阅读说明：本技术 一种基于光纤双腔游标效应增敏的气压传感器 (Air pressure sensor based on optical fiber double-cavity vernier effect sensitization ) 是由 张亮 张洪达 孙巍 柳贡强 关艳玲 迟敬元 付丽君 王晗 徐超 高颖 于 2020-12-03 设计创作，主要内容包括：一种基于光纤双腔游标效应增敏的气压传感器,它属于气压传感技术领域。本发明解决了现有的气压传感器对气压测量的灵敏度低的问题。本发明采用基于单模光纤、石英管和悬浮芯光纤制备的传感头,即基于双腔级联产生游标效应来提高环境气压检测灵敏度,而且本发明传感器具有结构相对简单,便于制备,不需要套管及胶固,结构稳定的特点。采用本发明的级联双腔的灵敏度为单个空气腔灵敏度的M/2,显著提高了气压检测的灵敏度。本发明可以应用于环境气压检测。(An air pressure sensor based on optical fiber double-cavity vernier effect sensitization belongs to the technical field of air pressure sensing. The invention solves the problem that the existing air pressure sensor has low sensitivity to air pressure measurement. The sensor head is prepared based on the single-mode optical fiber, the quartz tube and the suspension core optical fiber, namely, the vernier effect is generated based on the double-cavity cascade to improve the detection sensitivity of the environmental air pressure. The sensitivity of the cascade double-cavity is M/2 of the sensitivity of a single air cavity, so that the sensitivity of air pressure detection is obviously improved. The invention can be applied to environmental air pressure detection.)

1. The utility model provides an atmospheric pressure sensor based on sensitization of optic fibre two-chamber vernier effect which characterized in that, atmospheric pressure sensor includes broadband light source, optic fibre circulator, sensing head and spectrum appearance, wherein:

the broadband light source is used for emitting optical signals; the optical signal emitted by the broadband light source is input into the optical fiber circulator through the first connecting end of the optical fiber circulator, and the optical signal input through the first connecting end is output to the sensing head through the second connecting end of the optical fiber circulator;

the optical signal reflected by the sensing head is input into the optical fiber circulator through the second connecting end, and the optical signal input into the optical fiber circulator is output to the spectrometer through the third connecting end of the optical fiber circulator;

the sensing head comprises a single-mode fiber, a quartz tube and a suspension core fiber, one end of the single-mode fiber is welded with one end of the quartz tube, and the other end of the quartz tube is welded with one end of the suspension core fiber.

2. The fiber-optic double-cavity vernier effect sensitization-based air pressure sensor according to claim 1, wherein the spectrometer detects changes in air pressure according to the translation of the received interference spectrum envelope.

3. The air pressure sensor based on the fiber double-cavity vernier effect sensitization of claim 2, wherein the outer diameter of the single-mode fiber is 125 microns, and the fiber core diameter of the single-mode fiber is 8-10 microns.

4. The fiber-optic double-cavity vernier effect sensitization-based air pressure sensor according to claim 3, wherein the outer diameter of the quartz tube is 125 micrometers, and the inner diameter of the quartz tube is 70-100 micrometers.

5. The fiber-optic double-cavity vernier effect sensitization-based air pressure sensor according to claim 4, wherein the outer diameter of the floating-core fiber is 125 microns.

6. The optical fiber double-cavity vernier effect sensitization-based air pressure sensor according to claim 5, wherein the suspension core optical fiber comprises a suspension core and an air hole inside, the suspension core is located at the center of the suspension core optical fiber, the diameter of the suspension core is 8-10 microns, and the diameter of the air hole is 30-50 microns.

7. The optical fiber double-cavity vernier effect sensitization-based air pressure sensor as claimed in claim 6, wherein the length of the quartz tube is 100-300 μm, and the length of the floating core optical fiber is 1.4 times of the length of the quartz tube.

8. The optical fiber double-cavity vernier effect sensitization-based air pressure sensor according to claim 7, wherein the translation amount of the interference spectrum envelope received by the spectrometer is as follows:

when the ambient air pressure changes, the refractive index of the gas in the sensing head changes, the envelope of the interference spectrum moves along with the change of the ambient air pressure, and the translation quantity delta lambda of the envelope of the interference spectrum_EnvelopeExpressed as:

wherein M is an envelope amplification factor, Δ λ_airIs the air cavity interference spectrum translation.

Technical Field

The invention belongs to the technical field of air pressure sensing, and particularly relates to an air pressure sensor based on optical fiber double-cavity vernier effect sensitization.

Background

The air pressure sensor is a sensor that converts pressure into a signal output. The air pressure is an important process parameter in the production process and aerospace and national defense industries, and not only needs to be rapidly and dynamically measured, but also needs to be digitally displayed and recorded. Therefore, the air pressure sensor is a sensor which is greatly valued and rapidly developed.

However, the existing air pressure sensor has a problem of low air pressure measurement sensitivity, so it is necessary to design an air pressure sensor to improve the air pressure measurement sensitivity.

Disclosure of Invention

The invention aims to solve the problem that the conventional air pressure sensor has low sensitivity to air pressure measurement, and provides an air pressure sensor based on optical fiber double-cavity vernier effect sensitization.

The technical scheme adopted by the invention for solving the technical problems is as follows: the utility model provides an atmospheric pressure sensor based on sensitization of optic fibre two-chamber vernier effect, atmospheric pressure sensor includes broadband light source, optic fibre circulator, sensing head and spectrum appearance, wherein:

the broadband light source is used for emitting optical signals; the optical signal emitted by the broadband light source is input into the optical fiber circulator through the first connecting end of the optical fiber circulator, and the optical signal input through the first connecting end is output to the sensing head through the second connecting end of the optical fiber circulator;

the optical signal reflected by the sensing head is input into the optical fiber circulator through the second connecting end, and the optical signal input into the optical fiber circulator is output to the spectrometer through the third connecting end of the optical fiber circulator;

the sensing head comprises a single-mode optical fiber, a quartz tube and a suspension core optical fiber, wherein one end of the single-mode optical fiber is welded with one end of the quartz tube, and the other end of the quartz tube is welded with one end of the suspension core optical fiber;

further, the spectrometer detects changes in air pressure based on the amount of translation of the received interference spectrum envelope;

further, the outer diameter of the single-mode optical fiber is 125 micrometers, and the core diameter of the single-mode optical fiber is 8-10 micrometers;

further, the outer diameter of the quartz tube is 125 micrometers, and the inner diameter of the quartz tube is 70-100 micrometers;

further, the outer diameter of the suspended core optical fiber is 125 micrometers;

furthermore, the suspension core optical fiber comprises a suspension core and air holes inside, the suspension core is positioned at the center of the suspension core optical fiber, the diameter of the suspension core is 8-10 microns, and the diameter of the air holes is 30-50 microns;

further, the length of the quartz tube is 100-300 microns, and the length of the suspended core optical fiber is 1.4 times that of the quartz tube;

further, the translation amount of the interference spectrum envelope received by the spectrometer is as follows:

when the ambient air pressure changes, the refractive index of the gas in the sensing head changes, the envelope of the interference spectrum moves along with the change of the ambient air pressure, and the translation quantity delta lambda of the envelope of the interference spectrum_EnvelopeExpressed as:

wherein M is an envelope amplification factor, Δ λ_airFor air cavity interference spectrum translationAmount of the compound (A).

The invention has the beneficial effects that: the invention provides an optical fiber double-cavity vernier effect sensitization-based air pressure sensor, which adopts a sensing head prepared based on a single-mode optical fiber, a quartz tube and a suspension core optical fiber, namely, the vernier effect is generated based on double-cavity cascade to improve the environmental air pressure detection sensitivity. The invention uses the suspended core fiber to replace the photonic crystal fiber, and the pore diameter of the double-pore fiber is far larger than that of the photonic crystal fiber, so the fusion process is not easy to collapse.

The sensitivity of the cascade double-cavity is M/2 of the sensitivity of a single air cavity, so that the sensitivity of air pressure detection is obviously improved.

Drawings

FIG. 1 is a schematic diagram of the optical fiber double-cavity vernier effect sensitization-based air pressure sensor of the present invention;

FIG. 2 is a schematic view of a sensor head;

FIG. 3 is a schematic diagram of a single mode optical fiber;

FIG. 4 is a schematic view of a quartz tube;

fig. 5 is a schematic view of a suspended core optical fiber.

Detailed Description

The first embodiment is as follows: the present embodiment will be described with reference to fig. 1 to 5. The working principle of the air pressure sensor based on the optical fiber double-cavity vernier effect sensitization in the embodiment is as follows:

when incident light emitted by a broadband light source enters the interface of the single-mode fiber and the coreless fiber through the fiber circulator, one part of the incident light is reflected and the other part of the incident light is continuously transmitted due to the difference of the refractive indexes of media at two sides of the interface, when the continuously transmitted part of light is transmitted through the interface of the coreless fiber and the suspended core fiber, one part of the incident light is reflected and the other part of the light is continuously transmitted, and the continuously transmitted part of light is transmitted to the top end of the suspended core fiber and is partially reflected. The three beams of reflected light generate interference with each other, the interference between the first beam of reflected light and the second beam of reflected light is the beam interference in an air cavity interferometer formed by coreless fibers, the interference between the second beam of reflected light and the third beam of reflected light is the beam interference in a quartz cavity interferometer formed by the coreless fibers, and the interference between the first beam of reflected light and the third beam of reflected light is the beam interference in a composite cavity formed by the air cavity and the quartz cavity.

The suspended core of the suspended core optical fiber is positioned at the central position, the diameter is 8-10 microns, part of the suspended core is exposed in air holes, and the diameter of the air holes is 30-50 microns.

The complex amplitudes of the three beams of light reflected back into the single mode fiber by the first, second, and third reflective surfaces M1, M2, and M3, respectively, may be expressed as:

wherein phi₁＝(4πn_airL_air)/λ，Φ₂＝(4πn_silicaL_silica)/λ，A＝E₀R^1/2，B＝E₀(1-α)(1-R)R^1/2，C＝E₀(1-α)(1-R)²R^1/2(ii) a R is the reflectance at the interface of air and quartz, which is about 3%; α is the loss of the air cavity, which is greater than 90% for this sensor. Thus, the complex amplitude A, B, C has a relationship A>B>C；L_airAnd L_silicaThe lengths of the air cavity and the quartz cavity are respectively; n is_airAnd n_silicaThe refractive indices of the air and quartz cavities, respectively.

The three reflected lights interfere with each other in the single-mode fiber to form a quartz cavity interference spectrum (I)₁) Air cavity interference spectrum (I)₂) And long cavity interference spectrum (I)₃) I.e. by

The total interference spectrum of the sensor consists of the interference spectra of the three cavities. From the relationship a > B > C, it can be seen that AB > AC > BC, i.e., the air cavity and the long cavity, are decisive for the shape of the interference spectrum envelope, which can be confirmed from simulation results that the quartz cavity interference spectrum only slightly changes the peak and valley values of the sensor interference spectrum, but does not change the peak positions, and therefore the sensor interference spectrum envelope is mainly determined by the air cavity and the long cavity interference spectrum.

Considering only the air cavity and long cavity cases, the free spectral range of the interference spectral envelope is

FSR_envelope＝M·FSR_air (3)

M is an envelope amplification factor, FSR_airFree spectral Range, FSR, of the air Cavity_silicaFree spectral Range, FSR, of Quartz Chambers₃The free spectral range of the long cavity.

When the refractive index of gas is changed under the action of gas pressure, the envelope of interference spectrum is moved, and its movement quantity is delta lambda_EnvelopeCan be approximately expressed as

Δλ_Envelope＝M(Δλ_air-Δλ_hybrid) (5)

Wherein, Δ λ_airAnd Δ λ_hybridRespectively, air cavity and long cavity interferogram translation amounts, which can be expressed as

Wherein β is a constant and Δ P is a variation in air pressure.

Substituting equation (6) into equation (5) and considering n_airL_air≈n_silicaL_silicaTo obtain

Equation (7) shows: when the air pressure changes, the translation of the interference spectrum envelope is M/2 of the air cavity interference spectrum translation, i.e. the cascaded dual cavity sensitivity is M/2 of the single air cavity sensitivity.

The above-described calculation examples of the present invention are merely to explain the calculation model and the calculation flow of the present invention in detail, and are not intended to limit the embodiments of the present invention. It will be apparent to those skilled in the art that other variations and modifications of the present invention can be made based on the above description, and it is not intended to be exhaustive or to limit the invention to the precise form disclosed, and all such modifications and variations are possible and contemplated as falling within the scope of the invention.