A gas sensing module based on a photonic chip

Abstract

The application discloses a kind of gas sensing module based on photonic chip, belong to photonic chip gas sensing and photoelectric integrated packaging technical field;Module includes: photonic chip, optical fiber array, semiconductor refrigerator, temperature sensitive resistance, integrated drive and demodulation circuit and sensing gas chamber;Through the collaborative design to light path, gas path, circuit and temperature control unit, laser can be stably coupled into photonic chip, measured gas can effectively flow through sensing area, temperature signal can feedback control semiconductor refrigerator to realize temperature stabilization regulation, and integrated drive and demodulation circuit can realize laser drive, photoelectric signal amplification, data acquisition and demodulation processing and other functions;The application is favorable to improve module integration, temperature stability and engineering application adaptability, suitable for gas detection module design based on absorption spectrum sensing.

Description

Technical Field

[0001] This invention belongs to the field of photonic chip gas sensing and optoelectronic integrated packaging technology, and particularly relates to a gas sensing module based on a photonic chip. Background Technology

[0002] Laser absorption spectroscopy (LAS)-based gas detection technology boasts advantages such as high sensitivity, fast response, good selectivity, and excellent long-term stability, making it a crucial technological approach for trace gas analysis and online monitoring. Existing LAS gas sensors typically employ free-space optical components like gas absorption cells, mirrors, and hollow optical fibers, resulting in drawbacks such as large size, the need for optical path calibration, and sensitivity to mechanical vibration and environmental disturbances. These limitations hinder their ability to meet the demands of long-term stable operation, mass production, and large-scale deployment. Currently, emerging demands for optical gas sensors are expanding into applications requiring real-time and continuous monitoring, such as environmental monitoring and industrial process control. Therefore, developing photonic chip gas sensors with high integration, miniaturization, and high reliability is of great significance. Researchers have conducted extensive studies in this area.

[0003] Currently, slow-light enhanced photonic crystal waveguide gas sensing technology, employing 2D photonic crystal waveguides with a group refractive index up to 114, has achieved a detection limit of 277 ppm for acetylene. Suspended nanophotonic waveguides for isotope-specific carbon dioxide detection, using a suspended waveguide gas sensor with a photonic crystal cladding, have achieved CO2 isotope-specific gas detection of 20 ppb in the 4.345 μm band. Suspended helical waveguides supported by subwavelength gratings, combined with convolutional neural networks and multilayer perceptron regressors, have enabled the identification, decomposition, and concentration prediction of IPA / acetone binary VOC mixtures.

[0004] Currently, existing technologies integrate infrared thermal light sources, photonic crystal waveguide array beam splitters, measurement gas chambers, reference gas chambers, and corresponding infrared detection arrays on silicon substrates to achieve gas type identification and concentration measurement through the infrared transmission spectrum of the gas. They also connect the through and add ends of microrings using feedback waveguides to form Fano resonances, and combine this with microfluidic encapsulation structures to improve sensing sensitivity and detection performance. While photonic chip-based gas sensing device designs exist, none have achieved a fully integrated package of temperature control units, signal driving and demodulation units, fiber optic interfaces, and sensing gas chambers. Therefore, there is still room for improvement in system-level integration, miniaturized deployment, and adaptability to complex environments.

[0005] Although photonic chip gas sensing technology has developed rapidly in recent years, discrete photonic chip gas sensors and sensing control systems still have shortcomings in terms of system integration, size, stability, and adaptability to complex environments, which limit their further miniaturization, integration, and engineering applications. Therefore, developing a gas sensing module that integrates a photonic chip, temperature control unit, signal driving and demodulation unit, and sensing chamber is of great significance for improving system miniaturization, high stability, and adaptability to complex environments. Summary of the Invention

[0006] The purpose of this invention is to provide a gas sensing module based on a photonic chip, addressing the problems of low integration, large size, need for optical path calibration, poor stability, and insufficient adaptability to complex environments in existing technologies. This invention integrates the photonic chip, temperature control unit, integrated driving and demodulation circuit, fiber array, and sensing chamber into a single design and package, achieving synergistic integration of the optical path, gas path, circuitry, and temperature control. This significantly improves the module's miniaturization, stability, and engineering adaptability, meeting the requirements for high integration, mass production, and large-scale deployment in gas sensing.

[0007] To achieve the above objectives, the present invention provides a gas sensing module based on a photonic chip, comprising: a photonic chip, an optical fiber array, a semiconductor cooler, a temperature-sensitive resistor, an integrated driving and demodulation circuit, and a sensing gas chamber; A photonic chip is mounted on a semiconductor cooler, and a temperature-sensitive resistor is located on one side of the photonic chip for real-time temperature detection. An optical fiber array is connected to the input and output coupling structures of the photonic chip to achieve optical coupling between the incident and emitted light and the photonic chip. An integrated driving and demodulation circuit is connected to the semiconductor cooler, the temperature-sensitive resistor, and an external laser and / or photodetector to achieve temperature control, laser driving, photoelectric signal amplification, and data acquisition functions. A sensing gas chamber covers or surrounds the photonic chip and the optical fiber array, and is equipped with an inlet, an outlet, and an optical interface to allow the gas to be measured to flow through the photonic chip. The optical interface is correspondingly arranged with the optical fiber array to form an optical fiber channel, enabling optical coupling between the optical fiber array and the photonic chip. The gas sensing module has an electrical interface connected to the integrated driving and demodulation circuit.

[0008] Preferably, the photonic chip includes an optical input coupling structure, a sensing optical waveguide, and an optical output coupling structure. The optical waveguide is located within the sensing region corresponding to the sensing gas chamber, and the optical waveguide measures the infrared absorption spectrum of the gas to be measured through an evanescent field.

[0009] Preferably, the optical fiber array and the photonic chip are optically coupled using either end-face coupling or grating coupling.

[0010] Preferably, the semiconductor cooler and the temperature-sensitive resistor constitute a closed-loop temperature control structure for the photonic chip. The temperature-sensitive resistor is used to detect the temperature of the photonic chip in real time. The integrated drive and demodulation circuit controls the semiconductor cooler to perform cooling and / or heating based on the temperature signal output by the temperature-sensitive resistor.

[0011] Preferably, the integrated driving and demodulation circuit includes a semiconductor cooling control module, a laser driving module, a photoelectric signal amplification module, and a data acquisition module; the semiconductor cooling control module is connected to a semiconductor cooler and a temperature-sensitive resistor to achieve stable temperature control; the laser driving module is used to output a driving signal to an external laser; the photoelectric signal amplification module is used to amplify the electrical signal output by an external photodetector; and the data acquisition module is used to acquire the amplified electrical signal.

[0012] Preferably, the integrated drive and demodulation circuit further includes a digital-to-analog converter unit and / or an analog-to-digital converter unit, wherein the digital-to-analog converter unit is used to convert digital drive signals into analog drive signals, and the analog-to-digital converter unit is used to convert acquired analog detection signals into digital signals.

[0013] Preferably, the sensing chamber includes a cavity, an air inlet, an air outlet, an optical interface, and a sealing structure. The sealing structure is disposed at the contact point between the sensing chamber and the fiber optic array to reduce leakage of the gas to be measured and to direct the gas to be measured through the sensing area.

[0014] Preferably, the integrated driving and demodulation circuit is disposed on a circuit board, and the circuit board, together with the photonic chip, semiconductor cooler, fiber array and sensing air chamber, is packaged on the same module housing or mounting base to form an integrated module with optical interface, electrical interface, air inlet interface and air outlet interface.

[0015] Therefore, the present invention employs the above-mentioned gas sensing module based on a photonic chip, which has the following beneficial effects: (1) By integrating and packaging the photonic chip, temperature control unit, integrated driving and demodulation circuit, fiber coupling structure and sensing gas chamber, the problems of large volume and manual calibration required in traditional discrete gas sensing systems are reduced. This is conducive to improving the integration of modules, system stability and feasibility of large-scale deployment, and provides an effective solution for the miniaturization and modular application of gas sensing systems. (2) The photonic chip used in this invention can be designed based on different material platforms. The optical fiber array and the chip can be connected by end-face coupling or grating coupling. It can also be combined with different laser light sources and photodetectors to form corresponding detection systems. Therefore, it can adapt to the absorption detection needs of different target gases in the visible light, near-infrared, mid-infrared and other bands. It has strong universality and can be compatible with the absorption sensing technology of multiple gases, multiple working bands and multiple laser light sources. It has good application flexibility and scene expansion capability. (3) By introducing integrated driving and demodulation circuits in the same module, the driving control of semiconductor lasers, the amplification and acquisition of photoelectric detection signals, and the closed-loop temperature control management of semiconductor coolers are realized. This allows the traditionally separate functions of light source driving, signal processing and temperature control to be completed on the same platform, thereby improving the integration and operational synergy of the gas sensing system and providing a new path for the development of high-performance, miniaturized and intelligent photoelectric sensing modules. (4) The photonic chip material platform and modular design concept adopted in this invention are compatible with existing standard semiconductor manufacturing processes, which is conducive to achieving consistent device fabrication, low-cost processing and large-scale integration. It can meet the batch application needs of gas sensing modules in environmental monitoring, industrial process control, smart cities and industrial Internet of Things, and has high engineering application value and promotion prospects.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a front view of a gas sensing module based on a photonic chip according to the present invention; Figure 2 This is an architectural diagram of a gas sensing module based on a photonic chip according to the present invention; Figure 3 This is a normalized direct absorption spectrum (DAS) signal obtained by a gas sensing module based on a photonic chip according to the present invention under different methane concentration conditions. Figure 4 The graph shows the linear fit between the normalized DAS signal peak amplitude and methane concentration. Figure 5 Stability graph for continuous testing for 1 minute under zero gas conditions; Figure 6 The Allan deviation plot is calculated under zero gas conditions; Figure 7 The graph shows the linear fit between the methane concentration measured by supercontinuum absorption spectroscopy and the actual methane concentration. Figure 8 This is a stability graph for continuous testing for 100 minutes under zero gas conditions.

[0018] Reference numerals: 1. Photonic chip; 2. Fiber optic array; 3. Semiconductor cooler; 4. Temperature-sensitive resistor; 5. Integrated drive and demodulation circuit; 6. Sensing chamber; 7. Inlet port; 8. Outlet port; 9. Optical interface; 10. Electrical interface. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0020] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as a process, method, system, product, or server that includes a series of steps or units, not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or device.

[0021] The following is combined with Figures 1-8 The embodiments of the present invention will be described in detail below.

[0022] Example 1 like Figure 1 and Figure 2As shown, this invention proposes a gas sensing module based on a photonic chip 1, including a photonic chip 1, an optical fiber array 2, a semiconductor cooler 3, a temperature-sensitive resistor 4, an integrated driving and demodulation circuit 5, and a sensing gas chamber 6. The photonic chip 1 is disposed on the semiconductor cooler 3, and the temperature-sensitive resistor 4 is disposed adjacent to the photonic chip 1 for real-time temperature detection. The optical fiber array 2 is connected to the input coupling structure and output coupling structure of the photonic chip 1 to achieve optical coupling connection between the incident light and the emitted light and the photonic chip 1. The integrated driving and demodulation circuit 5 is connected to the semiconductor cooler 3, the temperature-sensitive resistor 4, and the sensing gas chamber 6. An external laser and / or photodetector are connected to achieve functions such as temperature control, laser driving, photoelectric signal amplification, and data acquisition. The sensing gas chamber 6 covers or surrounds the photonic chip 1 and the fiber array 2, and is provided with an inlet port 7, an outlet port 8, and an optical interface 9. The inlet port 7 and the outlet port 8 are located on opposite sides of the sensing gas chamber 6 so that the gas to be measured flows through the photonic chip 1. The optical interface 9 is correspondingly arranged with the fiber array 2 to form a fiber optic channel so that the fiber array 2 and the photonic chip 1 can be optically coupled. The gas sensing module is provided with an electrical interface 10, which is connected to the integrated driving and demodulation circuit 5.

[0023] The aforementioned gas sensing module, through optoelectronic integration, achieves the coordinated integration of photonic chip 1, temperature control unit, signal driving and demodulation circuit, and sensing chamber 6, enabling real-time gas concentration detection in complex environments. Specifically, the detection laser is coupled into photonic chip 1 via fiber array 2, interacts with the target gas within sensing chamber 6, and is output by photonic chip 1 and received by an external photodetector. According to the theory of gas molecule absorption spectroscopy, when light of a specific wavelength passes through the target gas, gas molecules absorb the corresponding wavelength, causing attenuation of the output light intensity. This process satisfies Beer-Lambert's law; in gas sensing based on photonic chip 1, the emitted light intensity can be expressed as: ,in It is the intensity of transmitted light. It is the intensity of the incident light. It is the gas absorption coefficient. It refers to gas concentration. This is the effective absorption optical path length of light in photonic chip 1. Therefore, the gas sensing signal of photonic chip 1 is related to factors such as gas concentration, absorption intensity, effective path length, input light intensity, and waveguide loss. After the output optical signal is converted into an electrical signal by a photodetector, it is amplified, acquired, and demodulated by the integrated drive and demodulation circuit 5 to ultimately obtain the absorption information of the gas to be measured, and the concentration of the gas to be measured can be further inverted.

[0024] Example 2 This embodiment demonstrates the application of a gas sensing module based on photonic chip 1 in tunable diode laser absorption spectroscopy (TDLAS) methane sensing. The sensing chamber 6 encapsulates a helical waveguide based on the silicon-based photonic chip 1. The inlet port 7 connects to a micro-pump, and the outlet port 8 connects to an exhaust gas pipe. The internal pressure of the chamber is approximately one standard atmosphere. A semiconductor cooler 3 stabilizes the operating temperature of the photonic chip 1 at 25°C. A temperature-sensitive resistor 4 monitors the chip temperature in real time and feeds it back to the temperature control circuit. The output wavelength of the distributed feedback laser is tuned by controlling the operating temperature and drive current. During the experiment, the laser operating temperature was 25.5°C, and the integrated drive and demodulation circuit 5 output a sawtooth wave signal with a scanning range of 60~70 mA and a scanning frequency of 5 Hz, completely covering the characteristic absorption peak of methane in the 2268.6 nm band. The laser is coupled into the photonic chip 1 via the fiber array 2, transmitted in the spiral waveguide and fully interacts with the gas to be measured in the sensing chamber 6. The emitted light carrying the absorption spectrum information is output through the fiber to the photodetector and converted into an electrical signal. The signal is then acquired and processed by the integrated drive and demodulation circuit 5.

[0025] Normalized direct absorption spectral signals measured under different methane concentration conditions are as follows: Figure 3 As shown in the figure. The 0% concentration uses pure nitrogen as the baseline calibration signal. Experimental results show that the gas sensing module based on photonic chip 1 can detect concentrations ranging from 0% to 50%, achieving real-time detection of methane concentrations as low as 3%. The direct absorption spectrum signal was normalized, and the absorption peak amplitude was linearly fitted; the results are shown in the figure. Figure 4 As shown, there is a highly linear relationship between the normalized signal amplitude and the gas concentration, with a goodness of fit R0. 2 More than 0.997. Figure 5 The results of a 1-minute stability test under zero-gas conditions are presented, showing an average concentration drift rate of approximately 0.24% / min. Allan bias was calculated under zero-gas conditions, and the results are as follows... Figure 6 As shown, the optimal integration time of 13.2 s resulted in the minimum Allan bias of 445.9 ppm. Experimental results demonstrate that the gas sensing module based on photonic chip 1 can effectively perform TDLAS methane testing, exhibiting good detection performance and scenario adaptability. It can be widely applied in industrial safety fields such as coal mine gas early warning and pipeline leak detection.

[0026] Example 3 This embodiment demonstrates the application of a gas sensing module based on photonic chip 1 in methane sensing using supercontinuum laser absorption spectroscopy (SCLAS). The sensing chamber 6 of this gas sensing module encapsulates a helical waveguide based on the silicon-based photonic chip 1. The chamber's inlet 7 connects to a miniature gas pump, and the outlet 8 connects to an exhaust gas pipe. The internal pressure of the chamber is approximately one standard atmosphere. A semiconductor cooler 3 stabilizes the operating temperature of the photonic chip 1 at 21°C, and a temperature-sensitive resistor 4 monitors the chip temperature in real time and feeds it back to the temperature control circuit. During the experiment, the supercontinuum chip light source operated at 21°C, and its output spectrum completely covered the characteristic absorption peaks of methane in the 2260-2420 nm wavelength range. The output broadband laser is coupled into the photonic chip 1 via the fiber array 2, propagates in the helical waveguide and fully interacts with the gas to be measured in the sensing chamber 6. The outgoing light carrying the methane absorption information is output through the fiber to the photodetector and converted into an electrical signal. The signal acquisition and processing are then completed by the integrated drive and demodulation circuit 5.

[0027] After normalization, the supercontinuum absorption spectra obtained under different methane concentrations were used to extract the amplitude of the target absorption characteristics and perform linear fitting. The results are as follows: Figure 7 As shown. Experimental results indicate that there is a highly linear relationship between the normalized signal amplitude and the methane concentration, with a goodness of fit R0. 2 More than 0.9997. Figure 8 The results of a 100-minute stability test under zero gas conditions were presented, showing an average concentration drift rate of approximately 0.0077% / minute. Experimental results demonstrate that the gas sensing module based on photonic chip 1 can effectively achieve SCLAS methane detection, exhibiting excellent broadband absorption information acquisition capabilities, detection stability, and scene adaptability, making it suitable for industrial safety scenarios such as coal mine gas early warning and pipeline leak detection.

[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A gas sensing module based on a photonic chip, characterized in that, include: Photonic chips, fiber optic arrays, semiconductor coolers, temperature-sensitive resistors, integrated driving and demodulation circuits, and sensing chambers; A photonic chip is mounted on a semiconductor cooler, and a temperature-sensitive resistor is located on one side of the photonic chip for real-time temperature detection. An optical fiber array is connected to the input and output coupling structures of the photonic chip to achieve optical coupling between the incident and emitted light and the photonic chip. An integrated driving and demodulation circuit is connected to the semiconductor cooler, the temperature-sensitive resistor, and an external laser and / or photodetector to achieve temperature control, laser driving, photoelectric signal amplification, and data acquisition functions. A sensing gas chamber covers or surrounds the photonic chip and the optical fiber array, and is equipped with an inlet, an outlet, and an optical interface to allow the gas to be measured to flow through the photonic chip. The optical interface is correspondingly arranged with the optical fiber array to form an optical fiber channel, enabling optical coupling between the optical fiber array and the photonic chip. The gas sensing module has an electrical interface connected to the integrated driving and demodulation circuit.

2. The gas sensing module based on a photonic chip according to claim 1, characterized in that: The photonic chip includes an optical input coupling structure, a sensing optical waveguide, and an optical output coupling structure. The optical waveguide is located in the sensing region corresponding to the sensing gas chamber, and the optical waveguide measures the infrared absorption spectrum of the gas to be tested through an evanescent field.

3. The gas sensing module based on a photonic chip according to claim 1, characterized in that: The optical fiber array and the photonic chip are optically coupled using either end-face coupling or grating coupling.

4. The gas sensing module based on a photonic chip according to claim 1, characterized in that: The semiconductor cooler and the temperature-sensitive resistor constitute a closed-loop temperature control structure for the photonic chip. The temperature-sensitive resistor is used to detect the temperature of the photonic chip in real time. The integrated drive and demodulation circuit controls the semiconductor cooler to perform cooling and / or heating based on the temperature signal output by the temperature-sensitive resistor.

5. The gas sensing module based on a photonic chip according to claim 1, characterized in that: The integrated driving and demodulation circuit includes a semiconductor cooling control module, a laser driving module, a photoelectric signal amplification module, and a data acquisition module. The semiconductor cooling control module is connected to a semiconductor cooler and a temperature-sensitive resistor to achieve stable temperature control. The laser driving module is used to output a driving signal to an external laser. The photoelectric signal amplification module is used to amplify the electrical signal output by an external photodetector. The data acquisition module is used to acquire the amplified electrical signal.

6. The gas sensing module based on a photonic chip according to claim 1, characterized in that: The integrated drive and demodulation circuit further includes a digital-to-analog converter unit and / or an analog-to-digital converter unit. The digital-to-analog converter unit is used to convert digital drive signals into analog drive signals, and the analog-to-digital converter unit is used to convert the acquired analog detection signals into digital signals.

7. The gas sensing module based on a photonic chip according to claim 1, characterized in that: The sensing chamber includes a cavity, an air inlet, an air outlet, an optical interface, and a sealing structure. The sealing structure is located at the contact point between the sensing chamber and the fiber optic array to reduce leakage of the gas to be measured and to direct the gas to be measured through the sensing area.

8. The gas sensing module based on a photonic chip according to claim 1, characterized in that: The integrated driving and demodulation circuit is mounted on a circuit board. The circuit board, along with the photonic chip, semiconductor cooler, fiber array, and sensing air chamber, is encapsulated in the same module housing or mounting base to form an integrated module with optical interface, electrical interface, air inlet interface, and air outlet interface.

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