Gas detection system and method

Abstract

The present application provides a gas detection system and method that can simultaneously prevent a signal receiving module from direct contact with gas molecules and lasers, thereby protecting the signal receiving module from damage by corrosive gases and reducing the system's thermal noise, thereby ensuring the accuracy of gas detection and improving the system's signal-to-noise ratio. The system includes a temperature-controlled current source, a laser, a gas absorption cell, a hot-wire optical fiber, and a signal receiving and demodulation module; the temperature-controlled current source is connected to the laser, the output optical fiber of the laser is connected to the input end of the gas absorption cell, the output optical fiber of the gas absorption cell is connected to the hot-wire optical fiber, and the hot-wire optical fiber is close to the signal receiving and demodulation module, wherein the hot-wire optical fiber can convert light energy into heat energy, and the signal receiving and demodulation module can use the heat energy converted by the hot-wire optical fiber to detect the concentration of the gas to be detected in the gas absorption cell.

Description

Technical Field

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

[0002] With the advancement of society and science and technology, high-precision monitoring of gas concentrations is crucial for ensuring oil and gas extraction, biopharmaceutical safety, air pollution prevention, food and drug safety, and many other fields. Currently, the most common quartz-enhanced photoacoustic spectroscopy (QPS) gas detection technology is a gas contact measurement technique. The quartz tuning fork is embedded in the gas sample to be measured, limiting its application in areas such as long-distance measurement. Furthermore, if the gas to be measured is corrosive, it can damage the metal film on the surface of the quartz tuning fork, causing frequency drift or even damage.

[0003] At present, some scholars have proposed quartz-enhanced photothermal spectroscopy gas detection technology. Quartz-enhanced photothermal spectroscopy gas detection technology is a non-contact gas detection technology. After being absorbed in the gas absorption cell, light is directly incident on the quartz tuning fork arm, and the gas is detected based on the photothermal effect. However, this method requires direct contact between the laser and the quartz tuning fork, which inevitably generates a large amount of thermal noise. Since the photothermal signal is proportional to the laser power, but the thermal noise of the quartz tuning fork is exponentially related to the laser power, the signal-to-noise ratio of the system will be greatly reduced. Summary of the Invention

[0004] The present application provides a gas detection system and method that can simultaneously avoid direct contact between a signal receiving module and gas molecules and lasers, thereby protecting the signal receiving module from damage by corrosive gases and reducing the thermal noise of the system, thereby ensuring the accuracy of gas detection and further improving the signal-to-noise ratio of the system.

[0005] In a first aspect, the present application provides a gas detection system, comprising a temperature-controlled current source, a laser, a gas absorption cell, a hot-wire optical fiber, and a signal receiving and demodulation module;

[0006] The temperature-controlled current source is connected to the laser, the output optical fiber of the laser is connected to the input end of the gas absorption cell, the output optical fiber of the gas absorption cell is connected to the hot-wire optical fiber, and the hot-wire optical fiber is close to the signal receiving and demodulation module, wherein the hot-wire optical fiber can convert light energy into thermal energy, and the signal receiving and demodulation module can use the thermal energy converted by the hot-wire optical fiber to detect the concentration of the gas to be measured in the gas absorption cell.

[0007] Optionally, the signal receiving and demodulation module includes a signal receiving module and a signal demodulation module, the signal receiving module includes a quartz tuning fork, and the signal demodulation module includes a preamplifier, a lock-in amplifier and an oscilloscope;

[0008] The hot-wire optical fiber is placed around the quartz tuning fork, the output end of the quartz tuning fork is connected to the input end of the preamplifier, the output end of the preamplifier is connected to the input end of the lock-in amplifier, and the output end of the lock-in amplifier is connected to the oscilloscope.

[0009] Optionally, placing the hot-wire optical fiber around the quartz tuning fork includes:

[0010] The hot-wire optical fiber is placed between the two arms of the quartz tuning fork or on the front side of the quartz tuning fork or on the side of the quartz tuning fork.

[0011] Optionally, the signal receiving and demodulating module includes a signal receiving module and a signal demodulating module, the signal receiving module includes a fiber Bragg grating, and the signal demodulating module includes a broadband light source, a fiber circulator and a spectrum analyzer;

[0012] The hot-wire optical fiber is fixed on the fiber Bragg grating, the broadband light source optical fiber is connected to the input end of the fiber circulator, the middle end of the fiber circulator is connected to the fiber Bragg grating, and the output end optical fiber of the fiber circulator is connected to the spectrum analyzer.

[0013] Optionally, fixing the hot-wire optical fiber on the fiber Bragg grating includes:

[0014] The hot-line optical fiber and the optical fiber grating are pasted together in parallel.

[0015] Optionally, the hot-line optical fiber is a high-loss cobalt-doped optical fiber, and the coating layer is removed.

[0016] In a second aspect, a gas detection method is provided, using the gas detection system of the first aspect and any embodiment, the method comprising:

[0017] Step S1: connecting the gas detection system, turning on the power of each part of the gas detection system, and injecting the gas to be tested into the gas absorption cell;

[0018] Step S2: The temperature-controlled current source generates a driving signal, wherein the driving signal is used to drive the laser. The wavelength of the light output by the laser corresponds to the absorption peak of the gas to be measured. The gas absorption cell inputs the light absorbed by the gas molecules therein into the hot-wire optical fiber. The hot-wire optical fiber converts the light energy absorbed by the gas molecules in the gas absorption cell into thermal energy. The signal receiving and demodulation module uses the thermal energy converted by the hot-wire optical fiber to detect the concentration of the gas to be measured in the gas absorption cell.

[0019] Optionally, the signal receiving and demodulation module includes a signal receiving module and a signal demodulation module, the signal receiving module includes a quartz tuning fork, the signal demodulation module includes a preamplifier, a lock-in amplifier, and an oscilloscope, the driving signal is a low-frequency sawtooth wave superimposed on a high-frequency sine wave with half the resonant frequency of the quartz tuning fork, and the signal receiving and demodulation module uses the thermal energy converted by the hot-wire optical fiber to detect the concentration of the gas to be measured in the gas absorption cell, including:

[0020] The heat energy converted by the hot-wire optical fiber causes periodic changes in the ambient temperature, which in turn causes periodic changes in pressure, generating sound waves, thereby causing the quartz tuning fork to vibrate. The quartz tuning fork generates a piezoelectric current signal, the preamplifier converts the piezoelectric current signal into a voltage signal, and the lock-in amplifier demodulates the voltage signal, thereby inverting the concentration of the gas to be measured on the oscilloscope.

[0021] Optionally, the signal receiving and demodulation module includes a signal receiving module and a signal demodulation module, the signal receiving module includes a fiber Bragg grating, the signal demodulation module includes a broadband light source, a fiber circulator and a spectrum analyzer, the driving signal is a DC signal, and the signal receiving and demodulation module uses the heat energy converted by the hot-wire optical fiber to detect the concentration of the gas to be measured in the gas absorption cell, including:

[0022] Recording the first wavelength displayed on the spectrum analyzer when there is no gas in the gas absorption cell;

[0023] The gas to be measured is introduced into the gas absorption cell. After the light output by the laser is absorbed by the gas to be measured, the light intensity of the light input into the hot-wire optical fiber is attenuated compared to when there is no gas in the gas absorption cell. The temperature of the hot-wire optical fiber decreases, causing the wavelength of the fiber Bragg grating to drift, and the spectrum analyzer displays a second wavelength.

[0024] The concentration of the gas to be measured is inverted according to the difference between the first wavelength and the second wavelength.

[0025] As can be seen from the above embodiment, during use, a temperature-controlled current source inputs a drive signal to the laser so that the wavelength of the light output by the laser corresponds to the absorption peak of the gas to be measured. After being absorbed by the gas absorption cell, the light output by the laser is incident on the hot-wire optical fiber, which converts the light energy into heat energy. The signal receiving and demodulation module then uses the heat energy converted by the hot-wire optical fiber to detect the concentration of the gas to be measured in the gas absorption cell. The signal receiving and demodulation module includes a signal receiving module and a signal demodulation module. In this system, the signal receiving module is separated from the gas, protecting the signal receiving module from damage by corrosive gases, thereby ensuring the accuracy of gas detection. In addition, the hot-wire optical fiber converts light energy into heat energy, avoiding direct laser light injection into the signal receiving module, which can reduce the system's thermal noise and improve the system's signal-to-noise ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 is a schematic diagram of a gas detection system provided by the present application according to some embodiments;

[0028] Figure 2 is a schematic diagram of another gas detection system provided by the present application according to some embodiments;

[0029] Figure 3 This is a schematic diagram of the locations of the hot-wire optical fiber and the quartz tuning fork;

[0030] Figure 4 is a schematic diagram of another gas detection system provided by the present application according to some embodiments;

[0031] Figure 5 This is a driving signal diagram of a laser provided in this application;

[0032] Figure 6 This is an example of a signal diagram displayed by an oscilloscope provided by this application;

[0033] Figure 7 This is a schematic diagram of gas concentration corresponding to different central wavelengths of an optical fiber Bragg grating provided in this application.

[0034] Reference numerals

[0035] 1. Temperature-controlled current source, 2. Laser, 3. Gas absorption cell, 4. Hot-wire optical fiber, 5. Quartz tuning fork, 6. Preamplifier, 7. Lock-in amplifier, 8. Oscilloscope, 9. Fiber Bragg grating (FBG), 10. Broadband light source, 11. Fiber circulator, 12. Spectrum analyzer. DETAILED DESCRIPTION

[0036] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and are not to be construed as limiting the present application.

[0037] It will be understood by those skilled in the art that, unless expressly stated otherwise, the singular forms "a", "an", "said" and "the" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present application refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, "connected" or "coupled" as used herein may include wireless connections or wireless couplings. The term "and / or" used herein includes all or any units and all combinations of one or more associated listed items.

[0038] Gas concentration detection is crucial in numerous fields, including biopharmaceutical safety, air pollution prevention, and food and drug safety. Quartz-enhanced photoacoustic spectroscopy (QPS) gas detection is a common technique. This technique embeds a quartz tuning fork into the gas sample to be measured. The photoinduced thermoelastic effect causes the fork to vibrate, generating a piezoelectric signal to detect gas concentration. This approach not only limits its application in areas such as long-distance measurement, but also, if the gas being measured is corrosive, it can damage the metal film on the fork's surface, causing frequency drift or even damage.

[0039] In response to the above problems, some scholars have proposed quartz-enhanced photothermal spectroscopy gas detection technology, which is a non-contact gas detection technology. After being absorbed in the gas absorption cell, light is directly incident on the quartz tuning fork arm, and the gas is detected based on the photothermal effect. However, the quartz tuning fork in this method generates a large amount of thermal noise and the signal-to-noise ratio is low. To address this defect, the present application proposes the following solution. The gas detection system provided by the present application is explained below with reference to the accompanying drawings.

[0040] Figure 1 This is a schematic diagram of a gas detection system provided by the present application according to some embodiments, such as Figure 1 As shown, the gas detection system includes a temperature-controlled current source 1, a laser 2, a gas absorption cell 3, a hot-wire optical fiber 4 and a signal receiving and demodulation module.

[0041] Among them, the temperature-controlled current source 1 is connected to the laser 2, the output optical fiber of the laser 2 is connected to the input end of the gas absorption pool 3, the output optical fiber of the gas absorption pool 3 is connected to the hot-wire optical fiber 4, and the hot-wire optical fiber 4 is close to the signal receiving and demodulation module. Among them, the hot-wire optical fiber 4 can convert light energy into thermal energy, and the signal receiving and demodulation module can use the thermal energy converted by the hot-wire optical fiber 4 to detect the concentration of the gas to be measured in the gas absorption pool 3.

[0042] Optionally, the temperature-controlled current source 1 is electrically connected or communicatively connected to the laser 2 .

[0043] Optionally, the hot-line optical fiber 4 is a high-loss cobalt-doped optical fiber, and the coating layer is removed. Removing the coating layer allows the hot-line optical fiber 4 to dissipate heat better.

[0044] Optionally, the gas to be measured may be acetylene, methane, carbon dioxide or ammonia.

[0045] It should be noted that the signal receiving and demodulating module includes a signal receiving module and a signal demodulating module.

[0046] During operation, a temperature-controlled current source 1 inputs a drive signal to the laser 2, ensuring that the wavelength of the light output by the laser 2 corresponds to the absorption peak of the gas to be measured. After being absorbed by the gas absorption cell 3, the light output by the laser 2 is incident on the hot-wire optical fiber 4, which converts the light energy into heat energy. The signal receiving and demodulation module then uses the heat energy converted by the hot-wire optical fiber 4 to detect the concentration of the gas to be measured in the gas absorption cell 3. In this system, the signal receiving module is separated from the gas, protecting it from corrosive gases and ensuring accurate gas detection. Furthermore, the hot-wire optical fiber 4 converts light energy into heat energy, preventing the laser from being directly injected into the signal receiving module, thereby reducing the system's thermal noise and improving its signal-to-noise ratio.

[0047] Figure 2 is a schematic diagram of another gas detection system provided by the present application according to some embodiments. Optionally, as Figure 2 As shown, the signal receiving and demodulation module includes a quartz tuning fork 5, a preamplifier 6, a lock-in amplifier 7 and an oscilloscope 8.

[0048] Among them, the hot wire optical fiber 4 is placed around the quartz tuning fork 5, the output end of the quartz tuning fork 5 is connected to the input end of the preamplifier 6, the output end of the preamplifier 6 is connected to the input end of the phase-locked amplifier 7, and the output end of the phase-locked amplifier 7 is connected to the oscilloscope 8.

[0049] In the device, the signal receiving module includes a quartz tuning fork 5 , and the signal demodulation module includes a preamplifier 6 , a lock-in amplifier 7 and an oscilloscope 8 .

[0050] Figure 3is a schematic diagram of the position of the hot-wire optical fiber and the quartz tuning fork, optionally, as Figure 3 As shown, the hot-wire optical fiber 4 is placed around the quartz tuning fork 5 and includes:

[0051] The hot-wire optical fiber 4 is placed between the two arms of the quartz tuning fork 5 or on the front side of the quartz tuning fork 5 or on the side of the quartz tuning fork 5 .

[0052] During use, the temperature-controlled current source 1 generates a drive signal consisting of a low-frequency sawtooth wave superimposed on a high-frequency sine wave at half the resonant frequency of the quartz tuning fork 5. This drive signal causes the laser 2 to output modulated light, the wavelength of which corresponds to the absorption peak of the gas to be measured (for example, the central wavelength of the laser 2 is 1368.597 nm, corresponding to the absorption peak of water vapor). The modulation frequency of this light is half the resonant frequency of the quartz tuning fork 5. The light output from the gas absorption cell 3 is input into the hot-wire optical fiber 4. Due to its own thermal effect, the hot-wire optical fiber 4 converts the light energy into heat energy, causing periodic changes in the ambient temperature, which in turn causes periodic changes in pressure, generating acoustic waves, and causing the quartz tuning fork 5 to vibrate. The quartz tuning fork 5 generates a piezoelectric current signal due to the piezoelectric effect. The preamplifier 6 converts the current signal into a voltage signal, and the phase-locked amplifier 7 demodulates the voltage signal, so that the concentration of the gas to be measured can be inverted on the oscilloscope 8. The system avoids direct contact between the quartz tuning fork 5 and the gas to be measured, protecting the quartz tuning fork 5 from being damaged by corrosive gases, thereby ensuring its detection accuracy; on the other hand, the hot-wire optical fiber 4 converts light energy into heat energy, avoiding direct incidence of light on the quartz tuning fork 5, reducing the thermal noise of the system and improving the signal-to-noise ratio of the system; it also overcomes the shortcomings of the quartz enhanced photoacoustic spectroscopy gas detection system that it is not suitable for long-distance measurement, remote sensing, combustion diagnosis and other fields. The system has the characteristics of simple structure.

[0053] The wavelength of light corresponding to the absorption peak of the gas to be measured means that the light of this wavelength can be absorbed the most by the gas.

[0054] Figure 4 is a schematic diagram of another gas detection system provided by the present application according to some embodiments. Optionally, as Figure 4 As shown, the signal receiving and demodulating module includes a fiber Bragg grating 9, a broadband light source 10, a fiber circulator 11 and a spectrum analyzer 12.

[0055] The hot-wire optical fiber 4 is fixed on the fiber grating 9, the broadband light source 10 is connected to the input end of the fiber circulator 11, the middle end of the fiber circulator 11 is connected to the fiber grating 9, and the output end of the fiber circulator 11 is connected to the spectrum analyzer 12.

[0056] In the device, the signal receiving module includes a fiber Bragg grating 9 , and the signal demodulation module includes a broadband light source 10 , a fiber circulator 11 and a spectrum analyzer 12 .

[0057] Optionally, the hot-wire optical fiber 4 and the fiber grating 9 are pasted together in parallel.

[0058] During operation, a temperature-controlled current source 1 generates a DC signal as the driving signal for the laser 2. The DC driving signal and temperature are adjusted to ensure that the output wavelength of the laser 2 is at the gas absorption peak (i.e., the wavelength at which the gas absorbs the most light). Due to its own thermal effect, the hot-wire optical fiber 4 converts optical energy into thermal energy, causing the wavelength of the fiber Bragg grating 9 to shift. The first wavelength displayed on the spectrum analyzer 12 when the gas absorption cell 3 is empty is recorded. The gas to be measured is then introduced into the gas absorption cell 3. After the light output by the laser 2 is absorbed by the gas to be measured, the intensity of the light input to the hot-wire optical fiber 4 is attenuated compared to when the gas absorption cell 3 is empty. The temperature of the hot-wire optical fiber 4 decreases, causing the wavelength of the fiber Bragg grating 9 to shift. At this point, a second wavelength is displayed on the spectrum analyzer 12. The difference between the first and second wavelengths is used to infer the concentration of the gas to be measured. By using a grating to demodulate the signal, this system can respond to light across the entire wavelength range, reducing system cost and simplifying its structure.

[0059] Based on the above-mentioned gas detection system, this application proposes a gas concentration detection method, including:

[0060] Step S1: Connect the gas detection system, turn on the power of each part of the gas detection system, and inject the gas to be tested into the gas absorption cell 3;

[0061] Step S2: The temperature-controlled current source 1 generates a driving signal, which is used to drive the light output by the laser 2. The wavelength of the light output by the laser 2 corresponds to the absorption peak of the gas to be measured. The gas absorption cell 3 inputs the processed light into the hot-line optical fiber 4. The hot-line optical fiber 4 converts the optical energy of the light processed by the gas absorption cell 3 into thermal energy. The signal receiving and demodulation module uses the thermal energy converted by the hot-line optical fiber 4 to detect the concentration of the gas to be measured in the gas absorption cell 3.

[0062] Step S3: After signal processing is completed, the power is turned off.

[0063] Optionally, the signal receiving and demodulation module includes a quartz tuning fork 5, a preamplifier 6, a lock-in amplifier 7 and an oscilloscope 8. Figure 5 This is an example of a laser driving signal diagram provided by this application. The driving signal (such as Figure 5 As shown in FIG5 , a low-frequency sawtooth wave is superimposed on a high-frequency sine wave with half the resonance frequency of the quartz tuning fork 5. The signal receiving and demodulation module uses the heat energy converted by the hot-wire optical fiber 4 to detect the concentration of the gas to be measured in the gas absorption cell 3.

[0064] The heat energy converted by the hot-wire optical fiber 4 causes the ambient temperature to change periodically, which in turn causes the pressure to change periodically, generating sound waves, which in turn causes the quartz tuning fork 5 to vibrate. The quartz tuning fork 5 generates a piezoelectric current signal, which is converted by the preamplifier 6 into a voltage signal. The phase-locked amplifier 7 demodulates the voltage signal, and the concentration of the gas to be measured is inverted on the oscilloscope 8. The signal displayed on the oscilloscope 8 is shown in Figure 1. Figure 6 ,in, Figure 6 This is an example of a signal diagram displayed by an oscilloscope provided in this application.

[0065] Optionally, the signal receiving and demodulation module includes a fiber Bragg grating 9, a broadband light source 10, a fiber circulator 11 and a spectrum analyzer 12, the driving signal is a DC signal, and the signal receiving and demodulation module uses the heat energy converted by the hot-wire optical fiber 4 to detect the concentration of the gas to be measured in the gas absorption cell 3, including:

[0066] The light emitted by the broadband light source 10 is reflected by the fiber grating 9 and then monitored by the spectrum analyzer 12. The first wavelength displayed on the spectrum analyzer 12 when there is no gas in the gas absorption cell 3 is recorded.

[0067] The gas to be measured is introduced into the gas absorption cell 3. After the light output by the laser 2 is absorbed by the gas to be measured, the light intensity of the light input to the hot-wire optical fiber 4 is attenuated compared to when there is no gas in the gas absorption cell 3. The temperature of the hot-wire optical fiber 4 decreases, causing the wavelength of the fiber grating 9 to drift, and the spectrum analyzer 12 displays a second wavelength.

[0068] The concentration of the gas to be measured is inverted according to the difference between the first wavelength and the second wavelength.

[0069] For example, the laser 2 is a semiconductor laser 2, and its central wavelength is 1532.83nm, which corresponds to the absorption peak of acetylene gas. The wavelength range of the broadband light source 10 is 1520nm-1580nm, and the central wavelength of the fiber Bragg grating 9 is 1550nm. The central wavelength of the fiber Bragg grating 9 is different for different gas concentrations, for example Figure 7 As shown, Figure 7 This is a schematic diagram of gas concentration corresponding to different central wavelengths of an optical fiber Bragg grating provided in this application.

[0070] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown in sequence as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified 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 of the steps in the flowcharts of the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0071] The above description is only part of the implementation methods of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A gas detection system, characterized in that: It includes a temperature-controlled current source, a laser, a gas absorption cell, a hot-wire optical fiber, and a signal receiving and demodulation module; The temperature-controlled current source is connected to the laser, the output optical fiber of the laser is connected to the input end of the gas absorption cell, the output optical fiber of the gas absorption cell is connected to the hot-wire optical fiber, and the hot-wire optical fiber is close to the signal receiving and demodulation module, wherein the hot-wire optical fiber can convert light energy into heat energy, and the signal receiving and demodulation module can use the heat energy converted by the hot-wire optical fiber to detect the concentration of the gas to be measured in the gas absorption cell; The signal receiving and demodulation module includes a signal receiving module and a signal demodulation module, the signal receiving module includes a quartz tuning fork, and the signal demodulation module includes a preamplifier, a lock-in amplifier and an oscilloscope; The hot-wire optical fiber is placed between the two arms of the quartz tuning fork or on the front or side of the quartz tuning fork to achieve physical isolation between the gas absorption cell and the signal receiving module, preventing the quartz tuning fork from direct contact with the laser and gas. The output end of the quartz tuning fork is connected to the input end of the preamplifier, the output end of the preamplifier is connected to the input end of the phase-locked amplifier, and the output end of the phase-locked amplifier is connected to the oscilloscope.

2. The gas detection system according to claim 1, characterized in that The hot-line optical fiber is a high-loss cobalt-doped optical fiber, and the coating layer is removed.

3. A gas detection method, characterized in that: Utilizing the gas detection system according to claim 1 or 2, the system includes a temperature-controlled current source, a laser, a gas absorption cell, a hot-wire optical fiber, and a signal receiving and demodulation module, the signal receiving and demodulation module includes a signal receiving module and a signal demodulation module, the signal receiving module includes a quartz tuning fork, and the signal demodulation module includes a preamplifier, a lock-in amplifier, and an oscilloscope, wherein the hot-wire optical fiber is placed between the two arms of the quartz tuning fork or on the front or side of the quartz tuning fork to achieve physical isolation between the gas absorption cell and the signal receiving module, thereby preventing the quartz tuning fork from direct contact with laser light and gas. The method comprises: Step S1: connecting the gas detection system, turning on the power of each part of the gas detection system, and injecting the gas to be tested into the gas absorption cell; Step S2: causing the temperature-controlled current source to generate a driving signal, the driving signal being used to drive the laser, the wavelength of the laser output light corresponding to the absorption peak of the gas to be measured, the gas absorption cell inputting the light absorbed by the gas molecules therein into the hot-wire optical fiber, the hot-wire optical fiber converting the light energy absorbed by the gas molecules in the gas absorption cell into thermal energy, the signal receiving and demodulation module using the thermal energy converted by the hot-wire optical fiber to detect the concentration of the gas to be measured in the gas absorption cell, wherein the driving signal is a low-frequency sawtooth wave superimposed on a high-frequency sine wave having half the resonant frequency of the quartz tuning fork, and the signal receiving and demodulation module using the thermal energy converted by the hot-wire optical fiber to detect the concentration of the gas to be measured in the gas absorption cell includes: The heat energy converted by the hot-wire optical fiber causes periodic changes in the ambient temperature, which in turn causes periodic changes in pressure, generating sound waves, thereby causing the quartz tuning fork to vibrate. The quartz tuning fork generates a piezoelectric current signal, the preamplifier converts the piezoelectric current signal into a voltage signal, and the lock-in amplifier demodulates the voltage signal, thereby inverting the concentration of the gas to be measured on the oscilloscope.

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