Gas sensor and gas detection apparatus

Abstract

The embodiment of the application provides a kind of gas sensor and gas detection equipment.It relates to gas detection technical field, for improving the performance of gas sensor.Gas sensor includes substrate, first waveguide and decondensation structure.First waveguide is arranged on substrate, and decondensation structure is arranged on substrate, for inhibiting the formation of condensation on the surface of first waveguide.Decondensation structure can inhibit the formation of condensation on the surface of first waveguide, thereby reducing the influence of condensation on the performance of gas sensor, to improve the sensitivity, reliability, stability, service life and other performances of gas sensor.First waveguide uses ultra-low loss waveguide, which can reduce transmission loss and improve detection sensitivity.

Description

Technical Field

[0001] This application relates to the field of gas detection technology, and in particular to a gas sensor and a gas detection device. Background Technology

[0002] Gas sensors play a crucial role in ensuring the safe operation of natural gas pipelines, safe production in coal mines, and safe gas use for residential purposes. They are also of great significance for environmental protection and atmospheric monitoring.

[0003] Traditional chemical reaction-based gas sensors are simple in structure and low in cost, but suffer from short lifespan, require regular calibration, and have poor anti-interference capabilities. In contrast, laser spectral absorption gas sensors detect the infrared absorption spectra of gas molecules, offering advantages such as high sensitivity, good selectivity, and long lifespan. However, traditional laser spectral absorption gas sensors require precisely aligned discrete optical elements to construct the optical path, resulting in large size, high cost, and poor structural stability, thus affecting the performance of the gas sensor.

[0004] Therefore, improving the performance of laser spectral absorption gas sensors has become the key to enhancing gas sensor detection technology. Summary of the Invention

[0005] This application provides a gas sensor and a gas detection device for achieving high sensitivity and high reliability gas detection.

[0006] A first aspect of this application provides a gas sensor, which includes a substrate, a first waveguide, and a decondensation structure. The first waveguide is disposed on the substrate, and the decondensation structure is disposed on the substrate to suppress condensation formation on the surface of the first waveguide.

[0007] The gas sensor provided in this application includes an anti-condensation structure, which can suppress the formation of condensation on the surface of the first waveguide, thereby reducing the impact of condensation on the performance of the gas sensor and improving the sensitivity, reliability, stability, service life and other performance of the gas sensor.

[0008] In one possible implementation, the decondensation structure includes a temperature controller; the temperature controller and the first waveguide are disposed on opposite sides of the substrate; the temperature controller generates heat in response to a control signal. By using the temperature controller to generate heat, condensation formation is suppressed, achieving complete or significant condensation removal to optimize the performance of the gas sensor. Alternatively, the decondensation structure can be made of a moisture-absorbing material, with the decondensation structure and the first waveguide disposed on the same side of the substrate, and a gap between them. By placing the moisture-absorbing material on the substrate, water vapor near the surface of the first waveguide can be adsorbed, suppressing condensation formation; the structure is simple and the principle is straightforward.

[0009] In one possible implementation, the first waveguide is an ultra-low loss waveguide. Ultra-low loss waveguides have very low loss per unit length while maintaining a large evanescent field proportion, thereby reducing energy loss during light propagation in the first waveguide, allowing for longer optical path designs, and improving detection sensitivity.

[0010] In one possible implementation, the gas sensor further includes a photodetector; the photodetector is disposed on a substrate; the photodetector is coupled to a first waveguide and located on the same side of the substrate as the first waveguide. The photodetector is used to receive the optical signal coupled out from the first waveguide and convert the optical signal into an electrical signal. A photodetector with high sensitivity and high dynamic range can accurately measure changes in light intensity after passing through a gaseous environment and can measure a wide range of gas concentrations.

[0011] In one possible implementation, the photodetector is coupled to the first waveguide using one of the following methods: direct coupling, optical path corner coupling, or flip-chip coupling. Using one of these methods to couple the photodetector to the first waveguide can improve the integration density of the gas sensor and reduce its size.

[0012] In one possible implementation, the gas sensor further includes a polarization controller; the polarization controller is integrated on the substrate; the polarization controller is coupled to a first waveguide and located on the same side of the substrate as the first waveguide. The polarization controller is used to adjust the polarization state of the output light, ensuring that the propagation of the optical signal in the first waveguide meets the requirements, and avoiding increased coupling loss, transmission loss, and deviation of the evanescent field ratio from the design expectation due to polarization mismatch. The polarization controller can guarantee the accuracy and stability of the gas sensor. Integrating the polarization controller on the substrate can improve the integration density of the gas sensor and reduce its size.

[0013] In one possible implementation, the polarization controller is directly coupled to the first waveguide. Directly coupling the polarization controller to the first waveguide can improve the integration of the gas sensor and reduce its size.

[0014] In one possible implementation, the gas sensor further includes a laser; the laser is disposed on a substrate and coupled to a polarization controller; the laser and a first waveguide are located on the same side of the substrate. The laser has narrow linewidth and wavelength tuning characteristics, and its wavelength can be controlled by current and temperature. The laser can emit infrared light of a specific wavelength and tune the wavelength of the infrared light to near the absorption peak of the gas to be measured, which can meet the requirements of high-sensitivity gas detection. Integrating the laser on the substrate can improve the integration density of the gas sensor and reduce its size.

[0015] In one possible implementation, the gas sensor further includes a second waveguide, with its two ends coupled to a laser and a polarization controller, respectively. This coupling of the second waveguide to the laser and polarization controller reduces light loss during propagation and facilitates the integration of the laser, the second waveguide, and the polarization controller onto the substrate.

[0016] In one possible implementation, the gas sensor further includes an encapsulation layer covering at least one of the laser, polarization controller, or photodetector. The encapsulation layer enables on-chip hermetically sealed packaging, reducing the impact of moisture on the laser, polarization controller, or photodetector, and improving the accuracy and lifespan of the gas sensor.

[0017] In one possible implementation, the gas sensor further includes a processor; the processor is coupled to a temperature controller for transmitting control signals to the temperature controller; using the processor enables high-precision, high signal-to-noise ratio gas concentration inversion. Alternatively, the gas sensor may also include a humidity sensor, coupled to the temperature controller for transmitting control signals to the temperature controller; this coupling allows for precise transmission of control signals to the temperature controller, thereby reducing the impact of condensation on the gas sensor. Alternatively, the gas sensor may also include a temperature sensor, coupled to the temperature controller for transmitting control signals to the temperature controller. The temperature sensor accurately determines whether to transmit a control signal to the temperature controller by detecting the temperature of the detection environment where the first waveguide is located.

[0018] In one possible implementation, the first waveguide includes a core layer and a cladding layer, with the cladding layer located between the core layer and a substrate, covering the surface of the core layer facing the substrate. The core layer is made of at least one of silicon nitride, silicon oxynitride, silicon, germanium, lithium niobate, chalcogenide glass, III-V compounds, or organic polymers. The cladding layer is made of at least one of silicon dioxide, nitrides, sapphire, calcium fluoride, chalcogenide glass, III-V compounds, or organic polymers. The material platform (core material, cladding material) should be selected based on the characteristic wavelength range of the gas to be measured and the properties of each material. Using such an ultra-low loss waveguide material platform can reduce the loss per unit length of the first waveguide, thereby reducing energy loss during light transmission in the first waveguide.

[0019] In one possible implementation, where the condensation structure includes the temperature controller, the projection of the first waveguide onto the substrate overlaps with the projection of the temperature controller onto the substrate. This overlap enhances the heating effect of the temperature controller on the first waveguide, thereby improving the decondensation effect.

[0020] A second aspect of this application provides a gas detection device, which includes a chamber and a gas sensor according to any one of the first aspects. The gas sensor is disposed in the chamber, and the chamber is provided with an inlet and an outlet, enabling gas exchange with the gas environment to be measured.

[0021] In one possible implementation, the gas detection device further includes a moisture-absorbing structure disposed within the chamber. This moisture-absorbing structure further suppresses condensation on the first waveguide surface of the gas sensor, thereby reducing the impact of condensation on the performance of the gas sensing device and improving its sensitivity, reliability, stability, and lifespan. The structure and principle are both simple.

[0022] The gas detection device provided in the second aspect of the embodiments of this application includes the gas sensor of any one of the first aspects, and its beneficial effects are the same as those of the gas sensor, which will not be repeated here. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a gas detection device provided in an embodiment of this application;

[0024] Figure 2 A schematic diagram of a gas sensor based on TDLAS technology provided in this application embodiment;

[0025] Figure 3 A schematic diagram of another gas sensor based on TDLAS technology provided in this application embodiment;

[0026] Figure 4 This is a schematic diagram of the structure of a gas sensor provided in an embodiment of this application;

[0027] Figure 5 This is a schematic diagram of another gas sensor provided in an embodiment of this application;

[0028] Figure 6 This is a schematic diagram of the structure of another gas sensor provided in an embodiment of this application;

[0029] Figure 7 This is a schematic diagram of the structure of another gas sensor provided in an embodiment of this application;

[0030] Figure 8 This is a schematic diagram of the structure of another gas sensor provided in an embodiment of this application;

[0031] Figure 9 This is a schematic diagram of the structure of another gas sensor provided in an embodiment of this application;

[0032] Figure 10This is a schematic diagram of the structure of another gas sensor provided in an embodiment of this application;

[0033] Figure 11 This is a schematic diagram of the architecture of a gas sensor provided in an embodiment of this application. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0035] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by those skilled in the art. The terms "first," "second," "third," and similar words used in this application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Thus, a feature defined with "first," "second," or "third" may explicitly or implicitly include one or more of that feature.

[0036] In the embodiments of this application, unless otherwise explicitly specified and limited, the term "coupling" should be interpreted broadly. For example, "coupling" can be direct contact coupling or indirect coupling through an intermediate medium.

[0037] In this embodiment of the application, "and / or" describes the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following associated objects have an "or" relationship.

[0038] It should be noted that the dimensions of the components in the gas sensor and gas sensing device shown in the embodiments of this application are only schematic diagrams and do not represent the actual scale of the sensor.

[0039] This application provides a gas detection device, which, for example, includes a gas detection instrument, an air quality monitoring system, a smart home device, and an environmental sensor. For instance, the gas detection device can be applied in the field of industrial safety, used to detect combustible gases (such as methane) or toxic gases (such as carbon monoxide and hydrogen sulfide), ensuring personnel safety in high-risk environments such as natural gas pipelines, chemical plants, mines, and residential areas, or for environmental protection or atmospheric monitoring. Alternatively, the gas detection device can also be applied in the field of environmental monitoring, used to monitor air pollutants (such as nitrogen oxides and ozone) or greenhouse gases (such as carbon dioxide and methane) in real time, supporting grid-based monitoring of urban air quality and pollution source control. Furthermore, the gas detection device can also be applied in fields such as medical diagnosis and vehicle emissions testing.

[0040] Figure 1 This is a schematic diagram of a gas detection device provided in an embodiment of this application.

[0041] For example, such as Figure 1 As shown, the gas detection device 1 includes a gas sensor 10 and a chamber 20, with the gas sensor 10 disposed within the chamber 20. For example, the gas detection device 1 also includes an inlet 30 and an outlet 50. The gas to be tested enters the chamber 20 through the inlet 30, the gas sensor 10 detects the gas, and the gas is discharged through the outlet 50. The gas to be tested can be any type of gas, and this embodiment does not limit this.

[0042] Traditional chemical reaction-type gas sensors 10 are simple in structure and low in cost, but suffer from problems such as short lifespan, the need for periodic calibration, and poor anti-interference capability. In contrast, laser spectral absorption gas sensors 10 sense gas by detecting the infrared characteristic absorption spectrum of gas molecules, offering advantages such as high sensitivity, good selectivity, and long lifespan. In particular, laser spectral absorption gas sensors 10 employing tunable diode laser absorption spectroscopy (TDLAS) technology, by utilizing wavelength modulation spectroscopy and lock-in amplification techniques, not only achieve the aforementioned advantages but also effectively suppress system noise and significantly improve the signal-to-noise ratio.

[0043] Figure 2 This is a schematic diagram of the structure of a gas sensor based on TDLAS technology provided in an embodiment of this application.

[0044] In some embodiments, such as Figure 2As shown, the gas sensor 10 based on TDLAS technology includes a laser 11, a collimating lens 12, a gas chamber 13, a photodetector 14, a multi-channel amplifier 15, a processor 16, a temperature controller 17, a laser driver 18, and a pressure sensor 19.

[0045] The laser driver 18 is used to tune the laser 11 based on TDLAS technology and wavelength modulation technology, emitting a laser beam according to a low-frequency sawtooth wave or a high-frequency sine wave. The temperature controller 17 is used to control the temperature of the gas chamber 13, and the pressure sensor 19 is used to detect the pressure inside the gas chamber 13. The temperature and pressure data are used for calibration of gas concentration detection.

[0046] The gas to be tested enters the gas chamber 13 through the inlet 131 and exits through the outlet 132.

[0047] The laser beam emitted by laser 11, after being tuned, is collimated by collimating lens 12 and enters gas chamber 13, where it propagates. To improve the sensitivity of gas detection, gas chamber 13 typically employs a long optical path design and is a structure containing two high-precision reflectors. The beam is reflected multiple times within the gas chamber environment before being received by photodetector 14. Because gas molecules absorb light beams of specific wavelengths, the intensity of light matching the characteristic wavelengths of the gas molecules changes after propagation in the gas environment, with the change corresponding to the gas concentration.

[0048] The photodetector 14 receives the changed light beam and converts the optical signal into an electrical signal, which is then transmitted to the multi-channel amplifier 15. The multi-channel amplifier 15 amplifies the received electrical signal and transmits it to the processor 16. The processor 16 demodulates the received electrical signal (e.g., a 2f harmonic signal) and the detection result is fed back by the terminal device.

[0049] Since each gas molecule has a unique absorption spectrum at a specific wavelength, these spectra can be used as a "fingerprint" for gas identification. Therefore, the gas sensor 10 based on TDLAS technology can measure gas concentration by utilizing the absorption characteristics of the gas to the laser. When the laser beam emitted by the laser 11 passes through the gas chamber 13, the beam sweeps across the specific absorption spectrum of the gas molecules being measured. If the wavelength of the light in the beam is tuned to near the characteristic absorption peak of the target gas, the intensity of the emitted beam will decrease due to absorption by the gas molecules. By accurately measuring the change in the intensity of the beam after passing through the gas chamber 13, the concentration of the gas to be measured can be determined.

[0050] Although the gas sensor 10 based on TDLAS technology has high sensitivity and strong selectivity, it also has certain limitations. As described above, such as... Figure 2As shown, the gas sensor 10 based on TDLAS technology requires the use of multiple precisely aligned discrete optical elements to construct the optical path system, often referred to in the art as a spatial optical path type TDLAS gas sensor. The alignment accuracy of the optical path in the gas sensor 10 is very high; even minute optical errors or component position deviations can affect the performance of the gas sensor 10, increasing the complexity of debugging and maintenance. Furthermore, the long optical path design of the gas chamber 13 is complex and space-consuming, resulting in a relatively slow response time. The stability of the optical path and the gas chamber 13 is also affected by factors such as ambient temperature and humidity. Condensation can easily occur on the reflectors inside the gas chamber 13, leading to its failure and thus affecting the reliability of the gas sensor 10. In other words, the gas sensor 10 based on TDLAS technology suffers from problems such as large size, high cost, slow response, poor structural stability, and poor performance.

[0051] Figure 3 This is a schematic diagram of another gas sensor based on TDLAS technology provided in an embodiment of this application.

[0052] In some embodiments, such as Figure 3 As shown, the gas sensor 10 based on TDLAS technology includes a laser 11, a gas chamber 13, a first photodetector 141, a second photodetector 142, a processor 16, a laser driver 18, an optical isolator 21, a beam splitter 22, a polarization controller 23, a flow meter 24, and a waveguide 25.

[0053] The laser driver 18 is used to tune the laser beam emitted by the laser 11. The beam emitted by the laser 11 passes through the optical isolator 21 and enters the beam splitter 22. The beam splitter 22 splits the received beam into two paths, which enter the gas chamber 13 respectively.

[0054] One beam of light enters the first photodetector 141 via an open-circuit free-space sensor inside the gas chamber 13, while the other beam is coupled to a waveguide 25 located within the gas chamber 13. Propagating within the waveguide 25, the beam interacts with the gas being measured through the evanescent field (or vanishing field) within the waveguide 25, and is then coupled to a second photodetector 142. The first and second photodetectors 141 and 142 respectively transmit the electrical signals corresponding to the received beams to the processor 16. The processor 16 processes the received electrical signals, and the terminal device provides feedback on the detection results.

[0055] For example, waveguide 25 may include a suspended waveguide, a slotted waveguide, a photonic crystal waveguide, or a rectangular silicon-based waveguide, such that waveguide 25 has a high evanescent field ratio.

[0056] The flow meter 24 controls the flow rate of the gas to be measured entering the gas chamber 13 from the inlet, and the measured gas is discharged from the outlet. The optical isolator 21 prevents the light beam from returning to the laser 11.

[0057] For example, the laser 11, optical isolator 21, beam splitter 22, and polarization controller 23 can be integrated into the same chip to reduce the size of the gas sensor 10. This type of gas sensor 10 is commonly referred to in the art as an on-chip integrated TDLAS gas sensor.

[0058] Unlike traditional spatial optical path type TDLAS gas sensors, on-chip integrated gas sensors utilize integrated optics technology to integrate optical components onto a chip, significantly reducing the size of the gas sensor 10. In other words, the on-chip integrated TDLAS gas sensor combines the waveguide evanescent field effect and slow light effect of TDLAS technology and integrated optics. While maintaining high sensitivity and accuracy, the on-chip coupled integrated structure is compact and has good stability. Therefore, the on-chip integrated TDLAS gas sensor has the advantages of small size, low cost, and good stability.

[0059] The main factors determining the sensitivity and detection limit of an on-chip integrated TDLAS gas sensor are the evanescent field ratio and loss of the waveguide. To achieve a high-performance on-chip integrated TDLAS gas sensor, the waveguide 25 must have both a high evanescent field ratio and low loss.

[0060] However, while conventional devices such as suspended waveguides, slotted waveguides, and photonic crystal waveguides have a relatively high evanescent field ratio, which is beneficial for enhancing the interaction strength between the gas and the waveguide evanescent field, they also have high transmission losses and are complex to manufacture and difficult to mass-produce. Although silicon-based waveguides can achieve a relatively high evanescent field ratio, their transmission losses are still on the order of dB / cm, remaining significant. High transmission losses limit the length of waveguide 25, thus affecting the sensitivity of the gas sensor 10 it comprises. Furthermore, on-chip integrated TDLAS gas sensors are susceptible to condensation interference, affecting the stability of their sensing performance.

[0061] Based on this, this application provides an on-chip integrated TDLAS gas sensor with low loss, high evanescent field ratio, and anti-condensation function, which is used to improve the integration, sensitivity, reliability, stability and other performance of the gas sensor 10.

[0062] Figure 4 This is a schematic diagram of the structure of a gas sensor provided in an embodiment of this application.

[0063] This application provides a gas sensor 10, such as... Figure 4 As shown, the gas sensor 10 includes a substrate 31, a first waveguide 32, and an anti-condensation structure 33.

[0064] The first waveguide 32 is disposed on the substrate 31, for example, the first waveguide 32 is disposed on the surface of the substrate 31. The substrate 31 is used to provide mechanical support and a stable structure for the entire gas sensor 10. The embodiments of this application do not limit the material, thickness, or shape of the substrate 31. Figure 4 This is just an illustration.

[0065] The decondensation structure 33 is disposed on the substrate 31 and on the same side of the substrate 31 as the first waveguide 32. There is a gap between the decondensation structure 33 and the first waveguide 32 to suppress the formation of condensation on the surface of the first waveguide 32.

[0066] For example, eliminating or reducing condensation on the surface of the first waveguide 32, or preventing condensation from forming, can be understood as suppression in the embodiments of this application, as long as the amount of condensation on the surface of the first waveguide 32 can be reduced.

[0067] "Dew" is a natural phenomenon, usually referring to the phenomenon where water vapor in the air condenses into liquid water when it encounters cold air under certain temperature and humidity conditions.

[0068] The gas sensor 10 provided in this application embodiment includes an anti-condensation structure 33. The anti-condensation structure 33 can suppress the formation of condensation on the surface of the first waveguide 32, thereby reducing the impact of condensation on the performance of the gas sensor 10 and improving the sensitivity, reliability, stability, and service life of the gas sensor 10. In some embodiments, the first waveguide 32 is an ultra-low loss waveguide. An ultra-low loss waveguide is a waveguide structure with extremely low transmission loss.

[0069] For example, the core material of the first waveguide 32 includes silicon nitride, silicon oxynitride, silicon, germanium, lithium niobate, chalcogenide glass, III-V compounds, organic polymers, etc., while the cladding material includes silicon dioxide, nitrides, sapphire, calcium fluoride, chalcogenide glass, III-V compounds, organic polymers, etc. Different materials can be selected for the first waveguide 32 to suit different gases or detection environments.

[0070] Specifically, the cladding layer is located between the core layer and the substrate 31, covering the surface of the core layer facing the substrate 31. For example, the cladding layer is located between the core layer and the substrate 31, contacting the lower surface of the core layer but not covering the sides and upper surface of the core layer.

[0071] The first waveguide 32 in this application is an ultra-low loss waveguide, which can reduce the loss per unit length of the first waveguide 32, thereby reducing the energy loss of light when it is transmitted in the first waveguide 32.

[0072] For example, silicon nitride materials exhibit good stability and reliability in integrated optics, which can improve the lifespan of the gas sensor 10. Furthermore, silicon nitride-based waveguide devices can achieve extremely low transmission losses on the order of dB / m, thereby significantly increasing the optical path length and improving the sensitivity of the gas sensor 10.

[0073] In particular, thick silicon nitride waveguide devices can use narrower waveguide widths, and compared to thin silicon nitride waveguide devices (which require wider waveguide widths to support guided mode propagation), they have a larger evanescent field ratio, which can further reduce losses.

[0074] For example, the cross-sectional shape of the first waveguide 32 is rectangular to simplify the design, reduce the difficulty of fabricating the first waveguide 32, reduce costs, and improve the reliability of the gas sensor 10.

[0075] For example, the first waveguide 32 adopts a two-dimensional spiral layout or a Z-shaped curved layout. This increases the length of the first waveguide 32 per unit area within a fixed area, thereby increasing the effective optical path and improving detection sensitivity.

[0076] By selecting an ultra-low loss waveguide, the first waveguide 32 can achieve a high evanescent field ratio to enhance the efficiency of light-gas molecule interaction while having low loss, thereby further improving the detection sensitivity of gas concentration.

[0077] In some embodiments, such as Figure 4 As shown, the material of the decondensation structure 33 includes a moisture-absorbing material. The decondensation structure 33 is disposed on the substrate 31 and on the same side of the substrate 31 as the first waveguide 32. There is a gap between the decondensation structure 33 and the first waveguide 32.

[0078] For example, the materials used for decondensation structure 33 include silica gel, activated carbon, molecular sieves, etc.

[0079] By setting an anti-condensation structure 33 on the substrate 31, condensation on the surface of the first waveguide 32 can be adsorbed. The structure is simple and the principle is simple.

[0080] For example, such as Figure 4 As shown, both the decondensation structure 33 and the first waveguide 32 are disposed on the surface of the substrate 31. A gap exists between the decondensation structure 33 and the first waveguide 32 along a direction parallel to the substrate 31. For example, the gap between the decondensation structure 33 and the first waveguide 32 along a direction parallel to the substrate 31 can be understood as a gap between the side of the first waveguide 32 and the decondensation structure 33.

[0081] Figure 5 This is a schematic diagram of another gas sensor provided in an embodiment of this application.

[0082] Or, for example, such as Figure 5 As shown, the gas sensor 10 also includes a support structure placed on the substrate 31 to support the decondensation structure 33. Along the direction perpendicular to the substrate 31, there is a gap between the decondensation structure 33 and the first waveguide 32. The projection of the decondensation structure 33 on the substrate 31 overlaps with the projection of the first waveguide 32 on the substrate 31.

[0083] For example, along a direction perpendicular to the substrate 31, there is a gap between the decondensation structure 33 and the first waveguide 32, which can be understood as the gap between the upper side of the first waveguide 32 and the decondensation structure 33. By setting the decondensation structure 33 near the upper surface of the first waveguide 32 through a support structure, condensation on the surface of the first waveguide 32 can be adsorbed. The structure is simple and the principle is simple.

[0084] Figure 6 This is a schematic diagram of the structure of another gas sensor provided in an embodiment of this application.

[0085] In other embodiments, such as Figure 6 As shown, the decondensation structure 33 includes a temperature controller, which is disposed on the side of the substrate 31 away from the first waveguide 32. The temperature controller is used to generate heat in response to a control signal.

[0086] For example, after receiving a control signal to start heating, the temperature controller responds by generating heat. This heat can disrupt the conditions for condensation, such as by evaporating the condensate, thus suppressing condensation. Conversely, after receiving a shutdown signal to stop heating, the temperature controller responds by ceasing heat generation, thereby reducing module power consumption.

[0087] By using a temperature controller to suppress the formation of condensation by controlling whether heat is generated, the condensation suppression effect can be adjusted by controlling the heating temperature, so as to completely remove condensation or remove condensation to a large extent, thereby optimizing the performance of the gas sensor 10.

[0088] Optionally, the gas sensor 10 also includes a processor coupled to the temperature controller (decondensation structure 33) for transmitting control signals to the temperature controller. For example, the processor determines whether to transmit a control signal to the temperature controller based on whether the first harmonic signal is abnormal.

[0089] Alternatively, the gas sensor 10 may also include a humidity sensor coupled to the temperature controller (anti-condensation structure 33) for transmitting control signals to the temperature controller. For example, the humidity sensor determines whether to transmit a control signal to the temperature controller by detecting the humidity of the detection environment where the first waveguide 32 is located.

[0090] Alternatively, the gas sensor 10 may also include a temperature sensor coupled to the temperature controller (decondensation structure 33) for transmitting control signals to the temperature controller. For example, the temperature sensor determines whether to transmit a control signal to the temperature controller by detecting the temperature of the detection environment where the first waveguide 32 is located.

[0091] For example, after the processor, humidity sensor, or temperature sensor transmits a control signal to the temperature controller, it continues until the gas detection ends, and then transmits a shutdown signal to the temperature controller to control the temperature sensor to stop heating, so as to reduce energy loss while effectively suppressing condensation during the detection stage.

[0092] In some embodiments, the substrate 31 is made of materials such as glass, silicon, and ceramics.

[0093] This ensures that the substrate 31 has a low coefficient of thermal expansion and good thermal conductivity, which on the one hand guarantees the stability of the gas sensor 10 when the temperature changes, and on the other hand improves the heat transfer efficiency.

[0094] In some embodiments, the projection of the first waveguide 32 onto the substrate 31 overlaps with the projection of the temperature controller (decondensation structure 33) onto the substrate 31.

[0095] For example, Figure 6 As shown, the area of ​​the decondensation structure 33 is equal to the area of ​​the substrate 31, and the projection of the first waveguide 32 onto the decondensation structure 33 falls within the outline of the decondensation structure 33.

[0096] By placing the temperature controller below the first waveguide 32, the heating effect of the temperature controller on the first waveguide 32 can be improved, thereby enhancing the decondensation effect.

[0097] In some embodiments, such as Figure 6 As shown, the gas sensor 10 also includes a photodetector 34 and a first optical fiber 35, with the two ends of the first optical fiber 35 coupled to the photodetector 34 and the first waveguide 32, respectively.

[0098] The photodetector 34 is used to receive the optical signal coupled out from the first waveguide 32 and convert the optical signal into an electrical signal. By setting a photodetector 34 with high sensitivity and high dynamic range in the gas sensor 10, the light intensity change after passing through the gas environment can be accurately measured, and a large range of gas concentrations can be measured.

[0099] The first optical fiber 35 is used to connect the photodetector 34 and the first waveguide 32, enabling efficient transmission of optical signals between different components. Optical fibers are characterized by low loss and high stability; therefore, connecting the photodetector 34 and the first waveguide 32 via the first optical fiber 35 allows for flexible configuration of their positions, providing convenient integration and optimization options.

[0100] Figure 7 This is a schematic diagram of the structure of another gas sensor provided in an embodiment of this application.

[0101] In other embodiments, such as Figure 7 As shown, the gas sensor 10 also includes a photodetector 34. Both the photodetector 34 and the first waveguide 32 are disposed on the substrate 31, or can be understood as both being integrated on the substrate 31, and the photodetector 34 and the first waveguide 32 are located on the same side of the substrate 31. For example, the photodetector 34 and the first waveguide 32 are integrated on the same surface of the substrate 31.

[0102] By integrating the photodetector 34 onto the substrate 31, the integration density of the gas sensor 10 can be increased, the volume of the gas sensor 10 can be reduced, the cost can be lowered, and the reliability can be improved.

[0103] For example, photodetector 34 is coupled to first waveguide 32. The coupling method can be direct coupling, optical path corner coupling, or flip-chip coupling. By coupling photodetector 34 to first waveguide 32, no optical fiber is needed between them, which can further reduce the size of gas sensor 10.

[0104] In some embodiments, such as Figure 6 As shown, the gas sensor 10 also includes a polarization controller 36 and a second optical fiber 37, which are coupled to the polarization controller 36 and the first waveguide 32, respectively.

[0105] The second optical fiber 37 is used to connect the polarization controller 36 and the first waveguide 32, enabling efficient transmission of optical signals between different components. Optical fibers are characterized by low loss and high stability; therefore, connecting the polarization controller 36 and the first waveguide 32 via the second optical fiber 37 allows for flexible configuration of their positions, providing convenient integration and optimization options.

[0106] Figure 8 This is a schematic diagram of the structure of another gas sensor provided in an embodiment of this application.

[0107] In other embodiments, such as Figure 8As shown, the gas sensor 10 also includes a polarization controller 36. The polarization controller 36 is disposed on the substrate 31, or can be understood as integrated on the substrate 31. The polarization controller 36 is coupled to the first waveguide 32, and the polarization controller 36 and the first waveguide 32 are located on the same side of the substrate 31. For example, the polarization controller 36 and the first waveguide 32 are located on the same surface of the substrate 31.

[0108] By integrating the polarization controller 36 onto the substrate 31, the integration density of the gas sensor 10 can be increased and the volume of the gas sensor 10 can be reduced.

[0109] For example, the polarization controller 36 is directly coupled to the first waveguide 32. By directly coupling the polarization controller 36 to the first waveguide 32, there is no need to install optical fibers between them, which can further reduce the size of the gas sensor 10.

[0110] In some embodiments, such as Figure 6 As shown, the gas sensor 10 also includes a laser 38 and a third optical fiber 44, with the laser 38 coupled to the polarization controller 36 via the third optical fiber 44.

[0111] For example, laser 38 is a separately packaged tunable semiconductor laser with narrow linewidth and wavelength tuning characteristics, and its wavelength can be controlled by current and temperature. For instance, laser 38 can emit infrared light of a specific wavelength and tune the wavelength of the infrared light to near the absorption peak of the gas to be measured, in order to meet the requirements of high-sensitivity gas detection.

[0112] In other embodiments, such as Figure 8 As shown, the gas sensor 10 also includes a third waveguide 45, with its two ends coupled to a third optical fiber 44 and a polarization controller 36, respectively. The third waveguide 45 is placed on the substrate 31, or it can be understood that the third waveguide 45 is integrated on the substrate 31. The coupling of the third waveguide 45 to the third optical fiber 44 and the polarization controller 36 can reduce light loss during propagation and facilitate the integration of the polarization controller 36 onto the substrate 31.

[0113] The optical signal emitted by laser 38 is coupled into the first waveguide 32 for transmission after being polarized by polarization controller 36. At this time, polarization controller 36 is used to adjust the polarization state of the output light of laser 38 to ensure that the propagation of the optical signal in the first waveguide 32 meets the design requirements, and to avoid increased coupling loss and transmission loss due to mismatch in optical polarization state, as well as deviation of the evanescent field ratio from the design expectation, so as to ensure the high efficiency and stability of gas sensor 10.

[0114] Figure 9 This is a schematic diagram of the structure of another gas sensor provided in an embodiment of this application.

[0115] In other embodiments, such as Figure 9 As shown, the gas sensor 10 also includes a laser 38. The laser 38 is disposed on the substrate 31, or can be understood as the laser 38 being integrated on the substrate 31. The laser 38 is coupled to the polarization controller 36 through a second waveguide 39, and the laser 38 and the first waveguide 32 are located on the same side of the substrate 31. For example, the laser 38 and the first waveguide 32 are located on the same surface of the substrate 31.

[0116] By integrating the laser 38 onto the substrate 31, the integration density of the gas sensor 10 can be increased and the volume of the gas sensor 10 can be reduced.

[0117] For example, the gas sensor 10 also includes a second waveguide 39. The two ends of the second waveguide 39 are coupled to the laser 38 and the polarization controller 36, respectively. Using the second waveguide 39 to couple the laser 38 to the polarization controller 36 can reduce light loss during propagation and also makes it easier to integrate the laser 38, the second waveguide 39, and the polarization controller 36 onto the substrate.

[0118] By integrating the components onto the chip, the size of the gas sensor 10 can be reduced. The miniaturized gas sensor 10 can be placed in a smaller chamber 20, allowing the gas sensor 10 to quickly contact the gas to be measured, thereby improving the response speed and enhancing the practicality of the gas sensor 10.

[0119] Figure 10 This is a schematic diagram of the structure of another gas sensor provided in an embodiment of this application.

[0120] In some embodiments, such as Figure 10 As shown, the gas sensor 10 also includes an encapsulation layer 40 that covers at least one of the laser 38, the polarization controller 36, or the photodetector 34. Figure 10 In the example shown, the laser 38, polarization controller 36 and photodetector 34 are covered by the encapsulation layer 40.

[0121] For example, encapsulation layer 40 is used to achieve on-chip hermetic packaging. For example, encapsulation layer 40 is a glass encapsulation layer.

[0122] By encapsulating the laser 38, polarization controller 36, or photodetector 34 with encapsulation layer 40, the effects of oxygen and water vapor on the laser 38, polarization controller 36, or photodetector 34 can be reduced, thereby improving the accuracy and lifespan of the gas sensor 10.

[0123] Figure 11 This is a schematic diagram of the architecture of a gas sensor provided in an embodiment of this application.

[0124] In some embodiments, such as Figure 11As shown, the gas sensor 10 also includes a laser driver 41, which is coupled to the laser 38.

[0125] For example, the laser driver 41 is used for TDLAS technology and wavelength modulation technology, and the tuned laser 38 emits a wavelength-tuned laser beam according to a low-frequency sawtooth wave or a high-frequency sine wave.

[0126] In some embodiments, the gas sensor 10 further includes a transimpedance amplifier 42 coupled to the photodetector 34. For example, the transimpedance amplifier 42 is used to amplify the received electrical signal.

[0127] In some embodiments, the gas sensor 10 further includes a processor 43, which is coupled to a transimpedance amplifier 42. For example, after the processor 43 demodulates the received electrical signal, the detection result is fed back by the terminal device to achieve high-precision gas concentration inversion.

[0128] For example, processor 43 includes a modulation and demodulation circuit (such as a modulation and demodulation lock-in amplifier), a signal processing circuit, and a control circuit. The modulation circuit modulates the laser through wavelength modulation or frequency modulation. The demodulation circuit demodulates and filters the received signal to extract the harmonic signals of the gas absorption spectrum. The signal processing circuit further analyzes and processes the extracted harmonic signals and converts them into the concentration of the gas to be measured. The control circuit outputs a corresponding control signal to the temperature controller based on the analysis of the harmonic signals by the signal processing circuit, thereby adjusting the operating state (on / off and heating intensity) of the temperature controller.

[0129] For example, processor 43 is also coupled to laser driver 41 for controlling the operating state of laser driver, including adjusting the output current or voltage of laser driver, thereby controlling the output power and wavelength of laser.

[0130] Figure 11 The architecture of the gas sensor 10 shown is merely illustrative and does not constitute a limitation on the embodiments of this application.

[0131] The gas sensor 10 provided in this embodiment controls a laser 38 to output wavelength-tuned laser light, which is then coupled into a first waveguide 32 after passing through a polarization controller 36. The laser light is transmitted in a specific mode within the first waveguide 32 and absorbed by the gas. A photodetector 34 detects changes in laser intensity and converts the optical signal into an electrical signal. The electrical signal output by the photodetector 34 is amplified by a transimpedance amplifier 42 and then demodulated by a demodulation circuit in a processor 43 to obtain the second harmonic signal and the first harmonic signal. The first harmonic signal is proportional to the power of the laser 38 and is affected by condensation; it can be used to identify condensation and fed back by the processor 43 to a temperature controller (anti-condensation structure 33) to remove condensation. The ratio of the second harmonic signal to the first harmonic signal is proportional to the concentration of the gas to be measured and is unaffected by disturbances from the laser 38 and the photodetector 34, enabling high signal-to-noise ratio and high sensitivity gas concentration detection. The gas sensor 10 can be used for monitoring the concentration of one or more gases in various scenarios, including underground spaces, atmospheric environments, industrial and commercial environments, and residential environments.

[0132] The laser propagates in a specific mode in the first waveguide 32, which can be understood as the laser propagating in the waveguide in a transverse electric mode (TE) or a transverse magnetic mode (TM), etc. The laser can propagate in any mode in the first waveguide 32, and this embodiment does not limit this.

[0133] The gas sensor 10 provided in this application embodiment can be applied in the gas sensing device 1 provided in this application embodiment. For example, the gas sensor 10 can be placed in the chamber 20 of the gas sensing device 1.

[0134] In some embodiments, the gas sensing device 1 further includes a moisture-absorbing structure disposed within the chamber 20.

[0135] For example, the projection of the moisture-absorbing structure onto the substrate 31 does not overlap with the projection of the first waveguide 32 onto the substrate 31. For instance, the moisture-absorbing structure is disposed on the sidewall of the chamber 20.

[0136] Alternatively, for example, the projection of the moisture-absorbing structure onto the substrate 31 overlaps with the projection of the first waveguide 32 onto the substrate 31. For instance, the moisture-absorbing structure is disposed between the top of the chamber 20 and the first waveguide 32. Optionally, the moisture-absorbing structure is disposed on the inner surface of the top of the chamber 20. Alternatively, the moisture-absorbing structure is optionally fixed above the first waveguide 32 by a support structure.

[0137] A moisture-absorbing structure is installed in the chamber 20 of the gas detection device 1, which can further suppress the formation of condensation on the surface of the first waveguide 32, thereby reducing the impact of condensation on the performance of the gas sensing device 1 and improving the sensitivity, reliability, stability and service life of the gas sensing device 1. The structure is simple and the principle is simple.

[0138] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A gas sensor, characterized in that, The gas sensor includes: Substrate; A first waveguide is disposed on the substrate; A decondensation-reducing structure is disposed on the substrate to suppress condensation formation on the surface of the first waveguide.

2. The gas sensor according to claim 1, characterized in that, The decondensation removal structure includes a temperature controller; the temperature controller and the first waveguide are disposed on opposite sides of the substrate; the temperature controller is used to generate heat in response to a control signal; or, The material of the decondensation structure includes a moisture-absorbing material. The decondensation structure and the first waveguide are disposed on the same side of the substrate, and there is a gap between the decondensation structure and the first waveguide.

3. The gas sensor according to claim 1 or 2, characterized in that, The first waveguide is an ultra-low loss waveguide.

4. The gas sensor according to any one of claims 1-3, characterized in that, The gas sensor further includes a photodetector; the photodetector is disposed on the substrate; the photodetector is coupled to the first waveguide and is located on the same side of the substrate as the first waveguide.

5. The gas sensor according to claim 4, characterized in that, The photodetector is coupled to the first waveguide using one of the following methods: direct coupling, optical path corner coupling, or flip-chip coupling.

6. The gas sensor according to any one of claims 1-5, characterized in that, The gas sensor also includes a polarization controller; the polarization controller is integrated on the substrate; the polarization controller is coupled to the first waveguide and is located on the same side of the substrate as the first waveguide.

7. The gas sensor according to claim 6, characterized in that, The polarization controller is directly coupled to the first waveguide.

8. The gas sensor according to claim 6 or 7, characterized in that, The gas sensor also includes a laser; the laser is disposed on the substrate and coupled to the polarization controller; the laser and the first waveguide are located on the same side of the substrate.

9. The gas sensor according to claim 8, characterized in that, The gas sensor also includes a second waveguide; the two ends of the second waveguide are coupled to the laser and the polarization controller, respectively.

10. The gas sensor according to claim 8 or 9, characterized in that, The gas sensor further includes an encapsulation layer; the encapsulation layer covers at least one of the laser, the polarization controller, or the photodetector.

11. The gas sensor according to any one of claims 2-10, characterized in that, The gas sensor further includes a processor; the processor is coupled to the temperature controller and is used to transmit the control signal to the temperature controller; or, The gas sensor also includes a humidity sensor, which is coupled to the temperature controller and is used to transmit the control signal to the temperature controller. or, The gas sensor also includes a temperature sensor, which is coupled to the temperature controller and is used to transmit the control signal to the temperature controller.

12. The gas sensor according to any one of claims 1-11, characterized in that, The first waveguide includes a core layer and a cladding layer, the cladding layer being located between the core layer and the substrate, the cladding layer covering the surface of the core layer facing the substrate; the core layer is made of at least one of silicon nitride, silicon oxynitride, silicon, germanium, lithium niobate, chalcogenide glass, III-V compounds, or organic polymers, and the cladding layer is made of at least one of silicon dioxide, nitride, sapphire, calcium fluoride, chalcogenide glass, III-V compounds, or organic polymers.

13. The gas sensor according to any one of claims 2-12, characterized in that, When the decondensation structure includes the temperature controller, the projection of the first waveguide on the substrate overlaps with the projection of the temperature controller on the substrate.

14. A gas detection device, characterized in that, The gas detection device includes a chamber and a gas sensor as described in any one of claims 1-13, wherein the gas sensor is disposed in the chamber.

15. The gas detection device according to claim 14, characterized in that, The gas detection device also includes a moisture-absorbing structure, which is disposed within the chamber.

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