Carbon dioxide optical fiber sensing structure and carbon dioxide optical fiber sensor

Abstract

The embodiment of the invention provides a carbon dioxide optical fiber sensing structure and a carbon dioxide optical fiber sensor, relates to the technical field of optical fibers, can consider the requirements of high sensitivity and wide range in a carbon dioxide monitoring process, and further improves the monitoring effect and monitoring quality of carbon dioxide, so as to realize timely warning and improve the monitoring efficiency. Therefore, the safety risk can be reduced. The carbon dioxide optical fiber sensing structure comprises an optical fiber main body, and the optical fiber main body comprises a first end face and a second end face in the extension direction of the optical fiber main body; the light-transmitting structure is connected with the first end face of the optical fiber main body, external light rays enter the light-transmitting structure through the second end face, and the refractive index of the light-transmitting structure is related to the concentration of carbon dioxide gas in a gas environment where the light-transmitting structure is located; the grating structure is located in the optical fiber main body, and the period of the grating structure is related to the concentration of the carbon dioxide gas in the gas environment.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical fiber technology, and in particular to a carbon dioxide optical fiber sensing structure and a carbon dioxide optical fiber sensor. Background Art

[0002] With the acceleration of urbanization and the continuous development of society, fire safety issues are becoming increasingly prominent. In the early stages of a fire, a large amount of carbon dioxide gas will be produced. Therefore, by improving the efficiency and sensitivity of carbon dioxide detection, an effective warning can be given, thereby further protecting life and property safety.

[0003] Optical fiber sensors have advantages such as moisture resistance, corrosion resistance, passive detection end, and high temperature resistance, so they are widely used in early safety warning monitoring of fires. However, in traditional carbon dioxide optical fiber sensors, it is difficult to meet the requirements of high sensitivity and large range at the same time, resulting in limited carbon dioxide monitoring effect, further causing the concentration of carbon dioxide gas to be untimely and increase safety risks. Summary of the invention

[0004] The embodiments of the present application provide a carbon dioxide optical fiber sensing structure and a carbon dioxide optical fiber sensor, which can take into account the requirements for high sensitivity and a large range in the carbon dioxide monitoring process, further improve the monitoring effect and monitoring quality of carbon dioxide, so as to achieve timely alarms, thereby reducing safety risks and protecting life and property.

[0005] A first aspect of an embodiment of the present application provides a carbon dioxide optical fiber sensing structure, comprising:

[0006] An optical fiber body, wherein in an extending direction of the optical fiber body, the optical fiber body comprises a first end face and a second end face;

[0007] A light-transmitting structure, wherein the light-transmitting structure is connected to the first end face of the optical fiber body, external light is incident on the light-transmitting structure through the second end face, and the refractive index of the light-transmitting structure is related to the concentration of carbon dioxide gas in the gas environment;

[0008] A grating structure is located inside the optical fiber body, and a period of the grating structure is related to the concentration of carbon dioxide gas in the gas environment.

[0009] In some embodiments, the optical fiber body includes an optical fiber cladding layer and an optical fiber core, and the optical fiber cladding layer is disposed around the circumference of the optical fiber core;

[0010] The orthographic projection of the light-transmitting structure toward the first end surface covers the orthographic projection of the optical fiber core toward the first end surface.

[0011] In some embodiments, an orthographic projection edge of the optical fiber coating layer toward the first end surface coincides with an orthographic projection edge of the light-transmitting structure toward the first end surface.

[0012] In some embodiments, the optical fiber body includes an optical fiber cladding layer and an optical fiber core, and the optical fiber cladding layer is disposed around the circumference of the optical fiber core;

[0013] The optical fiber core includes a first optical fiber core and a second optical fiber core, and two ends of the grating structure are connected to the first optical fiber core and the second optical fiber core respectively.

[0014] In some embodiments, the material of the light-transmitting structure includes at least polyhexamethylene biguanide hydrochloride.

[0015] In some embodiments, the material of the grating structure includes at least polyethersulfone.

[0016] In some embodiments, a surface of the light-transmitting structure away from the first end surface includes a curved surface.

[0017] A second aspect of an embodiment of the present application provides a carbon dioxide optical fiber sensor, comprising:

[0018] The carbon dioxide optical fiber sensing structure according to any one of the first aspects above;

[0019] a detection unit, the detection unit being used to determine the concentration of carbon dioxide gas in the gas environment where the carbon dioxide optical fiber sensing structure is located according to at least one of the phase of light emitted from the optical fiber body in the carbon dioxide optical fiber sensing structure at the second end face and the wavelength of the grating structure in the carbon dioxide optical fiber sensing structure;

[0020] An alarm unit is used to generate alarm information according to the concentration of the carbon dioxide gas, and an input end of the alarm unit is electrically connected to an output end of the detection unit.

[0021] In some embodiments, external light incident through the second end face is reflected by the first end face to obtain a first reflected light, and the external light incident through the second end face is reflected by a surface of the light-transmitting structure on a side away from the first end face to obtain a second reflected light, and the first reflected light and the second reflected light interfere with each other inside the optical fiber to form interference light;

[0022] The detection unit includes an interference detection unit, which is used to obtain an interference spectrum of the interference light and determine the concentration of carbon dioxide gas in the gas environment according to the drift amplitude of the interference peak and the interference trough on the interference spectrum.

[0023] In some embodiments, the detection unit includes a grating detection unit, and the grating detection unit is used to determine the concentration of carbon dioxide gas in the gas environment according to the drift amplitude of the wavelength of the grating structure.

[0024] The embodiment of the present application provides a carbon dioxide optical fiber sensing structure and a carbon dioxide optical fiber sensor. By arranging a light-transmitting structure on one side of the first end face of the optical fiber body, the light incident on the second end face of the optical fiber body can be reflected by the first end face of the light-transmitting structure and the surface of the light-transmitting structure away from the first end face, so as to obtain two beams of reflected light. When the two beams of reflected light are incident on the optical fiber body, interference occurs inside the optical fiber, so that when the concentration of carbon dioxide gas in the external environment changes, the refractive index of the light-transmitting structure can be changed, and the amount of light reflected by the surface of the light-transmitting structure away from the first end face can be changed, and the phase of the interference light can be changed, so as to facilitate the determination of the concentration of carbon dioxide according to the interference spectrum of the interference light. At the same time, by arranging a grating structure inside the optical fiber body, the period of the grating structure changes with the change of the concentration of carbon dioxide gas, and the wavelength of the grating structure changes, so as to facilitate the determination of the concentration of carbon dioxide according to the change of the wavelength of the grating structure. Therefore, by integrating two carbon dioxide sensing structures with different detection principles on a single optical fiber body, it is possible to take into account the requirements for high sensitivity and a large range in the carbon dioxide monitoring process, further improve the monitoring effect and quality of carbon dioxide, so as to achieve timely alarms, thereby reducing safety risks and protecting life and property. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions 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 related drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic structural diagram of a carbon dioxide optical fiber sensing structure provided in an embodiment of the present application;

[0027] Figure 2 A schematic structural diagram of an optical fiber body provided in an embodiment of the present application;

[0028] Figure 3 A schematic structural diagram of a carbon dioxide optical fiber sensor provided in an embodiment of the present application.

[0029] Description of reference numerals:

[0030] 100 - optical fiber body, 110 - optical fiber cladding, 120 - optical fiber core, 121 - first optical fiber core, 122 - second optical fiber core, 200 - light-transmitting structure, 300 - grating structure, 1000 - carbon dioxide optical fiber sensing structure, 2000 - detection unit, 2001 - interference detection unit, 2002 - grating detection unit, 3000 - alarm unit. DETAILED DESCRIPTION

[0031] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0033] When used herein, the singular forms "a", "an" and " / the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof. At the same time, in this specification, the term "and / or" includes any and all combinations of the relevant listed items.

[0034] With the acceleration of urbanization and the continuous development of society, fire safety issues are becoming increasingly prominent. In the early stages of a fire, a large amount of carbon dioxide gas will be produced. Therefore, by improving the efficiency and sensitivity of carbon dioxide detection, an effective warning can be given, thereby further protecting life and property safety.

[0035] Optical fiber sensors have advantages such as moisture resistance, corrosion resistance, passive detection end, and high temperature resistance, so they are widely used in early safety warning monitoring of fires. However, in traditional carbon dioxide optical fiber sensors, it is difficult to meet the requirements of high sensitivity and large range at the same time, resulting in limited carbon dioxide monitoring effect, further causing the concentration of carbon dioxide gas to be untimely and increase safety risks.

[0036] It should be noted that, based on the different modulation parameters, optical fiber sensors can be divided into intensity modulation, phase modulation, wavelength modulation, etc., among which phase modulation mainly uses the principle of optical interference. Common optical fiber interference devices include optical fiber Michelson interferometer, optical fiber Mach-Zehnder interferometer, and optical fiber Fabry-Perot interferometer. Due to its single-ended reflection characteristics, the optical fiber Fabry-Perot interferometer is suitable for being made into a form of optical fiber sensing probe, especially suitable for carbon dioxide gas sensing. In the existing optical fiber Fabry-Perot interferometer, it is usually necessary to combine with a specific gas-sensitive material to realize the modulation of the phase of the optical fiber interference light through the response of the gas-sensitive material to carbon dioxide. The polyhexamethylene biguanide hydrochloride material has a relatively sensitive response to carbon dioxide gas. The polyhexamethylene biguanide hydrochloride material can be coated on the surface of the optical fiber Fabry-Perot interferometer to develop a highly sensitive optical fiber carbon dioxide optical fiber sensor.

[0037] In addition, carbon dioxide gas can also be sensed by wavelength modulation. As a typical wavelength-sensitive sensor structure, fiber Bragg grating structure is particularly suitable for fiber-optic gas sensing. Each type of grating structure has a specific reflection peak wavelength. Changes in external factors will cause the reflection peak wavelength to drift. Similar to the aforementioned phase modulation sensor, the fiber Bragg grating structure also needs to be combined with a specific gas-sensitive material. Polyether sulfone is another typical carbon dioxide gas-sensitive material. Combining the fiber Bragg grating structure with polyether sulfone material can also achieve fiber-optic carbon dioxide gas sensing.

[0038] However, although the polyhexamethylene biguanide hydrochloride material has an extremely high sensitivity response to carbon dioxide, with a maximum response sensitivity of more than 10pm / ppm, the polyhexamethylene biguanide hydrochloride material has a relatively small response range to carbon dioxide and a poor linearity. It has a good linear response effect only in the range of 0 to 600ppm, and the response sensitivity gradually weakens after exceeding 600ppm, resulting in a relatively limited response range of the fiber Fabry-Perot interferometer formed by the polyhexamethylene biguanide hydrochloride material, making it difficult to achieve high-concentration carbon dioxide monitoring. Although the polyethersulfone fiber grating structure sensor has a large response range and can still achieve a linear response within a concentration range of 100%, the polyethersulfone material has a slow response speed to carbon dioxide, a long response time, and a high response lower limit, making it difficult to detect concentration changes of carbon dioxide gas below 1%.

[0039] Therefore, based on the importance of carbon dioxide gas concentration monitoring for safety, it is an urgent problem to propose a carbon dioxide fiber optic sensing structure and a carbon dioxide fiber optic sensor that takes into account the requirements of high sensitivity and a large range in the carbon dioxide monitoring process.

[0040] like Figure 1 As shown, Figure 1A schematic structural diagram of a carbon dioxide optical fiber sensing structure provided in an embodiment of the present application. In a first aspect of an embodiment of the present application, a carbon dioxide optical fiber sensing structure is provided, comprising: an optical fiber body 100, a light-transmitting structure 200, and a grating structure 300. In the extension direction of the optical fiber body 100, the optical fiber body 100 comprises a first end face and a second end face; the light-transmitting structure 200 is connected to the first end face of the optical fiber body 100, and external light is incident on the light-transmitting structure 200 through the second end face, and the refractive index of the light-transmitting structure 200 is related to the concentration of carbon dioxide gas in the gas environment; the grating structure 300 is located inside the optical fiber body 100, and the period of the grating structure 300 is related to the concentration of carbon dioxide gas in the gas environment.

[0041] It should be noted that the first end surface is a smooth end surface.

[0042] Exemplarily, the optical fiber body 100 may be a single-mode optical fiber. The grating structure 300 may be obtained by etching the optical fiber core 100. The grating structure 300 may be located on one side of the optical fiber body 100 close to the first end face. The material of the light-transmitting structure 200 and the material of the grating structure 300 may include a carbon dioxide gas-sensitive material. The expansion rate of the material of the grating structure 300 may change with the change of the concentration of the carbon dioxide gas.

[0043] It should be noted that when the carbon dioxide optical fiber sensing structure is in a carbon dioxide gas environment, the refractive index of the light-transmitting structure 200 will be modulated accordingly with the change in the concentration of the carbon dioxide gas, which will cause the optical path of the light incident from the optical fiber body 100 to the light-transmitting structure 200 to change, and further cause the amount of reflected light incident on the optical fiber body 100 by the reflected light on the inner wall surface of the light-transmitting structure 200 away from the first end face to change, and further cause the amount of interference light formed by the first end face of the light-transmitting structure 200 and the two reflected light beams on the inner wall surface of the light-transmitting structure 200 away from the first end face to change, so as to cause the phase of the interference light emitted from the second end face of the optical fiber body 100 to change, and then the concentration of carbon dioxide gas can be detected by detecting the phase of the light emitted from the second end face of the optical fiber body 100.

[0044] It should be noted that the grating structure 300 expands during the process of absorbing carbon dioxide gas, which causes the period of the grating structure 300 to stretch, further causing the wavelength of the grating structure 300 to drift, and then the concentration of carbon dioxide gas can be detected by detecting the wavelength of the grating structure 300.

[0045] The carbon dioxide optical fiber sensing structure provided by the embodiment of the present application can make the light incident on the second end face of the optical fiber body 100 be reflected by the first end face of the light-transmitting structure 200 and the surface of the light-transmitting structure 200 away from the first end face, so as to obtain two beams of reflected light. When the two beams of reflected light are incident on the optical fiber body 100, interference occurs inside the optical fiber, so that when the concentration of carbon dioxide gas in the external environment changes, the refractive index of the light-transmitting structure 200 can be changed, and the amount of light reflected by the surface of the light-transmitting structure 200 away from the first end face can be changed, and the phase of the interference light can be changed, so as to facilitate the determination of the concentration of carbon dioxide according to the interference spectrum of the interference light. At the same time, by setting the grating structure 300 inside the optical fiber body 100, the period of the grating structure 300 changes with the change of the concentration of carbon dioxide gas, and further the wavelength of the grating structure 300 changes, so as to facilitate the determination of the concentration of carbon dioxide according to the change of the wavelength of the grating structure 300. Therefore, by integrating two carbon dioxide sensing structures with different detection principles on an optical fiber body 100, it is possible to take into account the requirements of high sensitivity and a large range in the carbon dioxide monitoring process, further improve the monitoring effect and quality of carbon dioxide, so as to achieve timely alarms, thereby reducing safety risks and protecting life and property.

[0046] like Figure 1 As shown, in some feasible embodiments, the optical fiber body 100 includes an optical fiber cladding 110 and an optical fiber core 120, and the optical fiber cladding 110 is arranged around the circumference of the optical fiber core 120; the orthographic projection of the light-transmitting structure 200 toward the first end face covers the orthographic projection of the optical fiber core 120 toward the first end face.

[0047] The carbon dioxide optical fiber sensing structure provided in the embodiment of the present application can increase the contact area between the light-transmitting structure 200 and the optical fiber body 100 at the first end face by setting the orthographic projection of the light-transmitting structure 200 toward the first end face to cover the orthographic projection of the optical fiber core 120 toward the first end face, thereby increasing the amount of light incident on the light-transmitting structure 200, and further increasing the amount of interference light formed by interference of reflected light, thereby improving the sensitivity of carbon dioxide monitoring and the accuracy of monitoring results, improving the alarm efficiency, and further reducing safety risks.

[0048] like Figure 1 As shown, in some feasible implementations, the orthographic edge of the optical fiber coating 110 facing the first end surface coincides with the orthographic edge of the light-transmitting structure 200 facing the first end surface.

[0049] The carbon dioxide optical fiber sensing structure provided in the embodiment of the present application can avoid that the contact area between the light-transmitting structure 200 and the optical fiber body 100 at the first end face is too large, by arranging the orthographic projection edge of the optical fiber coating layer 110 toward the first end face to coincide with the orthographic projection edge of the light-transmitting structure 200 toward the first end face, so as to prevent the light reflected from the inner wall surface of the light-transmitting structure 200 away from the first end face from being incident on the optical fiber body 100, thereby further increasing the amount of light incident on the light-transmitting structure 200 and increasing the amount of interference light formed by the interference of the reflected light, thereby improving the sensitivity of carbon dioxide monitoring and the accuracy of the monitoring results, improving the alarm efficiency, and further reducing the safety risks.

[0050] like Figure 2 As shown, Figure 2 A schematic structural diagram of an optical fiber body provided in an embodiment of the present application. In some feasible embodiments, the optical fiber body 100 includes an optical fiber cladding layer 110 and an optical fiber core 120, and the optical fiber cladding layer 110 is arranged around the circumference of the optical fiber core 120; the optical fiber core 120 includes a first optical fiber core 121 and a second optical fiber core 122, and the two ends of the grating structure 300 are connected to the first optical fiber core 121 and the second optical fiber core 122 respectively.

[0051] Illustratively, the material of the first optical fiber core 121 and the material of the second optical fiber core 122 may be different.

[0052] In some feasible implementations, the material of the light-transmitting structure 200 at least includes polyhexamethylene biguanide hydrochloride.

[0053] It should be noted that polyhexamethylene biguanide hydrochloride has a high gas sensitivity to carbon dioxide gas, and has a high linearity of response in a low concentration range.

[0054] The carbon dioxide optical fiber sensing structure provided in the embodiment of the present application can further enhance the sensitivity of the carbon dioxide optical fiber sensing structure to the response of carbon dioxide gas, improve the response quality of the carbon dioxide optical fiber sensing structure to carbon dioxide gas, improve the accuracy of the detection results, and accelerate the detection speed, thereby enhancing the detection capability of the carbon dioxide optical fiber sensing structure to low-concentration carbon dioxide gas, achieving effective warning in the early stage of a fire, and further reducing safety risks.

[0055] In some feasible implementations, the material of the grating structure 300 includes at least polyethersulfone.

[0056] It should be noted that the response range of polyethersulfone to carbon dioxide gas is relatively wide, and in a high concentration carbon dioxide gas environment, the response linearity of polyethersulfone is relatively high.

[0057] The carbon dioxide optical fiber sensing structure provided in the embodiment of the present application forms a grating structure 300 by polyethersulfone, which can further increase the response range of the carbon dioxide optical fiber sensing structure, thereby enhancing the detection capability of the carbon dioxide optical fiber sensing structure for high-concentration carbon dioxide gas, and can accurately warn when the concentration of carbon dioxide gas in the environment is high, thereby achieving effective warning and further reducing safety risks.

[0058] For example, in some feasible implementations, the material of the light-transmitting structure 200 includes polyhexamethylene biguanide hydrochloride, and the material of the grating structure 300 includes polyethersulfone.

[0059] By integrating the above two carbon dioxide sensing structures on a single optical fiber body 100, a light-transmitting structure 200 can be formed by polyhexamethylene biguanide hydrochloride, so that the carbon dioxide optical fiber sensing structure has the advantages of high response sensitivity and high response speed, so that it can be applied to the rapid detection of carbon dioxide in a low concentration state at the initial stage of a fire, and play a role in rapid early warning. Further, the grating structure 300 formed by polyethersulfone can make the carbon dioxide optical fiber sensing structure have the advantage of a large response test range, and when the fire influence further spreads and escalates, and the concentration of carbon dioxide gas gradually increases, the re-alarm of the fire emergency level can be realized, so that the requirements for high sensitivity and a large range in the carbon dioxide monitoring process can be taken into account, and the effect of comprehensive early warning for different development stages of the fire scene can be achieved, and the monitoring effect and monitoring quality of carbon dioxide can be further improved, so as to realize timely warning, thereby reducing safety risks and protecting the safety of life and property.

[0060] like Figure 1 As shown, in some feasible implementations, the surface of the light-transmitting structure 200 away from the first end surface includes a curved surface.

[0061] The carbon dioxide optical fiber sensing structure provided in the embodiment of the present application can enhance the reflective ability of the surface of the light-transmitting structure 200 away from the first end face for light by setting the surface of the light-transmitting structure 200 away from the first end face as an arc surface, thereby increasing the amount of light incident on the light-transmitting structure 200 and increasing the amount of interference light formed by interference of reflected light, thereby improving the sensitivity of carbon dioxide monitoring and the accuracy of monitoring results, improving the warning efficiency, and further reducing safety risks.

[0062] like Figure 3 As shown, Figure 3A schematic structural diagram of a carbon dioxide optical fiber sensor provided in an embodiment of the present application. In a second aspect of the embodiment of the present application, a carbon dioxide optical fiber sensor is provided, comprising: a carbon dioxide optical fiber sensing structure 1000 according to any one of the first aspects above, a detection unit 2000 and an alarm unit 3000. The detection unit 2000 is used to determine the concentration of carbon dioxide gas in the gas environment where the carbon dioxide optical fiber sensing structure 1000 is located according to at least one of the phase of the light emitted by the optical fiber body 100 in the carbon dioxide optical fiber sensing structure 1000 at the second end face and the wavelength of the grating structure 300 in the carbon dioxide optical fiber sensing structure 1000; the alarm unit 300 is used to generate alarm information according to the concentration of carbon dioxide gas, and the input end of the alarm unit 3000 is electrically connected to the output end of the detection unit 2000.

[0063] Exemplarily, the alarm information may include the concentration of carbon dioxide gas in the gas environment, the number of alarms, and the speed of change of the concentration of carbon dioxide gas in the gas environment. The alarm unit 3000 may be used for sound and light alarms, and the alarm unit 3000 may be used for networking to send alarm information to management personnel according to the concentration of carbon dioxide gas in the gas environment.

[0064] The carbon dioxide optical fiber sensor provided by the embodiment of the present application can make the light incident on the second end face of the optical fiber body 100 be reflected by the first end face of the light-transmitting structure 200 and the surface of the light-transmitting structure 200 away from the first end face, so as to obtain two beams of reflected light. When the two beams of reflected light are incident on the optical fiber body 100, interference occurs inside the optical fiber, so that when the concentration of carbon dioxide gas in the external environment changes, the refractive index of the light-transmitting structure 200 can be changed, and the amount of light reflected by the surface of the light-transmitting structure 200 away from the first end face can be changed, and the phase of the interference light can be changed, so that the concentration of carbon dioxide can be determined by the detection unit 2000 according to the interference spectrum of the interference light. At the same time, by setting the grating structure 300 inside the optical fiber body 100, the period of the grating structure 300 changes with the change of the concentration of carbon dioxide gas, and the wavelength of the grating structure 300 is further changed, so that the concentration of carbon dioxide can be determined by the detection unit 2000 according to the change of the wavelength of the grating structure 300. Therefore, by integrating two carbon dioxide sensing structures with different detection principles on an optical fiber body 100, it is possible to take into account the requirements of high sensitivity and a large range in the carbon dioxide monitoring process, further improve the monitoring effect and quality of carbon dioxide, so as to facilitate timely alarms through the alarm unit 3000, thereby reducing safety risks and protecting life and property.

[0065] In some feasible embodiments, external light incident through the second end face is reflected by the first end face to obtain a first reflected light, and external light incident through the second end face is reflected by the surface of the light-transmitting structure 200 away from the first end face to obtain a second reflected light, and the first reflected light and the second reflected light interfere with each other inside the optical fiber to form interference light; the detection unit 2000 includes an interference detection unit 2001, and the interference detection unit 2001 is used to obtain an interference spectrum of the interference light, and determine the concentration of carbon dioxide gas in the gas environment according to the drift amplitude of the interference peak and the interference trough on the interference spectrum.

[0066] It should be noted that when the phase of the interference light changes, the interference spectrum of the interference light can be obtained through the interference spectrometer, and the phase shift amplitude of the interference light can be determined by detecting the change in the difference between the interference peak and the interference trough of the interference spectrum. Therefore, the concentration of carbon dioxide gas in the gas environment can be determined by detecting the phase change of the light emitted from the second end face of the optical fiber body 100.

[0067] Exemplarily, the input end of the interference detection unit 2001 is used to receive the light emitted from the second end face of the optical fiber body 100 , and the output end of the interference detection unit 2001 is electrically connected to the alarm unit 3000 .

[0068] The carbon dioxide fiber optic sensor provided in the embodiment of the present application can realize quantitative monitoring of the concentration of carbon dioxide gas through the interference detection unit 2001, which can improve the accuracy of carbon dioxide gas concentration detection and further improve the warning effect of the carbon dioxide fiber optic sensor.

[0069] In some feasible implementations, the detection unit 2000 includes a grating detection unit 2002 , and the grating detection unit 2002 is used to determine the concentration of carbon dioxide gas in the gas environment according to the drift amplitude of the wavelength of the grating structure 300 .

[0070] Exemplarily, the input end of the grating detection unit 2002 is used to receive the diffracted light of the grating 300 , and the output end of the grating detection unit 2002 is electrically connected to the alarm unit 3000 .

[0071] It should be noted that when the grating structure 300 expands in a carbon dioxide environment, the period of the grating structure 300 will form a corresponding stretching change, which will further cause the wavelength of the grating structure 300 to change. Therefore, by obtaining the wavelength change of the grating structure 300, the drift amplitude of the wavelength of the grating structure 300 can be determined, and thus the concentration of carbon dioxide gas in the gas environment can be determined.

[0072] The carbon dioxide optical fiber sensor provided in the embodiment of the present application can realize quantitative monitoring of the concentration of carbon dioxide gas through the grating detection unit 2002, which can improve the accuracy of carbon dioxide gas concentration detection and further improve the warning effect of the carbon dioxide optical fiber sensor.

[0073] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0074] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features of the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A carbon dioxide optical fiber sensing structure, characterized in that: include: An optical fiber body, wherein in an extending direction of the optical fiber body, the optical fiber body comprises a first end face and a second end face; A light-transmitting structure, wherein the light-transmitting structure is connected to the first end face of the optical fiber body, external light is incident on the light-transmitting structure through the second end face, and the refractive index of the light-transmitting structure is related to the concentration of carbon dioxide gas in the gas environment; A grating structure is located inside the optical fiber body, and a period of the grating structure is related to the concentration of carbon dioxide gas in the gas environment.

2. The carbon dioxide optical fiber sensing structure according to claim 1, characterized in that: The optical fiber body comprises an optical fiber cladding layer and an optical fiber core, and the optical fiber cladding layer is arranged around the circumference of the optical fiber core; The orthographic projection of the light-transmitting structure toward the first end surface covers the orthographic projection of the optical fiber core toward the first end surface.

3. The carbon dioxide optical fiber sensing structure according to claim 2, characterized in that: An orthographic projection edge of the optical fiber coating layer toward the first end surface coincides with an orthographic projection edge of the light-transmitting structure toward the first end surface.

4. The carbon dioxide optical fiber sensing structure according to claim 1, characterized in that: The optical fiber body comprises an optical fiber cladding layer and an optical fiber core, and the optical fiber cladding layer is arranged around the circumference of the optical fiber core; The optical fiber core includes a first optical fiber core and a second optical fiber core, and two ends of the grating structure are connected to the first optical fiber core and the second optical fiber core respectively.

5. The carbon dioxide optical fiber sensing structure according to claim 1, characterized in that: The material of the light-transmitting structure at least includes polyhexamethylene biguanide hydrochloride.

6. The carbon dioxide optical fiber sensing structure according to claim 1, characterized in that: The material of the grating structure at least includes polyethersulfone.

7. The carbon dioxide optical fiber sensing structure according to claim 1, characterized in that: A surface of the light-transmitting structure away from the first end surface includes an arc-shaped surface.

8. A carbon dioxide optical fiber sensor, characterized in that: include: The carbon dioxide optical fiber sensing structure according to any one of claims 1 to 7; a detection unit, the detection unit being used to determine the concentration of carbon dioxide gas in the gas environment where the carbon dioxide optical fiber sensing structure is located according to at least one of the phase of light emitted from the optical fiber body in the carbon dioxide optical fiber sensing structure at the second end face and the wavelength of the grating structure in the carbon dioxide optical fiber sensing structure; An alarm unit is used to generate alarm information according to the concentration of the carbon dioxide gas, and an input end of the alarm unit is electrically connected to an output end of the detection unit.

9. The carbon dioxide optical fiber sensing structure according to claim 8, characterized in that: External light incident through the second end face is reflected by the first end face to obtain a first reflected light, and the external light incident through the second end face is reflected by a surface of the light-transmitting structure on a side away from the first end face to obtain a second reflected light, and the first reflected light and the second reflected light interfere with each other inside the optical fiber to form interference light; The detection unit includes an interference detection unit, which is used to obtain an interference spectrum of the interference light and determine the concentration of carbon dioxide gas in the gas environment according to the drift amplitude of the interference peak and the interference trough on the interference spectrum.

10. The carbon dioxide optical fiber sensing structure according to claim 8, characterized in that: The detection unit comprises a grating detection unit, and the grating detection unit is used to determine the concentration of carbon dioxide gas in the gas environment according to the drift amplitude of the wavelength of the grating structure.

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