrum on a spectrum analyzer after a broadband light source device is opened;
(3) repeating the step (2) to detect all solutions and record transmission spectrums of the solutions, selecting interference troughs in the same section of each transmission spectrum, and obtaining y ═ a + bx through linear fitting, namely x ═ y-a)/b, wherein y is a central wavelength corresponding to the selected troughs in the transmission spectrum, a is the central wavelength corresponding to the troughs when the refractive index approaches 0, b is the sensitivity of the refractive index, and x is the refractive index;
(4) obtaining a solution with unknown refractive index, placing an optical fiber refractive index sensor in the solution with unknown refractive index, wherein the thin-core optical fiber, the coreless optical fiber, the welding parts of the thin-core optical fiber and the coreless optical fiber in the optical fiber refractive index sensor and the single-mode optical fiber are respectively in the solution with unknown refractive index, the central lines of the thin-core optical fiber and the coreless optical fiber are positioned on the same straight line, recording a transmission spectrum on a spectrum analyzer after opening a broadband light source device, selecting a trough corresponding to the same section of the transmission spectrum in the step (2), obtaining a central wavelength value for the trough, and substituting the formula x ═ y-a)/b to obtain the refractive index of the solution.
As an optimization, the optical fiber fixing device and the two optical fiber supports are obtained, in the step (2) and the step (4), when obtaining a transmission spectrogram of a solution, the optical fiber refractive index sensor firstly penetrates through the two fixing rings, so that the welding parts of the thin core optical fiber, the coreless optical fiber, the thin core optical fiber and the coreless optical fiber with the single mode optical fiber are respectively located between the two fixing rings, then the fixing base is placed in the solution, then the two optical fiber supports are respectively and correspondingly erected at the two single mode optical fibers outside the solution, the fiber bodies of the single mode optical fibers are placed on the inner bottom surfaces of the two U-shaped supports at the corresponding sides, then the balancing weight is hung on the fiber bodies of the single mode optical fibers and located between the two U-shaped supports at the same side, and the thin core optical fiber and the coreless optical fiber are in a straightened state by utilizing the gravity of the balancing weight, and finally, recording the transmission spectrum on the spectrum analyzer after the broadband light source device is opened.
In conclusion, the beneficial effects of the invention are as follows: the optical fiber sensing detection device has the advantages of simple structure, low cost, high sensitivity to the refractive index detected by the solution and large detection range of the refractive index.
Drawings
For purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made in detail to the present invention as illustrated in the accompanying drawings, in which:
FIG. 1 is a schematic diagram of a fusion-splicing structure of an optical fiber refractive index sensor according to the present invention;
FIG. 2 is a graph showing the transmission spectrum of a solution in the mode of combining a thin core optical fiber having a length of 9.5cm and a coreless optical fiber having a length of 8.5cm in accordance with an embodiment of the present invention;
FIG. 3 is a graph showing the transmission spectrum of a solution in the mode of combining a thin core optical fiber having a length of 8.5cm and a coreless optical fiber having a length of 9.5cm in accordance with an embodiment of the present invention;
FIG. 4 is a graph showing the transmission spectrum of a solution in the mode of combining a thin core optical fiber having a length of 8.5cm and a coreless optical fiber having a length of 8.5cm in accordance with an embodiment of the present invention;
FIG. 5 is a graph of the transmission spectra of corresponding valleys in solutions having refractive indices 1.3331, 1.3377, 1.3424, and 1.3470 for a fiber optic refractive index sensor in an embodiment of the present invention;
FIG. 6 is a graph of the transmission spectra of corresponding valleys in solutions having refractive indices 1.3516, 1.3562, 1.3609, and 1.3655 for a fiber optic refractive index sensor in an embodiment of the present invention;
FIG. 7 is a graph of the transmission spectra of corresponding valleys in a fiber optic refractive index sensor in solutions having refractive indices of 1.3701, 1.3747, and 1.3794 in an embodiment of the present invention;
FIG. 8 is a transmitted light spectrum of the optical fiber refractive index sensor in the solution at the temperature of 15 deg.C, 25 deg.C, 35 deg.C and 45 deg.C according to the embodiment of the present invention;
FIG. 9 is a transmitted light spectrum of the optical fiber refractive index sensor in the solution at the temperature of 55 deg.C, 65 deg.C, 75 deg.C and 85 deg.C according to the embodiment of the present invention;
FIG. 10 is a graph of the transmission spectra of sodium chloride solution, alcohol, sucrose solution and glycerol at the same refractive index for an optical fiber refractive index sensor in an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The optical fiber sensing detection device that solution refractive index detected in this embodiment, including broadband light source device, optical fiber refractive index sensor and spectral analysis appearance, optical fiber refractive index sensor includes thin core fiber 2, centreless fiber 3 and two single mode fiber 1, the core diameter of thin core fiber 2 is less than single mode fiber 1's core diameter, thin core fiber 2's one end is in the same place with the one end butt fusion of centreless fiber 3, one end of one of them single mode fiber 1 and thin core fiber 2 and the one end butt fusion of keeping away from centreless fiber 3, the output of broadband light source device is inserted to the other end, the one end of another single mode fiber 1 and the one end butt fusion of just keeping away from thin core fiber 2 of centreless fiber 3, the input at the spectral analysis appearance is connected to the other end, thin core fiber 2 is linear state with centreless.
In this embodiment, the optical fiber refractive index sensor is provided with an optical fiber fixing device at the positions of the thin core optical fiber and the coreless optical fiber, the optical fiber fixing device comprises a fixing base, the upper surface of the fixing base is separated and fixedly connected with two fixing rings which are arranged on the same central line, the central line of the fixing rings is horizontally arranged, the optical fiber refractive index sensor passes through the two fixing rings, the thin core optical fiber, the coreless optical fiber, the thin core optical fiber and the coreless optical fiber are respectively positioned between the two fixing rings and the welding position of the single mode optical fiber, the fixing base is respectively provided with an optical fiber bracket at the outer side along the opposite direction of the two fixing rings, the top of the optical fiber bracket is relatively provided with two U-shaped brackets positioned on the same horizontal direction, the planes of the U-shaped brackets are arranged in parallel, and the horizontal height of the U-shaped brackets is, the bottom fixedly connected with branch of U-shaped support just fixes on its place fiber support through branch, two single mode fiber wears respectively and places in on the interior bottom surface of U-shaped support inside two U-shaped supports on one side of its place and its fine body, single mode fiber and lie in with having hung on one's body between two U-shaped supports with the fine balancing weight that has connect in order to be right thin core fiber with coreless fiber straightens and provides the pulling force.
The sensing head is composed of three parts, and is formed by welding a single mode fiber, a thin core fiber and a coreless fiber, and if only the core mode and one of the main cladding modes are considered, the sensing head can be expressed as follows
Wherein IcoreThe propagation intensity of light in the fiber core;
is the intensity of light propagating in the cladding. Phi is akFor phase difference of light propagation in core and cladding
Where L is the sensor response length, taking into account phik＝(2k+1)π，
From equation (2) one can deduce
Suppose that
With neffVarying by variation, peak wavelength nthThe attenuation tilt angle is expressed as
The free spectral range of the interference of the Mach-Zehnder of the FSR is shown in the following formula
The core effective index remains constant as the surrounding index changes. The effective refractive index of the cladding changes, and the phase difference changes, so that the wavelength of the characteristic peak shifts. Then by measuring the wavelength shift the change in ambient refraction can be determined.
For temperature measurement of the sensor, both the effective refractive index and the sensor response length L are independent variables of the temperature function due to thermal expansion response and thermal effects. The relationship between the temperature change and the wavelength is expressed as
Wherein
Is the thermo-optic coefficient, namely ξ;
is the coefficient of thermal expansion, i.e., α f, so equation (6) is simplified to
The transmission spectra of the sensing fiber structure in the combined mode of the thin-core fiber and the coreless fiber with different lengths are shown in fig. 1 to 3, and it can be seen from fig. 1 to 3 that the free spectral range decreases with the increase of the length of the interference arm, and the extinction ratio is inversely proportional to the length of the interference arm. This structure is identical to the theoretical formulae (3) and (5). Meanwhile, it can be presumed from equation (2) that the sensitivity of the sensor is mainly related to the effective length of the sensor and the elapsed condition of the transmission mode. In general, the longer the length of the sensor, the higher the number of stages of cladding modes in the evanescent wave, the higher the sensitivity of the sensor. In this embodiment, a fiber structure in which both the thin core fiber and the coreless fiber are 8.5cm in length is selected.
For the investigation of the liquid refractive index properties, room temperature was first set at 28 ℃ and the temperature was controlled to stabilize. The thin-core optical fiber and the coreless optical fiber are always kept in a linear placement state, and the bending loss is eliminated. By varying the refractive index value of the solution, the drift of the interference wavelength is recorded, as shown in fig. 4 to 6, in order to analyze its sensing characteristics. And selecting an interference trough with the wavelength of 1543nm to realize the measurement of the refractive index. The refractive index liquid is prepared by sodium chloride solutions with different concentrations, and the refractive index value of the solution is 1.3331-1.37935. After each sample measurement, the portion of the optical fiber refractive index sensor immersed in the solution was repeatedly washed with deionized water and then dried to a constant weight. Experimental results show that the wavelength of a characteristic peak with the wavelength of 1543nm can be in red shift with the increase of the external refractive index, and the refractive index sensitivity is obtained through linear fitting and is 101.94462nm/RIU respectively. The refractive index sensitivity of the selected characteristic peaks is different because the characteristic peaks are formed by the corresponding interference fringes formed by the core mode and the different cladding modes respectively, and the propagation coefficient and the excitation coefficient of each cladding mode are different, so that the characteristic peaks are different. It is known that the change of temperature can affect the measurement of the refractive index, and if the two change at the same time, the larger deviation of the experimental result can be caused, and the credibility of the test data is affected. The transmission spectrum of the experimental temperature for the sensing performance response is shown in fig. 7 and 8, when the temperature changes from 15 ℃ to 85 ℃, the maximum wavelength shift of 0.3nm is caused, and the characteristic peak temperature sensitivity of 1543nm wavelength is only-0.00348 nm/DEG C. Since the temperature sensitivity is closely related to the thermo-optic coefficient of the optical fiber itself, the greater the thermo-optic coefficient, the more sensitive the optical fiber is to temperature changes. The coreless optical fiber is an optical fiber formed by quartz, not only has low thermo-optic coefficient, but also can interact with a single-mode optical fiber to excite multi-order cladding modes, and the multi-order cladding modes form multi-mode interference due to different propagation coefficients, and the multi-order cladding modes can be continuously re-excited and recombined, so that the coreless optical fiber is insensitive to the external temperature response. I.e. a temperature change of 1 ℃ corresponds toThe maximum variation of the refractive index was 4.4186 × 10-5Within the tolerance range, the measurement influence of temperature on the refractive index can be ignored.
The response of the optical fiber refractive index sensor to different substances is researched, solutions with different solutes with the same refractive index are prepared and researched, the solutions with the refractive index of 1.3516 are prepared by respectively using alcohol, salt, cane sugar and glycerin, the obtained transmission spectrum is shown in figure 9, the characteristic wavelengths of the transmission spectrum of the sensor are consistent under the same refractive index, the energy of interference minimum values is different due to different solutes, because light is transmitted in an interference arm, evanescent waves can be generated on the surface of the interference arm to enter the external solution, the absorption effects of different solutes on the evanescent waves are different, and the interference minimum values of an emergent spectrum have energy difference.
In order to verify the stability of the sensor, the thin core optical fiber and the coreless optical fiber in the optical fiber refractive index sensor were immersed in a sodium chloride aqueous solution having a mass concentration of 15%, and immersed for 1 hour at room temperature, and the wavelength was recorded every 10 minutes. The standard deviations of the characteristic peaks at a wavelength of 1543nm calculated from the transmission spectrum over 1 hour were each 0.00766 nm. This deviation is mainly caused by the stability of the light source and the fiber refractive index sensor and temperature variations. By optimizing the optical fiber fusion parameters, the optical fiber sensor has better coupling points, and the stability of the sensor is improved.
A method for detecting the refractive index of a solution comprises the following steps:
(1) obtaining the optical fiber sensing detection device for detecting the solution refractive index, and configuring a plurality of solutions with different refractive indexes;
(2) placing an optical fiber refractive index sensor in a solution with one refractive index, wherein when the optical fiber refractive index sensor is placed in the solution, the thin-core optical fiber, the coreless optical fiber and the welding positions of the thin-core optical fiber and the coreless optical fiber in the optical fiber refractive index sensor and the single-mode optical fiber are all in the solution, the thin-core optical fiber and the coreless optical fiber are in a linear state, and recording a transmission spectrum on a spectrum analyzer after a broadband light source device is opened;
(3) repeating the step (2) to detect all solutions and record transmission spectrums of the solutions, selecting interference troughs in the same section of each transmission spectrum, and obtaining y ═ a + bx through linear fitting, namely x ═ y-a)/b, wherein y is a central wavelength corresponding to the selected troughs in the transmission spectrum, a is the central wavelength corresponding to the troughs when the refractive index approaches 0, b is the sensitivity of the refractive index, and x is the refractive index;
(4) obtaining a solution with unknown refractive index, placing an optical fiber refractive index sensor in the solution with unknown refractive index, wherein the thin-core optical fiber, the coreless optical fiber, the welding parts of the thin-core optical fiber and the coreless optical fiber in the optical fiber refractive index sensor and the single-mode optical fiber are respectively in the solution with unknown refractive index, the central lines of the thin-core optical fiber and the coreless optical fiber are positioned on the same straight line, recording a transmission spectrum on a spectrum analyzer after opening a broadband light source device, selecting a trough corresponding to the same section of the transmission spectrum in the step (2), obtaining a central wavelength value for the trough, and substituting the formula x ═ y-a)/b to obtain the refractive index of the solution.
In this embodiment, in the step (2) and the step (4), when obtaining the transmission spectrogram of the solution, the optical fiber refractive index sensor is first passed through the two fixing rings, so that the welding points of the thin-core optical fiber, the coreless optical fiber, and the thin-core optical fiber and the coreless optical fiber with the single-mode optical fiber are located between the two fixing rings, then the fixing base is placed in the solution, then the two optical fiber supports are correspondingly erected at the two single-mode optical fibers outside the solution, the fiber bodies of the single-mode optical fibers are placed on the inner bottom surfaces of the two U-shaped supports on the corresponding sides, and then the weight block is hung on the fiber body of the single-mode optical fiber and located between the two U-shaped supports on the same side, and utilizing the gravity of a balancing weight to enable the thin-core optical fiber and the coreless optical fiber to be in a straightening state, and finally, opening the broadband light source device and recording the transmission spectrum on the spectrum analyzer.
Measuring sodium chloride solutions with different concentrations (refractive index values from 1.3331 to 1.37935) to obtain corresponding transmission spectra, selecting a wave trough between 1551nm and 1557nm in a spectrogram, and passing the wave troughUsing origin software to perform linear fitting to obtain y ═ a + bx, and fitting coefficient R20.98447, the sensitivity of the refractive index is 101.94462nm/RIU, i.e., (y-1415.3405)/101.94462.
And measuring a sodium chloride solution with unknown refractive index to obtain a transmission spectrum, selecting the central wavelength of the corresponding characteristic peak as 1552.19nm, and calculating according to a formula to obtain the refractive index of the solution as 1.3424.
Measuring a sucrose solution with unknown refractive index to obtain a transmission spectrum, selecting the central wavelength of the corresponding characteristic peak to be 1554.55nm, and calculating according to a formula to obtain the refractive index of the solution to be 1.3655.
And measuring a glycerol solution with unknown refractive index to obtain a transmission spectrum, selecting the central wavelength of the corresponding characteristic peak as 1555.48nm, and calculating according to a formula to obtain the solution with the refractive index of 1.3747.
Finally, it is noted that the above-mentioned embodiments illustrate rather than limit the invention, and that, while the invention has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (4)
1. An optical fiber sensing detection device for detecting solution refractive index is characterized in that: including broadband light source device, optic fibre refractive index sensor and spectral analysis appearance, optic fibre refractive index sensor includes thin core fiber, centreless fiber and two single mode fiber, the fibre core diameter of thin core fiber is less than single mode fiber's fibre core diameter, the one end of thin core fiber is in the same place with the one end butt fusion of centreless fiber, the one end of one of them single mode fiber and thin core fiber just keep away from the one end butt fusion of centreless fiber, the output of broadband light source device is inserted to the other end, the one end of another single mode fiber and the one end butt fusion of the thin core fiber just keep away from with centreless fiber, the input at the spectral analysis appearance is connected to the other end, thin core fiber is.
2. The optical fiber sensing detection device for detecting the refractive index of a solution according to claim 1, wherein: the optical fiber refractive index sensor is provided with an optical fiber fixing device at the positions of the thin core optical fiber and the coreless optical fiber, the optical fiber fixing device comprises a fixing base, the upper surface of the fixing base is separated and fixedly connected with two fixing rings which are arranged at the same central line, the central lines of the fixing rings are horizontally arranged, the optical fiber refractive index sensor penetrates through the two fixing rings, the thin core optical fiber, the coreless optical fiber, the thin core optical fiber and the coreless optical fiber are respectively positioned between the two fixing rings and the fusion splicing part of the single mode optical fiber, the fixing base is respectively provided with an optical fiber support at the outer sides along the opposite directions of the two fixing rings, the top of the optical fiber support is oppositely provided with two U-shaped supports positioned in the same horizontal direction, the planes of the U-shaped supports are arranged in parallel, and the horizontal height of the U-, the bottom fixedly connected with branch of U-shaped support just fixes on its place fiber support through branch, two single mode fiber wears respectively and places in on the interior bottom surface of U-shaped support inside two U-shaped supports on one side of its place and its fine body, single mode fiber and lie in with having hung on one's body between two U-shaped supports with the fine balancing weight that has connect in order to be right thin core fiber with coreless fiber straightens and provides the pulling force.
3. A method for detecting the refractive index of a solution is characterized in that: the method comprises the following steps:
(1) obtaining an optical fiber sensing detection device for detecting the refractive index of the solution in claim 1, and configuring a plurality of solutions with different refractive indexes;
(2) placing an optical fiber refractive index sensor in a solution with one refractive index, wherein when the optical fiber refractive index sensor is placed in the solution, the thin-core optical fiber, the coreless optical fiber and the welding positions of the thin-core optical fiber and the coreless optical fiber in the optical fiber refractive index sensor and the single-mode optical fiber are all in the solution, the thin-core optical fiber and the coreless optical fiber are in a linear state, and recording a transmission spectrum on a spectrum analyzer after a broadband light source device is opened;
(3) repeating the step (2) to detect all the solutions and record the transmission spectrums, selecting interference troughs in the same section in each transmission spectrum, and obtaining y = a + bx through linear fitting, namely x = (y-a)/b, wherein y is the central wavelength corresponding to the selected troughs in the transmission spectrum, a is the central wavelength corresponding to the troughs when the refractive index approaches 0, b is the sensitivity of the refractive index, and x is the refractive index;
(4) obtaining a solution with unknown refractive index, placing an optical fiber refractive index sensor in the solution with unknown refractive index, wherein the thin-core optical fiber, the coreless optical fiber, the welding positions of the thin-core optical fiber and the coreless optical fiber in the optical fiber refractive index sensor and the single-mode optical fiber are respectively in the solution with unknown refractive index, the central lines of the thin-core optical fiber and the coreless optical fiber are positioned on the same straight line, recording a transmission spectrum on a spectrum analyzer after opening a broadband light source device, selecting a trough corresponding to the same section of the transmission spectrum in the step (2), obtaining a central wavelength value for the trough, and substituting the central wavelength value into a formula x = (y-a)/b to obtain the refractive index of the solution.
4. The method for detecting the refractive index of a solution according to claim 3, wherein: the optical fiber fixing device and the two optical fiber supports of claim 2 are obtained, in the step (2) and the step (4), when obtaining the transmission spectrum of the solution, the optical fiber refractive index sensor is first passed through the two fixing rings, so that the welding points of the thin core optical fiber, the coreless optical fiber, and the thin core optical fiber and the coreless optical fiber with the single mode optical fiber are located between the two fixing rings, then the fixing base is placed in the solution, then the two optical fiber supports are correspondingly erected at the two single mode optical fibers outside the solution, respectively, the bodies of the single mode optical fibers are placed on the inner bottom surfaces of the two U-shaped supports at the corresponding sides, then the weight block is hung on the body of the single mode optical fiber between the two U-shaped supports at the same side, and the thin core optical fiber and the coreless optical fiber are in the straightened state by using the gravity of the weight block, and finally, recording the transmission spectrum on the spectrum analyzer after the broadband light source device is opened.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010478275.1A CN111579534B (en) | 2020-05-29 | 2020-05-29 | Optical fiber sensing detection device for detecting refractive index of solution and refractive index detection method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010478275.1A CN111579534B (en) | 2020-05-29 | 2020-05-29 | Optical fiber sensing detection device for detecting refractive index of solution and refractive index detection method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111579534A true CN111579534A (en) | 2020-08-25 |
| CN111579534B CN111579534B (en) | 2023-06-27 |
Family
ID=72114333
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010478275.1A Active CN111579534B (en) | 2020-05-29 | 2020-05-29 | Optical fiber sensing detection device for detecting refractive index of solution and refractive index detection method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111579534B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113945542A (en) * | 2021-09-10 | 2022-01-18 | 汕头大学 | Optical fiber sensor, detection device based on optical fiber sensor and application of detection device |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103969221A (en) * | 2013-01-25 | 2014-08-06 | 中国计量学院 | Optical fiber refractive index sensor based on single mode-fine core-multimode-single mode structure |
| CN203894161U (en) * | 2014-04-18 | 2014-10-22 | 深圳大学 | All-fiber refractometer based on michelson interferometer and system |
| CN104713660A (en) * | 2015-03-13 | 2015-06-17 | 天津大学 | Optical fiber sensor, manufacturing method and simultaneous measuring method for liquid temperature and refractive index |
| US20150168216A1 (en) * | 2013-12-17 | 2015-06-18 | Macau University Of Science And Technology | Optical Fiber-Based Environmental Detection System and the Method Thereof |
| CN105259117A (en) * | 2015-08-14 | 2016-01-20 | 江苏双仪光学器材有限公司 | Mode interference-based fine core cascaded optical fiber biosensor |
| CN108760683A (en) * | 2018-05-02 | 2018-11-06 | 南昌大学 | A method of being more than core mode wavelength region internal resonance using wavelength and measures solution refractive index |
| CN110530822A (en) * | 2019-08-30 | 2019-12-03 | 河南师范大学 | A method of hollow-core fiber structure measurement refractive index is cascaded using taper coreless fiber |
-
2020
- 2020-05-29 CN CN202010478275.1A patent/CN111579534B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103969221A (en) * | 2013-01-25 | 2014-08-06 | 中国计量学院 | Optical fiber refractive index sensor based on single mode-fine core-multimode-single mode structure |
| US20150168216A1 (en) * | 2013-12-17 | 2015-06-18 | Macau University Of Science And Technology | Optical Fiber-Based Environmental Detection System and the Method Thereof |
| CN203894161U (en) * | 2014-04-18 | 2014-10-22 | 深圳大学 | All-fiber refractometer based on michelson interferometer and system |
| CN104713660A (en) * | 2015-03-13 | 2015-06-17 | 天津大学 | Optical fiber sensor, manufacturing method and simultaneous measuring method for liquid temperature and refractive index |
| CN105259117A (en) * | 2015-08-14 | 2016-01-20 | 江苏双仪光学器材有限公司 | Mode interference-based fine core cascaded optical fiber biosensor |
| CN108760683A (en) * | 2018-05-02 | 2018-11-06 | 南昌大学 | A method of being more than core mode wavelength region internal resonance using wavelength and measures solution refractive index |
| CN110530822A (en) * | 2019-08-30 | 2019-12-03 | 河南师范大学 | A method of hollow-core fiber structure measurement refractive index is cascaded using taper coreless fiber |
Non-Patent Citations (1)
| Title |
|---|
| 徐伟: "基于无芯光纤的多模干涉型光纤传感技术研究", 《中国博士学位论文全文数据库基础科学辑》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113945542A (en) * | 2021-09-10 | 2022-01-18 | 汕头大学 | Optical fiber sensor, detection device based on optical fiber sensor and application of detection device |
| CN113945542B (en) * | 2021-09-10 | 2023-11-14 | 汕头大学 | Optical fiber sensor, detection device based on optical fiber sensor and application of detection device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111579534B (en) | 2023-06-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Novais et al. | Optical fiber tip sensor for the measurement of glucose aqueous solutions | |
| Zibaii et al. | Non-adiabatic tapered optical fiber sensor for measuring the interaction between α-amino acids in aqueous carbohydrate solution | |
| Zhang et al. | Refractive index sensor based on tapered multicore fiber | |
| Wang et al. | Fabry–Pérot fiber sensor for simultaneous measurement of refractive index and temperature based on an in-fiber ellipsoidal cavity | |
| CN110530822A (en) | A method of hollow-core fiber structure measurement refractive index is cascaded using taper coreless fiber | |
| Hu et al. | A narrow groove structure based plasmonic refractive index sensor | |
| Teng et al. | High-sensitivity refractive index sensor based on a cascaded core-offset and macrobending single-mode fiber interferometer | |
| Li et al. | Sagnac ring humidity sensor with a melting cone based on graphene properties | |
| Khanikar et al. | Reflectance-based no core fiber sensor with enhanced Sensitivity for salinity detection | |
| Xu et al. | High-sensitivity two-axis vector bending sensor based on side-grooved long period grating in eccentric core fiber | |
| Jin et al. | A strain sensor with low temperature crosstalk based on re-modulation of D-shaped LPFG | |
| CN111579534B (en) | Optical fiber sensing detection device for detecting refractive index of solution and refractive index detection method | |
| Zhao et al. | Refractive index sensor based on a gradually hot-pressed flatted plastic optical fiber | |
| Belal Sara et al. | Laser biosensor as for pregnancy test by using photonic crystal fiber | |
| Li et al. | High sensitivity sensor based on mode interference of fiber arc-shaped misaligned welding structure for strain and torsion sensing | |
| CN102168970B (en) | One-dimensional inclination angle sensor based on PCF-LPG (Long-Period Grating written in Photonic Crystal Fiber) and device | |
| CN202126259U (en) | Two-dimensional inclination angle sensor based on PCF (Photonic Crystal Fiber)-LPG (liquid propane gas) | |
| Lu et al. | Liquid level sensor based on PM-MD fiber structure loop mirror | |
| CN110006846B (en) | Trace liquid refractive index measuring device of V-shaped special optical fiber and preparation method | |
| Wang | Fiber loop ringdown sensors and sensing | |
| Alameri et al. | Design in line lma-10 photonic crystal fiber mzi for detection and investigation of beta thalassemia | |
| Mohd Arif et al. | Bend loss fiber optics design based on sinusoidal and ellipse configurations | |
| Yang et al. | Optical fiber current sensing based on a macro-bending no-core fiber structure and magnetic fluid | |
| Tai et al. | Sensitive handheld refractometer by using combination of a tapered fiber tip and a multimode fiber | |
| Sulaiman et al. | An experimental analysis on the performance of single mode-multimode-single mode and multimode-single mode-multimode fiber optic sensor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |