A laser radar chip integration method for gas cloud imaging

Abstract

The application belongs to the technical field of infrared laser radar, and provides a laser radar chip integration method for gas cloud imaging, which comprises the following steps: integrating a mid-infrared band intercascade laser and a mid-infrared detector on a same silicon substrate; when the integrated chip is packaged, a micro-mirror, a MEMS mirror and a transceiver chip are combined and packaged in a same module; the laser rear end transmits light to the micro-mirror, the micro-mirror moves forward and backward through a piezoelectric ceramic, the light emitted by the laser front end hits the MEMS mirror, the light emitted by the MEMS mirror is reflected after hitting the detected gas and is received by the detector; the application realizes the integration of emission, reception and spatial scanning, gives a gas distribution diagram of the whole space through scanning spectrum imaging, can provide accurate gas concentration at any position in the space, and can detect multiple gases simultaneously through spectrum tuning of a wide spectrum light source.

Description

Technical Field

[0001] This invention belongs to the field of infrared lidar technology, specifically a lidar chip integration method for gas cloud imaging. Background Technology

[0002] Currently, lidar is based on laser ranging three-dimensional imaging sensors. Traditional lidar does not utilize the spectral information provided by the light source, but only uses the intensity information of the light source to calculate the distance.

[0003] Traditional lidar uses lasers with wavelengths of 800nm-900nm to achieve high-power detection over long distances. However, there is very little spectral information in this range, as most of the intrinsic gas absorption spectrum is concentrated in the mid-infrared band.

[0004] Secondly, the short wavelength of the near-infrared band makes it difficult to penetrate obstacles such as fog, haze, smoke, dust, and snow, which greatly limits the application of lidar in many scenarios; and currently, the sensors used for gas imaging are all two-dimensional, which can only determine the average gas concentration in a certain space.

[0005] To address these issues, a method for integrating lidar chips for gas cloud imaging is proposed. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for integrating a lidar chip for gas cloud imaging, thereby resolving the issues raised in the background section.

[0007] A method for integrating a lidar chip for gas cloud imaging includes integrating a mid-infrared interband cascaded laser and a mid-infrared detector onto the same silicon substrate. During chip packaging, a micro-mirror, a MEMS mirror, and a transceiver chip are encapsulated in the same module. A broadband mid-infrared semiconductor laser is driven by voltage to emit laser light. The back end of the broadband mid-infrared semiconductor laser transmits the transmitted light onto the micro-mirror, which moves back and forth via piezoelectric ceramics. The light emitted from the front end of the broadband mid-infrared semiconductor laser hits the MEMS mirror, which undergoes periodic angular deflection under voltage. The emitted light is reflected back after encountering the detected gas and is received by the detector.

[0008] Preferably, the broadband mid-infrared semiconductor laser is coated with anti-reflection and anti-reflection films at its front and rear ends, respectively.

[0009] Preferably, the micromirror causes the light it hits to undergo periodic changes in the optical path of the reflected light as it moves back and forth.

[0010] Preferably, the optical path change causes the wavelength of the light excited within the cavity of the broadband mid-infrared semiconductor laser to change periodically.

[0011] Preferably, the implementation method of infrared on-chip lidar includes the following steps:

[0012] S1. A mid-infrared quantum cascade laser is fabricated using molecular beam epitaxy and semiconductor photolithography and etching processes. The mid-infrared quantum cascade laser is, but is not limited to, a combination of InAs / GaSb quantum wells.

[0013] S2. Infrared detectors in quantum wells are fabricated using molecular beam epitaxy and semiconductor photolithography and etching processes. The infrared detectors in quantum wells include, but are not limited to, infrared detectors in quantum wells with InAs / GaSb superlattice structures.

[0014] S3. Optoelectronic devices that form SiN heterojunction optical waveguides on silicon substrates through silicon-based integration technology and processes;

[0015] S4. Integrate a mid-infrared quantum cascade laser onto a silicon substrate with a SiN heterojunction optical waveguide by bonding welding. The mid-infrared quantum cascade laser includes, but is not limited to, quantum cascade lasers and interband cascade lasers with InGaAs / InAlAs, GaAs / AlGaAs, and InGaAsP superlattice structures.

[0016] S5. Spectral tuning and spatial scanning of light are performed by combining optical adjustment and micromirror.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. This invention achieves chip-based gas detection and three-dimensional imaging by using optoelectronic integration to realize a tunable broadband light source, MEMS galvanometer and detector in a three-in-one package.

[0019] 2. The light source used in this invention is a 3-5 micrometer semiconductor laser, which can realize the absorption detection of most organic volatile gases such as alkanes. Furthermore, it uses a longer wavelength and has stronger diffraction ability, so that small particles will not hinder its propagation.

[0020] 3. This invention integrates the light source and detector onto a single integrated chip, and encapsulates the MEMS galvanometer used for space scanning within the same integrated module, thereby achieving the integration of transmission and reception with space scanning. It provides a gas distribution map of the entire space through scanning spectral imaging, and can provide accurate gas concentration at any location in space. At the same time, it achieves spectral scanning through spectral tuning of a broadband light source, enabling the simultaneous detection of multiple gases. Attached Figure Description

[0021] Figure 1This is a diagram of the on-chip spectral radar module of the present invention.

[0022] In the picture:

[0023] 1. Broad-spectrum mid-infrared semiconductor laser; 2. Piezoelectric ceramic chip; 3. Micro-mirror; 4. MEMS mirror. Detailed Implementation

[0024] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0025] As attached Figure 1 As shown:

[0026] Example 1: This invention provides a method for integrating a lidar chip for gas cloud imaging. The method includes integrating a mid-infrared interband cascaded laser and a mid-infrared detector onto the same silicon substrate. During chip packaging, a micro-mirror, a MEMS mirror, and a transceiver chip are encapsulated in the same module, resulting in a gas detection lidar system capable of spectral tuning and spatial scanning. A voltage-driven broadband mid-infrared semiconductor laser emits laser light. The back end of the broadband mid-infrared semiconductor laser transmits the transmitted light onto the micro-mirror, which moves back and forth via piezoelectric ceramics. The light emitted from the front end of the broadband mid-infrared semiconductor laser strikes the MEMS mirror, which undergoes periodic angular deflection under voltage. The emitted light is reflected back after encountering the detected gas and received by the detector. By employing optoelectronic integration, a tunable broadband light source, a MEMS mirror, and a detector are packaged together to achieve chip-based gas detection and three-dimensional imaging.

[0027] The broadband mid-infrared semiconductor laser has antireflection and antireflection coatings at both ends, and its light source is a 3-5 micrometer semiconductor laser, which can realize the absorption detection of most organic volatile gases such as alkanes.

[0028] As the micromirror moves back and forth, the optical path of the light it hits changes periodically as it is reflected back.

[0029] The change in optical path causes the wavelength of light excited inside the cavity of a broadband mid-infrared semiconductor laser to change periodically.

[0030] Example 2: The implementation method of infrared on-chip lidar includes the following steps:

[0031] S1. A mid-infrared quantum cascade laser is fabricated using molecular beam epitaxy and semiconductor photolithography and etching processes. The mid-infrared quantum cascade laser is, but is not limited to, a combination of InAs / GaSb quantum wells.

[0032] S2. Infrared detectors in quantum wells are fabricated using molecular beam epitaxy and semiconductor photolithography and etching processes. The infrared detectors in quantum wells include, but are not limited to, infrared detectors in quantum wells with InAs / GaSb superlattice structures.

[0033] S3. Through silicon-based integration technology and processes, SiN heterojunction optical waveguides and other related optoelectronic devices are formed on silicon substrates;

[0034] S4. Integrate a mid-infrared quantum cascade laser onto a silicon substrate with a SiN heterojunction optical waveguide by bonding welding. The mid-infrared quantum cascade laser includes, but is not limited to, quantum cascade lasers and interband cascade lasers with InGaAs / InAlAs, GaAs / AlGaAs, and InGaAsP superlattice structures.

[0035] S5. Spectral tuning and spatial scanning of light are performed by combining optical adjustment and micromirror.

[0036] Working principle: A broadband mid-infrared semiconductor laser emits laser light under voltage drive. Anti-reflection and anti-reflection coatings are deposited at its front and rear ends, respectively. The transmitted light from the rear end of the laser strikes a micromirror. Driven by piezoelectric ceramics, the micromirror moves back and forth, causing the optical path of the reflected light to change periodically. This change in optical path causes a periodic change in the wavelength of the light excited within the laser cavity, which is then emitted through the anti-reflection surface at the front end, achieving spectral tuning of the laser's emission wavelength.

[0037] The emitted light strikes a MEMS galvanometer, which, driven by a voltage, undergoes periodic angular deflection, thus achieving spatial scanning of the emitted laser. The emitted light is reflected back after encountering the gas being detected and received by the detector. Due to the scanning action of the MEMS galvanometer, spatial scanning of the gas is achieved, and the signal reflected to the detector carries spatial information, ultimately enabling the detection of the spatial distribution of the gas.

[0038] As can be seen from the above, the overall system achieves significantly improved resistance to sunlight interference compared to near-infrared lasers, and is more suitable for weather conditions such as smoke, haze, rain, and snow than near-infrared lidars. At the same time, compared to near-infrared on-chip integrated lidars, the waveguide structure is easier to process and the processing precision requirements are lower, reducing the cost of the on-chip system. It also has the ability to obtain spatial distribution information of gas compared to two-dimensional gas cloud imaging and to achieve gas spectral detection, which is not possible with traditional three-dimensional spatial imaging.

[0039] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Therefore, all such modifications are intended to be included within the scope of the invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and not only structurally equivalent but also equivalent in structure. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0040] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features that are not relevant to the best mode of carrying out the invention as currently considered, or those features that are not relevant to implementing the invention) may be omitted.

[0041] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0042] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. 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 be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for integrating a lidar chip for gas cloud imaging, characterized in that: This involves integrating a mid-infrared interband cascaded laser and a mid-infrared detector onto the same silicon substrate. During integrated chip packaging, a micro-mirror, a MEMS mirror, and a transceiver chip are encapsulated in the same module. A broadband mid-infrared semiconductor laser is driven by voltage to emit laser light. The back end of the broadband mid-infrared semiconductor laser transmits the transmitted light onto the micro-mirror, which moves back and forth via piezoelectric ceramics. The light emitted from the front end of the broadband mid-infrared semiconductor laser hits the MEMS mirror, which undergoes periodic angular deflection under voltage. The emitted light is reflected back after encountering the detected gas and is received by the detector.

2. The lidar chip integration method for gas cloud imaging as described in claim 1, characterized in that: The broadband mid-infrared semiconductor laser has anti-reflection and anti-reflection coatings deposited at its front and rear ends, respectively.

3. The lidar chip integration method for gas cloud imaging as described in claim 1, characterized in that: As the micromirror moves back and forth, the optical path of the light it hits changes periodically as it is reflected back.

4. The lidar chip integration method for gas cloud imaging as described in claim 3, characterized in that: The change in optical path causes the wavelength of the light excited within the cavity of the broadband mid-infrared semiconductor laser to change periodically.

5. The lidar chip integration method for gas cloud imaging as described in claim 1, characterized in that: The implementation method of infrared on-chip lidar includes the following steps: S1. A mid-infrared quantum cascade laser is fabricated using molecular beam epitaxy and semiconductor photolithography and etching processes. The mid-infrared quantum cascade laser is, but is not limited to, a combination of InAs / GaSb quantum wells. S2. Infrared detectors in quantum wells are fabricated using molecular beam epitaxy and semiconductor photolithography and etching processes. The infrared detectors in quantum wells include, but are not limited to, infrared detectors in quantum wells with InAs / GaSb superlattice structures. S3. Optoelectronic devices using SiN heterojunction optical waveguides formed on silicon substrates through silicon-based integration technology and processes; S4. Integrate a mid-infrared quantum cascade laser onto a silicon substrate with a SiN heterojunction optical waveguide by bonding and welding. The mid-infrared quantum cascade laser includes, but is not limited to, quantum cascade lasers with InGaAs / InAlAs, GaAs / AlGaAs, and InGaAsP superlattice structures and interband cascade lasers. S5. Spectral tuning and spatial scanning of light are performed by combining optical adjustment and micromirror.

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