Gas concentration sensing system and gas concentration detection method

Abstract

The invention relates to a gas concentration sensing system and a gas concentration detection method. The system comprises a plurality of graphene tilted fiber bragg gratings, each graphene tilted fiber bragg grating is composed of a tilted fiber bragg grating and single-layer graphene, and the single-layer graphene is attached to a grating area of the tilted fiber bragg grating; the wide-spectrum light source is used for generating wide-spectrum light and inputting the wide-spectrum light into the plurality of graphene tilted fiber gratings; the spectrum analyzer is used for carrying out spectrum analysis on the light transmitted by each of the plurality of graphene tilted fiber gratings to obtain spectrum analysis results corresponding to each of the plurality of graphene tilted fiber gratings; and the demodulation system is used for acquiring the spectral analysis results corresponding to the plurality of graphene tilted fiber bragg gratings sent by the spectrum analyzer, and calculating the gas concentrations of the plurality of preset gases based on the spectral analysis results. By adopting the system, the gas concentrations of various gases can be measured at the same time.

Description

Technical Field

[0001] The present application relates to the technical field of gas concentration detection, and in particular to a gas concentration sensing system and a gas concentration detection method. Background Art

[0002] As one of the current frontiers of science and technology, sensing technology is not only an important pillar of the modern information industry, but also a key driving force for technological innovation. It has great application potential in various industries and is widely regarded as one of the most promising high-tech technologies at home and abroad. In this field, fiber optic sensing technology has rapidly emerged with its good anti-electromagnetic interference ability and excellent sensing performance, and is highly integrated with the fiber optic transmission system, attracting much attention.

[0003] As an important branch of fiber optic sensing technology, fiber optic gas sensors have shown unique advantages in gas detection. Compared with traditional electrochemical gas sensors, fiber optic gas sensors have faster response speeds and higher sensitivity. With accurate gas detection capabilities and efficient data transmission, they have shown broad application potential in environmental monitoring, industrial safety, and medical diagnosis. The reliability, real-time performance, and adaptability to complex environments of this type of sensor provide strong support for coping with various challenges in the real world.

[0004] At present, fiber optic sensing technology mainly relies on the diversity of devices and demodulation systems to achieve sensing. However, due to the inert characteristics of fiber optic materials, they have difficulty in effectively adsorbing gases. In addition, most of the current sensors are single gas sensors, which are difficult to adapt to the complex gas mixture in the real environment. Therefore, the traditional fiber optic sensing-based gas sensing system cannot measure the gas concentration of multiple gases at the same time. Summary of the invention

[0005] Based on this, it is necessary to provide a gas concentration sensing system and a gas concentration detection method to address the above technical problems, which can simultaneously measure the gas concentrations of multiple gases.

[0006] The present application provides a gas concentration sensing system, comprising:

[0007] A plurality of graphene tilted fiber Bragg gratings, each of which is composed of a tilted fiber Bragg grating and a single layer of graphene, and the single layer of graphene is attached to a grating region of the tilted fiber Bragg grating;

[0008] A broadband light source, used for generating broadband light and inputting it into a plurality of graphene tilted fiber gratings;

[0009] A spectrum analyzer, used for performing spectrum analysis on the light transmitted by each of the multiple graphene tilted fiber gratings to obtain spectrum analysis results corresponding to each of the multiple graphene tilted fiber gratings;

[0010] The demodulation system is used to obtain the spectrum analysis results corresponding to each of the multiple graphene tilted fiber gratings sent by the spectrum analyzer, and calculate the gas concentrations of multiple preset gases based on the spectrum analysis results.

[0011] In one embodiment, the system further comprises a plurality of polarization controllers; the plurality of polarization controllers are connected to the plurality of graphene tilted fiber gratings in a one-to-one correspondence; each polarization controller is used to tune the polarization state of the broadband light when entering the connected graphene tilted fiber grating.

[0012] In one embodiment, the wavelength range of the broadband light source covers the wavelength range of the central wavelength of the resonance peak of the tilted fiber grating.

[0013] In one embodiment, the tilt angles corresponding to the plurality of tilted graphene fiber gratings are different, and the number of the tilted graphene fiber gratings is the same as the number of the types of the preset gases.

[0014] In one of the embodiments, the demodulation system is also used to determine a target cladding mode among multiple cladding modes of each graphene tilted fiber grating; determine the sensitivity coefficient of each graphene tilted fiber grating to multiple preset gases according to the target cladding mode and the tilt angle of each graphene tilted fiber grating; and determine the gas concentrations of multiple preset gases according to the multiple sensitivity coefficients corresponding to the multiple graphene tilted fiber gratings and the corresponding spectral analysis results.

[0015] In one of the embodiments, the spectral analysis result corresponding to each graphene tilted fiber grating includes the resonance peak center wavelength position of the target cladding mode; the demodulation system is also used to determine the wavelength drift according to the resonance peak center wavelength position of the target cladding mode; and determine the gas concentration of multiple preset gases according to multiple sensitivity coefficients corresponding to each of the multiple graphene tilted fiber gratings and their corresponding wavelength drifts.

[0016] In one embodiment, the demodulation system is further used to traverse a plurality of graphene tilted fiber gratings, and for a first graphene tilted fiber grating, determine a target cladding mode of the first graphene tilted fiber grating from a plurality of cladding modes of the first graphene tilted fiber grating;

[0017] For the i-th graphene tilted fiber Bragg grating, multiple candidate cladding modes that are not overlapped with the resonance peaks of the target cladding modes of other graphene tilted fiber Bragg gratings are determined from the multiple cladding modes of the i-th graphene tilted fiber Bragg grating, and the target cladding mode of the i-th graphene tilted fiber Bragg grating is determined from the multiple candidate cladding modes, wherein i is an integer greater than 1.

[0018] The present application provides a gas concentration detection method, the above-mentioned gas concentration sensing system, the method comprises:

[0019] Obtaining spectrum analysis results corresponding to each of a plurality of graphene tilted fiber gratings;

[0020] Based on the spectral analysis results, the gas concentrations of multiple preset gases are calculated.

[0021] In one embodiment, the gas concentrations of multiple preset gases are calculated based on the spectrum analysis results, including:

[0022] determining a target cladding mode among a plurality of cladding modes of each graphene tilted fiber Bragg grating;

[0023] Determine the sensitivity coefficient of each graphene tilted fiber grating to a plurality of preset gases according to the target cladding mode and tilt angle of each graphene tilted fiber grating;

[0024] The gas concentrations of the plurality of preset gases are determined according to the plurality of sensitivity coefficients corresponding to the plurality of graphene tilted fiber gratings and the corresponding spectrum analysis results.

[0025] In one embodiment, the spectrum analysis result corresponding to each graphene tilted fiber grating includes the resonance peak center wavelength position of the target cladding mode; and the gas concentrations of multiple preset gases are determined according to the multiple sensitivity coefficients corresponding to the multiple graphene tilted fiber gratings and the corresponding spectrum analysis results, including:

[0026] Determine the wavelength drift according to the resonance peak center wavelength position of the target cladding mode;

[0027] The gas concentrations of the plurality of preset gases are determined according to the plurality of sensitivity coefficients and the wavelength drifts corresponding to the plurality of graphene tilted fiber gratings.

[0028] The gas concentration sensing system and gas concentration detection method form a graphene tilted fiber Bragg grating by attaching a single layer of graphene to the grating region of a tilted fiber Bragg grating, and utilize the graphene's ability to adsorb gas molecules, which is beneficial to improving the detection accuracy of gas concentration; the adsorption of external gas molecules will change the Fermi level of graphene, and the transmission effects of different gas types and concentrations on graphene are also different, which will lead to the drift of the central wavelength of the tilted fiber Bragg grating cladding mode resonance peak; through a wide-spectrum light source, the shift of the specific cladding mode resonance peak wavelength of multiple graphene tilted fiber Bragg grating devices can be monitored simultaneously, thereby realizing the simultaneous detection of multiple gases. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] FIG1 is a structural diagram of a gas concentration sensor system in one embodiment;

[0031] FIG2 is a schematic diagram of a graphene tilted fiber Bragg grating in one embodiment;

[0032] FIG3 is a transmission spectrum diagram of a graphene tilted fiber Bragg grating generated in one embodiment;

[0033] FIG4 is a schematic diagram of the linear relationship between gas concentration and central wavelength in one embodiment;

[0034] FIG5 is a schematic diagram of a flow chart of a gas concentration detection method in one embodiment;

[0035] FIG6 is a block diagram of a gas concentration detection device in one embodiment;

[0036] FIG. 7 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0038] The gas concentration sensing system provided in the embodiment of the present application can be applied in the application environment as shown in FIG. 1 . The gas concentration sensing system includes a plurality of graphene tilted fiber gratings 101 (the plurality of graphene tilted fiber gratings 101 in the figure include 101A, 101B, and 101C respectively), a broadband light source 102, a spectrum analyzer 103, and a demodulation system 104, wherein the plurality of graphene tilted fiber gratings 101, each of which is composed of a tilted fiber grating and a single layer of graphene, and the single layer of graphene is attached to the grating region of the tilted fiber grating; the broadband light source 102 is used to generate broadband light and input it into the plurality of graphene tilted fiber gratings 101; the spectrum analyzer 103 is used to perform spectrum analysis on the light transmitted by each of the plurality of graphene tilted fiber gratings 101 to obtain spectrum analysis results corresponding to each of the plurality of graphene tilted fiber gratings 101; the demodulation system 104 is used to obtain spectrum analysis results corresponding to each of the plurality of graphene tilted fiber gratings 101 sent by the spectrum analyzer 103, and calculate the gas concentrations of a plurality of preset gases based on the spectrum analysis results.

[0039] Among them, graphene is a two-dimensional lattice nanomaterial. Fiber Bragg grating is a diffraction grating formed by periodically modulating the refractive index of the optical fiber core in the axial direction through a certain method. It is a passive filter device. Fiber Bragg grating achieves wavelength selective reflection or transmission through periodic changes in the refractive index of the optical fiber axial direction. Its main feature is narrowband filtering. Only light that meets specific wavelength conditions will be reflected, and other wavelengths will be transmitted. When the periodic refractive index change area is at a certain angle to the optical fiber axial direction, a tilted fiber Bragg grating is formed. That is, the tilted fiber Bragg grating is made from a single-mode optical fiber using a tilted fiber Bragg grating production device.

[0040] The preparation method of the tilted fiber Bragg grating is as follows: first, remove the cladding of the single-mode fiber, place it in the middle of the instrument, and adjust the angle between the plane where the fiber is located and the operating platform to obtain the required tilt angle. Then, the ultraviolet laser beam output by the laser is vertically irradiated onto the phase mask, and through the mechanism of photoinduced refractive index change, periodic refractive index modulation is generated in the photosensitive fiber that is in contact with or very close to the mask, and finally a tilted fiber Bragg grating is obtained.

[0041] A single layer of graphene is attached to the grating region of the tilted fiber Bragg grating to form a graphene tilted fiber Bragg grating. FIG2 is a schematic diagram of a graphene tilted fiber Bragg grating in an embodiment, wherein a single layer of graphene 201 is attached to the grating region 203 of the tilted fiber Bragg grating 202.

[0042] The single-layer graphene is attached to the grating area of ​​the tilted fiber Bragg grating by wet transfer, so that the transmission spectrum of the tilted fiber Bragg grating can be regulated by graphene. Specifically, first, polymethyl methacrylate (PMMA) is spin-coated on the composite film of the single-layer graphene and copper foil. Then, the composite film is cut to a preset size, for example, 0.5×1.5 cm 2 , and soaked in a 1.5 mol / L ferric chloride solution to remove the copper foil. Then, the remaining composite film is attached to the tilted fiber Bragg grating, and the device is placed in a 60°C acetone solution and allowed to stand until the PMMA is completely removed. Finally, the acetone solution remaining on the device is washed off and dried to obtain a graphene-attached tilted fiber Bragg grating. In some embodiments, the effective interaction area between the device and graphene is about 12×10 -8 m 2 , and finally completed the preparation of graphene tilted fiber Bragg grating devices.

[0043] The broadband light source may be an ASE (Amplified Spontaneous Emission) light source. The broadband light generated by the ASE light source is passed into a plurality of graphene tilted fiber gratings. The light transmitted by the graphene tilted fiber gratings is directly connected to a spectrum analyzer for spectrum analysis.

[0044] In some embodiments, the spectrum analyzer is used to analyze the resonance peak center wavelength position of the selected cladding mode in the graphene tilted fiber Bragg grating, and the spectrum analysis result can be the resonance peak center wavelength position of the selected cladding mode in the graphene tilted fiber Bragg grating. The demodulation system calculates the drift of the center wavelength based on the spectrum analysis result sent by the spectrum analyzer, thereby inversely calculating the gas concentration of multiple preset gases.

[0045] In some embodiments, the preset gas may be a polar gas to ensure the adsorption of the preset gas by graphene, for example, it may be H2S, SO2 and NH3.

[0046] The above-mentioned gas concentration sensing system forms a graphene tilted fiber Bragg grating by attaching a single layer of graphene to the grating area of ​​the tilted fiber Bragg grating, and utilizes the graphene's ability to adsorb gas molecules, which is beneficial to improving the detection accuracy of gas concentration; the adsorption of external gas molecules will change the Fermi level of graphene, and the transmission effects of different gas types and concentrations on graphene are also different, which will lead to the drift of the central wavelength of the tilted fiber Bragg grating cladding mode resonance peak; through a wide-spectrum light source, the shift of the specific cladding mode resonance peak wavelength of multiple graphene tilted fiber Bragg grating devices can be monitored simultaneously, thereby realizing the simultaneous detection of multiple gases.

[0047] In an exemplary embodiment, referring to FIG. 1 , the system further includes a plurality of polarization controllers 105, the plurality of polarization controllers 105 include 105A, 105B and 105C; the plurality of polarization controllers 105 are connected to the plurality of graphene tilted fiber gratings 101 in a one-to-one correspondence; each polarization controller 105 is used to tune the polarization state of broadband light when it enters the connected graphene tilted fiber grating 101.

[0048] The polarization controller can adjust the polarization state of the broadband light when it enters the graphene tilted fiber grating connected to the polarization controller.

[0049] By adjusting the polarization state, the loss in the device and the intensity of the resonance peak of each cladding mode in the reflection spectrum can be adjusted, thereby tuning the reflection spectrum in the device.

[0050] In some embodiments, the system further includes a fiber coupler 106. The broadband light generated by the broadband light source 102 passes through the fiber coupler 106 and a plurality of polarization controllers 105 in sequence, and is injected into a plurality of graphene tilted fiber gratings 101 respectively.

[0051] In this embodiment, since graphene is in contact with the tilted fiber Bragg grating and a polarization controller is used to tune the central wavelength of the resonance peak of the tilted fiber Bragg grating cladding mode, graphene can interact with external gas molecules to further achieve tuning of the central wavelength of the tilted fiber Bragg grating cladding mode.

[0052] In an exemplary embodiment, the wavelength range of the broadband light source covers the wavelength range of the central wavelength of the resonance peak of the tilted fiber grating.

[0053] According to the transmission characteristics of the tilted fiber Bragg grating, only light within its transmission bandwidth can pass through, therefore, the wavelength range of the wide-spectrum light source to be selected should cover the wavelength range of the central wavelength of the resonance peak of the tilted fiber Bragg grating, and the transmission bandwidth of the wide-spectrum light source should cover the transmission bandwidth of the tilted fiber Bragg grating. For example, the central wavelength of the resonance peak of the tilted fiber Bragg grating is 1520nm-1570nm, and the transmission bandwidth is 1-3nm, so that only light within the transmission bandwidth can pass through the tilted fiber Bragg grating, and the wavelength of the ASE light source is 1515nm-1575nm to meet the working wavelength and transmission bandwidth of the tilted fiber Bragg grating.

[0054] In this embodiment, a wide-spectrum light source having a wavelength range that can cover the wavelength range of the central wavelength of the resonance peak of the tilted fiber Bragg grating is selected, which is conducive to ensuring that the wide-spectrum light source meets the working wavelength and transmission bandwidth requirements of the tilted fiber Bragg grating.

[0055] In an exemplary embodiment, the tilt angles corresponding to the plurality of tilted graphene fiber gratings are different, and the number of the tilted graphene fiber gratings is the same as the number of the types of the preset gases.

[0056] Among them, the fiber Bragg grating realizes wavelength selective reflection or transmission through the periodic change of the refractive index in the axial direction of the optical fiber. Its main feature is narrowband filtering. Only light that meets the specific wavelength conditions will be reflected, and other wavelengths will be transmitted. When the periodic change area of ​​the refractive index is at a certain angle to the axial direction of the optical fiber, a tilted fiber Bragg grating is formed, resulting in a coupling effect between different optical fiber modes. This includes the coupling between the forward core mode and the reverse core mode, and the coupling between the forward core mode and the reverse cladding mode and the radiation mode. These coupling effects are affected by the refractive index of the surrounding medium, and the refractive index change can be detected by the movement of the resonance peak in the transmission spectrum. When the gas is adsorbed on the surface of the graphene tilted fiber Bragg grating, its cladding refractive index will change, thereby causing the center wavelength of the resonance peak of the cladding mode in the transmission spectrum of the tilted fiber Bragg grating to shift. At the same time, the shift of the resonance peak is also related to the tilt angle of the tilted fiber Bragg grating, that is, the cladding mode of the tilted fiber Bragg grating with different tilt angles has different sensitivity to the concentration changes of the three gases H2S, SO2 and NH3, and responds differently. Therefore, the multiple graphene tilted fiber Bragg gratings selected in the embodiment of the present application each correspond to a different tilt angle. By selecting a suitable tilt angle, the resonance peak center wavelength can be guaranteed to have the maximum offset, which is beneficial to improve the calculation precision and accuracy of the gas concentration. For example, three tilted fiber gratings with tilt angles of 8°, 6° and 4° are selected as initial devices, and three graphene tilted fiber grating devices are obtained after the above graphene attachment operation.

[0057] In some embodiments, the number of graphene tilted fiber gratings is the same as the number of types of preset gases, so that for concentration detection of multiple preset gases, a corresponding number of graphene tilted fiber gratings can be set.

[0058] In this embodiment, since the offset of the resonance peak is related to the tilt angle of the tilted fiber Bragg grating, by selecting a plurality of tilted fiber Bragg gratings with different tilt angles to prepare a graphene tilted fiber Bragg grating device, it can be ensured that the central wavelength of the resonance peak has the maximum offset degree, which is beneficial to improving the calculation precision and accuracy of the gas concentration; in addition, the number of graphene tilted fiber Bragg gratings is the same as the number of preset gas types, which can ensure gas concentration detection for multiple preset gases.

[0059] In an exemplary embodiment, the demodulation system is also used to determine a target cladding mode among multiple cladding modes of each graphene tilted fiber grating; determine the sensitivity coefficient of each graphene tilted fiber grating to multiple preset gases according to the target cladding mode and tilt angle of each graphene tilted fiber grating; determine the gas concentrations of multiple preset gases according to the multiple sensitivity coefficients corresponding to the multiple graphene tilted fiber gratings and the corresponding spectral analysis results.

[0060] FIG3 is a transmission spectrum diagram of a graphene tilted fiber Bragg grating in one embodiment. As can be seen from the figure, the tilted fiber Bragg grating has multiple cladding modes, and the bandwidth of each cladding mode resonance peak is about 0.5 nm. The demodulation system can determine the target cladding mode among the multiple cladding modes of each graphene tilted fiber Bragg grating, and it should be ensured that the resonance peaks of the multiple target cladding modes are not overlapped.

[0061] The cladding mode of the tilted fiber Bragg grating is more sensitive to changes in the external environment. At the same time, the cladding modes of the tilted fiber Bragg gratings with different tilt angles have different sensitivities to changes in the concentration of the preset gas. Therefore, the sensitivity coefficients of each graphene tilted fiber Bragg grating to a plurality of preset gases can be determined according to the target cladding mode and tilt angle of each graphene tilted fiber Bragg grating. In some embodiments, the mapping relationship between the cladding mode, tilt angle, preset gas type and sensitivity coefficient is pre-stored in the demodulation system. By querying the mapping relationship, the sensitivity coefficients of each graphene tilted fiber Bragg grating to a plurality of preset gases can be determined.

[0062] When the system is used for gas sensing, gas molecules will be adsorbed onto the graphene in the fiber grating region of each device, and the refractive index of the graphene will change accordingly, thereby changing the central wavelength of the resonance peak of each graphene tilted fiber grating. At the same time, since the tilt angles of each graphene tilted fiber grating are different, the responses of each cladding mode to multiple preset gases are different, that is, the changes in the central wavelength are different. Therefore, based on multiple sensitivity coefficients and multiple spectral analysis results, the gas concentrations of multiple preset gases can be calculated.

[0063] In this embodiment, the target cladding mode of each graphene tilted fiber Bragg grating is determined, combined with the tilt angle, to determine the sensitivity coefficients for each of the multiple preset gases, and the gas concentrations of the multiple preset gases are calculated based on the sensitivity coefficients and the spectral analysis results. This method of real-time demodulation and rapid calculation of multi-channel signals can achieve rapid sensing of multiple preset gases.

[0064] In an exemplary embodiment, the spectral analysis results corresponding to each graphene tilted fiber grating include the resonance peak center wavelength position of the target cladding mode; the demodulation system is also used to determine the wavelength drift according to the resonance peak center wavelength position of the target cladding mode; and determine the gas concentrations of multiple preset gases according to the multiple sensitivity coefficients corresponding to each of the multiple graphene tilted fiber gratings and the corresponding wavelength drifts.

[0065] The wavelength drift refers to the change in the center wavelength position of the resonance peak of the target cladding mode. The demodulation system takes the center wavelength position of the resonance peak of the target cladding mode before the transmission of the broad-spectrum light as the initial position, and takes the change in the center wavelength position of the resonance peak of the target cladding mode after the transmission relative to the initial position as the wavelength drift.

[0066] The demodulation system determines the gas concentration of multiple preset gases according to the multiple sensitivity coefficients and wavelength drifts corresponding to the multiple graphene tilted fiber gratings. The following takes the concentration detection of three preset gases (H2S, SO2 and NH3) as an example. Assume that the wavelength drifts corresponding to the three graphene tilted fiber gratings are λ1, λ2, λ3, the sensitivity coefficients of the target cladding mode of the graphene tilted fiber Bragg grating 101A to H2S, SO2 and NH3 are S1, S2, S3 respectively, the sensitivity coefficients of the target cladding mode of the graphene tilted fiber Bragg grating 101B to H2S, SO2 and NH3 are S4, S5, S6 respectively, and the sensitivity coefficients of the target cladding mode of the graphene tilted fiber Bragg grating 101C to H2S, SO2 and NH3 are S7, S8, S9 respectively. The gas concentrations of H2S, SO2 and NH3 are expressed as ρ1, ρ2 and ρ3 respectively. The gas concentrations of each preset gas are solved by the matrix calculation method, and the calculation method is as follows:

[0067]

[0068] FIG4 is a schematic diagram showing the linear relationship between the gas concentration and the central wavelength of the target cladding mode of the graphene tilted fiber Bragg grating device when sensing H2S gas in one embodiment. Since each graphene tilted fiber Bragg grating has a cross-response to the three preset gases, the specific concentrations of the three gases in the gas sensing environment can be obtained by real-time demodulation and calculation of a linear equation group. For a more complex gas environment, the number of graphene tilted fiber Bragg gratings can be increased to obtain the gas concentration of each preset gas by solving the linear equation.

[0069] In this embodiment, by determining the wavelength drift corresponding to the target cladding mode of each graphene tilted fiber grating device, thereby multiple sensitivity coefficients and multiple wavelength drifts, the gas concentration of each preset gas is solved by a matrix calculation method, thereby achieving rapid calculation of multiple gas concentrations and improving the sensing precision and accuracy of gas concentration.

[0070] In an exemplary embodiment, the demodulation system is further used to traverse a plurality of graphene tilted fiber gratings, and for a first graphene tilted fiber grating, determine a target cladding mode of the first graphene tilted fiber grating among a plurality of cladding modes of the first graphene tilted fiber grating;

[0071] For the i-th graphene tilted fiber Bragg grating, multiple candidate cladding modes that are not overlapped with the resonance peaks of the target cladding modes of other graphene tilted fiber Bragg gratings are determined from the multiple cladding modes of the i-th graphene tilted fiber Bragg grating, and the target cladding mode of the i-th graphene tilted fiber Bragg grating is determined from the multiple candidate cladding modes, wherein i is an integer greater than 1.

[0072] Among them, for the selection of the target cladding mode, it should be ensured that the resonance peaks do not intersect each other. For multiple graphene tilted fiber gratings, the target cladding mode should be selected for each graphene tilted fiber grating in turn. For the first graphene tilted fiber grating, any cladding mode can be selected from the multiple cladding modes of the first graphene tilted fiber grating as the target cladding mode of the first graphene tilted fiber grating.

[0073] For the graphene tilted fiber gratings traversed after the first graphene tilted fiber grating, the i-th graphene tilted fiber grating is taken as an example for explanation. From the multiple cladding modes of the i-th graphene tilted fiber grating, multiple candidate cladding modes that do not overlap with the resonance peaks of the target cladding modes of other graphene tilted fiber gratings are determined, and then the target cladding mode of the i-th graphene tilted fiber grating is determined from the multiple candidate cladding modes, so that it can be ensured that the resonance peaks of the i-th graphene tilted fiber grating and the target cladding modes of other graphene tilted fiber gratings are not overlapped.

[0074] In this embodiment, target cladding modes are selected in sequence for multiple graphene tilted fiber gratings, thereby ensuring that the resonance peaks of each target cladding mode are not overlapped, which is beneficial to improving the gas concentration sensing accuracy.

[0075] The gas concentration detection method provided in the embodiment of the present application, as shown in Fig. 5, can be applied to the gas concentration sensing system shown in Fig. 1. Taking the method applied to the demodulation system 104 in the gas concentration sensing system as an example, the method includes the following steps 502 to 504.

[0076] Step 502, obtaining the spectrum analysis results corresponding to each of the plurality of graphene tilted fiber gratings.

[0077] Step 504: Calculate the gas concentrations of the plurality of preset gases based on the spectrum analysis results.

[0078] The spectrum analyzer is used to analyze the resonance peak center wavelength position of the selected cladding mode in the graphene tilted fiber Bragg grating, and the spectrum analysis result can be the resonance peak center wavelength position of the selected cladding mode in the graphene tilted fiber Bragg grating. The demodulation system calculates the drift of the center wavelength based on the spectrum analysis result sent by the spectrum analyzer, and thus inversely calculates the gas concentration of multiple preset gases.

[0079] In some embodiments, the preset gas may be a polar gas to ensure the adsorption of the preset gas by graphene, for example, it may be H2S, SO2 and NH3.

[0080] The above-mentioned gas concentration detection method forms a graphene tilted fiber Bragg grating by attaching a single layer of graphene to the grating area of ​​a tilted fiber Bragg grating, and utilizes the graphene's adsorption ability for gas molecules, which is beneficial to improving the detection accuracy of gas concentration; the adsorption of external gas molecules will change the Fermi level of graphene, and the transmission effects of different gas types and concentrations on graphene are also different, which will lead to the drift of the central wavelength of the tilted fiber Bragg grating cladding mode resonance peak; through a wide-spectrum light source, the shift of the specific cladding mode resonance peak wavelength of multiple graphene tilted fiber Bragg grating devices can be monitored simultaneously, thereby realizing the simultaneous detection of multiple gases.

[0081] In an exemplary embodiment, based on the spectral analysis results, the gas concentrations of multiple preset gases are calculated, including: determining a target cladding mode among multiple cladding modes of each graphene tilted fiber grating; determining the sensitivity coefficient of each graphene tilted fiber grating to the multiple preset gases according to the target cladding mode and the tilt angle of each graphene tilted fiber grating; and determining the gas concentrations of the multiple preset gases according to the multiple sensitivity coefficients corresponding to the multiple graphene tilted fiber gratings and the corresponding spectral analysis results.

[0082] The demodulation system can determine the target cladding mode among the multiple cladding modes of each graphene tilted fiber grating, and it should be ensured that the resonance peaks of the multiple target cladding modes are not overlapped.

[0083] The cladding mode of the tilted fiber Bragg grating is more sensitive to changes in the external environment. At the same time, the cladding modes of the tilted fiber Bragg gratings with different tilt angles have different sensitivities to changes in the concentration of the preset gas. Therefore, the sensitivity coefficients of each graphene tilted fiber Bragg grating to a plurality of preset gases can be determined according to the target cladding mode and tilt angle of each graphene tilted fiber Bragg grating. In some embodiments, the mapping relationship between the cladding mode, tilt angle, preset gas type and sensitivity coefficient is pre-stored in the demodulation system. By querying the mapping relationship, the sensitivity coefficients of each graphene tilted fiber Bragg grating to a plurality of preset gases can be determined.

[0084] When the system is used for gas sensing, gas molecules will be adsorbed onto the graphene in the fiber grating region of each device, and the refractive index of the graphene will change accordingly, thereby changing the central wavelength of the resonance peak of each graphene tilted fiber grating. At the same time, since the tilt angles of each graphene tilted fiber grating are different, the responses of each cladding mode to multiple preset gases are different, that is, the changes in the central wavelength are different. Therefore, based on multiple sensitivity coefficients and multiple spectral analysis results, the gas concentrations of multiple preset gases can be calculated.

[0085] In this embodiment, the target cladding mode of each graphene tilted fiber Bragg grating is determined, combined with the tilt angle, to determine the sensitivity coefficients for each of the multiple preset gases, and the gas concentrations of the multiple preset gases are calculated based on the sensitivity coefficients and the spectral analysis results. This method of real-time demodulation and rapid calculation of multi-channel signals can achieve rapid sensing of multiple preset gases.

[0086] In an exemplary embodiment, the spectral analysis result corresponding to each graphene tilted fiber grating includes the resonance peak center wavelength position of the target cladding mode; the gas concentrations of multiple preset gases are determined according to the multiple sensitivity coefficients corresponding to the multiple graphene tilted fiber gratings and the corresponding spectral analysis results, including: determining the wavelength drift according to the resonance peak center wavelength position of the target cladding mode; determining the gas concentrations of multiple preset gases according to the multiple sensitivity coefficients corresponding to the multiple graphene tilted fiber gratings and the corresponding wavelength drift.

[0087] The wavelength drift refers to the change in the center wavelength position of the resonance peak of the target cladding mode. The demodulation system takes the center wavelength position of the resonance peak of the target cladding mode before the transmission of the broad-spectrum light as the initial position, and takes the change in the center wavelength position of the resonance peak of the target cladding mode after the transmission relative to the initial position as the wavelength drift.

[0088] The demodulation system determines the gas concentration of multiple preset gases according to the multiple sensitivity coefficients and wavelength drifts corresponding to the multiple graphene tilted fiber gratings. The following takes the concentration detection of three preset gases (H2S, SO2 and NH3) as an example. Assume that the wavelength drifts corresponding to the three graphene tilted fiber gratings are λ1, λ2, λ3, the sensitivity coefficients of the target cladding mode of the graphene tilted fiber Bragg grating 101A to H2S, SO2 and NH3 are S1, S2, S3 respectively, the sensitivity coefficients of the target cladding mode of the graphene tilted fiber Bragg grating 101B to H2S, SO2 and NH3 are S4, S5, S6 respectively, and the sensitivity coefficients of the target cladding mode of the graphene tilted fiber Bragg grating 101C to H2S, SO2 and NH3 are S7, S8, S9 respectively. The gas concentrations of H2S, SO2 and NH3 are expressed as ρ1, ρ2 and ρ3 respectively. The gas concentrations of each preset gas are solved by the matrix calculation method, and the calculation method is as follows:

[0089]

[0090] Referring to Figure 4, since each graphene tilted fiber Bragg grating has a cross-response to the three preset gases, the specific concentrations of the three gases in the gas sensing environment can be obtained through real-time demodulation and calculation of a linear equation group. For a more complex gas environment, the number of graphene tilted fiber Bragg gratings can be increased to obtain the gas concentration of each preset gas by solving the linear equation.

[0091] In this embodiment, by determining the wavelength drift corresponding to the target cladding mode of each graphene tilted fiber grating device, thereby multiple sensitivity coefficients and multiple wavelength drifts, the gas concentration of each preset gas is solved by a matrix calculation method, thereby achieving rapid calculation of multiple gas concentrations and improving the sensing precision and accuracy of gas concentration.

[0092] In an exemplary embodiment, determining a target cladding mode among a plurality of cladding modes of each tilted graphene fiber grating comprises:

[0093] Traversing multiple graphene tilted fiber Bragg gratings, and determining a target cladding mode of the first graphene tilted fiber Bragg grating from multiple cladding modes of the first graphene tilted fiber Bragg grating for the first graphene tilted fiber Bragg grating;

[0094] For the i-th graphene tilted fiber Bragg grating, multiple candidate cladding modes that are not overlapped with the resonance peaks of the target cladding modes of other graphene tilted fiber Bragg gratings are determined from the multiple cladding modes of the i-th graphene tilted fiber Bragg grating, and the target cladding mode of the i-th graphene tilted fiber Bragg grating is determined from the multiple candidate cladding modes, wherein i is an integer greater than 1.

[0095] Among them, for the selection of the target cladding mode, it should be ensured that the resonance peaks do not intersect each other. For multiple graphene tilted fiber gratings, the target cladding mode should be selected for each graphene tilted fiber grating in turn. For the first graphene tilted fiber grating, any cladding mode can be selected from the multiple cladding modes of the first graphene tilted fiber grating as the target cladding mode of the first graphene tilted fiber grating.

[0096] For the graphene tilted fiber gratings traversed after the first graphene tilted fiber grating, the i-th graphene tilted fiber grating is taken as an example for explanation. From the multiple cladding modes of the i-th graphene tilted fiber grating, multiple candidate cladding modes that do not overlap with the resonance peaks of the target cladding modes of other graphene tilted fiber gratings are determined, and then the target cladding mode of the i-th graphene tilted fiber grating is determined from the multiple candidate cladding modes, so that it can be ensured that the resonance peaks of the i-th graphene tilted fiber grating and the target cladding modes of other graphene tilted fiber gratings are not overlapped.

[0097] In this embodiment, target cladding modes are selected in sequence for multiple graphene tilted fiber gratings, thereby ensuring that the resonance peaks of each target cladding mode are not overlapped, which is beneficial to improving the gas concentration sensing accuracy.

[0098] To explain the gas concentration sensing system, gas concentration detection method and effect in detail, the following is a most detailed embodiment:

[0099] The gas concentration sensing system includes multiple graphene tilted fiber gratings, a broadband light source, a fiber coupler, a polarization controller, a spectrum analyzer and a demodulation system.

[0100] The graphene tilted fiber Bragg grating is composed of a tilted fiber Bragg grating and a single layer of graphene. The tilted fiber Bragg grating is made from a single-mode optical fiber using a tilted fiber Bragg grating production device. The single layer of graphene is attached to the grating region of the tilted fiber Bragg grating by wet transfer, so that the transmission spectrum of the tilted fiber Bragg grating can be regulated by graphene.

[0101] The broadband light source generates broadband light, which passes through the optical fiber coupler and the polarization controller in turn and enters into a plurality of graphene tilted fiber gratings. The light transmitted by the graphene tilted fiber gratings is directly connected to the spectrum analyzer for spectrum analysis.

[0102] The polarization controller is used to tune the polarization state of the broadband light when it enters each tilted fiber grating, thereby tuning the reflection spectrum in the device.

[0103] The spectrum analyzer is used to analyze the position of the resonance peak center wavelength of the selected cladding mode of the graphene tilted fiber grating.

[0104] The demodulation system is used to obtain the spectral analysis results corresponding to each of the multiple graphene tilted fiber gratings sent by the spectrum analyzer, that is, the position of the central wavelength of the resonance peak, and calculate the wavelength drift based on the spectral analysis results, thereby inversely calculating the gas concentration of multiple preset gases.

[0105] For example, the central wavelength of the selected tilted fiber grating resonance peak may be 1520 nm-1570 nm, and the transmission bandwidth may be 1-3 nm, so that only light within the transmission bandwidth can pass through the tilted fiber grating.

[0106] Exemplarily, the wavelength of the broadband light source is 1515 nm-1575 nm to meet the working wavelength and transmission bandwidth of the tilted fiber grating.

[0107] For example, three tilted fiber Bragg gratings with tilt angles of 8°, 6° and 4° were selected as initial devices. After the above operations, three graphene tilted fiber Bragg grating devices were obtained, and a fiber gas sensing system was formed through a coupler and a polarization controller. H2S, SO2 and NH3 were selected as preset gases, and the obtained gas sensing system was placed in an environment where gas sensing was required. The light generated by the broadband light source was injected into the device after passing through the fiber coupler and polarization controller.

[0108] The demodulation system is further used to determine a target cladding mode from among multiple cladding modes of each graphene tilted fiber grating. Specifically, the multiple graphene tilted fiber gratings are traversed, and for the first graphene tilted fiber grating, the target cladding mode of the first graphene tilted fiber grating is determined from among multiple cladding modes of the first graphene tilted fiber grating; for the i-th graphene tilted fiber grating, multiple candidate cladding modes whose resonance peaks are not overlapped with the target cladding modes of other graphene tilted fiber gratings are determined from among the multiple cladding modes of the i-th graphene tilted fiber grating, and the target cladding mode of the i-th graphene tilted fiber grating is determined from among the multiple candidate cladding modes, wherein i is an integer greater than 1.

[0109] The calculation method of the gas concentration of multiple preset gases is as follows, taking the concentration detection of three preset gases (H2S, SO2 and NH3) as an example for explanation. Assume that the wavelength drifts corresponding to the three graphene tilted fiber gratings are λ1, λ2, λ3, the sensitivity coefficients of the target cladding mode of the graphene tilted fiber Bragg grating 101A to H2S, SO2 and NH3 are S1, S2, S3 respectively, the sensitivity coefficients of the target cladding mode of the graphene tilted fiber Bragg grating 101B to H2S, SO2 and NH3 are S4, S5, S6 respectively, and the sensitivity coefficients of the target cladding mode of the graphene tilted fiber Bragg grating 101C to H2S, SO2 and NH3 are S7, S8, S9 respectively. The gas concentrations of H2S, SO2 and NH3 are expressed as ρ1, ρ2 and ρ3 respectively. The gas concentrations of each preset gas are solved by the matrix calculation method, and the calculation method is as follows:

[0110]

[0111] Since graphene is in contact with the tilted fiber Bragg grating, the central wavelength of the resonance peak of the tilted fiber Bragg grating cladding mode is tuned. Moreover, graphene can interact with external gas molecules to further tune the central wavelength of the tilted fiber Bragg grating cladding mode. The gas concentration sensing system is based on the sensing principle of graphene tilted fiber Bragg grating. The system is composed of tilted fiber Bragg grating devices. Graphene is attached to the grating area, which effectively tunes the central wavelength of the resonance peak of the tilted fiber Bragg grating cladding mode. The tuning effect of graphene is affected by its Fermi level. The adsorption of external gas molecules will change the Fermi level of graphene. Different gas types and concentrations have different effects on it, which leads to the drift of the central wavelength of the resonance peak of the tilted fiber Bragg grating cladding mode. Through a wide-spectrum light source, the shift of the specific cladding mode resonance peak wavelength of multiple graphene tilted fiber Bragg grating devices can be monitored simultaneously, so that the real-time sensing of multiple gases can be realized by using equation calculation.

[0112] In summary, the combination of graphene and tilted fiber Bragg gratings uses a new structure to realize a low-cost, easy-to-operate and easy-to-integrate fiber gas sensing system that can detect multiple gases at the same time. Combining the optoelectronics of two-dimensional materials, fiber microstructure processing technology, the central wavelength control principle of tilted fiber Bragg gratings, and gas sensing technology, it successfully solves the problems of complex operation and difficulty in multi-component gas detection of existing fiber optic gas sensing systems, and contributes new ideas and application potential for the further development of the field of gas sensing.

[0113] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0114] Based on the same inventive concept, the embodiment of the present application also provides a gas concentration detection device for implementing the gas concentration detection method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more gas concentration detection device embodiments provided below can refer to the limitations of the gas concentration detection method above, and will not be repeated here.

[0115] In an exemplary embodiment, as shown in FIG6 , a gas concentration detection device 600 is provided, including: an acquisition module 620 and a calculation module 640, wherein:

[0116] An acquisition module 620 is used to acquire spectrum analysis results corresponding to each of the plurality of graphene tilted fiber gratings;

[0117] The calculation module 640 is used to calculate the gas concentration of multiple preset gases based on the spectrum analysis result.

[0118] The above-mentioned gas concentration detection device forms a graphene tilted fiber Bragg grating by attaching a single layer of graphene to the grating area of ​​the tilted fiber Bragg grating, and utilizes the adsorption ability of graphene to gas molecules, which is beneficial to improving the detection accuracy of gas concentration; the wide-spectrum light generated by the wide-spectrum light source is transmitted through multiple graphene tilted fiber Bragg gratings respectively. Since the sensitivity of the graphene tilted fiber Bragg grating to gases of different types and concentrations is different, the wavelength drift of the transmitted light is different. Therefore, the light transmitted by each of the multiple graphene tilted fiber Bragg gratings is spectrally analyzed by a spectrum analyzer. Based on the spectral analysis results, the gas concentrations of multiple preset gases can be calculated, thereby realizing simultaneous detection of multiple gas concentrations.

[0119] In one embodiment, based on the spectral analysis results, the gas concentrations of multiple preset gases are calculated, and the calculation module 640 is also used to: determine the target cladding mode among the multiple cladding modes of each graphene tilted fiber grating; determine the sensitivity coefficient of each graphene tilted fiber grating to the multiple preset gases according to the target cladding mode and the tilt angle of each graphene tilted fiber grating; determine the gas concentrations of the multiple preset gases according to the multiple sensitivity coefficients corresponding to the multiple graphene tilted fiber gratings and the corresponding spectral analysis results.

[0120] In one embodiment, the spectral analysis result corresponding to each graphene tilted fiber grating includes the resonance peak center wavelength position of the target cladding mode; the gas concentrations of multiple preset gases are determined according to the multiple sensitivity coefficients corresponding to the multiple graphene tilted fiber gratings and the corresponding spectral analysis results. The calculation module 640 is also used to: determine the wavelength drift according to the resonance peak center wavelength position of the target cladding mode; determine the gas concentrations of multiple preset gases according to the multiple sensitivity coefficients corresponding to the multiple graphene tilted fiber gratings and the corresponding wavelength drift.

[0121] In one embodiment, a target cladding mode is determined from among multiple cladding modes of each graphene tilted fiber grating, and the calculation module 640 is further used to: traverse multiple graphene tilted fiber gratings, and for a first graphene tilted fiber grating, determine the target cladding mode of the first graphene tilted fiber grating from among multiple cladding modes of the first graphene tilted fiber grating; for the i-th graphene tilted fiber grating, determine from among the multiple cladding modes of the i-th graphene tilted fiber grating, multiple candidate cladding modes that are not overlapped with the resonance peaks of the target cladding modes of other graphene tilted fiber gratings, and determine the target cladding mode of the i-th graphene tilted fiber grating from among the multiple candidate cladding modes, wherein i is an integer greater than 1.

[0122] Each module in the above-mentioned gas concentration detection device can be implemented in whole or in part by software, hardware and a combination thereof. Each of the above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory in the computer device in the form of software, so that the processor can call and execute the corresponding operations of each of the above modules.

[0123] In an exemplary embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be shown in FIG7. The computer device includes a processor, a memory, an input / output interface, a communication interface, a display unit, and an input device. The processor, the memory, and the input / output interface are connected via a system bus, and the communication interface, the display unit, and the input device are connected to the system bus via the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner may be implemented through WIFI, a mobile cellular network, near field communication (NFC) or other technologies. When the computer program is executed by the processor, a gas concentration detection method is implemented. The display unit of the computer device is used to form a visually visible picture, which may be a display screen, a projection device, or a virtual reality imaging device. The display screen can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad set on the computer device shell, or an external keyboard, touchpad or mouse.

[0124] Those skilled in the art will understand that the structure shown in FIG. 7 is merely a block diagram of a partial structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different arrangement of components.

[0125] In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0126] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0127] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0128] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0129] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., but are not limited to this.

[0130] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above 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 application.

[0131] 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 understood as limiting the scope of the present 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 present application shall be subject to the attached claims.

Claims

1. A gas concentration sensing system, characterized in that: The system comprises: A plurality of graphene tilted fiber Bragg gratings, each of which is composed of a tilted fiber Bragg grating and a single layer of graphene, wherein the single layer of graphene is attached to a grating region of the tilted fiber Bragg grating; A broadband light source, used for generating broadband light and inputting it into a plurality of graphene tilted fiber gratings; A spectrum analyzer, used for performing spectrum analysis on the light transmitted by each of the multiple graphene tilted fiber gratings to obtain spectrum analysis results corresponding to each of the multiple graphene tilted fiber gratings; The demodulation system is used to obtain the spectrum analysis results corresponding to each of the multiple graphene tilted fiber gratings sent by the spectrum analyzer, and calculate the gas concentrations of multiple preset gases based on the spectrum analysis results.

2. The system according to claim 1, characterized in that The system also includes a plurality of polarization controllers; the plurality of polarization controllers are connected to a plurality of graphene tilted fiber gratings in a one-to-one correspondence; each polarization controller is used to tune the polarization state of the broadband light when entering the connected graphene tilted fiber grating.

3. The system according to claim 1, characterized in that The wavelength range of the wide-spectrum light source covers the wavelength range of the central wavelength of the resonance peak of the tilted fiber grating.

4. The system according to claim 1, characterized in that The tilt angles corresponding to the plurality of tilted graphene fiber gratings are different, and the number of the tilted graphene fiber gratings is the same as the number of the types of the preset gases.

5. The system according to claim 1, characterized in that The demodulation system is also used to determine a target cladding mode among multiple cladding modes of each graphene tilted fiber grating; determine the sensitivity coefficient of each graphene tilted fiber grating to multiple preset gases according to the target cladding mode and the tilt angle of each graphene tilted fiber grating; and determine the gas concentrations of multiple preset gases according to the multiple sensitivity coefficients corresponding to the multiple graphene tilted fiber gratings and the corresponding spectral analysis results.

6. The system according to claim 5, characterized in that The spectral analysis result corresponding to each graphene tilted fiber grating includes the resonance peak center wavelength position of the target cladding mode; the demodulation system is also used to determine the wavelength drift according to the resonance peak center wavelength position of the target cladding mode; and determine the gas concentration of multiple preset gases according to the multiple sensitivity coefficients corresponding to each of the multiple graphene tilted fiber gratings and the corresponding wavelength drifts.

7. The system according to claim 5, characterized in that The demodulation system is also used to traverse multiple graphene tilted fiber gratings, and for a first graphene tilted fiber grating, determine a target cladding mode of the first graphene tilted fiber grating among multiple cladding modes of the first graphene tilted fiber grating; For the i-th graphene tilted fiber grating, multiple candidate cladding modes that are not overlapped with the resonance peaks of the target cladding modes of other graphene tilted fiber gratings are determined from the multiple cladding modes of the i-th graphene tilted fiber grating, and the target cladding mode of the i-th graphene tilted fiber grating is determined from the multiple candidate cladding modes, wherein i is an integer greater than 1.

8. A gas concentration detection method, characterized in that: Applied to the gas concentration sensing system according to claims 1-7, the method comprises: Obtaining spectrum analysis results corresponding to each of a plurality of graphene tilted fiber gratings; Based on the spectrum analysis results, the gas concentrations of the plurality of preset gases are calculated.

9. The method according to claim 8, characterized in that The calculating the gas concentrations of a plurality of preset gases based on the spectral analysis results includes: determining a target cladding mode among a plurality of cladding modes of each graphene tilted fiber Bragg grating; Determine the sensitivity coefficient of each graphene tilted fiber grating to a plurality of preset gases according to the target cladding mode and tilt angle of each graphene tilted fiber grating; The gas concentrations of the plurality of preset gases are determined according to the plurality of sensitivity coefficients corresponding to the plurality of graphene tilted fiber gratings and the corresponding spectrum analysis results.

10. The method according to claim 9, characterized in that The spectrum analysis result corresponding to each graphene tilted fiber grating includes the resonance peak center wavelength position of the target cladding mode; the gas concentrations of multiple preset gases are determined according to the multiple sensitivity coefficients corresponding to the multiple graphene tilted fiber gratings and the corresponding spectrum analysis results, including: Determining the wavelength drift according to the resonance peak center wavelength position of the target cladding mode; The gas concentrations of the plurality of preset gases are determined according to the plurality of sensitivity coefficients and the wavelength drifts corresponding to the plurality of graphene tilted fiber gratings.

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