Interference type carbon dioxide sensor based on optical fiber vortex light
By using spiral long-period fiber grating and gas-sensitive film in fiber vortex optical interference carbon dioxide sensors, the problems of unstable performance and long-term performance degradation of traditional fiber grating sensors are solved, and high-precision and high-stability carbon dioxide detection are achieved.
Patent Information
- Application Number
- CN202421107538.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-20
- Publication Date
- 2025-03-28
- Estimated Expiration
- 2034-05-20
AI Technical Summary
Existing fiber grating sensors prepared based on phase mask plates and photosensitive methods have problems of unstable performance and long-term performance degradation.
Using a fiber vortex optical interference type carbon dioxide sensor, the gas-sensitive film is covered on the surface of the spiral long-period fiber grating, and the expansion effect of the Fabry-Perot interference structure and the gas-sensitive film are used to achieve high sensitivity and high precision gas detection.
It realizes the high stability and high response sensitivity of fiber-optic gas sensors, and can accurately detect carbon dioxide concentration on the ppb order, avoiding the performance degradation of traditional fiber gratings.
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Figure CN222689635U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of optical sensors, and in particular to a carbon dioxide sensor based on optical fiber vortex light interference. Background Art
[0002] There are many trace gases in the atmosphere, such as methane (CH4), carbon monoxide (CO), carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides (NO X ), etc., with concentrations in the ppt-ppm range. Although their content is very low, they have a great impact on the environment. Long-term and accurate monitoring of carbon dioxide in the region is of great scientific significance for carbon peak and carbon neutrality, and is also of great significance for the diagnosis of the physiological status of humans, animals and plants.
[0003] In order to effectively regulate the emission of various pollutants and pollutants, more and more sensor devices have appeared in industrial production and people's lives. Such devices mainly realize the type identification and content analysis of the measured object by physical or chemical reactions with the measured object. Most of the existing sensors are based on electricity and related principles as the sensing mechanism. In a specific gas atmosphere, the gas is detected by the change of relevant parameters such as the conductivity and resistance value of the sensor. However, this type of gas sensor has obvious limitations in application. First, because the sensor is based on electrical principles, the sensor cannot be used in flammable and explosive environments. Secondly, the control circuit and other related devices of the sensor are greatly affected by factors such as current, magnetic field and temperature, resulting in a large difference between the test results and the true value. Optical fiber sensors have gradually attracted people's attention due to a series of advantages such as small size, high sensitivity, anti-electromagnetic interference, acid and alkali corrosion resistance, and can be used under extreme conditions such as high temperature, high pressure and strong radiation. At present, most of the optical fiber gas sensors are based on the change of refractive index. Although there is a small minimum detection limit, the preparation process is relatively complicated and the sensor is relatively fragile. Most sensors based on periodic changes use fiber Bragg gratings as the sensing platform, which has the advantages of low temperature and bending cross sensitivity, and many works have been reported.
[0004] In the development process of optical fiber carbon dioxide sensors, many types of products have emerged. For example, Shivananju et al. etched FBG into the core and coated PAA-amino-CNTS material on the surface of the grating area. The refractive index of the gas-sensitive material in carbon dioxide will change and affect the refractive index of the core, thus realizing the measurement of carbon dioxide concentration. Wu et al. deposited PAVB on the tip of the optical fiber to detect carbon dioxide, affecting the interference of light by changing the refractive index of the optical fiber, and analyzing the interference spectrum to realize the detection of carbon dioxide. Li et al. even generated microbubbles in the optical fiber core by electric shock, and coated the gas-sensitive material on the inner wall of the microbubble. When carbon dioxide passes through the microbubble, it will interact with the sensitive material on the inner wall of the microbubble to change the refractive index of the core, thus realizing the detection of CO2 concentration. However, the traditional optical fiber grating prepared based on phase mask and photosensitive method has the problem of refractive index modulation and spectral performance degradation caused by material property changes over time, so the performance and long-term stability of sensors based on this design are limited. Summary of the invention
[0005] The embodiment of the present application provides a carbon dioxide sensor based on fiber vortex light interferometry, which is used to solve the problem of poor sensor performance and long-term stability of fiber gratings prepared based on phase mask plates and photosensitivity methods in the prior art.
[0006] The embodiment of the present application provides a carbon dioxide sensor based on optical fiber vortex light interferometry, comprising:
[0007] Gas pool;
[0008] A fiber Bragg grating is located inside the gas pool, and the fiber Bragg grating is a spiral structure formed by twisting the optical fiber in a molten state around the axial direction;
[0009] A gas-sensitive film is arranged on the outer surface of the fiber grating;
[0010] One end of the detection optical fiber extends into the gas pool and is connected to one end of the optical fiber grating.
[0011] In a possible implementation, the gas pool further has a gas inlet and a gas outlet.
[0012] In a possible implementation, the fiber grating is provided with an end face reflector at an end away from the detection optical fiber.
[0013] In a possible implementation, the detection optical fiber and the fiber grating are integrated.
[0014] In a possible implementation, the gas-sensitive film is formed by covering the nanomaterial on the optical fiber Bragg grating using an electrostatic spinning technique, a pulling method or a dripping method.
[0015] In a possible implementation, the nanomaterial is ZnO or a polymer material.
[0016] The optical fiber vortex light interferometer-based carbon dioxide sensor in this application has the following advantages:
[0017] 1. Covering the surface of the spiral long-period fiber grating with a gas-sensitive film has the advantages of simple process, compactness, and high visibility of interference fringes. Combined with the high stability and repeatability of the physical deformation fiber grating, it solves the problem of unstable performance of the fiber-optic gas sensor. Relying on the high response sensitivity of the fiber-optic sensor, high-precision stress and refractive index detection can be achieved.
[0018] 2. The high sensitivity of the Fabry-Perot interferometer (FPI) structure, the high precision of vortex light interference and the expansion effect of the gas-sensitive film are utilized to convert the gas concentration into grating external stress and refractive index parameters. It has extremely high gas detection sensitivity and can achieve ultra-low detection limit monitoring. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0020] Figure 1 A schematic diagram of the structure of a carbon dioxide sensor based on fiber vortex light interferometry provided in an embodiment of the present application.
[0021] Explanation of the accompanying drawings: 100, gas pool; 110, air inlet; 120, air outlet; 200, fiber grating; 210, gas sensitive film; 300, detection optical fiber. DETAILED DESCRIPTION
[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0023] Figure 1 The present invention provides a carbon dioxide sensor based on fiber vortex light interferometry, including:
[0024] Gas pool 100;
[0025] The fiber grating 200 is located inside the gas pool 100. The fiber grating 200 is a spiral structure formed by twisting the optical fiber in a molten state around the axial direction.
[0026] A gas-sensitive film 210 is disposed on the outer surface of the fiber grating 200;
[0027] One end of the detection optical fiber 300 extends into the gas pool 100 and is connected to one end of the fiber grating 200 .
[0028] Exemplarily, the gas pool 100 is used to contain the gas to be detected, which may contain a certain amount of carbon dioxide. Accordingly, the gas pool 100 also has an air inlet 110 and an air outlet 120. The air inlet 110 is used to deliver the gas to be detected to the gas pool 100 at a certain flow rate under the action of an air pump or other equipment, while the air outlet 120 is used to output the gas in the gas pool 100 to the outside of the gas pool 100 at the same flow rate as the input flow rate of the air inlet 110. By using the same input and output flow rates, the air pressure inside the gas pool 100 can be ensured to be constant, avoiding the pressure change from affecting the fiber grating 200 or the gas sensitive film 210 inside the gas pool 100, thereby reducing the detection accuracy of the sensor.
[0029] For the convenience of manufacturing, the detection optical fiber 300 and the fiber Bragg grating 200 can be integrated, that is, a portion of the detection optical fiber 300 near the end is heated to a softened or molten state and then twisted to form the above-mentioned fiber Bragg grating 200. Of course, it is also possible to use an optical fiber completely independent of the detection optical fiber 300, such as a single-mode optical fiber, a multi-mode optical fiber or a photonic crystal, which is pre-twisted to a spiral structure and then fused to the end of the detection optical fiber 300.
[0030] Further, the fiber grating 200 is provided with an end face reflector at one end away from the detection fiber 300. The end face reflector can be formed by coating a reflective film on the end face of the fiber grating 200. After the optical signal input from the detection fiber 300 propagates through the fiber grating 200, it will be reflected by the end face reflector. The reflected optical signal and the optical signal input from the detection fiber grating 300 form two conjugated vortex beams inside the fiber grating 200. The two conjugated vortex beams will interfere in the fiber grating 200. This interference will form an interference pattern after being output from the detection fiber 300. When the gas containing carbon dioxide is input into the gas pool 100, the carbon dioxide will cause the gas sensitive film 210 to produce stress and refractive index changes. This change will cause the interference pattern output by the detection fiber 300 to change. The concentration of carbon dioxide can be obtained by analyzing this change. Specifically, the change of the interference image is reflected in the change of the angle of the interference image. The angle of rotation can be determined by comparing the interference pattern after the change with the standard interference pattern before the change, and then the corresponding carbon dioxide concentration can be determined according to the angle.
[0031] It should be understood that the pitch and other parameters of the twisted fiber Bragg grating 200 determine its operating wavelength. Therefore, the wavelength of the optical signal input by the detection optical fiber 300 should match the operating wavelength of the fiber Bragg grating 200 .
[0032] The combination of the spiral-structured fiber Bragg grating 200 and the gas-sensitive film 210 enables the detection accuracy of the carbon dioxide concentration in the present application to reach the ppb level. Moreover, the fiber Bragg grating 200 in the present application is a periodic structure formed by twisting the molten optical fiber, which is a periodic physical deformation that produces a periodic modulation of the effective refractive index. Compared with the traditional long-period fiber Bragg grating, it has the advantages of no degradation of grating spectrum performance and higher sensitivity in sensing and application.
[0033] In a possible embodiment, the gas-sensitive film 210 is formed by covering the fiber grating 200 with nanomaterials by using electrostatic spinning technology, a pulling method, or a dripping method.
[0034] For example, the nano material may be ZnO or a polymer material. After the above method is used, the thickness of the gas sensitive film 210 covering the fiber grating 200 is preferably 3-10 μm.
[0035] The carbon dioxide sensor in this application can be used in many fields such as smart manufacturing, smart home, smart building, smart campus and smart agriculture.
[0036] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.
[0037] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.
Claims
1. A carbon dioxide sensor based on optical fiber vortex light interferometry, characterized in that: include: Gas pool (100); A fiber grating (200) is located inside the gas pool (100), and the fiber grating (200) is a spiral structure formed by twisting the optical fiber in a molten state around the axial direction; A gas-sensitive film (210) is arranged on the outer surface of the optical fiber grating (200); One end of the detection optical fiber (300) extends into the gas pool (100) and is connected to one end of the optical fiber grating (200).
2. The optical fiber vortex light interferometer-based carbon dioxide sensor according to claim 1, characterized in that: The gas pool (100) also has a gas inlet (110) and a gas outlet (120).
3. The optical fiber vortex light interferometer-based carbon dioxide sensor according to claim 1, characterized in that: The fiber grating (200) is provided with an end face reflector at one end away from the detection optical fiber (300).
4. The optical fiber vortex light interferometer-based carbon dioxide sensor according to claim 1, characterized in that: The detection optical fiber (300) and the optical fiber grating (200) are integrated.
5. The optical fiber vortex light interferometer-based carbon dioxide sensor according to claim 1, characterized in that: The gas-sensitive film (210) is formed by covering the optical fiber grating (200) with nano materials using electrostatic spinning technology, a pulling method or a dripping method.
6. The optical fiber vortex light interferometry carbon dioxide sensor according to claim 5, characterized in that: The nano material is ZnO or a polymer material.