Tunable semiconductor laser spectrum absorption method

Abstract

The invention discloses a tunable semiconductor laser spectrum absorption method, and relates to the technical field of spectral analysis. The method comprises the following steps: step 1, constructing a multi-optical-path measurement gas chamber; 2, setting light source parameters; 3, gas concentration calculation; 4, correcting and outputting a result; by means of the gas chamber structure for multi-optical-path measurement, the optical path length is increased, the intensity of absorbed signals is improved, the spectrum quality and the signal-to-noise ratio are guaranteed through optimized mid-infrared light source and laser output light parameters, the stability and reliability of an optical path are guaranteed, and high-precision and high-efficiency detection of the gas concentration is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of spectrum analysis, and in particular to a tunable semiconductor laser spectrum absorption method. Background Art

[0002] As the requirements for gas concentration detection accuracy in environmental monitoring, industrial process control and other fields continue to increase, traditional gas detection methods can no longer meet the needs. As a new type of spectral technology, tunable semiconductor laser absorption spectroscopy has attracted widespread attention for its high-precision, high-sensitivity and high-efficiency in-situ chemical and physical measurement capabilities. Now, regarding the semiconductor laser spectral absorption method, a Chinese patent with publication number: CN112432921B discloses a tunable semiconductor laser absorption spectroscopy method based on special gain fiber. First, according to the characteristic absorption spectrum line of the substance to be measured, a special gain fiber of a certain length is selected; according to the characteristic absorption spectrum line of the substance to be measured and the working band of the special gain fiber, the corresponding semiconductor laser, pump laser and photodetector are selected; secondly, according to the type of special gain fiber, a suitable special gain fiber contact method is selected to inject the laser output by the semiconductor laser and the pump laser into the special gain fiber; then, the laser output from the special gain fiber is filtered to remove the pump light, retain the signal light, and injected into the photodetector; finally, the multifunctional circuit module collects the electrical signal after the photoelectric conversion, and obtains the concentration information of the substance to be measured according to the laser absorption spectrum signal processing algorithm.

[0003] The above patent uses special gain optical fiber to replace the traditional multi-pass cell, but the following problems still exist: In the prior art, although special gain optical fibers have unique gain characteristics, their gain efficiency and stability may be affected by factors such as ambient temperature and pump power fluctuations, causing changes in the gain characteristics of the optical fiber, thereby affecting the transmission and detection accuracy of the laser. In addition, factors such as the dispersion and nonlinear effects of the optical fiber may cause the spectral resolution to decrease, affecting the accuracy of identifying specific absorption spectra. Summary of the invention

[0004] The object of the present invention is to provide a tunable semiconductor laser spectral absorption method, which increases the optical path length and improves the absorption signal intensity by simulating the gas chamber structure of multi-path measurement, thereby realizing high-precision and high-efficiency detection of gas concentration to solve the problems raised in the above-mentioned background technology.

[0005] The present invention provides the following technical solution: a tunable semiconductor laser spectral absorption method, comprising the following steps: Step 1: Construct a multi-optical path measurement chamber: construct a sealed chamber structure including multiple reflectors as the multi-optical path measurement chamber, wherein the multiple reflectors are made of a mirror material with high reflectivity and low loss; Step 2: Set light source parameters: Determine the light source type of the laser according to the obtained research requirements, cost budget and laser spectrum characteristics, and adjust the light source parameters of the laser based on the light source characteristics of the determined light source type, including wavelength range, output power and line width; Step 3: Calculation of gas concentration: Input a high-frequency current into the laser to adjust the laser to generate a high-frequency scanning spectrum, detect the absorption signal of the absorption spectrum at the detection end, and calculate the gas concentration value based on the detected absorption signal; Step 4: Result correction and output: Correct the measurement result based on the signal of the constructed reference optical path to eliminate the influence of the absorption of components in the air, and output and display the corrected gas concentration value.

[0006] Furthermore, the step 1 of constructing a multi-optical path measurement chamber further includes: Construct a simulation model of the multi-path measurement gas cell and determine the material properties of the multi-path measurement gas cell; One or more laser sources are set to simulate the propagation path and reflection of laser in the multi-path measurement chamber; Record the path of the laser after multiple reflections in the air chamber, evaluate the effect of increasing the optical path, observe the change in the size of the beam during propagation, and evaluate the divergence of the beam; According to the absorption characteristics of the target gas, the corresponding absorption coefficient is set in the simulation, the interaction between the laser and the gas when passing through the gas chamber is simulated, and the intensity of the absorption signal is calculated; By changing the position and number of reflectors to simulate absorption signals under different optical path lengths and comparing the intensity changes of the absorption signals, the effectiveness of the simulated laser in the multi-optical path measurement chamber is verified.

[0007] Further verification of the effectiveness of the simulated laser in the multi-path measurement chamber also includes: According to the constructed simulation model of the multi-optical path measurement gas chamber, an experimental device with the same structure is built, including a laser, a detector and a reflector; The absorption signal intensity at different optical path lengths is measured as the experimental measurement result, and the difference between the simulation model and the experimental measurement results is compared to evaluate the accuracy and effectiveness of the simulation model. If the evaluation result is less than the preset value, the parameters in the simulation model are adjusted based on the evaluation result. If the evaluation result is greater than the preset value, it is considered that the simulation model can effectively simulate the propagation and reflection of the laser in the multi-path measurement chamber.

[0008] Furthermore, the multiple reflection mirror includes: a dielectric film reflection mirror, a metal film reflection mirror, a mirror aluminum plate and an acrylic mirror panel.

[0009] Furthermore, in step 2, the light source category is determined, specifically: Based on the selection of output light parameters of mid-infrared light sources and lasers, the light energy density and spectral parameters of black body, mid-infrared LED, quantum cascade laser and optical parametric oscillator are determined; Based on the comparison results of black body, mid-infrared LED, quantum cascade laser and optical parametric oscillator light sources, combined with research needs, cost budget and laser spectral characteristics, quantum cascade laser is determined as the definite laser light source category.

[0010] Furthermore, after setting the light source parameters in step 2, it also includes: adjusting the optical path layout based on the propagation and reflection of the laser in the multi-optical path measurement chamber, and at the same time, setting a group of lasers and detectors identical to the test optical path in the multi-optical path measurement chamber to construct a reference optical path parallel to the measurement optical path.

[0011] Furthermore, the measuring optical path is a light beam emitted by a laser that passes through the gas to be measured, and the reference optical path is a light beam emitted by a laser that does not pass through the gas to be measured.

[0012] Furthermore, the gas concentration calculation in step 3 specifically includes: Optical path transmission: adjust the laser driving current to generate a high-frequency scanning spectrum. The laser beam passes through a multi-optical path gas chamber and is reflected multiple times in the gas chamber to increase the optical path. Signal extraction: The laser signal after gas absorption is received at the detection end, converted into an electrical signal through the detector, and the received electrical signal is amplified and filtered to extract the absorption signal; Concentration calculation: According to the Beer-Lambert law and the known absorption coefficient, the concentration of the gas is calculated based on the intensity of the extracted absorption signal.

[0013] Furthermore, the gas concentration value is calculated based on the Beer-Lambert law, and is calculated by the following formula: In the formula, Expressed as gas concentration; Expressed as incident light intensity; Expressed as transmitted light intensity; It is expressed as the absorption coefficient; Expressed as optical path length.

[0014] Furthermore, the measurement result is corrected in step 4, and further includes: By comparing the light signal intensity of the measurement light path and the reference light path, the signal attenuation caused by gas absorption is calculated; A signal attenuation model between gas concentration and optical signal attenuation is established according to the gas absorption law, and the signal intensity of the measuring optical path is converted into a gas concentration value based on the signal attenuation model; Acquire multi-component gas, distinguish the absorption characteristics of different components to light signals, and calibrate the components with different absorption characteristics based on the distinction results.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. By constructing a multi-optical path measurement chamber and using a high-reflectivity, low-loss reflector to increase the optical path, the airtight design of the chamber structure ensures the stability of the internal gas concentration and avoids external factors such as air flow and temperature changes. Interference with the detection results, the optical path is reasonably arranged to reduce energy loss and interference in the optical path and enhance the stability of the system. According to the Beer-Lambert law, the increase in the optical path can effectively increase the intensity of the absorption signal, thereby improving the accuracy of gas detection. At the same time, the measurement results are corrected using the signal of the reference optical path, which can effectively eliminate the influence of the absorption of components in the air on the measurement results and improve the anti-interference ability of the system.

[0016] 2. The simulation model can accurately record the propagation path and reflection of the laser in the air chamber, as well as the changes in beam size and divergence angle, providing an important reference for evaluating system performance and allowing rapid parameter adjustment and performance evaluation in a virtual environment without rebuilding the experimental setup. At the same time, by comparing the differences between the simulation model and the experimental measurement results, the accuracy and effectiveness of the simulation model can be further verified, thereby ensuring that the system can achieve the expected performance indicators in actual applications, which can significantly improve the performance, reliability, experimental success rate and cost-effectiveness of the detection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a step diagram of the tunable semiconductor laser spectral absorption method of the present invention; Figure 2 The figure is a flow chart of the tunable semiconductor laser spectral absorption method of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In order to solve the technical problems that the gain efficiency and stability may be affected by factors such as ambient temperature and pump power fluctuations, which may cause the gain characteristics of the optical fiber to change, thereby affecting the transmission and detection accuracy of the laser, and the dispersion and nonlinear effects of the optical fiber may cause the spectral resolution to decrease, affecting the recognition accuracy of specific absorption lines, please refer to Figure 1-2, this embodiment provides the following technical solutions: A tunable semiconductor laser spectral absorption method comprises the following steps: Step 1: Construct a multi-path measurement chamber: Construct a sealed chamber structure including multiple reflectors as the multi-path measurement chamber, wherein the multiple reflectors are made of high-reflectivity, low-loss mirror materials, and the multiple reflectors are low-loss reflectors, so that the laser beam is reflected multiple times in the chamber, thereby increasing the optical path, ensuring that the energy loss of the laser in the reflection process is minimal, and ensuring that the chamber has good sealing to maintain the stability of the internal gas concentration. The multiple reflectors include: a dielectric film reflector, a metal film reflector, a mirror aluminum plate, and an acrylic mirror plate; Step 2: Set light source parameters: Determine the light source type of the laser based on the obtained research requirements, cost budget and laser spectrum characteristics, and adjust the light source parameters of the laser based on the light source characteristics of the determined light source type, including wavelength range, output power and line width, to meet the needs of gas detection, specifically: Based on the selection of output light parameters of mid-infrared light sources and lasers, the light energy density and spectral parameters of black body, mid-infrared LED, quantum cascade laser and optical parametric oscillator are determined; Based on the comparison results of black body, mid-infrared LED, quantum cascade laser and optical parametric oscillator, combined with research needs, cost budget and laser spectrum characteristics, quantum cascade laser is determined as the definite laser light source category; In this embodiment, although the black body can emit a continuous spectrum, the spectral resolution is low and it is not suitable for accurate gas detection. The mid-infrared LED has a low cost, but a wide spectral width, limited spectral resolution and output power. The quantum cascade laser has high output power, narrow linewidth and good tunability. The optical parametric oscillator is suitable for high-precision gas detection, has a wide tunable range, but is expensive and requires a complex control system. Based on the above comparison, it is reasonable to choose the quantum cascade laser as the light source. The high output power, narrow linewidth and good tunability of the QCL make it very suitable for high-precision gas detection. In this embodiment, after setting the light source parameters in step 2, the method further includes: adjusting the optical path layout based on the propagation and reflection of the laser in the multi-optical path measurement chamber to reduce energy loss and interference in the optical path; at the same time, in the multi-optical path measurement chamber, a group of lasers and detectors identical to the test optical path are set to construct a reference optical path parallel to the measurement optical path; the measurement optical path is a light beam emitted by the laser that passes through the gas to be measured, and the reference optical path is a light beam emitted by the laser that does not pass through the gas to be measured; In this embodiment, the setting of the reference optical path provides a reference signal which is parallel to the measuring optical path and is not affected by gas absorption. By comparing the signal difference between the measuring optical path and the reference optical path, the signal attenuation caused by gas absorption can be more accurately calculated, thereby further improving the measurement accuracy and helping to monitor the stability of the system state. The reference optical path can be used for rapid calibration and correction to ensure the accuracy and reliability of the measurement results. Step 3: Calculation of gas concentration: Input a high-frequency current into the laser to adjust the laser to generate a high-frequency scanning spectrum, detect the absorption signal of the absorption spectrum at the detection end, and calculate the gas concentration value based on the detected absorption signal; Step 4: Result correction and output: Correct the measurement result based on the signal of the constructed reference optical path to eliminate the influence of the absorption of components in the air, and output and display the corrected gas concentration value.

[0020] In this embodiment, a multi-optical path measurement chamber is constructed and a high-reflectivity, low-loss reflector is used to increase the optical path. The sealing design of the chamber structure ensures the stability of the internal gas concentration and avoids external factors, such as air flow, temperature changes, etc., that interfere with the detection results. The optical path is reasonably arranged to reduce energy loss and interference in the optical path, thereby enhancing the stability of the system. According to the Beer-Lambert law, the increase in the optical path can effectively increase the intensity of the absorption signal, thereby improving the accuracy of gas detection. At the same time, the measurement results are corrected using the signal of the reference optical path, which can effectively eliminate the influence of the absorption of components in the air on the measurement results and enhance the anti-interference ability of the system.

[0021] In this embodiment, the step 1 of constructing a multi-optical path measurement chamber further includes: Construct a simulation model of the multi-path measurement gas cell and determine the material properties of the multi-path measurement gas cell, including the refractive index and absorption coefficient; the simulation model is usually constructed using professional optical design software (such as Zemax, CODE V, etc.), which is an existing technology; Set one or more laser sources, set the laser wavelength, beam size, divergence angle and other parameters, and simulate the propagation path and reflection of the laser in the multi-path measurement chamber; Record the path of the laser after multiple reflections in the air chamber, evaluate the effect of increasing the optical path, observe the change in the size of the beam during propagation, and evaluate the divergence of the beam; According to the absorption characteristics of the target gas, the corresponding absorption coefficient is set in the simulation, the interaction between the laser and the gas when passing through the gas chamber is simulated, and the intensity of the absorption signal is calculated; By changing the position and number of reflectors, the absorption signals under different optical paths are simulated, and the intensity changes of the absorption signals are compared to verify the effectiveness of the simulated laser in the multi-optical path measurement chamber. In this embodiment, the simulation model is used to pre-evaluate different material properties, such as refractive index and absorption coefficient, laser parameters, such as wavelength, beam size, divergence angle, and the effect of reflector configuration on the increase in optical path, beam divergence, and absorption signal intensity. This helps to optimize the gas chamber structure and laser parameters in the design stage and improve the overall performance of the detection system. Multiple simulations and parameter adjustments in a simulation environment can avoid expensive trial and error in the process of setting up the experimental device, which not only saves material costs but also shortens the research and development cycle. Through simulation verification, it can be ensured that the experimental device has been fully tested and optimized before construction, which greatly reduces the risk of experimental failure and improves the success rate of the experiment. The simulation model can simulate the impact of various factors in the actual working environment on the detection system.

[0022] According to the constructed simulation model of the multi-optical path measurement gas chamber, an experimental device with the same structure is built, including a laser, a detector and a reflector; The absorption signal intensity at different optical path lengths is measured as the experimental measurement result, and the difference between the simulation model and the experimental measurement results is compared to evaluate the accuracy and effectiveness of the simulation model. If the evaluation result is less than the preset value, the parameters in the simulation model are adjusted based on the evaluation result. If the evaluation result is greater than the preset value, it is considered that the simulation model can effectively simulate the propagation and reflection of the laser in the multi-path measurement chamber.

[0023] In this embodiment, the simulation model can accurately record the propagation path and reflection of the laser in the air chamber, as well as the changes in beam size and divergence angle, providing an important reference for evaluating system performance and allowing rapid parameter adjustment and performance evaluation in a virtual environment without rebuilding the experimental setup. At the same time, by comparing the differences between the simulation model and the experimental measurement results, the accuracy and effectiveness of the simulation model can be further verified, thereby ensuring that the system can achieve the expected performance indicators in actual applications, which can significantly improve the performance, reliability, experimental success rate and cost-effectiveness of the detection system.

[0024] In this embodiment, the gas concentration calculation in step 3 specifically includes: Optical path transmission: adjust the laser driving current to generate a high-frequency scanning spectrum. The laser beam passes through a multi-optical path gas chamber and is reflected multiple times in the gas chamber to increase the optical path. Signal extraction: The laser signal after gas absorption is received at the detection end, converted into an electrical signal through the detector, and the received electrical signal is amplified and filtered to extract the absorption signal; Concentration calculation: According to the Beer-Lambert law and the known absorption coefficient, the concentration of the gas is calculated based on the intensity of the extracted absorption signal, using the following formula: In the formula, Expressed as gas concentration; Expressed as incident light intensity; Expressed as transmitted light intensity; It is expressed as the absorption coefficient; Expressed as optical path length.

[0025] In this embodiment, a high-frequency scanning spectrum is generated by adjusting the laser driving current, and combined with the design of a multi-optical path gas chamber, the interaction time between the laser and the gas to be measured is significantly increased, thereby improving the detection sensitivity of weak absorption signals. High-frequency scanning spectrum technology helps to distinguish and reduce the interference of background noise in the signal processing process, and improve signal quality. After the detector converts the received laser signal into an electrical signal, it effectively enhances the amplitude of the absorption signal through amplification and filtering, and suppresses unnecessary noise components. Based on the Beer-Lambert law and the known absorption coefficient, combined with the extracted precise absorption signal intensity, the gas concentration value can be accurately calculated. It is not only scientific and rigorous, but also has high accuracy and reliability. The entire concentration calculation process can be completed in a relatively short time, meeting the needs of real-time monitoring of gas concentration, not only improving the sensitivity and accuracy of gas concentration detection, but also enhancing the real-time nature of the measurement results, expanding the scope of application of the method, and providing strong technical support for industrial monitoring, environmental monitoring and other fields.

[0026] In this embodiment, the measurement result is corrected in step 4, and further includes: By comparing the optical signal intensity of the measurement optical path and the reference optical path, the signal attenuation caused by gas absorption is calculated, which effectively eliminates the influence of other factors on the optical signal except gas absorption, and improves the accuracy of concentration measurement; A signal attenuation model between gas concentration and light signal attenuation is established according to the gas absorption law. A signal attenuation model, such as a linear model or a nonlinear model, is established according to the relationship between the absorption coefficient and the gas concentration. Based on the signal attenuation model, the signal intensity of the measurement light path is converted into a gas concentration value, and the known non-gas absorption factors in the reference light path are deducted, thereby further improving the measurement accuracy. Multi-component gas is obtained, and spectral analysis technology is used to distinguish the absorption characteristics of different components to light signals. Based on the distinction results, components with different absorption characteristics are corrected, avoiding the influence of mutual interference between components on the measurement results and improving the measurement capability of the system in complex gas environments.

[0027] In this embodiment, by comparing the optical signal intensity of the measurement optical path and the reference optical path, and applying the signal attenuation model for correction, the accuracy and reliability of the gas concentration measurement are significantly improved. The multi-component gas correction method enables the system to accurately measure the concentrations of various components in a complex gas environment, thereby enhancing the adaptability and practicality of the system. The correction process not only involves the processing and analysis of the original measurement data, but also includes the subtraction of non-gas absorption factors and the distinction of the absorption characteristics of multi-component gases, thereby optimizing the data processing flow and improving data processing efficiency. The high-precision measurement results and powerful multi-component gas correction capabilities enable users to understand the gas environment conditions more accurately, providing strong support for industrial monitoring, environmental monitoring and other fields, and improving user experience.

[0028] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A tunable semiconductor laser spectral absorption method, characterized in that: The following steps are involved: Step 1: Construct a multi-optical path measurement gas chamber: construct a sealed gas chamber structure including multiple reflectors as a multi-optical path measurement gas chamber; Step 2: Set light source parameters: Determine the light source type of the laser based on the obtained research requirements, cost budget and laser spectrum characteristics, adjust the light source parameters of the laser based on the light source characteristics of the determined light source type, including wavelength range, output power and line width, and construct a reference light path parallel to the measurement light path; Step 3: Calculation of gas concentration: Input a high-frequency current into the laser to adjust the laser to generate a high-frequency scanning spectrum, detect the absorption signal of the absorption spectrum at the detection end, and calculate the gas concentration value based on the detected absorption signal; Step 4: Result correction and output: Correct the measurement result based on the signal of the constructed reference optical path to eliminate the influence of the absorption of components in the air, and output and display the corrected gas concentration value.

2. A tunable semiconductor laser spectral absorption method as claimed in claim 1, characterized in that: The step 1 of constructing a multi-path measurement gas chamber also includes: Construct a simulation model of the multi-path measurement gas cell and determine the material properties of the multi-path measurement gas cell; One or more laser sources are set to simulate the propagation path and reflection of laser in the multi-path measurement chamber; Record the path of the laser after multiple reflections in the air chamber, evaluate the effect of increasing the optical path, observe the change in the size of the beam during propagation, and evaluate the divergence of the beam; According to the absorption characteristics of the target gas, the corresponding absorption coefficient is set in the simulation, the interaction between the laser and the gas when passing through the gas chamber is simulated, and the intensity of the absorption signal is calculated; By changing the position and number of reflectors to simulate absorption signals under different optical path lengths and comparing the intensity changes of the absorption signals, the effectiveness of the simulated laser in the multi-optical path measurement chamber is verified.

3. A tunable semiconductor laser spectral absorption method as claimed in claim 2, characterized in that: Verify the effectiveness of simulated laser in multi-path measurement chamber, including: According to the constructed simulation model of the multi-optical path measurement gas chamber, an experimental device with the same structure is built, including a laser, a detector and a reflector; The absorption signal intensity at different optical path lengths is measured as the experimental measurement result, and the difference between the simulation model and the experimental measurement results is compared to evaluate the accuracy and effectiveness of the simulation model. If the evaluation result is less than the preset value, the parameters in the simulation model are adjusted based on the evaluation result. If the evaluation result is greater than the preset value, it is considered that the simulation model can effectively simulate the propagation and reflection of the laser in the multi-path measurement chamber.

4. A tunable semiconductor laser spectral absorption method as claimed in claim 3, characterized in that: The multiple reflection mirror comprises: a dielectric film reflection mirror, a metal film reflection mirror, a mirror aluminum plate and an acrylic mirror plate.

5. A tunable semiconductor laser spectral absorption method as claimed in claim 4, characterized in that: In step 2, determine the light source category, specifically: Based on the selection of output light parameters of mid-infrared light sources and lasers, the light energy density and spectral parameters of black body, mid-infrared LED, quantum cascade laser and optical parametric oscillator are determined; Based on the comparison results of black body, mid-infrared LED, quantum cascade laser and optical parametric oscillator light sources, combined with research needs, cost budget and laser spectral characteristics, quantum cascade laser is determined as the definite laser light source category.

6. A tunable semiconductor laser spectral absorption method as claimed in claim 5, characterized in that: After setting the light source parameters in step 2, it also includes: adjusting the optical path layout based on the propagation and reflection of the laser in the multi-optical path measurement chamber. At the same time, in the multi-optical path measurement chamber, a group of lasers and detectors identical to the test optical path are set to construct a reference optical path parallel to the measurement optical path.

7. A tunable semiconductor laser spectral absorption method as claimed in claim 6, characterized in that: The measuring optical path is a light beam emitted by a laser that passes through the gas to be measured, and the reference optical path is a light beam emitted by a laser that does not pass through the gas to be measured.

8. A tunable semiconductor laser spectral absorption method as claimed in claim 7, characterized in that: The gas concentration calculation in step 3 specifically includes: Optical path transmission: adjust the laser driving current to generate a high-frequency scanning spectrum. The laser beam passes through a multi-optical path gas chamber and is reflected multiple times in the gas chamber to increase the optical path. Signal extraction: The laser signal after gas absorption is received at the detection end, converted into an electrical signal through the detector, and the received electrical signal is amplified and filtered to extract the absorption signal; Concentration calculation: According to the Beer-Lambert law and the known absorption coefficient, the concentration of the gas is calculated based on the intensity of the extracted absorption signal.

9. A tunable semiconductor laser spectral absorption method as claimed in claim 8, characterized in that: The gas concentration value is calculated based on the Beer-Lambert law, and is calculated by the following formula: In the formula, Expressed as gas concentration; It is expressed as the incident light intensity; Expressed as transmitted light intensity; It is expressed as the absorption coefficient; Expressed as optical path length.

10. The tunable semiconductor laser spectral absorption method according to claim 9, characterized in that: The measurement results are corrected in step 4, which also includes: By comparing the light signal intensity of the measurement light path and the reference light path, the signal attenuation caused by gas absorption is calculated; A signal attenuation model between gas concentration and optical signal attenuation is established according to the gas absorption law, and the signal intensity of the measuring optical path is converted into a gas concentration value based on the signal attenuation model; Acquire multi-component gas, distinguish the absorption characteristics of different components to light signals, and calibrate the components with different absorption characteristics based on the distinction results.

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