CN113945542A - Optical fiber sensor, detection device based on optical fiber sensor and application of detection device - Google Patents
Optical fiber sensor, detection device based on optical fiber sensor and application of detection device Download PDFInfo
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Abstract
The invention discloses an optical fiber sensor, a detection device based on the optical fiber sensor and application thereof, wherein the optical fiber sensor comprises: the single-mode optical fiber patch cord, the C-shaped optical fiber section and the single-mode optical fiber section; the diameter of the inner cavity of the C-shaped optical fiber section is 10-80 μm, the outer diameter of the C-shaped optical fiber section is 122-127 μm, and the opening angle alpha of the inner cavity of the C-shaped optical fiber section is 30-120 degrees; the outer diameter of the C-shaped optical fiber section is the same as that of the single-mode optical fiber section; and two ends of the C-shaped optical fiber are respectively welded with the single-mode optical fiber to form a first light reflecting surface and a second light reflecting surface, and the tail end surface of the single-mode optical fiber section forms a third light reflecting surface. The first light reflecting surface and the second light reflecting surface form an inflatable Fabry-Perot resonant cavity; the second light reflecting surface and the third light reflecting surface form a quartz Fabry-Perot resonant cavity. The utility model also provides a detection device and application based on optical fiber sensor simultaneously. The invention is mainly used in the technical field of optical fiber sensing.
Description
Technical Field
The invention relates to the technical field of optical fiber sensors, in particular to an optical fiber sensor, a detection device based on the optical fiber sensor and application of the detection device.
Background
Optical fiber-based refractive index sensing of gases and liquids has received much attention because of its advantages of electromagnetic interference resistance, small size, light weight, corrosion resistance, etc. Representative sensors include fabry-perot interferometer type sensors, mach-zehnder interferometer type sensors, michelson interferometer type sensors, fiber grating sensors, and the like. Fiber sensing detects various parameters such as temperature, strain, humidity, gases by monitoring changes in optical power, phase and polarization state in the fiber. However, the sensitivity of these sensors is generally low, such as the air pressure sensor based on the hollow-core photonic band gap fiber side-open channel fabry-perot interferometer proposed by Jian Tan et al, the air pressure sensitivity is only 1462 nm/RIU. Fangda Yu et al propose an offset in-line Mach-Zehnder fiber optic temperature sensor with a temperature sensitivity of only 20 nm/RIU. Furthermore, Ruohui Wang et al propose an open cavity Fabry-Perot gas refractive index sensor with a sensitivity of only 1042 nm/RIU. Therefore, the exploration of a new optical fiber sensing sensitization mechanism has important significance.
Disclosure of Invention
The present invention is directed to an optical fiber sensor, a detection device based on the optical fiber sensor, and an application thereof, which are used to solve one or more of the problems of the prior art and provide at least one of the advantages of the present invention.
The solution of the invention for solving the technical problem is as follows: in a first aspect, there is provided a fiber sensor comprising: the single-mode optical fiber patch cord, the C-shaped optical fiber section and the single-mode optical fiber section; the diameter of the inner cavity of the C-shaped optical fiber section is 10-80 μm, the outer diameter of the C-shaped optical fiber section is 122-127 μm, and the opening angle alpha of the inner cavity of the C-shaped optical fiber section is 30-120 degrees; the outer diameter of the C-shaped optical fiber section is the same as that of the single-mode optical fiber section; the head end face of the C-shaped optical fiber section is welded with one end face of the single-mode optical fiber jumper; the tail end face of the C-shaped optical fiber section is welded with the head end face of the single-mode optical fiber section;
the fiber core surface of one end surface of the single-mode optical fiber jumper forms a first light reflecting surface, the fiber core surface of the head end surface of the single-mode optical fiber section forms a second light reflecting surface, and the fiber core surface of the tail end surface of the single-mode optical fiber section forms a third light reflecting surface;
the first light reflecting surface and the second light reflecting surface form an inflatable Fabry-Perot resonant cavity; the second light reflecting surface and the third light reflecting surface form a quartz Fabry-Perot resonant cavity; the cavity length of the C-shaped optical fiber section is between 150 and 250 micrometers, and the cavity length of the single-mode optical fiber section is between 150 and 250 micrometers; the optical path difference of the two cavities is between 0 and 30 mu m.
Further, the butt end face of C type optic fibre section and the butt end face butt fusion of single mode fiber section, wherein, the butt fusion technology includes: and fusion is carried out by an optical fiber fusion splicer at 297bit discharge power, and the discharge time is 300ms to 500 ms.
In a second aspect, there is provided a detection device based on an optical fiber sensor, comprising: the device comprises a laser light source, an optical fiber circulator, a spectrometer and an optical fiber sensor;
the optical fiber sensor includes: the single-mode optical fiber patch cord, the C-shaped optical fiber section and the single-mode optical fiber section; the diameter of the inner cavity of the C-shaped optical fiber section is 10-80 μm, the outer diameter of the C-shaped optical fiber section is 122-127 μm, and the opening angle alpha of the inner cavity of the C-shaped optical fiber section is 30-120 degrees; the outer diameter of the C-shaped optical fiber section is the same as that of the single-mode optical fiber section; the head end face of the C-shaped optical fiber section is welded with one end face of the single-mode optical fiber jumper; the tail end face of the C-shaped optical fiber section is welded with the head end face of the single-mode optical fiber section;
the fiber core surface of one end surface of the single-mode optical fiber jumper forms a first light reflecting surface, the fiber core surface of the head end surface of the single-mode optical fiber section forms a second light reflecting surface, and the fiber core surface of the tail end surface of the single-mode optical fiber section forms a third light reflecting surface;
the first light reflecting surface and the second light reflecting surface form an inflatable Fabry-Perot resonant cavity; the second light reflecting surface and the third light reflecting surface form a quartz Fabry-Perot resonant cavity; the cavity length of the C-shaped optical fiber section is between 150 and 250 micrometers, and the cavity length of the single-mode optical fiber section is between 150 and 250 micrometers; the optical path difference of the two cavities is between 0 and 30 mu m;
the second port of the optical fiber circulator is connected with the other end of the single-mode optical fiber jumper; the first port of the optical fiber circulator is connected with the output end of the laser light source; and the third port of the optical fiber circulator is connected with the input end of the spectrometer.
Further, the butt end face of C type optic fibre section and the butt end face butt fusion of single mode fiber section, wherein, the butt fusion technology includes: and fusion is carried out by an optical fiber fusion splicer at 297bit discharge power, and the discharge time is 300ms to 500 ms.
Further, the laser source emits laser with continuous wavelength, and the wavelength range of the continuous wavelength emitted by the laser source is 480nm to 2200 nm.
In a third aspect, an application of the detection device based on the optical fiber sensor is provided, and the detection device based on the optical fiber sensor in the above technical solution is applied to detection of a refractive index of liquid, detection of air pressure, and detection of a refractive index of air.
The invention has the beneficial effects that: on the first hand, the optical fiber sensor uses a series double-resonant cavity structure, simplifies a Fabry-Perot interferometer type sensor structure based on a vernier effect on the basis of improving the sensitivity, simplifies the preparation process and reduces the production cost. The large-opening open cavity formed by the structure of the C-shaped optical fiber section can enable some transparent liquid and even liquid with larger viscosity to rapidly circulate so as to realize rapid and real-time sensing. The function that the small fluid channel cavity opening structure can not realize is realized. In the second aspect and the third aspect, the detection device based on the optical fiber sensor is provided, and the detection sensitivity of the liquid refractive index and the detection sensitivity of the air pressure and the refractive index are improved.
Drawings
In order to more clearly illustrate the technical solution in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below. It is clear that the described figures are only some embodiments of the invention, not all embodiments, and that a person skilled in the art can also derive other designs and figures from them without inventive effort.
FIG. 1 is a schematic structural diagram of an optical fiber sensor;
FIG. 2 is a schematic cross-sectional view of a C-shaped fiber segment;
FIG. 3 is a schematic structural diagram of a detection device based on an optical fiber sensor applied to NaCl solution detection;
FIG. 4 is a schematic structural diagram of a detection device based on an optical fiber sensor applied to an air pressure detection device;
FIG. 5 is a spectrum drift curve obtained by measuring the concentration of NaCl solution;
fig. 6 is a graph of spectral shift obtained from air pressure detection.
Detailed Description
The conception, the specific structure, and the technical effects produced by the present invention will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings to fully understand the objects, the features, and the effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention. In addition, all the coupling/connection relationships mentioned herein do not mean that the components are directly connected, but mean that a better coupling structure can be formed by adding or reducing coupling accessories according to specific implementation conditions. All technical characteristics in the invention can be interactively combined on the premise of not conflicting with each other.
Embodiment 1, referring to fig. 1 and 2, an optical fiber sensor includes: the single-mode optical fiber jumper 200, the C-shaped optical fiber section 100 and the single-mode optical fiber section 300; the diameter of the inner cavity 110 of the C-shaped optical fiber section 100 is 10-80 μm, the outer diameter of the C-shaped optical fiber section 100 is 122-127 μm, and the opening angle alpha of the inner cavity 110 of the C-shaped optical fiber section 100 is 30-120 degrees; the outer diameter of the C-shaped optical fiber section 100 is the same as that of the single-mode optical fiber section 300; the head end surface of the C-shaped optical fiber section 100 is welded with one end surface of the single-mode optical fiber jumper 200; the tail end face of the C-shaped optical fiber section 100 is welded with the head end face of the single-mode optical fiber section 300;
a first light reflecting surface 101 is formed on the fiber core surface of one end surface of the single-mode optical fiber jumper 200, a second light reflecting surface 102 is formed on the fiber core surface of the head end surface of the single-mode optical fiber section 300, and a third light reflecting surface 103 is formed on the fiber core surface of the tail end surface of the single-mode optical fiber section 300;
the first light reflecting surface 101 and the second light reflecting surface 102 form a gas-filled Fabry-Perot resonant cavity; the second light reflecting surface 102 and the third light reflecting surface 103 form a quartz Fabry-Perot resonant cavity; the cavity length of the C-shaped optical fiber section is between 150 and 250 micrometers, and the cavity length of the single-mode optical fiber section is between 150 and 250 micrometers; the optical path difference of the two cavities is between 0 and 30 mu m. Wherein the optical path is the product of the geometric path of light propagating in the medium and the refractive index of light in the medium.
In some preferred embodiments, the trailing end face of the C-shaped optical fiber segment 100 is fusion spliced with the leading end face of the single-mode optical fiber segment 300, wherein the fusion splicing process comprises: firstly, the C-shaped optical fiber section 100 and the single-mode optical fiber section 300 are welded by an optical fiber welding machine, and the C-shaped optical fiber section and the single-mode optical fiber section are welded for 300ms to 500ms by the optical fiber welding machine with 297bit discharge power. To ensure adequate welding. The welding power and the discharge time are required to be well controlled, and if the welding time is too long or the power is too high, an ideal effect cannot be achieved. After the fusion splicing is completed, the spliced C-shaped optical fiber section 100 and the single-mode optical fiber section 300 are then cut to a desired length by using an optical fiber cutter.
In actual practice, the fusion splicer is of type (fujikura, FSM-100M), the single-mode fiber section 300 is of type (G652D), and the fiber cleaver is of type (submitomo ELECTRIC equipment, LTD, FC-6S).
The working principle of the optical fiber sensor is as follows:
wherein, the length of the cavity of the gas-filled Fabry-Perot resonant cavity is set to be L1The length of the quartz Fabry-Perot resonant cavity is L2The refractive index of the object to be measured in the cavity of the C-shaped optical fiber section 100 is n1The core refractive index of the single mode fiber segment 300 is n2Since the C-shaped optical fiber segment 100 has an open inner cavity 110, the refractive index of the C-shaped optical fiber segment 100 is based on the effective refractive index of the measurement object。
The sensing principle of the optical fiber sensor probe is a high-sensitivity Fabry-Perot interferometer working principle based on a vernier effect.
The method specifically comprises the following steps: calculating the whole reflection electric field:
wherein:
φ1＝2πn1L1/λ，
φ2＝2πn2L2/λ，
Einis the electric field, k, of the input fiber sensing probe1Transmission loss, k, of a gas-filled Fabry-Perot resonator2Is the transmission loss, R, of a quartz Fabry-Perot resonator1Is the reflection coefficient, R, of the first light-reflecting surface 1012Is the reflection coefficient, R, of the second light-reflecting surface 1023Is the reflection coefficient of the third light reflecting surface 103. Phi is a1Is the phase, phi, transmitted in a gas-filled Fabry-Perot resonator2Is the phase of light transmitted in the quartz fabry-perot resonator. n1 is the refractive index of the object to be measured in the cavity of the C-shaped optical fiber section 100, n2Is the refractive index, L, of the core of the single mode fiber segment 3001Is the cavity length, L, of the gas-filled Fabry-Perot resonant cavity2Is the cavity length of the quartz fabry-perot resonator, and λ is the wavelength of the input light.
Since the C-shaped fiber segment 100 is a structure with an open inner cavity 110, the effective refractive index of the C-shaped fiber segment 100 is based on the refractive index of the measurement object.
The function of the reflection spectrum received from spectrometer 430 can be derived from equation (1):
the refractive index n can be found by the formula (2)1Will result in a phase phi1Changes occur, resulting in a shift of the spectrum. In order to produce the vernier effect, the optical path lengths of the gas-filled Fabry-Perot resonator and the quartz Fabry-Perot resonator are very close to each other, but not equal to each other.
The experimental spectrum is the superposition of the spectra of two independent Fabry-Perot cavities, namely an inflatable Fabry-Perot resonant cavity and a quartz Fabry-Perot resonant cavity. Because the difference between the FSRs (distances between two wave troughs of interference fringes) of the respective spectrums of the gas-filled Fabry-Perot resonant cavity and the quartz Fabry-Perot resonant cavity is very small, a large envelope appears in the superposed spectrums, and the large envelope is the vernier effect. The so-called envelope is obtained by connecting the valleys of the high frequency fringes.
On the other hand, referring to fig. 3, fig. 3 is a schematic structural diagram of the detection device based on the optical fiber sensor when applied to the detection of NaCl solution.
This embodiment also provides a detection device based on optical fiber sensor, including: the system comprises a laser light source 420, a fiber circulator 410, a spectrometer 430 and a fiber sensor, wherein the fiber sensor is called as a liquid refractive index detection fiber sensor probe 501 for distinguishing different detected media;
the liquid refractive index optical fiber sensor probe 501 includes: the single-mode optical fiber jumper 200, the C-shaped optical fiber section 100 and the single-mode optical fiber section 300; the diameter of the inner cavity 110 of the C-shaped optical fiber section 100 is 10-80 μm, the outer diameter of the C-shaped optical fiber section 100 is 122-127 μm, and the opening angle alpha of the inner cavity 110 of the C-shaped optical fiber section 100 is 30-120 degrees; the outer diameter of the C-shaped optical fiber section 100 is the same as that of the single-mode optical fiber section 300; the head end surface of the C-shaped optical fiber section 100 is welded with one end surface of the single-mode optical fiber jumper 200; the tail end face of the C-shaped optical fiber section 100 is welded with the head end face of the single-mode optical fiber section 300;
a first light reflecting surface 101 is formed on the fiber core surface of one end surface of the single-mode optical fiber jumper 200, a second light reflecting surface 102 is formed on the fiber core surface of the head end surface of the single-mode optical fiber section 300, and a third light reflecting surface 103 is formed on the fiber core surface of the tail end surface of the single-mode optical fiber section 300;
the first light reflecting surface 101 and the second light reflecting surface 102 form a gas-filled Fabry-Perot resonant cavity; the second light reflecting surface 102 and the third light reflecting surface 103 form a quartz Fabry-Perot resonant cavity; the cavity length of the C-shaped optical fiber section is between 150 and 250 micrometers, and the cavity length of the single-mode optical fiber section is between 150 and 250 micrometers; the optical path difference of the two cavities is between 0 and 30 mu m.
The second port of the optical fiber circulator 410 is connected with the other end of the single-mode optical fiber jumper 200; the first port of the fiber circulator 410 is connected with the output end of the laser source 420; the third port of the fiber optic circulator 410 is connected to the input of the spectrometer 430.
The laser source 420 emits laser with continuous wavelength, and the wavelength range of the continuous wavelength emitted by the laser source 420 is 480nm to 2200 nm.
In some preferred embodiments, the trailing end face of the C-shaped optical fiber segment 100 is fusion spliced with the leading end face of the single-mode optical fiber segment 300, wherein the fusion splicing process comprises: the C-shaped optical fiber section 100 and the single-mode optical fiber section 300 are firstly welded by an optical fiber welding machine, the C-shaped optical fiber section and the single-mode optical fiber section are welded by the optical fiber welding machine at 297bit discharge power, and the welding time is 300ms to 500 ms. To ensure adequate welding. The welding power and the discharge time are required to be well controlled, and if the welding time is too long or the power is too high, an ideal effect cannot be achieved. After the fusion splicing is completed, the spliced C-shaped optical fiber section 100 and the single-mode optical fiber section 300 are then cut to a desired length by using an optical fiber cutter.
In actual practice, the fusion splicer is of type (fujikura, FSM-100M), the single-mode fiber section 300 is of type (G652D), and the fiber cleaver is of type (submitomo ELECTRIC equipment, LTD, FC-6S).
When the detection device based on the optical fiber sensor is applied to NaCl solution detection, the liquid refractive index optical fiber sensor probe 501 is firstly placed into a NaCl solution container 440, and a NaCl solution with a certain concentration is placed into the NaCl solution container 440.
The NaCl solution concentration (mass fraction) was then increased from 0% to 0.1%, with a gradient of 0.01%, the spectral shift was recorded with spectrometer 430, and a linear fit was made to the spectral shift to obtain a spectral shift curve, as shown in fig. 5. From FIG. 5, it can be seen that the sensitivity of the liquid concentration experiment reached 44000 nm/RIU. The abscissa of the spectrum drift curve is the wavelength, and the ordinate is the light intensity.
On the other hand, referring to fig. 4, fig. 4 is a schematic structural diagram of the detection device based on the optical fiber sensor applied to the air pressure detection device.
This embodiment also provides a detection device based on optical fiber sensor, including: the system comprises a laser light source 420, a fiber circulator 410, a spectrometer 430 and a fiber sensor, wherein the fiber sensor is called an air pressure fiber sensor probe 502 for distinguishing different detected media conveniently;
the air pressure fiber optic sensor probe 502 includes: the single-mode optical fiber jumper 200, the C-shaped optical fiber section 100 and the single-mode optical fiber section 300; the diameter of the inner cavity 110 of the C-shaped optical fiber section 100 is 10-80 μm, the outer diameter of the C-shaped optical fiber section 100 is 122-127 μm, and the opening angle alpha of the inner cavity 110 of the C-shaped optical fiber section 100 is 30-120 degrees; the outer diameter of the C-shaped optical fiber section 100 is the same as that of the single-mode optical fiber section 300; the head end surface of the C-shaped optical fiber section 100 is welded with one end surface of the single-mode optical fiber jumper 200; the tail end face of the C-shaped optical fiber section 100 is welded with the head end face of the single-mode optical fiber section 300;
a first light reflecting surface 101 is formed on the fiber core surface of one end surface of the single-mode optical fiber jumper 200, a second light reflecting surface 102 is formed on the fiber core surface of the head end surface of the single-mode optical fiber section 300, and a third light reflecting surface 103 is formed on the fiber core surface of the tail end surface of the single-mode optical fiber section 300;
the first light reflecting surface 101 and the second light reflecting surface 102 form a gas-filled Fabry-Perot resonant cavity; the second light reflecting surface 102 and the third light reflecting surface 103 form a quartz Fabry-Perot resonant cavity; the cavity length of the C-shaped optical fiber section is between 150 and 250 micrometers, and the cavity length of the single-mode optical fiber section is between 150 and 250 micrometers; the optical path difference of the two cavities is between 0 and 30 mu m.
The second port of the optical fiber circulator 410 is connected with the other end of the single-mode optical fiber jumper 200; the first port of the fiber circulator 410 is connected with the output end of the laser source 420; the third port of the fiber optic circulator 410 is connected to the input of the spectrometer 430.
The laser source 420 emits laser with continuous wavelength, and the wavelength range of the continuous wavelength emitted by the laser source 420 is 480nm to 2200 nm.
In some preferred embodiments, the trailing end face of the C-shaped optical fiber segment 100 is fusion spliced with the leading end face of the single-mode optical fiber segment 300, wherein the fusion splicing process comprises: firstly, the C-shaped optical fiber section 100 and the single-mode optical fiber section 300 are welded by an optical fiber welding machine, and the C-shaped optical fiber section and the single-mode optical fiber section are welded for 300ms to 500ms by the optical fiber welding machine with 297bit discharge power. To ensure adequate welding. The welding power and the discharge time are required to be well controlled, and if the welding time is too long or the power is too high, an ideal effect cannot be achieved. After the fusion splicing is completed, the spliced C-shaped optical fiber section 100 and the single-mode optical fiber section 300 are then cut to a desired length by using an optical fiber cutter.
In actual practice, the fusion splicer is of type (fujikura, FSM-100M), the single-mode fiber section 300 is of type (G652D), and the fiber cleaver is of type (submitomo ELECTRIC equipment, LTD, FC-6S).
When the detection device based on the optical fiber sensor is applied to the working of the air pressure detection device, the air pressure optical fiber sensor probe 502 is firstly placed in the air chamber 450 and sealed, the air pressure in the air chamber 450 is controlled to be reduced from 0.8Mpa to 0Mpa by the air pump 460, and the spectrum drift is recorded by the spectrometer 430 by taking 0.08Mpa as a gradient, so as to obtain a spectrum drift curve, as shown in fig. 6. As can be seen from FIG. 6, the envelope profile is uniformly shifted in the long-wave direction as the pressure is gradually decreased from 0.8MPa to 0 MPa. To evaluate the linearity of the proposed detection device, the spectral drift is linearly fitted by tracking the movement of the envelope trough with pressure. The result shows that the pressure linearity of the detection device is good, and the sensitivity is 43000 nm/RIU. The abscissa of the spectrum drift curve is the wavelength, and the ordinate is the light intensity.
The air refractive index can be obtained from the obtained air pressure through the conversion relation between the air pressure and the air refractive index, so that the air refractive index can be detected.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that the present invention is not limited to the details of the embodiments shown and described, but is capable of numerous equivalents and substitutions without departing from the spirit of the invention and its scope is defined by the claims appended hereto.
Claims (6)
1. A fiber optic sensor, comprising: the single-mode optical fiber patch cord, the C-shaped optical fiber section and the single-mode optical fiber section; the diameter of the inner cavity of the C-shaped optical fiber section is 10-80 μm, the outer diameter of the C-shaped optical fiber section is 122-127 μm, and the opening angle alpha of the inner cavity of the C-shaped optical fiber section is 30-120 degrees; the outer diameter of the C-shaped optical fiber section is the same as that of the single-mode optical fiber section; the head end face of the C-shaped optical fiber section is welded with one end face of the single-mode optical fiber jumper; the tail end face of the C-shaped optical fiber section is welded with the head end face of the single-mode optical fiber section;
the fiber core surface of one end surface of the single-mode optical fiber jumper forms a first light reflecting surface, the fiber core surface of the head end surface of the single-mode optical fiber section forms a second light reflecting surface, and the fiber core surface of the tail end surface of the single-mode optical fiber section forms a third light reflecting surface;
the first light reflecting surface and the second light reflecting surface form an inflatable Fabry-Perot resonant cavity; the second light reflecting surface and the third light reflecting surface form a quartz Fabry-Perot resonant cavity; the cavity length of the C-shaped optical fiber section is between 150 and 250 micrometers, and the cavity length of the single-mode optical fiber section is between 150 and 250 micrometers; the optical path difference of the two cavities is between 0 and 30 mu m.
2. The fiber sensor of claim 1, wherein the trailing end face of the C-shaped fiber segment is fusion spliced to the leading end face of the single-mode fiber segment, wherein the fusion splicing process comprises: and fusion is carried out by an optical fiber fusion splicer at 297bit discharge power, and the discharge time is 300ms to 500 ms.
3. A fiber optic sensor-based detection device, comprising: the device comprises a laser light source, an optical fiber circulator, a spectrometer and an optical fiber sensor;
the optical fiber sensor includes: the single-mode optical fiber patch cord, the C-shaped optical fiber section and the single-mode optical fiber section; the diameter of the inner cavity of the C-shaped optical fiber section is 10-80 μm, the outer diameter of the C-shaped optical fiber section is 122-127 μm, and the opening angle alpha of the inner cavity of the C-shaped optical fiber section is 30-120 degrees; the outer diameter of the C-shaped optical fiber section is the same as that of the single-mode optical fiber section; the head end face of the C-shaped optical fiber section is welded with one end face of the single-mode optical fiber jumper; the tail end face of the C-shaped optical fiber section is welded with the head end face of the single-mode optical fiber section;
the fiber core surface of one end surface of the single-mode optical fiber jumper forms a first light reflecting surface, the fiber core surface of the head end surface of the single-mode optical fiber section forms a second light reflecting surface, and the fiber core surface of the tail end surface of the single-mode optical fiber section forms a third light reflecting surface;
the first light reflecting surface and the second light reflecting surface form an inflatable Fabry-Perot resonant cavity; the second light reflecting surface and the third light reflecting surface form a quartz Fabry-Perot resonant cavity; the cavity length of the C-shaped optical fiber section is between 150 and 250 micrometers, and the cavity length of the single-mode optical fiber section is between 150 and 250 micrometers; the optical path difference of the two cavities is between 0 and 30 mu m;
the second port of the optical fiber circulator is connected with the other end of the single-mode optical fiber jumper; the first port of the optical fiber circulator is connected with the output end of the laser light source; and the third port of the optical fiber circulator is connected with the input end of the spectrometer.
4. The optical fiber sensor-based detection device according to claim 3, wherein: the butt end face of C type optic fibre section and the butt end face butt fusion of single mode fiber section, wherein, the butt fusion technology includes: and fusion is carried out by an optical fiber fusion splicer at 297bit discharge power, and the discharge time is 300ms to 500 ms.
5. The optical fiber sensor-based detection device according to claim 3, wherein: the laser light source emits laser with continuous wavelength, and the wavelength range of the continuous wavelength emitted by the laser light source is 480nm to 2200 nm.
6. Use of a fiber-optic sensor based detection device according to any of claims 2 to 5 for the detection of the refractive index of a liquid, the detection of air pressure and the detection of the refractive index of air.
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