Gas concentration sensing system and gas concentration detection method

Abstract

The application 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 being composed of a tilted fiber Bragg grating and a single-layer graphene, the single-layer graphene being attached to a grating area of the tilted fiber Bragg grating; a wide-spectrum light source for generating wide-spectrum light and inputting the wide-spectrum light into the plurality of graphene tilted fiber Bragg gratings; a spectrum analyzer for performing spectrum analysis on light transmitted by the plurality of graphene tilted fiber Bragg gratings respectively to obtain spectrum analysis results corresponding to the plurality of graphene tilted fiber Bragg gratings respectively; and a demodulation system for acquiring the spectrum analysis results corresponding to the plurality of graphene tilted fiber Bragg gratings respectively sent by the spectrum analyzer and calculating gas concentrations of a plurality of preset gases based on the spectrum analysis results. The system can be used for simultaneously measuring gas concentrations of a plurality of gases.

Description

Technical Field

[0001] This application relates to the field of gas concentration detection technology, and in particular to a gas concentration sensing system and a gas concentration detection method. Background Technology

[0002] Sensing technology, as one of the cutting-edge technologies today, is not only a crucial pillar of the modern information industry but also a key driving force for technological innovation. It possesses enormous application potential across various industries and is widely considered one of the most promising high-tech fields both domestically and internationally. In this field, fiber optic sensing technology has rapidly emerged due to its excellent resistance to electromagnetic interference and outstanding sensing performance, and its high integration with fiber optic transmission systems has garnered significant attention.

[0003] As an important branch of fiber optic sensing technology, fiber optic gas sensors exhibit unique advantages in gas detection. Compared with traditional electrochemical gas sensors, fiber optic gas sensors offer faster response times and higher sensitivity. With their precise gas detection capabilities and efficient data transmission, they demonstrate broad application potential in fields such as environmental monitoring, industrial safety, and medical diagnostics. The reliability, real-time performance, and adaptability to complex environments of these sensors provide strong support for addressing various real-world challenges.

[0004] Currently, fiber optic sensing technology primarily relies on the diversity of devices and demodulation systems to achieve sensing. However, due to the inert nature of fiber optic materials, they face difficulties in effectively adsorbing gases. Furthermore, most current sensors are single-gas sensors, making it difficult to adapt to the complex gas mixtures in real-world environments. Therefore, traditional fiber optic-based gas sensing systems cannot simultaneously measure the concentrations of multiple gases. Summary of the Invention

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

[0006] This application provides a gas concentration sensing system, including:

[0007] Multiple graphene tilted fiber gratings, each graphene tilted fiber grating is composed of a tilted fiber grating and a single layer of graphene, with the single layer of graphene attached to the grating area of ​​the tilted fiber grating.

[0008] A broadband light source is used to generate broadband light and input it into multiple graphene tilted fiber gratings;

[0009] A spectrometer is used to perform spectral analysis on the light transmitted by multiple graphene tilted fiber gratings to obtain the spectral analysis results corresponding to each graphene tilted fiber grating.

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

[0011] In one embodiment, the system further includes multiple polarization controllers; the multiple polarization controllers are connected one-to-one with multiple graphene tilted fiber gratings; each polarization controller is used to tune the polarization state of broadband light when it enters the connected graphene tilted fiber grating.

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

[0013] In one embodiment, the multiple graphene tilted fiber gratings each have a different tilt angle, and the number of the graphene tilted fiber gratings is the same as the number of types of the preset gas.

[0014] In one embodiment, the demodulation system is further configured 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 based on the target cladding mode and tilt angle of each graphene tilted fiber grating; and determine the gas concentration of multiple preset gases based on the multiple sensitivity coefficients corresponding to each of the multiple graphene tilted fiber gratings and their corresponding spectral analysis results.

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

[0016] In one embodiment, the demodulation system is further configured to traverse multiple graphene tilted fiber gratings and, for the first graphene tilted fiber grating, determine the target cladding mode of the first graphene tilted fiber grating among multiple cladding modes of the first graphene tilted fiber grating.

[0017] For the i-th graphene tilted fiber grating, from the multiple cladding modes of the i-th graphene tilted fiber grating, determine multiple candidate cladding modes whose resonance peaks do not overlap with 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 the multiple candidate cladding modes, where i is an integer greater than 1.

[0018] This application provides a gas concentration detection method, comprising the above-mentioned gas concentration sensing system and the method including:

[0019] Obtain the spectral analysis results corresponding to each of the multiple graphene tilted fiber Bragg gratings;

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

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

[0022] The target cladding mode is determined among multiple cladding modes in each graphene tilted fiber grating;

[0023] Based on the target cladding mode and tilt angle of each graphene tilted fiber grating, the sensitivity coefficient of each graphene tilted fiber grating to a variety of preset gases is determined.

[0024] Based on the multiple sensitivity coefficients and spectral analysis results corresponding to each of the multiple graphene tilted fiber gratings, the gas concentrations of various preset gases are determined.

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

[0026] The wavelength drift is determined based on the position of the center wavelength of the resonance peak of the target cladding mode;

[0027] The gas concentrations of various preset gases are determined based on the multiple sensitivity coefficients and wavelength drifts corresponding to each of the multiple graphene tilted fiber gratings.

[0028] The aforementioned gas concentration sensing system and gas concentration detection method construct a graphene tilted fiber grating by attaching a single layer of graphene to the grating region of the tilted fiber grating. Utilizing graphene's adsorption capacity for gas molecules improves the accuracy of gas concentration detection. The adsorption of external gas molecules alters the Fermi level of graphene, and the transmission effect of graphene varies depending on the type and concentration of the gas, leading to a shift in the center wavelength of the cladding mode resonance peak of the tilted fiber grating. Using a broadband light source, the wavelength shifts of specific cladding mode resonance peaks of multiple graphene tilted fiber grating devices can be monitored simultaneously, thus enabling the simultaneous detection of multiple gases. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a structural diagram of a gas concentration sensing system in one embodiment;

[0031] Figure 2 This is a schematic diagram of a graphene tilted fiber optic grating in one embodiment;

[0032] Figure 3 This is a transmission spectrum generated by a graphene tilted fiber grating in one embodiment;

[0033] Figure 4 This is a schematic diagram illustrating the linear relationship between gas concentration and center wavelength in one embodiment;

[0034] Figure 5 This is a flowchart illustrating a gas concentration detection method in one embodiment;

[0035] Figure 6 This is a structural block diagram of a gas concentration detection device in one embodiment;

[0036] Figure 7 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0038] The gas concentration sensing system provided in this application embodiment can be applied to, for example... Figure 1The application environment shown. The gas concentration sensing system includes multiple graphene tilted fiber gratings 101 (the multiple graphene tilted fiber gratings 101 in the figure include 101A, 101B, and 101C respectively), a broadband light source 102, a spectrometer 103, and a demodulation system 104. Each graphene tilted fiber grating 101 is composed of a tilted fiber grating and a single layer of graphene, with the single layer of graphene attached to the grating region of the tilted fiber grating. The broadband light source 102 generates broadband light and inputs it into the multiple graphene tilted fiber gratings 101. The spectrometer 103 performs spectral analysis on the light transmitted from each of the multiple graphene tilted fiber gratings 101 to obtain the spectral analysis results corresponding to each of the multiple graphene tilted fiber gratings 101. The demodulation system 104 acquires the spectral analysis results corresponding to each of the multiple graphene tilted fiber gratings 101 sent by the spectrometer 103 and calculates the gas concentrations of various preset gases based on the spectral analysis results.

[0039] Graphene is a two-dimensional lattice nanomaterial. A fiber optic grating (FOP) is a diffraction grating formed by periodically modulating the refractive index of an optical fiber core along its axis; it is a passive filtering device. FOPs achieve wavelength-selective reflection or transmission through periodic changes in the refractive index along the fiber axis. Its main characteristic is narrowband filtering; only light meeting specific wavelength conditions is reflected, while other wavelengths are transmitted. When the periodically changing refractive index region forms a certain angle with the fiber axis, a tilted FOP is formed. In other words, a tilted FOP is fabricated from single-mode fiber using a tilted FOP fabrication device.

[0040] The fabrication method of the tilted fiber grating is as follows: First, the cladding of the single-mode fiber is removed, and the fiber is placed in the center of the instrument. The angle between the plane of the fiber and the operating platform is adjusted to obtain the required tilt angle. Then, the ultraviolet laser beam output from the laser is perpendicularly irradiated onto the phase mask. Through the mechanism of photoinduced refractive index change, periodic refractive index modulation is generated in the photosensitive fiber in contact with or very close to the mask, ultimately obtaining the tilted fiber grating.

[0041] A single layer of graphene is attached to the grating region of a tilted fiber grating to form a graphene tilted fiber grating. For example... Figure 2 The diagram shown is a schematic representation of a graphene tilted fiber grating in one embodiment. A single layer of graphene 201 is attached to the grating region 203 of the tilted fiber grating 202.

[0042] Monolayer graphene is wet-transfer-attached to the grating region of a tilted fiber Bragg grating, allowing the transmission spectrum of the tilted fiber Bragg grating to be modulated by the graphene. Specifically, firstly, polymethyl methacrylate (PMMA) is spin-coated onto a composite film of monolayer graphene and copper foil. Then, this composite film is cut to a predetermined size, for example, 0.5 × 1.5 cm. 2 The device is then immersed in a 1.5 mol / L ferric chloride solution to remove the copper foil. The remaining composite film is then attached to the tilted fiber grating, and the device is placed in an acetone solution at 60°C until the PMMA is completely removed. Finally, the residual acetone solution is washed off the device, and it is dried to obtain the graphene-attached tilted fiber grating. In some embodiments, the effective interaction area between the device and graphene is approximately 12 × 10⁻⁶. -8 m 2 Finally, the fabrication of the graphene tilted fiber grating device was completed.

[0043] The broadband light source can be an ASE (Amplified Spontaneous Emission) source. The broadband light generated by the ASE source is passed into multiple graphene tilted fiber gratings. The light transmitted by the graphene tilted fiber gratings is directly connected to the spectrometer for spectral analysis.

[0044] In some embodiments, the spectrometer is used to analyze the center wavelength position of the resonance peak of a selected cladding mode in a graphene tilted fiber grating. The spectrometer analysis result can be the center wavelength position of the resonance peak of the selected cladding mode in the graphene tilted fiber grating. The demodulation system calculates the center wavelength shift based on the spectrometer analysis result, thereby calculating the gas concentration of various preset gases.

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

[0046] The aforementioned gas concentration sensing system constructs a graphene tilted fiber grating by attaching a single layer of graphene to the grating region of the tilted fiber grating. Utilizing graphene's adsorption capacity for gas molecules improves the accuracy of gas concentration detection. The adsorption of external gas molecules alters the Fermi level of the graphene, and the transmission effect of graphene varies depending on the type and concentration of the gas, leading to a shift in the center wavelength of the cladding mode resonance peak of the tilted fiber grating. Using a broadband light source, the wavelength shifts of specific cladding mode resonance peaks of multiple graphene tilted fiber grating devices can be monitored simultaneously, thus enabling the simultaneous detection of multiple gases.

[0047] In one exemplary embodiment, reference is made to Figure 1The system also includes multiple polarization controllers 105, including 105A, 105B and 105C; the multiple polarization controllers 105 are connected one-to-one with multiple graphene tilted fiber gratings 101; 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 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 peaks 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 an optical fiber coupler 106. The broadband light generated by the broadband light source 102 passes sequentially through the optical fiber coupler 106 and multiple polarization controllers 105, and is injected into multiple graphene tilted fiber gratings 101 respectively.

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

[0052] In one exemplary embodiment, the wavelength range of the broadband light source covers the wavelength range of the center wavelength of the resonant peak of the tilted fiber grating.

[0053] Based on the transmission characteristics of tilted fiber gratings (GFCGs), only light within their transmission bandwidth can pass through. Therefore, the wavelength range of the selected broadband light source should cover the wavelength range of the center wavelength of the GFCG's resonant peak, and the transmission bandwidth of the broadband light source should also cover the GFCG's transmission bandwidth. For example, the center wavelength of the GFCG's resonant peak is 1520nm-1570nm, and its transmission bandwidth is 1-3nm, ensuring that only light within the transmission bandwidth can pass through the GFCG. An ASE light source with a wavelength of 1515nm-1575nm would satisfy both the GFCG's operating wavelength and transmission bandwidth requirements.

[0054] In this embodiment, a broadband light source with a wavelength range that can cover the center wavelength of the resonant peak of the tilted fiber grating is selected, which helps to ensure that the broadband light source meets the requirements of the working wavelength and transmission bandwidth of the tilted fiber grating.

[0055] In one exemplary embodiment, the multiple graphene tilted fiber gratings each correspond to a different tilt angle, and the number of graphene tilted fiber gratings is the same as the number of preset gas types.

[0056] Fiber Bragg gratings (FBGs) achieve wavelength-selective reflection or transmission through periodic changes in the refractive index along the fiber axis. Their main characteristic is narrowband filtering; only light meeting specific wavelength conditions is reflected, while other wavelengths are transmitted. When the periodically changing refractive index region forms a certain angle with the fiber axis, a tilted FBG is formed, leading to coupling effects between different fiber modes. This includes coupling between the forward core mode and the reverse core mode, as well as coupling between the forward core mode and the reverse cladding mode and radiation mode. These coupling effects are affected by the refractive index of the surrounding medium, and changes in refractive index can be detected by shifting the resonance peak in the transmission spectrum. When gases are adsorbed on the surface of the graphene tilted FBG, they change the cladding refractive index, causing a shift in the center wavelength of the resonance peak of the cladding mode in the transmission spectrum of the tilted FBG. Simultaneously, the shift of the resonance peak is also related to the tilt angle of the tilted FBG; that is, the cladding modes of tilted FBGs with different tilt angles have different sensitivities and responses to changes in the concentration of H2S, SO2, and NH3. Therefore, the multiple graphene tilted FBGs selected in this application correspond to different tilt angles. By selecting an appropriate tilt angle, the center wavelength of the resonance peak can be ensured to have the maximum shift, which is beneficial to improving the accuracy and precision of gas concentration calculation. 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 Bragg gratings is the same as the number of preset gas types, so that the corresponding number of graphene tilted fiber Bragg gratings can be set for the concentration detection of multiple preset gases.

[0058] In this embodiment, since the resonant peak shift is related to the tilt angle of the tilted fiber grating, by selecting multiple tilted fiber gratings with different tilt angles to prepare the graphene tilted fiber grating device, it is possible to ensure that the center wavelength of the resonant peak has the largest shift, which is beneficial to improving the calculation accuracy and precision of gas concentration. In addition, the number of graphene tilted fiber gratings is the same as the number of preset gas types, which can ensure the detection of gas concentration for multiple preset gases.

[0059] In an exemplary embodiment, the demodulation system is further configured 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 based on the target cladding mode and tilt angle of each graphene tilted fiber grating; and determine the gas concentration of multiple preset gases based on the multiple sensitivity coefficients corresponding to each of the multiple graphene tilted fiber gratings and their corresponding spectral analysis results.

[0060] Among them, such as Figure 3 The figure shows a transmission spectrum generated by a graphene tilted fiber grating in one embodiment. As can be seen, the tilted fiber grating has multiple cladding modes, each with a resonant peak bandwidth of approximately 0.5 nm. The demodulation system can determine the target cladding mode among the multiple cladding modes of each graphene tilted fiber grating, ensuring that the resonant peaks of the multiple target cladding modes do not overlap.

[0061] The cladding mode of a tilted fiber Bragg grating is highly sensitive to changes in the external environment. Furthermore, the cladding modes of tilted fiber Bragg gratings with different tilt angles exhibit varying degrees of sensitivity to changes in the concentration of a preset gas. Therefore, based on the target cladding mode and tilt angle of each graphene tilted fiber Bragg grating, the sensitivity coefficients of each grating to various preset gases can be determined. In some embodiments, the demodulation system pre-stores a mapping relationship between cladding modes, tilt angles, preset gas types, and sensitivity coefficients. By querying this mapping relationship, the sensitivity coefficients of each graphene tilted fiber Bragg grating to various preset gases can be determined.

[0062] When this system is used for gas sensing, gas molecules adsorb onto the graphene in the fiber Bragg grating region of each device, changing the refractive index of the graphene and thus altering the center wavelength of the resonant peak of each graphene-tiled fiber Bragg grating. Simultaneously, due to the different tilt angles of each graphene-tiled fiber Bragg grating, each cladding mode responds differently to various preset gases, meaning the change in center wavelength varies. Therefore, based on multiple sensitivity coefficients and spectral analysis results, the gas concentrations of various preset gases can be calculated.

[0063] In this embodiment, by determining the target cladding mode of each graphene tilted fiber grating and combining it with the tilt angle, the sensitivity coefficients for each of the various preset gases are determined. Based on the sensitivity coefficients and spectral analysis results, the gas concentrations of the various preset gases are calculated. This method of real-time demodulation and rapid calculation of multiple signals enables rapid sensing of various preset gases.

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

[0065] Wavelength drift refers to the change in the center wavelength position of the resonant peak of the target cladding mode. The demodulation system uses the center wavelength position of the resonant peak of the target cladding mode before broadband light transmission as the initial position, and the change in the center wavelength position of the resonant peak of the target cladding mode after transmission relative to the initial position as the wavelength drift.

[0066] The demodulation system determines the gas concentrations of various preset gases based on the multiple sensitivity coefficients and corresponding wavelength shifts of each of the three graphene tilted fiber gratings. The following explanation uses the concentration detection of three preset gases (H2S, SO2, and NH3) as an example. Let the wavelength shifts corresponding to the three graphene tilted fiber gratings be... λ1、 λ2、 The sensitivity coefficients of the target cladding mode of graphene tilted fiber grating 101A to H2S, SO2, and NH3 are S1, S2, and S3, respectively; those of the target cladding mode of graphene tilted fiber grating 101B to H2S, SO2, and NH3 are S4, S5, and S6, respectively; and those of the target cladding mode of graphene tilted fiber grating 101C to H2S, SO2, and NH3 are S7, S8, and S9, respectively. The gas concentrations of H2S, SO2, and NH3 are represented as ρ1, ρ2, and ρ3, respectively. The gas concentrations of each preset gas are solved using a matrix calculation method, as shown in the following formula:

[0067]

[0068] like Figure 4 This diagram illustrates the linear relationship between gas concentration and center wavelength of the target cladding mode in a graphene-tilted fiber Bragg grating device when sensing H2S gas, as shown in one embodiment. Since each graphene-tilted fiber Bragg grating exhibits 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 using a system of linear equations. For more complex gas environments, the number of graphene-tilted fiber Bragg gratings can be increased to obtain the gas concentration of each preset gas by solving linear equations.

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

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

[0071] For the i-th graphene tilted fiber grating, from the multiple cladding modes of the i-th graphene tilted fiber grating, determine multiple candidate cladding modes whose resonance peaks do not overlap with 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 the multiple candidate cladding modes, where i is an integer greater than 1.

[0072] In selecting the target cladding mode, it is essential to ensure that the resonance peaks do not intersect. For multiple graphene tilted fiber gratings, the target cladding mode should be selected sequentially for each graphene tilted fiber grating. For the first graphene tilted fiber grating, any one of its multiple cladding modes can be arbitrarily selected as the target cladding mode.

[0073] For the graphene tilted fiber gratings traversed after the first graphene tilted fiber grating, let's take the i-th graphene tilted fiber grating as an example. From the multiple cladding modes of the i-th graphene tilted fiber grating, we determine multiple candidate cladding modes whose resonance peaks do not overlap with the target cladding modes of other graphene tilted fiber gratings. Then, we determine the target cladding mode of the i-th graphene tilted fiber grating from these candidate cladding modes. This ensures that the resonance peaks of the i-th graphene tilted fiber grating do not overlap with the target cladding modes of other graphene tilted fiber gratings.

[0074] In this embodiment, by sequentially selecting target cladding modes from multiple graphene tilted fiber gratings, the resonance peaks of each target cladding mode are ensured to be non-overlapping, which is beneficial to improving the gas concentration sensing accuracy.

[0075] The gas concentration detection method provided in the embodiments of this application, such as Figure 5 As shown, it can be applied to, for example Figure 1 The gas concentration sensing system shown is illustrated. Taking the demodulation system 104 in the gas concentration sensing system as an example, the method is applied to include the following steps 502 to 504.

[0076] Step 502: Obtain the spectral analysis results corresponding to each of the multiple graphene tilted fiber gratings.

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

[0078] The spectrometer is used to analyze the center wavelength position of the resonance peak of a selected cladding mode in a graphene tilted fiber grating. The spectrometer analysis result can be used to determine the center wavelength position of the resonance peak of the selected cladding mode in the graphene tilted fiber grating. The demodulation system calculates the center wavelength shift based on the spectrometer analysis result, and then calculates the gas concentration of various preset gases.

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

[0080] The aforementioned gas concentration detection method constructs a graphene tilted fiber grating by attaching a single layer of graphene to the grating region of the tilted fiber grating. Utilizing graphene's adsorption capacity for gas molecules improves the accuracy of gas concentration detection. The adsorption of external gas molecules alters the Fermi level of graphene, and the transmission effect of graphene varies depending on the type and concentration of the gas, leading to a shift in the center wavelength of the cladding mode resonance peak of the tilted fiber grating. Using a broadband light source, the wavelength shifts of specific cladding mode resonance peaks of multiple graphene tilted fiber grating devices can be monitored simultaneously, thus enabling the simultaneous detection of multiple gases.

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

[0082] The demodulation system can determine the target cladding mode among multiple cladding modes of each graphene tilted fiber grating, and should ensure that the resonance peaks of the multiple target cladding modes do not overlap.

[0083] The cladding mode of a tilted fiber Bragg grating is highly sensitive to changes in the external environment. Furthermore, the cladding modes of tilted fiber Bragg gratings with different tilt angles exhibit varying degrees of sensitivity to changes in the concentration of a preset gas. Therefore, based on the target cladding mode and tilt angle of each graphene tilted fiber Bragg grating, the sensitivity coefficients of each grating to various preset gases can be determined. In some embodiments, the demodulation system pre-stores a mapping relationship between cladding modes, tilt angles, preset gas types, and sensitivity coefficients. By querying this mapping relationship, the sensitivity coefficients of each graphene tilted fiber Bragg grating to various preset gases can be determined.

[0084] When this system is used for gas sensing, gas molecules adsorb onto the graphene in the fiber Bragg grating region of each device, changing the refractive index of the graphene and thus altering the center wavelength of the resonant peak of each graphene-tiled fiber Bragg grating. Simultaneously, due to the different tilt angles of each graphene-tiled fiber Bragg grating, each cladding mode responds differently to various preset gases, meaning the change in center wavelength varies. Therefore, based on multiple sensitivity coefficients and spectral analysis results, the gas concentrations of various preset gases can be calculated.

[0085] In this embodiment, by determining the target cladding mode of each graphene tilted fiber grating and combining it with the tilt angle, the sensitivity coefficients for each of the various preset gases are determined. Based on the sensitivity coefficients and spectral analysis results, the gas concentrations of the various preset gases are calculated. This method of real-time demodulation and rapid calculation of multiple signals enables rapid sensing of various preset gases.

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

[0087] Wavelength drift refers to the change in the center wavelength position of the resonant peak of the target cladding mode. The demodulation system uses the center wavelength position of the resonant peak of the target cladding mode before broadband light transmission as the initial position, and the change in the center wavelength position of the resonant peak of the target cladding mode after transmission relative to the initial position as the wavelength drift.

[0088] The demodulation system determines the gas concentrations of various preset gases based on the multiple sensitivity coefficients and corresponding wavelength shifts of each of the three graphene tilted fiber gratings. The following explanation uses the concentration detection of three preset gases (H2S, SO2, and NH3) as an example. Let the wavelength shifts corresponding to the three graphene tilted fiber gratings be... λ1、 λ2、 The sensitivity coefficients of the target cladding mode of graphene tilted fiber grating 101A to H2S, SO2, and NH3 are S1, S2, and S3, respectively; those of the target cladding mode of graphene tilted fiber grating 101B to H2S, SO2, and NH3 are S4, S5, and S6, respectively; and those of the target cladding mode of graphene tilted fiber grating 101C to H2S, SO2, and NH3 are S7, S8, and S9, respectively. The gas concentrations of H2S, SO2, and NH3 are represented as ρ1, ρ2, and ρ3, respectively. The gas concentrations of each preset gas are solved using a matrix calculation method, as shown in the following formula:

[0089]

[0090] refer to Figure 4Since each graphene tilted fiber grating exhibits 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 using a system of linear equations. For more complex gas environments, the number of graphene tilted fiber gratings can be increased to obtain the gas concentration of each preset gas by solving linear equations.

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

[0092] In one exemplary embodiment, determining a target cladding mode among multiple cladding modes of each graphene tilted fiber grating includes:

[0093] By traversing multiple graphene tilted fiber gratings, and for the first graphene tilted fiber grating, the target cladding mode of the first graphene tilted fiber grating is determined among the multiple cladding modes of the first graphene tilted fiber grating.

[0094] For the i-th graphene tilted fiber grating, from the multiple cladding modes of the i-th graphene tilted fiber grating, determine multiple candidate cladding modes whose resonance peaks do not overlap with 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 the multiple candidate cladding modes, where i is an integer greater than 1.

[0095] In selecting the target cladding mode, it is essential to ensure that the resonance peaks do not intersect. For multiple graphene tilted fiber gratings, the target cladding mode should be selected sequentially for each graphene tilted fiber grating. For the first graphene tilted fiber grating, any one of its multiple cladding modes can be arbitrarily selected as the target cladding mode.

[0096] For the graphene tilted fiber gratings traversed after the first graphene tilted fiber grating, let's take the i-th graphene tilted fiber grating as an example. From the multiple cladding modes of the i-th graphene tilted fiber grating, we determine multiple candidate cladding modes whose resonance peaks do not overlap with the target cladding modes of other graphene tilted fiber gratings. Then, we determine the target cladding mode of the i-th graphene tilted fiber grating from these candidate cladding modes. This ensures that the resonance peaks of the i-th graphene tilted fiber grating do not overlap with the target cladding modes of other graphene tilted fiber gratings.

[0097] In this embodiment, by sequentially selecting target cladding modes from multiple graphene tilted fiber gratings, the resonance peaks of each target cladding mode are ensured to be non-overlapping, which is beneficial to improving the gas concentration sensing accuracy.

[0098] To illustrate the gas concentration sensing system, gas concentration detection method, and effects in this solution in detail, a specific embodiment is described below:

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

[0100] The graphene tilted fiber grating is composed of a tilted fiber grating and a single layer of graphene. The tilted fiber grating is fabricated from single-mode fiber using a tilted fiber grating fabrication apparatus. The single layer of graphene is wet-transfer bonded to the grating region of the tilted fiber grating, allowing the transmission spectrum of the tilted fiber grating to be modulated by the graphene.

[0101] A broadband light source generates broadband light, which is then passed sequentially through an optical fiber coupler and a polarization controller into multiple graphene tilted fiber gratings. The light transmitted through the graphene tilted fiber gratings is directly connected to a spectrometer for spectral analysis.

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

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

[0104] The demodulation system is used to acquire the spectral analysis results of each of the multiple graphene tilted fiber Bragg gratings sent by the spectrometer, i.e. the position of the center wavelength of the resonance peak, and calculate the wavelength drift based on the spectral analysis results, thereby calculating the gas concentration of multiple preset gases.

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

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

[0107] For example, three tilted fiber gratings with tilt angles of 8°, 6°, and 4° are selected as initial devices. After the above operations, three graphene tilted fiber grating devices are obtained, which are then used to form a fiber optic gas sensing system via couplers and polarization controllers. H2S, SO2, and NH3 are selected as preset gases. The prepared gas sensing system is placed in the environment where gas sensing is required. Light generated by a broadband light source is injected into the devices after passing through the fiber coupler and polarization controller.

[0108] The demodulation system is also used to determine the target cladding mode among multiple cladding modes of each graphene tilted fiber grating. Specifically, it traverses multiple graphene tilted fiber gratings, and for the first graphene tilted fiber grating, it determines the target cladding mode of the first graphene tilted fiber grating among its multiple cladding modes. For the i-th graphene tilted fiber grating, it determines multiple candidate cladding modes from its multiple cladding modes that do not overlap with the resonant peaks of the target cladding modes of other graphene tilted fiber gratings, and determines the target cladding mode of the i-th graphene tilted fiber grating from these candidate cladding modes, where i is an integer greater than 1.

[0109] The calculation methods for the gas concentrations of various preset gases are as follows, taking the concentration detection of three preset gases (H2S, SO2, and NH3) as an example. Let the wavelength drift corresponding to each of the three graphene tilted fiber gratings be... λ1、 λ2、 The sensitivity coefficients of the target cladding mode of graphene tilted fiber grating 101A to H2S, SO2, and NH3 are S1, S2, and S3, respectively; those of the target cladding mode of graphene tilted fiber grating 101B to H2S, SO2, and NH3 are S4, S5, and S6, respectively; and those of the target cladding mode of graphene tilted fiber grating 101C to H2S, SO2, and NH3 are S7, S8, and S9, respectively. The gas concentrations of H2S, SO2, and NH3 are represented as ρ1, ρ2, and ρ3, respectively. The gas concentrations of each preset gas are solved using a matrix calculation method, as shown in the following formula:

[0110]

[0111] Because graphene contacts the tilted fiber grating (GFCG) and tunes the center wavelength of the GFCG cladding mode resonance peak, and because graphene can interact with external gas molecules, further tuning the center wavelength of the GFCG cladding mode, a gas concentration sensing system is based on the sensing principle of graphene tilted fiber gratings. This system consists of tilted fiber grating devices, with graphene attached to the grating region, effectively tuning the center wavelength of the GFCG cladding mode resonance peak. The tuning effect of graphene is influenced by its Fermi level. The adsorption of external gas molecules alters the Fermi level of graphene, and different gas types and concentrations have varying effects, leading to a drift in the center wavelength of the GFCG cladding mode resonance peak. Using a broadband light source, the wavelength shifts of specific cladding mode resonance peaks of multiple graphene tilted fiber grating devices can be monitored simultaneously, allowing for real-time sensing of various gases through equation calculations.

[0112] In summary, combining graphene with tilted fiber gratings (GFGs) to achieve a novel, low-cost, easy-to-operate, and readily integrated fiber optic gas sensing system capable of simultaneously detecting multiple gases. By integrating optoelectronics of two-dimensional materials, fiber microstructure fabrication technology, the center wavelength modulation principle of tilted fiber gratings, and gas sensing technology, this approach successfully solves the problems of complex operation and difficulty in detecting multi-component gases in existing fiber optic gas sensing systems, contributing new ideas and application potential to the further development of the gas sensing field.

[0113] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0114] Based on the same inventive concept, this application also provides a gas concentration detection device for implementing the gas concentration detection method described above. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations of the one or more gas concentration detection device embodiments provided below can be found in the limitations of the gas concentration detection method described above, and will not be repeated here.

[0115] In one exemplary embodiment, such as Figure 6As shown, a gas concentration detection device 600 is provided, including: an acquisition module 620 and a calculation module 640, wherein:

[0116] The acquisition module 620 is used to acquire the spectral analysis results corresponding to each of the multiple graphene tilted fiber Bragg gratings;

[0117] The calculation module 640 is used to calculate the gas concentration of various preset gases based on the spectral analysis results.

[0118] The aforementioned gas concentration detection device constructs a graphene tilted fiber grating by attaching a single layer of graphene to the grating region of a tilted fiber grating. Utilizing graphene's adsorption capacity for gas molecules, the detection accuracy of gas concentration is improved. Broadband light generated by a broadband light source is transmitted through multiple graphene tilted fiber gratings. Since the graphene tilted fiber gratings have varying sensitivities to different types and concentrations of gases, the wavelength shift of the transmitted light differs. Therefore, a spectrometer is used to perform spectral analysis on the light transmitted from each graphene tilted fiber grating. Based on the spectral analysis results, the gas concentrations of various preset gases can be calculated, enabling 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. The calculation module 640 is further configured 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; 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 their corresponding spectral analysis results.

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

[0121] In one embodiment, the calculation module 640 is further configured to: traverse multiple graphene tilted fiber gratings, and for the first graphene tilted fiber grating, determine the target cladding mode of the first graphene tilted fiber grating from among its multiple cladding modes; for the i-th graphene tilted fiber grating, determine multiple candidate cladding modes from among its multiple cladding modes that do not overlap with the resonant 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, where i is an integer greater than 1.

[0122] Each module in the aforementioned gas concentration detection device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0123] In one exemplary embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 7 As shown, the computer device includes a processor, memory, input / output interfaces, a communication interface, a display unit, and an input device. The processor, memory, and input / output interfaces are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The input / output interfaces are used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, Near Field Communication (NFC), or other technologies. When the computer program is executed by the processor, it implements a gas concentration detection method. The display unit is used to form a visually visible image and can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

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

[0125] In one exemplary embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0126] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the above method embodiments.

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

[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, data stored, data displayed, 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 the relevant data must comply with relevant regulations.

[0129] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this 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. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0130] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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 embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A gas concentration sensing system, characterized by, The system comprises: a plurality of graphene tilted fiber gratings, each graphene tilted fiber grating being composed of a tilted fiber grating and a single-layer graphene attached to a grating region of the tilted fiber grating; a broadband light source configured to generate broadband light and input the broadband light into the plurality of graphene tilted fiber gratings; a spectrum analyzer configured to perform spectrum analysis on light transmitted by each of the plurality of graphene tilted fiber gratings to obtain a spectrum analysis result corresponding to each of the plurality of graphene tilted fiber gratings; a demodulation system configured to acquire the spectrum analysis result corresponding to each of the plurality of graphene tilted fiber gratings sent by the spectrum analyzer, and calculate gas concentrations of a plurality of preset gases based on the spectrum analysis result; the plurality of graphene tilted fiber gratings have different tilt angles, and the number of the graphene tilted fiber gratings is the same as the number of the preset gases; the demodulation system is further configured to determine a target cladding mode in a plurality of cladding modes of each graphene tilted fiber grating, determine a sensitivity coefficient of each graphene tilted fiber grating with respect to each of the plurality of preset gases based on the target cladding mode and the tilt angle of each graphene tilted fiber grating, and determine the gas concentrations of the plurality of preset gases based on the plurality of sensitivity coefficients corresponding to the plurality of graphene tilted fiber gratings and the spectrum analysis result corresponding to each of the plurality of graphene tilted fiber gratings; the spectrum analysis result corresponding to each graphene tilted fiber grating comprises a resonant peak center wavelength position of the target cladding mode, and the demodulation system is further configured to determine a wavelength shift based on the resonant peak center wavelength position of the target cladding mode, and determine the gas concentrations of the plurality of preset gases based on the plurality of sensitivity coefficients corresponding to the plurality of graphene tilted fiber gratings and the wavelength shift corresponding to each of the plurality of graphene tilted fiber gratings.

2. The system of claim 1, wherein, 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 one-to-one correspondence, and each polarization controller is configured to tune a polarization state of the broadband light when the broadband light enters a connected graphene tilted fiber grating.

3. The system of claim 1, wherein, The wavelength range of the broadband light source covers a wavelength range of a center wavelength of a resonant peak of the tilted fiber grating.

4. The system of claim 1, wherein, The demodulation system is further configured to traverse the plurality of graphene tilted fiber gratings, determine a target cladding mode of a first graphene tilted fiber grating in a plurality of cladding modes of the first graphene tilted fiber grating, determine a target cladding mode of an i-th graphene tilted fiber grating from a plurality of cladding modes of the i-th graphene tilted fiber grating, wherein i is an integer greater than 1, and the target cladding mode of the i-th graphene tilted fiber grating is determined from a plurality of candidate cladding modes that are not overlapped with resonant peaks of target cladding modes of other graphene tilted fiber gratings. The method is applied to the gas concentration sensing system of claims 1-4, and the method comprises:

5. A gas concentration detection method characterized by, acquiring a spectrum analysis result corresponding to each of the plurality of graphene tilted fiber gratings; calculating gas concentrations of a plurality of preset gases based on the spectrum analysis result; the calculation of the gas concentrations of the plurality of preset gases based on the spectrum analysis result comprises: determining a target cladding mode in a plurality of cladding modes of each graphene tilted fiber grating; ​ According to the target cladding mode and the tilt angle of each graphene tilted fiber grating, a sensitivity coefficient of each graphene tilted fiber grating to each of a plurality of preset gases is determined; According to the plurality of sensitivity coefficients and the spectrum analysis results of the plurality of graphene tilted fiber gratings, gas concentrations of the plurality of preset gases are determined. The spectrum analysis result corresponding to each graphene tilted fiber grating includes a resonance peak center wavelength position of the target cladding mode; and the determination of the gas concentrations of the plurality of preset gases according to the plurality of sensitivity coefficients and the spectrum analysis results of the plurality of graphene tilted fiber gratings includes: According to the resonance peak center wavelength position of the target cladding mode, a wavelength shift is determined; According to the plurality of sensitivity coefficients and the wavelength shifts of the plurality of graphene tilted fiber gratings, the gas concentrations of the plurality of preset gases are determined.

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