Gas detection chip based on optical waveguide and detection device

Abstract

The utility model relates to the technical field of gas detection, in particular to a gas detection chip based on optical waveguide and a detection device. The optical waveguide layer is arranged on the substrate layer; a groove is etched in the optical waveguide layer, a reflecting layer is arranged on the inner surface of the groove, and the groove and the reflecting layer form an optical path; the substrate layer is made of monocrystalline silicon materials, the optical waveguide layer is made of silicon dioxide materials, and the reflecting layer is made of silicon nitride materials. The gas measuring device solves the technical problems of large size and low integration level of the gas measuring device in the prior art.

Description

Technical Field

[0001] This application relates to the field of gas detection technology, and in particular to gas detection chips and detection devices based on optical waveguides. Background Technology

[0002] In industrial environmental monitoring, it is necessary to measure the concentration of many gases in real time, such as methane, oxygen, acetylene, water vapor, nitrogen oxides, and carbon oxides. These concentration values ​​are of great guiding significance for production and daily life. A common gas concentration detection method is the use of a fiber optic gas cell. This method selects the laser wavelength corresponding to the absorption peak of the target gas according to international standards. It uses a mirror array to construct a multiple-reflection optical path to extend the effective optical path. When the gas component concentration varies, the intensity of the received light signal will change. The concentration of the gas component is calculated by monitoring the intensity of the light signal.

[0003] In existing technologies, to extend the optical path, multiple sets of reflective mirrors need to be densely arranged in the gas chamber, resulting in a large device size. The optical path structure relies on manual fine-tuning of the incident / reflection angles of the mirrors, which significantly limits the adjustment accuracy. Furthermore, the manufacturing process of such gas chamber products is complex and inconsistent. Therefore, there is an urgent need for a gas concentration detection device that combines high precision, miniaturization, and mass production capabilities. Utility Model Content

[0004] The main purpose of this application is to provide a gas detection chip and detection device based on optical waveguides, which aims to solve the technical problems of large size and low integration of existing gas measurement devices. The gas detection chip based on optical waveguides achieves meter-level optical path within a millimeter-level chip by utilizing the high refractive index characteristics of silicon nitride, thus significantly improving the integration.

[0005] A first aspect of this application provides a gas detection chip based on an optical waveguide, comprising:

[0006] Substrate layer;

[0007] Optical waveguide layer disposed on the substrate layer;

[0008] The optical waveguide layer is etched with trenches, and a reflective layer is disposed on the inner surface of the trenches. The trenches and the reflective layer constitute an optical path.

[0009] The substrate layer is made of single-crystal silicon, the optical waveguide layer is made of silicon dioxide, and the reflective layer is made of silicon nitride.

[0010] In one embodiment, the optical path has an incident end, an exit end, and a transmission section located between the incident end and the exit end. The incident end is used to receive incident light, and the exit end is used to output outgoing light. The incident end and the exit end are arranged on the same side.

[0011] In one embodiment, the transmission segment includes at least one bend.

[0012] In one embodiment, the transmission segment is constructed in a spiral shape on the plane where the optical waveguide layer is located.

[0013] In one embodiment, the transmission segment is configured in an S-shape on the plane where the optical waveguide layer is located.

[0014] In one embodiment, the cross-section of the optical path is an arc-shaped structure with an opening.

[0015] In one embodiment, the arc structure is a circular arc, and the circular arc is a superior arc.

[0016] In one embodiment, the refractive index of the reflective layer is greater than that of air.

[0017] In one embodiment, the gas detection chip is constructed as a cylinder, with the inner layer of the cylinder being the substrate layer and the outer layer of the cylinder being the optical waveguide layer, and the optical path is constructed as a double helix structure.

[0018] The second aspect of this application provides a gas detection device, including the gas detection chip provided in the first aspect of the above embodiments, and further including a laser, a photodetector, a fiber array, and a signal processing circuit; the gas detection chip is placed in the environment to be tested;

[0019] The laser is used to generate an optical signal to enter the optical path, the photodetector is used to detect the optical signal after it has passed through the optical path, the fiber array is used to couple the optical signal and the gas detection chip; the signal processing circuit is connected to the photodetector and is used to calculate the gas concentration of the environment under test based on the optical signal.

[0020] The beneficial effects of this application embodiment compared with the prior art are as follows: an optical waveguide layer is set on the substrate layer, and trenches are etched on the optical waveguide layer. A reflective layer is set on the inner surface of the trenches. The trenches and the reflective layer constitute an optical path. By using single-crystal silicon material for the substrate layer, silicon dioxide material for the optical waveguide layer, and silicon nitride material for the reflective layer, the traditional meter-level optical path of the gas cell is compressed to the chip-level size, which greatly reduces the size of the product, improves the integration, and reduces the manufacturing difficulty and cost. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the cross-sectional structure of a gas detection chip provided in an embodiment of this application;

[0022] Figure 2 This is a schematic diagram of the optical path of a gas detection chip provided in an embodiment of this application;

[0023] Figure 3 This is a schematic diagram of the optical path of a gas detection chip provided in another embodiment of this application;

[0024] Figure 4 This is a schematic diagram of the structure of the end face of a gas detection chip provided in another embodiment of this application;

[0025] Figure 5 This is a schematic diagram of the optical path of a gas detection chip provided in another embodiment of this application;

[0026] Figure 6 This is a schematic diagram of the principle of a gas detection device provided in an embodiment of this application. Detailed Implementation

[0027] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0028] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0029] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0031] like Figure 1As shown, a first aspect of this application provides a gas detection chip 10 based on an optical waveguide. The gas detection chip 10 includes a substrate layer 100, an optical waveguide layer 200, and a reflective layer 300. The optical waveguide layer 200 is disposed above the substrate layer 100. Trench 201 is etched on the optical waveguide layer 200. A reflective layer 300 is disposed on the inner surface of the trench 201. The trench 201 and the reflective layer 300 constitute an optical path. The substrate layer 100 is made of single-crystal silicon material (Si), the optical waveguide layer 200 is made of silicon dioxide material (SiO2), and the reflective layer 300 is made of silicon nitride material (Si3N4).

[0032] The substrate 100 serves as the base material for the gas detection chip 10. Unlike traditional silicon photonic chips, the gas detection chip 10 provided in this embodiment does not require an additional layer of monocrystalline silicon to be deposited on top of silicon dioxide; it has only a two-layer structure. The thickness of the substrate 100 ranges from 2 to 10 micrometers. By growing a layer of silicon dioxide on the substrate 100 as an optical waveguide layer 200, the upper surface of the optical waveguide layer 200 is completely exposed to air, eliminating the need for an additional layer of monocrystalline silicon. The thickness of the optical waveguide layer 200 ranges from 20 to 40 micrometers.

[0033] A trench 201 is etched on the optical waveguide layer 200 using a reactive ion dry etching process. The diameter of the trench 201 ranges from 10 to 15 micrometers. A reflective layer 300 is uniformly fabricated on the trench 201 using a chemical vapor deposition (PECVD) process. The thickness of the reflective layer 300 ranges from 2 to 4 micrometers.

[0034] The gas detection chip 10 based on optical waveguide provided in this application embodiment has an optical waveguide layer 200 disposed on a substrate layer 100, and trenches 201 etched on the optical waveguide layer 200. A reflective layer 300 is disposed on the inner surface of the trenches 201. The trenches 201 and the reflective layer 300 constitute an optical path. By using single-crystal silicon material for the substrate layer 100, silicon dioxide material for the optical waveguide layer 200, and silicon nitride material for the reflective layer 300, the traditional meter-level optical path of gas cells is compressed to the chip-level size, which greatly reduces the product size, improves the integration, and reduces the manufacturing difficulty and cost.

[0035] In one embodiment, please refer to Figures 1-3The optical path has an incident end 210, an exit end 220, and a transmission segment 230 located between the incident end 210 and the exit end 220. The incident end 210 is used to receive incident light, and the exit end 220 is used to output outgoing light. The incident end 210 and the exit end 220 are arranged on the same side, which means that they are arranged on the same edge of the gas detection chip 10 with a square structure. In some embodiments, the gas detection chip 10 has other shapes, and its incident end 210 and exit end 220 are arranged adjacent to each other. By arranging the incident end 210 and the exit end 220 of the optical path on the same side or adjacent to each other, the optical path coupling and packaging process is greatly simplified. The light source (such as a laser) and the corresponding detector can be integrated on the same packaging substrate without the need for multi-angle alignment across the chip, which is beneficial to improving integration and miniaturization.

[0036] In one embodiment, please refer to Figures 1-3 The transmission segment 230 includes at least one bend segment 231, which extends the optical path on a small-volume chip. In some embodiments, by setting multiple bend segments 231, the optical path length can be extended to 1m, 2m, 3m or 5m, which can be set according to different detection accuracy requirements and chip size specifications.

[0037] In one embodiment, please refer to Figures 1-3 On the plane where the optical waveguide layer 200 is located, the transmission section 230 is constructed in a spiral shape, specifically as follows: Figure 2 As shown, the transmission segment 230, by incorporating a bend 231, is constructed with a spiral structure, thereby extending the optical path on a small-volume chip. In some embodiments, the transmission segment 230 is constructed as a circle. By constructing the transmission segment 230 as a spiral or a circle, a meter-level equivalent optical path can be achieved within a millimeter-level chip, significantly extending the effective optical path and improving detection sensitivity.

[0038] In one embodiment, please refer to Figures 1-3 On the plane where the optical waveguide layer 200 is located, the transmission section 230 is constructed in an S-shape, specifically as follows: Figure 3 As shown, the transmission segment 230 is constructed with several bends 231, forming an S-shaped structure, which can significantly extend the effective optical path and improve detection sensitivity.

[0039] In one embodiment, please refer to Figures 1-3 The cross-section of the optical path is an arc-shaped structure with an opening; please refer to [link / reference] for details. Figure 1 As shown, it can be understood that, since the reflective layer 300 has a uniform thickness, the cross-section of the optical path comes from the trench 201 structure. The structure of the trench 201 makes it have an arc-shaped structure with an opening, that is, the optical path is exposed to air or the gas to be detected.

[0040] In one embodiment, please refer to Figures 1-3 The arc structure is a circular arc, and the circular arc is a superior arc. Through the etched groove 201, the arc structure is a superior arc. The maximum diameter of the circle containing the arc is greater than the width of the opening above. The depth-to-width ratio of the superior arc enables the light field to form low-loss transmission at the bottom of the arc (large radius of curvature), while generating a high-intensity evanescent wave at the opening. The light-gas contact efficiency is greatly improved compared to the rectangular cross section, thus improving the light reflection efficiency of the reflective layer 300.

[0041] In one embodiment, please refer to Figures 1-3 The refractive index of the reflective layer 300 is greater than that of air. Specifically, the refractive index of the reflective layer 300 is 1.9 to 2.5. By setting the refractive index of the reflective layer 300 to be greater than that of air, it is beneficial to constrain the optical path transmission and reduce transmission loss.

[0042] In one embodiment, please refer to Figures 1-3 See Figures 4-5 The gas detection chip 10 is constructed as a cylinder, with an inner substrate layer 100 and an outer optical waveguide layer 200. The optical path is constructed as a double helix structure. By constructing the gas detection chip 10 as a cylinder, efficient optical path extension in three-dimensional space is achieved, improving the mechanical strength of the gas detection chip 10. The optical path is constructed as a double helix structure, with the incident end 210 and the exit end 220 located on the same side at one end of the cylinder. The transmission section 230 is constructed as a double helix structure, and the optical path is redirected through a closed-loop connection via a bending section 231, further improving the detection response speed.

[0043] Please see Figure 6 As shown, a second aspect of the present application provides a gas detection device, including a gas detection chip 10 provided in the first aspect of the present application, and further including a laser 30, a photodetector 40, a fiber array 20 and a signal processing circuit 50, wherein the gas detection chip 10 is placed in the environment to be tested.

[0044] The system includes a laser 30 to generate an optical signal that enters the optical path of the gas detection chip 10, a photodetector 40 to detect the optical signal after it passes through the optical path, an fiber optic array 20 to couple the optical signal to the gas detection chip 10, and a signal processing circuit 50 connected to the photodetector 40 to calculate the gas concentration in the test environment based on the optical signal. Understandably, light attenuates during long-distance transmission. The attenuation value of the gas detection chip 10 can be measured in a vacuum or inert gas environment as a reference for its own attenuation. When gas detection is required in the test environment, the measured attenuation value minus the original attenuation value gives the gas concentration attenuation, which is then used to calculate the gas concentration value.

[0045] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A gas detection chip based on optical waveguide, characterized in that, include: Substrate layer; Optical waveguide layer disposed on the substrate layer; The optical waveguide layer is etched with trenches, and a reflective layer is disposed on the inner surface of the trenches. The trenches and the reflective layer constitute an optical path. The substrate layer is made of single-crystal silicon, the optical waveguide layer is made of silicon dioxide, and the reflective layer is made of silicon nitride.

2. The gas detection chip as described in claim 1, characterized in that, The optical path has an incident end, an exit end, and a transmission section located between the incident end and the exit end. The incident end is used to receive incident light, and the exit end is used to output outgoing light. The incident end and the exit end are arranged on the same side.

3. The gas detection chip as described in claim 2, characterized in that, The transmission segment includes at least one bend.

4. The gas detection chip as described in claim 3, characterized in that, On the plane where the optical waveguide layer is located, the transmission segment is constructed in a spiral shape.

5. The gas detection chip as described in claim 3, characterized in that, On the plane where the optical waveguide layer is located, the transmission segment is constructed in an S-shape.

6. The gas detection chip according to any one of claims 1 to 5, characterized in that, The cross-section of the optical path is an arc-shaped structure with an opening.

7. The gas detection chip as described in claim 6, characterized in that, The arc-shaped structure is a circular arc, and the circular arc is a superior arc.

8. The gas detection chip as described in claim 1, characterized in that, The refractive index of the reflective layer is greater than that of air.

9. The gas detection chip as described in claim 1, characterized in that, The gas detection chip is constructed as a cylinder, with the inner layer of the cylinder being the substrate layer and the outer layer of the cylinder being the optical waveguide layer. The optical path is constructed as a double helix structure.

10. A gas detection device, characterized in that, The gas detection chip according to any one of claims 1 to 9 further includes a laser, a photodetector, a fiber array, and a signal processing circuit; the gas detection chip is placed in the environment to be tested; The laser is used to generate an optical signal to enter the optical path, the photodetector is used to detect the optical signal after it has passed through the optical path, the fiber array is used to couple the optical signal and the gas detection chip; the signal processing circuit is connected to the photodetector and is used to calculate the gas concentration of the environment under test based on the optical signal.

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