Dual-F-P cavity coupling tunable infrared radiation source and preparation method and application thereof

Abstract

The invention discloses a dual-F-P cavity coupling tunable infrared radiation source and a preparation method thereof. The dual-F-P cavity coupling tunable infrared radiation source comprises a substrate, a supporting layer, a heating electrode, an insulating layer, a metamaterial radiation layer and an actuator, the supporting layer is located on the substrate, and the heating electrode is located in the center area of the supporting layer; the insulating layer wraps the heating electrode; a plurality of first stand columns are arranged on the peripheral edge area of the supporting layer. The metamaterial radiation layer comprises a bottom reflecting layer, a lower layer fixed air cavity, a middle reflecting layer, an upper layer adjustable air cavity and a metasurface layer; the actuator comprises an upper pole plate and a lower pole plate. The technical problems that in the prior art, a micro infrared radiation source with a silicon substrate can only achieve single-peak narrow-band tuning, the tuning range is limited, and directivity and emission efficiency are insufficient are solved, and the micro infrared radiation source can be widely applied to multi-component gas detection scenes.

Description

Technical Field

[0001] The present invention belongs to the technical field of infrared radiation sources, and more particularly, relates to a dual-FP cavity coupled tunable infrared radiation source and a preparation method thereof. Background Art

[0002] Sensor technology, as an important component of modern sensing technology, involves multiple disciplines such as functional materials, optoelectronic components, and MEMS (micro-electromechanical systems). It is a key component widely used in industrial production, environmental monitoring, medical diagnosis, bioengineering, national defense and security, and other fields. Gas detection systems based on infrared absorption principles have become an important research direction in the field of gas detection due to their significant advantages such as strong environmental tolerance, high selectivity, stable performance, and long life. However, in practical applications, how to achieve efficient identification and accurate classification of target gases for multi-component mixed gas detection in complex scenarios has become a very urgent and important issue.

[0003] As the core component of an infrared gas sensor, the performance of the infrared radiation source directly affects the performance of the sensor. The main function of an infrared radiation source is to emit infrared light of a specific wavelength to match the absorption spectrum of the target gas, thereby achieving accurate measurement of gas concentration. However, existing infrared radiation source technology still has many limitations. For example, traditional solutions usually use external devices such as filters or tunable lasers to select infrared light of a specific wavelength. However, the introduction of filters increases the complexity and size of the device and cannot achieve continuous tuning of the wavelength. While tunable lasers can achieve wavelength tuning, they are expensive and power-intensive, making them difficult to meet the needs of portable gas sensors.

[0004] In recent years, with the rapid development of MEMS technology and nanomaterials science, silicon-based miniature infrared radiation sources have become a research hotspot. Silicon substrates, due to their low cost, high thermal conductivity, excellent mechanical stability, and high compatibility with MEMS processes, offer a new solution for the miniaturization and integration of infrared radiation sources. However, existing infrared radiation sources have numerous disadvantages for use in gas sensors. For example, conventional infrared radiation sources typically emit only a single wavelength of infrared light, making it impossible to simultaneously detect multiple gases. Their wide bandwidth results in low spectral resolution, making it difficult to precisely match the narrow absorption lines of gas molecules, thereby reducing detection accuracy and sensitivity. Furthermore, integration difficulties, high costs, and slow response speeds limit the performance and application scope of gas sensors. Consequently, existing infrared radiation sources are limited to single-peak narrowband tuning, with a limited tuning range and insufficient directivity and emission efficiency. With the growing demand for high-performance infrared radiation sources in applications such as gas detection and infrared communications, new infrared radiation sources with multi-peak emission and wide-range dynamic tuning capabilities are needed. Summary of the Invention

[0005] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a dual-FP cavity coupled tunable infrared radiation source and a preparation method thereof, thereby solving the technical problems in the prior art that the silicon-based miniature infrared radiation source can only achieve single-peak narrowband tuning, has a limited tuning range, and has insufficient directionality and emission efficiency.

[0006] To achieve the above objectives, according to one aspect of the present invention, a dual-FP cavity coupled tunable infrared radiation source is provided, comprising a substrate, a support layer, a heating electrode, an insulating layer, a metamaterial radiation layer, and an actuator; the support layer is disposed on top of the substrate; the heating electrode is disposed in the middle region of the support layer, and a plurality of first columns are disposed on the peripheral edge regions of the support layer; the heating electrode is covered by the insulating layer;

[0007] The metamaterial radiation layer includes a bottom reflective layer, a lower fixed air cavity, an intermediate reflective layer, an upper adjustable air cavity, and a metasurface layer; the actuator includes an upper plate and a lower plate;

[0008] The bottom reflection layer is located on the middle area of ​​the insulating layer; a plurality of second columns are arranged on the edge areas around the insulating layer, and the upper parts of the plurality of second columns cover the substrate, so that the area between the substrate and the bottom reflection layer is the lower fixed air cavity; the intermediate reflection layer and the lower electrode plate are both located on the substrate; the upper electrode plate covers the plurality of first columns, so that the area between the upper electrode plate and the intermediate reflection layer is the upper adjustable air cavity; the super surface layer is located on the lower surface of the upper electrode plate; a first electrode is also arranged on the upper electrode plate, and a second electrode is also arranged on the substrate.

[0009] Preferably, the upper electrode plate is composed of four cantilever beams, a movable film, and a substrate; each of the cantilever beams, movable film, and substrate is located on the same horizontal plane, the movable film is located inside the substrate to form a U-shape, and the movable film and the substrate are connected by several cantilever beams; the super surface layer is located on the lower surface of the movable film.

[0010] Preferably, the lower electrode plate and the intermediate reflective layer are arranged in a U-shape, and the lower electrode plate is located at the periphery of the intermediate reflective layer.

[0011] Preferably, the super surface layer has a micron-sized open pore structure, and the shape of the open pore structure is preferably selected from a circle, a square or a polygon; the area of ​​the open pore structure is 0.2 μm 2 ~9μm 2 The arrangement period of the open hole structure is 1.5um to 5um.

[0012] Preferably, the upper portion of the substrate is also covered with a silicon wafer; and the center of the base has a cavity structure.

[0013] Preferably, the material of the substrate is silicon; the material of the supporting layer is selected from silicon dioxide or silicon nitride; the material of the heating electrode is platinum; the material of the insulating layer is selected from silicon dioxide or silicon nitride; the materials of the bottom reflection layer and the intermediate reflection layer are independently selected from Au or Ag; the material of the upper plate is selected from Si or Si3N4.

[0014] Preferably, the thickness of the bottom reflection layer is 100-130 nm; the thickness of the intermediate reflection layer is 20-50 nm.

[0015] According to one aspect of the present invention, a method for preparing the dual-FP cavity coupled tunable infrared radiation source is provided, comprising the following steps:

[0016] (1) growing a support layer on the upper surface of the substrate;

[0017] (2) preparing a heating electrode on the support layer by a sputtering process;

[0018] (3) growing an insulating layer on the heating electrode by a plasma enhanced chemical vapor deposition process;

[0019] (4) forming a bottom reflective layer on the insulating layer by sputtering or evaporation process;

[0020] (5) depositing silicon on the insulating layer and forming a plurality of second pillars by photolithography and etching;

[0021] (6) preparing a substrate on top of the plurality of second pillars by a plasma enhanced chemical vapor deposition process, and depositing an intermediate reflective layer on top of the substrate;

[0022] (7) performing photolithography and etching on the lower surface of the substrate to form a cavity structure on the substrate;

[0023] (8) preparing a plurality of first pillars at both ends of the upper portion of the support layer by photolithography and etching processes;

[0024] (9) preparing a silicon wafer, wherein the silicon wafer comprises, from bottom to top, an upper plate, a buried oxide layer, and a silicon layer; and depositing a silicon nitride layer on the upper surface of the silicon wafer;

[0025] (10) etching a middle area of ​​the upper electrode plate to form a reverse solder step on the upper electrode plate;

[0026] (11) forming a super surface layer on the lower surface of the upper electrode plate by an evaporation process;

[0027] (12) depositing a silicon dioxide barrier layer on the super surface layer and the upper electrode plate, etching the upper electrode plate and the silicon dioxide barrier layer thereon by a deep etching process to form a cantilever beam, and then removing the unetched silicon dioxide barrier layer;

[0028] (13) etching the silicon nitride layer and the middle region of the silicon layer to form a cavity structure;

[0029] (14) etching the buried oxide layer located on the upper portion of the cantilever beam to release the cantilever beam structure;

[0030] (15) The first column is connected to the lower surface of the upper electrode plate through flip-chip bonding technology or bonding technology to form a complete infrared radiation source device.

[0031] According to one aspect of the present invention, an application of the dual-FP cavity coupled tunable infrared radiation source is provided, which is used in an infrared radiation source module of an infrared gas sensor.

[0032] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0033] 1. The present invention utilizes a dual FP cavity coupling design consisting of a fixed lower air cavity and an adjustable upper air cavity. A semi-transparent reflective layer is introduced between the upper and lower cavities to achieve optical coupling, enabling the simultaneous generation of dual resonance peaks. This significantly broadens the spectral tuning range, meeting the requirements for simultaneous multi-component gas detection. A metasurface aperture array is also introduced on the upper surface to control the emission bandwidth. The fixed lower air cavity, with its length d2, serves as a stable reference cavity. The upper cavity length d1 is adjusted via a MEMS microactuator to dynamically control the emission peak position, thus meeting the requirements for multi-component gas detection or broadband infrared modulation. The lower fixed air cavity and the upper adjustable air cavity form a cascade resonant system via an intermediate reflective layer. The lower fixed air cavity provides a stable fundamental resonance mode, while the upper adjustable air cavity is dynamically tuned via a MEMS actuator. The synergistic effect of the two gives the radiation source the unique advantages of both a narrow linewidth and a wide tuning range. This dual-cavity coupling design significantly improves the spectral purity and tuning flexibility of the radiation source, providing an ideal light source solution for multi-component gas detection.

[0034] 2. By providing a metasurface layer, the present invention not only meets the electromagnetic coupling requirements at the FP resonance peak, but also limits the coupling effect between electromagnetic radiation and the FP cavity over a wider wavelength range, thereby achieving bandpass selection for the FP radiation peak. By optimizing the combined structure of the metasurface and the FP cavity, the intensity of the target radiation peak can be maximized while suppressing radiation peaks of other orders, significantly improving the spectral selectivity and narrowband radiation performance of the radiation source. This design provides a reliable technical foundation for achieving high-precision and highly selective infrared radiation. The cantilever beam actuator design of the present invention ensures operational stability, and combined with the air medium dual-cavity structure, it achieves fast response and low power consumption.

[0035] 3. The present invention utilizes a MEMS electrostatic actuator as the adjustment mechanism. Driven by electrostatic force, this actuator can quickly and precisely adjust the FP cavity length, thereby achieving real-time tuning of the radiation wavelength. Furthermore, the MEMS electrostatic actuator features low power consumption and fast response, significantly reducing the overall power consumption of the device. Furthermore, its manufacturing process is compatible with standard silicon-based micro-nanofabrication techniques, making it suitable for large-scale production and effectively reducing the manufacturing cost of a single device.

[0036] 4. The present invention performs deep silicon etching on the back side of the silicon substrate to form a cavity structure to reduce heat conduction and improve thermal efficiency; the design of the cantilever beam structure of the present invention ensures that the super surface layer and the metal reflective layer always remain parallel, with a large deformation range and a fast response speed; the micron-scale open structure of the super surface layer of the present invention realizes narrow-band infrared radiation through FP resonance, and the radiation wavelength can be precisely adjusted by the geometric parameters of the open structure.

[0037] 5. The metamaterial radiation layer of this application can use air as the cavity filling medium. Its low refractive index can reduce optical losses and enhance FP resonance, thereby improving narrowband radiation performance. Secondly, the low heat capacity and low thermal conductivity of air give the device fast response and low power consumption characteristics, which are particularly suitable for tunable designs. In addition, the mechanical flexibility of air supports the movement of the cantilever beam in the MEMS structure, realizing dynamic wavelength adjustment. At the same time, its preparation process is simple and can be formed by releasing the sacrificial layer, reducing cost and process complexity.

[0038] 6. The present invention utilizes a silicon substrate and incorporates MEMS technology, resulting in a device with high integration and low power consumption. Its compact size and low power consumption make it suitable for integration into portable gas sensors and amenable to mass production. The infrared radiation source described herein can be widely used in multi-component gas detection scenarios, including environmental monitoring, smart homes, medical diagnostics, industrial control, and national defense security. It can achieve high-precision, high-sensitivity, and rapid-response real-time detection of typical gases such as carbon dioxide, methane, and formaldehyde, while exhibiting excellent stability and integration compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic structural diagram of a dual-cavity coupled tunable narrowband infrared radiation source provided in an embodiment of the present application.

[0040] Figure 2 for Figure 1 A diagram showing the working principle of the metamaterial infrared radiation source in the illustrated embodiment.

[0041] Figure 3 Schematic diagram of the structure of the circular metasurface layer of the dual-cavity coupled tunable narrowband infrared radiation source provided in an embodiment of the present application.

[0042] Figure 4 Schematic diagram of the structure of the square metasurface layer in the dual-cavity coupled tunable narrowband infrared radiation source provided in an embodiment of the present application.

[0043] Figure 5 Schematic diagram of the structure of the cross-shaped metasurface layer in the dual-cavity coupled tunable narrow-band infrared radiation source provided in an embodiment of the present application.

[0044] Figure 6 Schematic diagram of the structure of the actuator in the silicon-based tunable narrow-band infrared radiation source provided in the embodiment of the present application; (a) is a top view of the upper plate; (b) is a top view of the lower plate.

[0045] Figure 7 This is a simulation curve diagram of the actuator driving voltage-displacement provided in an embodiment of the present application.

[0046] Figure 8 The simulation curve diagram of the wavelength and radiance of the upper adjustable Fabry-Perot cavity provided in the embodiment of the present application, where (a) is the simulation result of the square opening pattern; (b) is the simulation result of the cross opening pattern.

[0047] Figure 9 This is a flow chart of the process for preparing an infrared radiation source according to an embodiment of the present application.

[0048] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0049] 1. Substrate; 2. Support layer; 3. Heating electrode; 4. Insulating layer; 5. Metamaterial radiation layer; 501. Reflection layer; 502. Lower fixed air cavity; 503. Intermediate reflection layer; 504. Upper adjustable air cavity; 505. Metasurface layer; 6. Actuator; 601. Upper electrode; 602. Lower electrode; 7. Cantilever beam; 8. Movable film; 9. First electrode; 10. Base plate; 11. Substrate; 12. Second electrode; 13. Silicon nitride layer; 14. Silicon layer; 15. Buried oxide layer; 16. First pillar; 17. Second pillar. DETAILED DESCRIPTION

[0050] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0051] This application addresses the shortcomings of existing infrared radiation sources in terms of wavelength adjustment capability, response speed, and integration compatibility. A tunable narrowband infrared radiation source based on a dual-cavity coupling structure is proposed. The device utilizes a silicon substrate with high thermal conductivity and high mechanical stability, and is highly compatible with established MEMS processes. This effectively overcomes the issues of conventional thermal radiation sources, such as fixed wavelength, limited tuning range, and slow response speed.

[0052] By integrating a fixed cavity and an intermediate reflective layer on a silicon substrate and combining it with MEMS actuation to dynamically adjust the upper cavity length, a dual-FP cavity structure is constructed, enabling high-precision continuous tuning of the infrared radiation wavelength. This solution offers advantages such as high integration, low power consumption, and miniaturization, making it suitable for a variety of microsystem applications, including multi-gas detection, tunable infrared sources, and integrated photonic chips.

[0053] The present invention provides a dual-FP cavity coupled tunable infrared radiation source, comprising a substrate 1, a support layer 2, a heating electrode 3, an insulating layer 4, a metamaterial radiation layer 5, and an actuator 6; the support layer 2 is located on the substrate 1, the heating electrode 3 is located in the central region of the support layer 2; the insulating layer 4 covers the heating electrode 3; and a plurality of first columns 16 are provided around the edge of the support layer 2.

[0054] The metamaterial radiation layer 5 includes a bottom reflective layer 501, a lower fixed air cavity 502, an intermediate reflective layer 503, an upper adjustable air cavity 504, and a metasurface layer 505;

[0055] The bottom reflective layer 501 is located in the center of the insulating layer 4. A plurality of second columns 17 are provided around the edges of the insulating layer 4. The upper portions of the plurality of second columns 17 cover the substrate 11, so that the area between the substrate 11 and the bottom reflective layer 501 forms the lower fixed air cavity 502. The intermediate reflective layer 503 is located on the substrate 11.

[0056] The actuator 6 includes an upper plate 601 and a lower plate 602; the upper plate 601 covers the plurality of first columns 16, so that the area between the upper plate 601 and the intermediate reflective layer 503 is the upper adjustable air cavity 504; the lower plate 602 is located on the substrate 11; the super surface layer 505 is located on the lower surface of the upper plate 601; a first electrode 9 is also provided on the upper plate 601, and a second electrode 12 is also provided on the substrate 11.

[0057] In some embodiments, the substrate 1 is a silicon substrate having a thickness of 300 μm to 600 μm and good thermal conductivity and mechanical stability. The substrate serves as a supporting structure for the entire device and provides a heat conduction path to ensure temperature uniformity of the radiation layer.

[0058] In some embodiments, the support layer 2 is made of an insulating material such as silicon nitride (Si3N4) or silicon dioxide (SiO2), and is used to support the heating electrode while providing electrical insulation and mechanical stability; the thickness of the support layer 2 is 100 to 300 nm.

[0059] In some embodiments, heating electrode 3 is made of a high-melting-point metal such as platinum (Pt) or tungsten (W) and is designed in a spiral shape to increase the heating area and improve thermal efficiency. By applying electrical heating, the temperature of the metamaterial's radiating layer is adjusted, thereby changing its optical properties and adjusting the radiation wavelength.

[0060] In some embodiments, the insulating layer 4 is made of insulating materials such as silicon nitride (Si3N4) or silicon dioxide (SiO2) to isolate the heating electrode and the metamaterial radiation layer to prevent electrical short circuits while providing a heat conduction path.

[0061] In some embodiments, the metamaterial radiation layer 5 is composed of a bottom reflector 501, a lower fixed air cavity 502, an intermediate reflector 503, an upper adjustable air cavity 504, and a metasurface layer 505, forming a resonant cavity of a dual FP cavity. The lower fixed air cavity 502 is formed between the bottom reflector 501 and the intermediate reflector 503, while the upper adjustable air cavity 504 is formed between the intermediate reflector 503 and the upper metasurface layer 505. The cavity length d2 of the lower fixed air cavity 502 is fixed, while the cavity length d1 of the upper adjustable air cavity 504 can be adjusted by driving a MEMS electrostatic actuator.

[0062] In some embodiments, the bottom reflective layer 501 has a thickness of 100-130 nm; and the intermediate reflective layer 503 has a thickness of 20-50 nm.

[0063] In some embodiments, the super surface layer 505 is designed as a micron-scale open pore structure, and the material is Au.

[0064] In some embodiments, the area of ​​the open pore structure is 0.2 μm 2 ~9μm 2 The arrangement period of the open hole structure is 1.5um to 5um.

[0065] In some embodiments, the materials of the first pillar and the second pillar are independently selected from silicon, silicon dioxide, or silicon nitride.

[0066] In some embodiments, the aperture structure of the metasurface layer 505 is designed to be a periodically arranged circular, square or cross hole array, and the structures are as follows: Figure 3 、 Figure 4 、 Figure 5 As shown. Through the micron-scale open hole structure, FP resonance is formed, and the super surface layer 505 optimizes the optical performance of the infrared radiation source through a specific design, so that the radiation source can adjust the radiation characteristics within a specific wavelength range and realize narrow-band spectrum adjustment. The structural parameters such as the repetition period, shape and size of the open hole structure directly affect the optical performance of the super surface layer. By optimizing the repetition period, shape and size of the open hole structure, the equivalent dielectric constant and magnetic permeability of the super surface layer can be adjusted, thereby realizing precise control of the infrared radiation spectrum characteristics. The super surface layer with each structural parameter can excite FP resonance, making the infrared radiation source suitable for a specific wavelength range.

[0067] In some embodiments, the actuator includes an upper plate 601 and a lower plate 602 , wherein the supersurface layer 505 is disposed on the surface of the upper plate 601 .

[0068] In some embodiments, the upper electrode 601 is composed of four cantilever beams 7, a movable film 8, and a substrate 10; the cantilever beams 7, the movable film 8, and the substrate 10 are located on the same horizontal plane, the movable film 8 is located inside the substrate 10 to form a U-shape, and the movable film 8 and the substrate 10 are connected by several cantilever beams 7; the super surface layer 505 is located on the lower surface of the movable film 8.

[0069] In some embodiments, the cantilever beam 7 is a rectangular frame with an open side, and the opening direction of the rectangular frame of each cantilever beam 7 is different, and the lengths of two opposite sides of the rectangular frame with an open side are different.

[0070] In some embodiments, an electrostatic force is generated by applying a voltage between the upper plate 601 and the lower plate 602. Since the resonant wavelength of an FP optical resonator is determined by both the cavity length and the resonant order, adjusting the cavity length can dynamically change the radiation wavelength corresponding to each resonant order. Combined with the frequency-selective properties of the metasurface layer, the radiation of specific resonant orders can be selectively enhanced, thereby achieving precise output of narrowband radiation peaks.

[0071] Figure 2 This is a schematic diagram of the working principle of the dual-cavity coupled tunable narrowband infrared radiation source of the present invention. By applying a voltage across the heating electrode 3, the present application utilizes the Joule heating effect to generate heat at the bottom of the device. This heat, through thermal conduction, causes the bottom structure to heat up, thereby heating the metamaterial radiation layer 5 above. By applying a voltage to the MEMS electrostatic actuator, the upper electrode 601 is driven to move in a direction perpendicular to the lower electrode 602, achieving continuous adjustment of the cavity length of the upper adjustable air cavity. When the upper adjustable air cavity 504 and the lower fixed air cavity 502 simultaneously approach resonance, cascade interference occurs within the cavity, forming a dual-cavity coupled resonance. This mechanism can selectively enhance the emission of a target wavelength band within the original broad-spectrum thermal radiation, producing a dual-peak or high-Q narrowband infrared output.

[0072] Example 1

[0073] The present invention provides a dual FP cavity coupled tunable infrared radiation source, the structure of which is as follows: Figure 1 As shown, it includes a substrate 1, a supporting layer 2, a heating electrode 3, an insulating layer 4, a metamaterial radiation layer 5 and an actuator 6; the supporting layer 2 is located on the substrate 1, and the heating electrode 3 is located in the central area of ​​the supporting layer 2; the insulating layer 4 covers the heating electrode 3; a plurality of first columns 16 are set in the edge areas around the supporting layer 2; the substrate 1 is silicon; the material of the supporting layer 2 is silicon dioxide; the material of the heating electrode 3 is platinum; the material of the insulating layer 4 is silicon dioxide; the materials of the bottom reflection layer 501 and the intermediate reflection layer 503 are both Au; the material of the upper plate 601 is Si3N4; the metal layer thickness of the bottom reflection layer is 100nm; the metal layer thickness of the intermediate reflection layer is 30nm.

[0074] The metamaterial radiation layer 5 includes a bottom reflective layer 501, a lower fixed air cavity 502, an intermediate reflective layer 503, an upper adjustable air cavity 504, and a metasurface layer 505; the bottom reflective layer 501 is located in the central area of ​​the insulating layer 4; a plurality of second columns 17 are arranged in the peripheral edge areas of the insulating layer 4, and the upper parts of the plurality of second columns 17 cover the substrate 11, so that the area between the substrate 11 and the bottom reflective layer 501 is the lower fixed air cavity 502; the intermediate reflective layer 50 3 is located on the substrate 11; the actuator 6 includes an upper plate 601 and a lower plate 602; the upper plate 601 covers the plurality of first pillars 16, so that the area between the upper plate 601 and the intermediate reflector 503 forms the upper adjustable air cavity 504; the lower plate 602 is located on the substrate 11; the metasurface layer 505 is located on the lower surface of the upper plate 601; the upper plate 601 is also provided with a first electrode 9, and the substrate 11 is also provided with a second electrode 12. The upper plate 601 is composed of four cantilever beams 7, a movable membrane 8, and a substrate 10 located in the same plane; the movable membrane 8 is square and located within the substrate 10 to form a U-shaped structure. The movable membrane 8 and the substrate 10 are connected via the cantilever beams 7; the metasurface layer 505 is located on the lower surface of the movable membrane 8. The lower plate 602 and the intermediate reflective layer 503 form a U-shaped structure, with the intermediate reflective layer 503 located within the lower plate 602. The metasurface layer has a micron-scale open pore structure, with the open pore structure having a shape selected from a circle, square, or polygon; the side length of the square open pore structure is 2 μm, and the arrangement period of the open pore structure is 3 μm.

[0075] Figure 6 FIG. 1 is a schematic structural diagram of an actuator in a silicon-based tunable narrow-band infrared radiation source according to an embodiment of the present application. Figure 6 (a) is a top view of the upper electrode plate 601. The upper electrode plate 601 is composed of four cantilever beams 7, a movable membrane 8, and a substrate 10. One end of each cantilever beam 7 is connected to the movable membrane 8. The movable membrane 8 is square, and its center area is hollowed out to expose the metasurface layer 505, thereby enhancing the selectivity and optical performance of the radiation spectrum. The first electrode 9 is disposed on the substrate 10; Figure 6Middle (b) is the lower electrode 602, which is located together with the intermediate reflective layer 503 on the substrate 11, which is located on the pillar 17. At the same time, a second electrode 12 is also provided on the substrate 11, which is connected to the lower electrode 602 via a lead or a conductive path to ensure the effective transmission of the electrostatic driving force. In the embodiment of the present application, by applying a voltage between the first electrode 9 and the second electrode 12, the upper electrode 601 and the lower electrode 602 are energized and generate an electrostatic force. The electrostatic force drives the movable film 8 to move the metasurface layer 505 toward the intermediate reflective layer 503, thereby changing the cavity length of the upper adjustable air cavity 504 formed between the metasurface layer 505 and the intermediate reflective layer 503, thereby achieving tuning of the radiation wavelength. The electrostatic force drives the cantilever beam 7 to undergo elastic deformation, while the movable film 8 in the middle remains almost parallel due to the symmetry and rigidity of the structure. This design ensures the relative parallelism between the movable film 8 and the intermediate reflective layer 503 during movement, thereby maintaining the optical stability of the FP optical resonant cavity. When the applied voltage is removed, the elastic restoring force of the cantilever beam 7 causes the movable film 8 and the super-surface layer 505 to return to their initial positions.

[0076] The substrate 10 is further covered with a silicon wafer; the silicon wafer is further covered with a silicon nitride layer 13, and the silicon wafer comprises an upper plate 10, a buried oxide layer 15 and a silicon layer 14 from bottom to top; the center of the base has a cavity structure.

[0077] The cavity length d1 of the upper adjustable air cavity (504) satisfies d1=mλ / 2, where λ is the characteristic absorption wavelength of the gas to be measured and m is the resonance order; the cavity length d2 of the lower fixed air cavity (502) is.

[0078] The upper plate 601 is 15 μm thick and has overall dimensions of 4.2 mm x 4.2 mm. The movable membrane 8 area measures 2 mm x 2 mm, with a central hollowed-out area measuring 0.5 mm x 0.5 mm, consistent with the dimensions of the intermediate reflector 503. The cantilever beam 7 is 3.6 mm long and 0.09 mm wide, designed to be symmetrically distributed to ensure that the movable membrane 8 remains parallel to the intermediate reflector 503 during movement. The lower plate 602 has an outer frame length of 4.2 mm and an inner frame length of 2 mm, designed to be annularly symmetrical to ensure uniform distribution of the electrostatic force. The initial cavity length of the FP optical resonator is set to 10 μm, with a corresponding cavity length adjustment range of 6.8 to 10 μm. Dynamic cavity length adjustment is achieved by applying voltages between 0 and 6.3 V. The cantilever beam 7 undergoes elastic deformation under the action of the electrostatic force, driving the movable film 8 and the metasurface layer 505 to move toward the intermediate reflective layer 503, thereby changing the cavity length of the FP optical resonant cavity and achieving precise tuning of the radiation wavelength.

[0079] In the embodiment of this application, numerical simulation analysis was conducted on the upper cavity FP structure to study the regulating effect of different metasurface opening structures on infrared radiation performance. By changing the opening pattern of the metasurface layer, the finite element analysis method was used to study the influence of different patterns on the radiation center wavelength and emissivity. Figure 8 As shown in Figure 1, (a) is the simulation result of a square opening pattern, where the opening side length is in the range of 0.8um to 1.5um and the arrangement period is 1.5um to 4um. The central wavelength of the radiation generated by this structure moves between 5.5 and 8.5um, with a half-peak width of approximately 58nm. It reaches the maximum emissivity R1 = 0.85 at a wavelength of λ1 = 5.6um, while the cross-shaped opening pattern produces a radiation peak as shown in Figure 1. Figure 8 As shown in (b), the radiation peak shifts within the wavelength range of 12 to 16 μm, reaching a maximum emissivity R2 of 0.91 at a wavelength of λ2 = 12.6 μm. Further analysis revealed that by optimizing the structural parameters of the aperture pattern, such as shape, size, and period, the central wavelength of the radiation can be precisely controlled, achieving efficient narrowband radiation.

[0080] In the embodiment of the present application, a dual-cavity FP infrared radiation structure is constructed, in which a fixed lower cavity is formed between the bottom reflective layer and the middle semi-transparent reflective layer, and the upper adjustable cavity is driven by a MEMS actuator to achieve dynamic cavity length adjustment. In view of the absorption line characteristics of gases such as CO2, the cavity length d2 of the lower cavity can be fixedly designed to 1 / 2 times the optical thickness corresponding to a wavelength of about 4.3μm, and the upper cavity can achieve fine scanning of the 3.8-4.5μm band through electrostatic adjustment. The structure can generate radiation peaks at two resonant wavelengths, and the peak spacing is closely related to the adjustment of the upper and lower cavity lengths and film thickness. Compared with a single-cavity device, this dual-cavity structure not only achieves more flexible spectral line matching, but also has higher spectral purity and multi-component gas co-detection capabilities.

[0081] Example 2

[0082] This embodiment provides a method for preparing a dual-FP cavity coupled tunable infrared radiation source. Figure 9 The following is a flowchart of the method for preparing an infrared radiation source according to an embodiment of the present application, which specifically includes:

[0083] 1. Preparation of the first component

[0084] (1) Cleaning the silicon substrate: Use acetone, ethanol, and deionized water to clean the silicon substrate in sequence to remove surface contaminants. Blow dry the substrate with nitrogen to ensure a clean surface.

[0085] (2) Deposition of support layer: SiO2 is deposited on the surface of the silicon substrate by chemical vapor deposition (CVD) or physical vapor deposition (PVD) process as a support layer.

[0086] (3) Photolithography-development: Spin-coat photoresist on the SiO2 layer and define the pattern of the heating electrode through photolithography and development processes.

[0087] (4) Sputtering Pt: A Pt metal layer is deposited on the photoresist pattern through a sputtering process to form a heating electrode.

[0088] (5) Stripping: Use the stripping process to remove excess photoresist and metal layers, retaining the pattern of the heating electrode.

[0089] (6) Chemical vapor deposition growth of SiO2: A SiO2 layer is grown on the heating electrode by plasma enhanced chemical vapor deposition process as an insulating layer.

[0090] (7) Photolithography-development: Spin-coat photoresist on the SiO2 layer and define the pattern of the bottom reflective layer through photolithography and development processes.

[0091] (8) Etching: Use the etching process to remove the SiO2 layer that is not protected by the photoresist.

[0092] (9) Photolithography-development: Spin-coat photoresist on the etched SiO2 layer, and define the pattern of the bottom reflective layer through photolithography and development processes.

[0093] (10) Deposition - bottom reflective layer: An Au layer is deposited on the photoresist pattern by sputtering or evaporation process to form a bottom reflective layer.

[0094] (11) Stripping: Use the stripping process to remove excess photoresist and gold layer, retaining the pattern of the bottom reflective layer.

[0095] (12) Deposition-photolithography and etching: Polysilicon is deposited on the insulating layer, and a plurality of second silicon pillars with a height of d2 are formed by photolithography and etching to support the intermediate reflective layer.

[0096] (13) Deposition of intermediate reflective layer: depositing a substrate on top of the second silicon pillar by a plasma chemical vapor deposition process, depositing an intermediate reflective layer on the substrate film by evaporation or magnetron sputtering, and defining the pattern of the intermediate reflective layer by a lift-off or patterning process;

[0097] (14) Backside etching: Photolithography and etching are performed on the middle area of ​​the lower surface of the substrate to form a cavity structure on the substrate to reduce heat conduction and improve thermal efficiency, thereby obtaining the first component.

[0098] 2. Preparation of the Second Component

[0099] (1) Select the actuator substrate: Use silicon wafer (SOI) as the actuator substrate with a thickness of 500 μm.

[0100] (2) Bottom deposition of silicon nitride: A silicon nitride layer is deposited on the bottom of the SOI substrate.

[0101] (3) Si etching-flip solder step: A flip solder step with a depth of 10 μm is formed on the SOI substrate through an etching process.

[0102] (4) Photolithography: Use photolithography to define the patterns of the metasurface and reflective surface.

[0103] (5) Evaporated Au-stripping metasurface and reflective surface: A gold (Au) layer is deposited by an evaporation process, and a stripping process is used to form the metasurface and reflective surface.

[0104] (6) Deposition of SiO2 barrier layer: Deposition of silicon dioxide (SiO2) barrier layer on the metasurface and reflective surface.

[0105] (7) Photolithography and etching of SiO2 layer: Use photolithography and etching processes to define the pattern of the SiO2 barrier layer.

[0106] (8) Deep etching of the cantilever beam structure and removal of the SiO2 barrier layer: The cantilever beam structure is formed by a deep etching process and the SiO2 barrier layer is removed.

[0107] (9) Backside photolithography and etching of silicon nitride: Photolithography and etching are performed on the back side of the silicon nitride layer to define the pattern of the silicon nitride layer.

[0108] (10) Back side deep silicon etching: etching the silicon nitride layer and the central area of ​​the silicon layer to form a cavity structure;

[0109] (11) The buried oxide layer is etched to release the cantilever beam structure and obtain the second component.

[0110] (12) The support layer of the first component and the upper plate of the second component are connected through the first column by flip-chip bonding technology or bonding technology to form a complete infrared radiation source device.

[0111] This application also provides an infrared gas detection application solution that integrates the dual-cavity coupled tunable narrowband infrared radiation source described herein into a gas detection system for detecting gas molecules with specific absorption bands. By adjusting the cavity length of the infrared radiation source's upper cavity, the output wavelength can be continuously and precisely tuned within the mid-infrared range, achieving a high degree of match with the molecular absorption spectrum of the target gas, thereby improving the system's selectivity and sensitivity to gas concentration.

[0112] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A dual-FP cavity coupled tunable infrared radiation source, characterized in that: The invention comprises a substrate (1), a support layer (2), a heating electrode (3), an insulating layer (4), a metamaterial radiation layer (5) and an actuator (6); the support layer (2) is arranged on the top of the substrate (1); the heating electrode (3) is arranged on the middle area of ​​the support layer (2), and a plurality of first columns (16) are arranged on the peripheral edge areas of the support layer (2); the heating electrode (3) is covered by the insulating layer (4); The metamaterial radiation layer (5) includes a bottom reflection layer (501), a lower fixed air cavity (502), an intermediate reflection layer (503), an upper adjustable air cavity (504), and a metasurface layer (505); the actuator (6) includes an upper plate (601) and a lower plate (602); The bottom reflective layer (501) is located on the middle area of ​​the insulating layer (4); a plurality of second columns (17) are arranged on the peripheral edge areas of the insulating layer (4); the upper parts of the plurality of second columns (17) cover the substrate (11), so that the area between the substrate (11) and the bottom reflective layer (501) is the lower fixed air cavity (502); the intermediate reflective layer (503) and the lower electrode (602) are both located on the substrate (11); the upper electrode (601) covers the plurality of first columns (16), so that the area between the upper electrode (601) and the intermediate reflective layer (503) is the upper adjustable air cavity (504); the super surface layer (505) is located on the lower surface of the upper electrode (601); a first electrode (9) is also arranged on the upper electrode (601), and a second electrode (12) is also arranged on the substrate (11).

2. The dual-FP cavity coupled tunable infrared radiation source according to claim 1, characterized in that: The upper electrode plate (601) is composed of four cantilever beams (7), a movable film (8), and a substrate (10); each of the cantilever beams (7), movable film (8), and substrate (10) is located on the same horizontal plane, the movable film (8) is located inside the substrate (10) to form a U-shaped structure, and the movable film (8) and the substrate (10) are connected via a plurality of cantilever beams (7); the super surface layer (505) is located on the lower surface of the movable film (8).

3. The dual-FP cavity coupled tunable infrared radiation source according to claim 1, characterized in that: The lower electrode plate (602) and the intermediate reflection layer (503) are arranged in a U-shaped structure, and the lower electrode plate (602) is located on the periphery of the intermediate reflection layer (503).

4. The dual-FP cavity coupled tunable infrared radiation source according to claim 1, characterized in that: The super surface layer has a micron-scale open pore structure, and the shape of the open pore structure is preferably selected from a circle, a square or a polygon; the area of ​​the open pore structure is 0.2 μm 2 ~9μm 2 The arrangement period of the open hole structure is 1.5um to 5um.

5. The dual-FP cavity coupled tunable infrared radiation source according to claim 2, characterized in that: The upper portion of the substrate (10) is also covered with a silicon wafer; and the center of the base has a cavity structure.

6. The dual-FP cavity coupled tunable infrared radiation source according to claim 1, characterized in that: The material of the substrate (1) is silicon; the material of the support layer (2) is selected from silicon dioxide or silicon nitride; the material of the heating electrode (3) is platinum; the material of the insulating layer (4) is selected from silicon dioxide or silicon nitride; the materials of the bottom reflection layer (501) and the intermediate reflection layer (503) are independently selected from Au or Ag; and the material of the upper plate (601) is selected from Si or Si3N4.

7. The dual-FP cavity coupled tunable infrared radiation source according to claim 1, characterized in that: The thickness of the bottom reflection layer (501) is 100-130 nm; the thickness of the intermediate reflection layer (503) is 20-50 nm.

8. The method for preparing a dual-FP cavity coupled tunable infrared radiation source according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) growing a support layer on the upper surface of the substrate; (2) preparing a heating electrode on the support layer by a sputtering process; (3) growing an insulating layer on the heating electrode by a plasma enhanced chemical vapor deposition process; (4) forming a bottom reflective layer on the insulating layer by sputtering or evaporation process; (5) depositing silicon on the insulating layer and forming a plurality of second pillars by photolithography and etching; (6) preparing a substrate on top of the plurality of second pillars by a plasma enhanced chemical vapor deposition process, and depositing an intermediate reflective layer on top of the substrate; (7) performing photolithography and etching on the lower surface of the substrate to form a cavity structure on the substrate; (8) preparing a plurality of first pillars at both ends of the upper portion of the support layer by photolithography and etching processes; (9) preparing a silicon wafer, wherein the silicon wafer comprises, from bottom to top, an upper plate, a buried oxide layer, and a silicon layer; and depositing a silicon nitride layer on the upper surface of the silicon wafer; (10) etching a middle area of ​​the upper electrode plate to form a reverse solder step on the upper electrode plate; (11) forming a super surface layer on the lower surface of the upper electrode plate by an evaporation process; (12) depositing a silicon dioxide barrier layer on the super surface layer and the upper electrode plate, etching the upper electrode plate and the silicon dioxide barrier layer thereon by a deep etching process to form a cantilever beam, and then removing the unetched silicon dioxide barrier layer; (13) etching the silicon nitride layer and the middle region of the silicon layer to form a cavity structure; (14) etching the buried oxide layer located on the upper portion of the cantilever beam to release the cantilever beam structure; (15) The first column is connected to the lower surface of the upper electrode plate through flip-chip bonding technology or bonding technology to form a complete infrared radiation source device.

9. Application of a dual-FP cavity coupled tunable infrared radiation source according to any one of claims 1 to 7, characterized in that: It is used in the infrared radiation source module of the infrared gas sensor.

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