On-chip frequency stabilization gas chamber of surface plasmon waveguide structure and preparation method

Abstract

The invention belongs to the technical field of frequency stabilization gas chambers, and particularly relates to an on-chip frequency stabilization gas chamber of a surface plasmon waveguide structure and a preparation method. The middle section of the silicon waveguide and the metal ridge waveguide are arranged in an equidistant solid mode, the air cavity is located between the silicon waveguide and the metal ridge waveguide, the longitudinal section of the air cavity is rectangular, the front end of the middle section is connected with the front connecting section, and the rear end of the middle section is connected with the rear connecting section. The front connecting section and the rear connecting section are of a single-side conical structure, the conical sides of the front connecting section and the rear connecting section are close to the metal ridge waveguide, and the width of the single-side conical structure in the front connecting section and the width of the single-side conical structure in the rear connecting section are gradually increased from inside to outside. According to the invention, the high light field local characteristic of surface plasmon polaritons is utilized, so that efficient light field limitation in a very small size is realized. Through optimization design and material selection, the structure overcomes the limitation of a traditional frequency stabilized laser in the aspects of miniaturization and integration, and a new technical scheme is provided for performance improvement of the chip-level frequency stabilized laser.

Description

Technical Field

[0001] The present invention belongs to the technical field of frequency-stabilizing gas chambers, and in particular relates to an on-chip frequency-stabilizing gas chamber of a surface plasmon waveguide structure and a preparation method thereof. Background Art

[0002] In the field of modern optics and optoelectronics, lasers, as an important light source, are widely used in communications, medical treatment, industrial processing and other fields. In particular, frequency-stabilized lasers have become key equipment for applications such as precision measurement and spectral analysis due to their high frequency stability and good coherence. In the design of frequency-stabilized lasers based on the principle of gas absorption, the absorption gas chamber is a key component for adjusting the stability of the laser frequency. Its structure and performance directly affect the stability and output quality of the laser. At present, the gas chamber structure is mostly macroscopic in size and difficult to integrate with other components of chip-level lasers. Therefore, the development of a new type of on-chip frequency-stabilized laser gas chamber has important research value and application prospects.

[0003] Most of the existing chip-level gas chambers use micro-electromechanical system technology MEMS, which reduces the size of the atomic gas chamber from the traditional centimeter level to the millimeter level, greatly reducing the volume of the physical system. During the preparation process, researchers usually use photolysis, electrochemical decomposition and other technologies to make microchannels and chambers. These chambers can provide the gas molecules required for photoreaction. The design of MEMS gas chambers usually adopts a "sandwich" structure, that is, a glass-silicon-glass structure, and the packaging is completed through a low-temperature anodic bonding process.

[0004] The existing chip-level frequency stabilization chamber design has the following main shortcomings: 1. Complex device: Setting up MEMS equipment requires complex optical components and brackets, which are difficult to assemble and maintain. Since it involves the precise docking of multiple optical components, the device construction requirements are high and it is easily affected by environmental interference.

[0005] 2. High cost: Some optical components used in MEMS air chambers are expensive, making the overall equipment expensive; and the maintenance cost is relatively high, because the cleaning, alignment and replacement of optical components require professional operation and may cause additional downtime.

[0006] 3. Limited environmental adaptability: It is greatly affected by external environmental factors such as environment and vibration. Since the MEMS air chamber is composed of multiple optical components and has a complex structure, it is difficult to integrate temperature control devices, and it is not suitable for extreme or changeable environmental conditions. Summary of the invention

[0007] In order to solve the problems existing in the prior art, the present invention provides an on-chip frequency-stabilizing gas chamber of a surface plasmon waveguide structure and a preparation method thereof.

[0008] The technical solution adopted by the present invention to solve the technical problem is as follows: an on-chip frequency-stabilizing gas chamber of a surface plasmon waveguide structure, comprising: a gas chamber structure and a cladding layer located around the gas chamber structure, The air chamber structure includes: a silicon waveguide, a metal ridge waveguide and an air cavity. The middle section of the silicon waveguide and the metal ridge waveguide are arranged in an equidistant entity. The air cavity is located between the silicon waveguide and the metal ridge waveguide. The longitudinal section of the air cavity is rectangular. The front end of the middle section is connected to the front connecting section, and the rear end is connected to the rear connecting section. Both the front connecting section and the rear connecting section have a single-sided conical structure, and one side of the cone is close to the metal ridge waveguide. The width of the single-sided conical structure in the front connecting section and the rear connecting section gradually increases from the inside to the outside.

[0009] Preferably, the equidistant distance between the silicon waveguide and the metal ridge waveguide is d, the front connecting section and the rear connecting section are projected to the left side in the form of a single-sided conical structure, and the projection width of the single-sided conical structure is D, where D≥d.

[0010] Preferably, the air cavity is filled with acetylene gas, and the optical path length of the air cavity is 20 mm.

[0011] Preferably, the middle section and the metal ridge waveguide are designed to be a serpentine structure.

[0012] Preferably, the bending radius of the serpentine structure is 20 μm.

[0013] Preferably, the cladding layer includes an original layer and a new layer, wherein the original layer is located below the air chamber structure, and the new layer is located around and above the same layer of the air chamber structure.

[0014] Preferably, two ends of the silicon waveguide respectively establish an optical transmission path with a spot converter through a straight waveguide, and the spot converter is in a trident structure.

[0015] Preferably, it also includes: a semiconductor cooler TEC, which is arranged below the air cavity.

[0016] The on-chip frequency stabilization gas chamber is prepared by a method compatible with silicon photonics technology and complementary metal oxide semiconductor process.

[0017] Preferably, the method for preparing the on-chip frequency stabilizing gas chamber comprises the following steps: S1. Substrate preparation: Si-SiO2-Si three-layer structure substrate is obtained by dissociation, cleaning and drying. S2, coating photoresist, coating a layer of photoresist on the upper surface of the substrate, removing the solvent in the photoresist to solidify it, S3, alignment and exposure, transfer the pattern designed on the mask to the photoresist, S4, development, remove unnecessary photoresist according to the design pattern of the mask, leaving only the photoresist at the position corresponding to the design pattern of the mask. S5, etching, removing the area not covered by photoresist from the upper layer of the substrate, S6, remove the photoresist, and the silicon waveguide structure is formed. S7, forming metal ridge waveguide, using complementary metal oxide semiconductor process to form metal ridge waveguide, S8, growing the cladding, using the chemical vapor deposition method, placing the wafer in the reaction chamber, heating the wafer, and introducing the reaction gas into the reaction chamber for thin film deposition, thereby completing the growth of the thin film. S9, etch the air cavity and etch away the space between the silicon waveguide and the metal ridge waveguide. S10, after the etching is completed, an air cavity is constructed by inflating the air cavity, and a silicon dioxide film is covered on the air cavity.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. Miniaturization design: The present invention proposes an on-chip frequency-stabilizing gas chamber of a surface plasmon waveguide structure. The gas chamber uses a metal structure made near the transmission waveguide to guide the waveguide, thereby realizing the chip-based design of the gas chamber, reducing the volume to the micron level, and achieving high integration. 2. Enhance the interaction between light and gas: By utilizing the characteristics of surface plasmon waveguides, the present invention can concentrate the light field in a very small space, thereby enhancing the interaction between light and gas in the air chamber, enhancing the absorption effect, and significantly improving the stability and accuracy of the laser frequency. 3. Precise control of environmental conditions: In order to improve the accuracy of frequency stabilization, the present invention integrates a temperature control system in the on-chip frequency-stabilized laser gas chamber. By precisely controlling the temperature, the laser frequency can be stably controlled, thereby improving the performance and reliability of the frequency-stabilized laser. 4. Low cost: The manufacturing process of the gas chamber of the present invention is compatible with the complementary metal oxide semiconductor CMOS process, and can be monolithically integrated and mass-produced, thereby reducing production costs. In addition, since there are no macroscopic moving parts and alignment requirements, the maintenance cost is also low, which greatly reduces the complexity and cost of maintenance and replacement. In summary, the present invention proposes an on-chip frequency-stabilizing gas chamber of a surface plasmon waveguide structure, which utilizes the localized characteristics of the strong light field of surface plasmons to achieve efficient light field confinement in a very small size. Through optimized design and material selection, this structure is expected to overcome the limitations of traditional frequency-stabilizing lasers in terms of miniaturization and integration, and provide a new technical solution for improving the performance of chip-level frequency-stabilizing lasers. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the overall structure diagram of the on-chip frequency stabilization chamber. Figure 2 for Figure 1 The enlarged view of the part at A in Figure (b) Figure 3 This is a schematic diagram of the process flow for making an on-chip frequency stabilization gas chamber. Figure 4 This is a schematic diagram of the optical transmission route in the on-chip frequency stabilization chamber and the optical mode field distribution in the chamber. in, 1. Silicon substrate, 2. Cladding, 3. Air chamber structure, 201, original layer, 202, new layer, 31. Silicon waveguide, 32. Metal ridge waveguide, 33. Air cavity, 311, front connecting section, 312, middle section, 313, rear connecting section, 314, straight waveguide, 315, spot converter, 316, positive cone section, 317, first guide, 318, second guide, Figure 1 (a) is the main view, (b) is the top view of the layout of each component in the optical transmission route, Figure 3 a~j correspond to steps S1~S10 in the method for preparing the on-chip frequency stabilizing gas chamber. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present invention, the present invention is described in more detail below in conjunction with the accompanying drawings and specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0021] Combination Figure 1 It is understood that an on-chip frequency-stabilizing gas chamber of a surface plasmon waveguide structure includes: a gas chamber structure 3 and a cladding layer 2 located around the gas chamber structure 3, The air chamber structure 3 includes: a silicon waveguide 31, a metal ridge waveguide 32 and an air cavity 33. The middle section 312 of the silicon waveguide 31 and the metal ridge waveguide 32 are arranged in an equidistant entity. The air cavity 33 is located between the silicon waveguide 31 and the metal ridge waveguide 32. The longitudinal section of the air cavity 33 is rectangular. The front end of the middle section 312 is connected to the front connecting section 311, and the rear end is connected to the rear connecting section 313. The front connecting section 311 and the rear connecting section 313 both have a single-sided conical structure, and one side of the conical structure is close to the metal ridge waveguide 32. The width of the single-sided conical structure in the front connecting section 311 and the rear connecting section 313 gradually increases from the inside to the outside. The tapered gradient structure at both ends can reduce light loss.

[0022] In one embodiment, the distance between the silicon waveguide 31 and the metal ridge waveguide 32 is d, the front connecting section 311 and the rear connecting section 313 are projected to the left side in a single-sided conical structure, and the projection width of the single-sided conical structure is D, D ≥ d, combined with Figure 2 understand.

[0023] In one embodiment, the gas cavity 33 is filled with acetylene gas, and the optical path length of the gas cavity 33 is 20 mm.

[0024] In one embodiment, the middle section 312 and the metal ridge waveguide 32 are designed to be a serpentine structure.

[0025] In one embodiment, the bending radius of the serpentine structure is 20 μm.

[0026] In one embodiment, the cladding 2 includes an original layer 201 and a new layer 202 , wherein the original layer 201 is located below the air chamber structure 3 , and the new layer 202 is located around and above the same layer of the air chamber structure 3 .

[0027] In one embodiment, the two ends of the silicon waveguide 31 respectively establish an optical transmission path with the spot converter 315 through a straight waveguide 314, and the spot converter 315 is a trident structure. There is a large mismatch between the optical fiber mode field and the transmission waveguide mode field in the air chamber. In order to achieve low-loss coupling between the two, it is necessary to design a suitable spot converter 315 on the silicon waveguide at the two end faces of the air chamber. In this embodiment, the spot converter 315 is designed as a trident structure. After parameter optimization, two tapered waveguide structures with an interval of 400nm are introduced to achieve lateral expansion of the mode field, thereby greatly improving the matching degree between the optical fiber mode field and the transmission waveguide mode field in the gain chip.

[0028] In one embodiment, it further includes: a semiconductor cooler TEC, which is arranged below the air cavity 33 to facilitate temperature control.

[0029] The on-chip frequency stabilization gas chamber is prepared by a method compatible with silicon photonics technology and complementary metal oxide semiconductor process.

[0030] In one embodiment, in combination Figure 3 Understand the preparation method of the on-chip frequency stabilization gas chamber. The steps are as follows: S1. Substrate preparation: Si-SiO2-Si three-layer structure substrate is obtained by dissociation, cleaning and drying. S2, coating photoresist, coating a layer of photoresist on the upper surface of the substrate, removing the solvent in the photoresist to solidify it, S3, alignment and exposure, transfer the pattern designed on the mask to the photoresist, S4, development, remove unnecessary photoresist according to the design pattern of the mask, leaving only the photoresist at the position corresponding to the design pattern of the mask. S5, etching, removing the area not covered by photoresist from the upper layer of the substrate, S6, remove the photoresist, and the silicon waveguide 31 structure is formed. S7, forming a metal ridge waveguide 32, using a complementary metal oxide semiconductor process to form the metal ridge waveguide 32, S8, growing cladding 2, using a chemical vapor deposition (CVD) method, placing the wafer in a reaction chamber, heating the wafer, and introducing reaction gas into the reaction chamber for thin film deposition, thereby completing the growth of the thin film. S9, etching the air cavity 33, etching away the space between the silicon waveguide 31 and the metal ridge waveguide 32, S10 , after etching is completed, the air cavity 33 is inflated to form the air cavity 33 , and a silicon dioxide film is covered on the air cavity 33 .

[0031] Example 1: The overall structure diagram of the air chamber is as follows Figure 1As shown, the air chamber structure 3 includes: a silicon waveguide 31, a metal ridge waveguide 32 and an air cavity 33. The middle section 312 of the silicon waveguide 31 and the metal ridge waveguide 32 are arranged in an equidistant entity. The air cavity 33 is located between the silicon waveguide 31 and the metal ridge waveguide 32. The longitudinal cross-section of the air cavity 33 is rectangular. The front end of the middle section 312 is connected to the front connecting section 311, and the rear end is connected to the rear connecting section 313. The front connecting section 311 and the rear connecting section 313 are both single-sided tapered structures, and one side of the tapered structure is close to the metal ridge waveguide 32 respectively. The width of the single-sided tapered structure in the front connecting section 311 and the rear connecting section 313 gradually increases from the inside to the outside. Among them, the cladding 2 is made of silicon dioxide, the light transmission silicon waveguide 31 is made of silicon, the transmission waveguide is 500nm wide and 220nm high; the metal ridge waveguide 32 is made of gold, the metal ridge waveguide 32 is 400nm wide and 220nm high, and the interval with the silicon waveguide 31 is 70nm. The silicon waveguide 31 part that is close and equidistantly arranged and the metal ridge waveguide 32 constitute a surface plasmon waveguide structure, and light can be transmitted in the gap; the silicon dioxide cladding is etched off above the air chamber area, filled with acetylene gas, and then sealed to form an air chamber structure, and the air chamber is placed on the TEC, and the air chamber structure is placed on the semiconductor cooler TEC. The temperature control system is integrated, and the laser frequency is stably controlled by the precise control of the temperature, thereby improving the performance and reliability of the frequency-stabilized laser. In addition, at the end face of the air chamber, an optical transmission path is established through the straight waveguide 314 and the pattern spot converter 315, and the pattern spot converter 315 is in a trident structure. The trident-structured spot converter 315 introduces two waveguide structures with a spacing of 400 nm to realize the lateral expansion of the optical fiber mode field, so as to realize the efficient coupling between the transmission waveguide mode field in the air chamber and the optical fiber mode field. In the middle of the spot converter 315 is a positive cone section 316 with symmetrical conical designs on both sides, and the two sides are respectively a first guide 317 and a second guide 318, and the first guide 317 and the second guide 318 are parallel and symmetrically arranged on both sides of the positive cone section 316 with a spacing of 400 nm.

[0032] Description of the optical transmission process: In this air chamber, the optical transmission route and the optical mode field distribution diagram in the air chamber are shown as follows: Figure 4As shown. First, the light in the straight waveguide 314 is transmitted to the connection part with the metal ridge waveguide 32, that is, the front connection section 311. The front connection section 311 adopts a tapered waveguide structure to reduce the loss caused by mode conversion. After passing through the tapered waveguide structure, more than 90% of the light is confined in the gap between the metal ridge waveguide 32 and the silicon waveguide 31, that is, the air cavity 33 filled with acetylene gas, and is transmitted forward. During the transmission process, the light in the air cavity 33 is absorbed by the gas; then the light in the air cavity 33 passes through the tapered structure of the rear connection section 313 at the end again and returns to the end transmission waveguide. In the structural design of the air chamber, while ensuring the optical path, the middle section 312 of the silicon waveguide 31 and the metal ridge waveguide 32 and the air cavity 33 between the two are designed as a serpentine waveguide to reduce the footprint, wherein the bending radius is 20μm and the optical path length is 2cm.

[0033] Principle description: Surface plasmon is an electromagnetic wave mode formed by the interaction between free electrons and photons at the interface between metal and dielectric. This mode can propagate along the metal surface and can confine more than 90% of the light field to a very small size, breaking through the diffraction limit of traditional optics.

[0034] Light field confinement mechanism: The metal-waveguide structure can provide super strong mode confinement capability. When light waves interact with the metal surface, the free electrons in the metal will collectively oscillate to form surface plasmons. This oscillation can confine the light field near the metal surface, that is, in the gap between the waveguide and the metal.

[0035] Coupling and propagation: Light waves can gradually diffuse outward from the straight waveguide through the tapered waveguide. The design of the tapered waveguide allows the mode field distribution of the input waveguide to gradually change to react to the contact with the surface of the metal medium. The tapered structure provides a gradual transition method that allows light waves to maintain their transmission characteristics while reducing their size. This structure helps to reduce reflection and scattering losses due to mode mismatch. At the end face of the air chamber, a trident-structured mode converter is used to achieve efficient coupling and mode conversion of the light field. The trident structure helps to compress and concentrate the light field in the middle transmission waveguide through the branch structures on both sides. Through this gradual change, the mode of the light wave during transmission is effectively adjusted, thereby reducing reflection and scattering losses caused by mode mismatch.

[0036] Different from the MEMS manufacturing process of the micro gas chamber, the gas chamber of the present invention is manufactured using silicon photonics technology and is compatible with complementary metal oxide semiconductor CMOS technology. The specific process flow is as follows: Figure 3 As shown, the steps are as follows: S1. Preparation of substrate: first dissociate to obtain a wafer of a specific size, then clean it, usually by chemical method, soak the wafer in acid solution and solvent and then clean it with ultra-clean water to remove surface pollutants and improve silicon adhesion, finally dry the wafer surface to obtain a Si-SiO2-Si three-layer structure substrate, the lower layer of the substrate is a silicon substrate 1, the middle is the original layer 201 of the cladding 2, the upper layer is a silicon wafer layer forming an air chamber structure 3, combined with Figure 3 Understanding of Figure A, S2, apply photoresist, use vacuum suction cup under the centrifugal force of rotation, apply a thin layer of photoresist on the surface of the wafer, bake to remove the solvent in the photoresist to solidify it, and combine Figure 3 Understanding of the middle b diagram S3, alignment and exposure, transfer the pattern designed on the mask to the photoresist, combined with Figure 3 Understanding of Figure C, S4, development, according to the design pattern of the mask, remove the unnecessary photoresist, leaving only the photoresist corresponding to the design pattern of the mask, and then bake to remove the solvent and increase the hardness of the photoresist, and finally perform pattern inspection, combined with Figure 3 Understanding of the middle d figure, S5, etching. After the above steps, the pattern on the mask will be solidified on the photoresist. Then, by etching, the areas on the silicon wafer where there is no photoresist coverage will be removed, and the designed pattern will be permanently flowed on the wafer surface. Figure 3 Zhonge diagram understanding, S6, removing the photoresist. After the etching is completed, the pattern on the mask has completed the second transfer. At this time, the photoresist no longer works. Usually, the wafer is immersed in sulfuric acid and oxidant solution to remove the photoresist. Only the silicon waveguide 31 is retained on the silicon wafer layer. Figure 3 Understanding of the middle f figure, S7, forming a metal ridge waveguide 32, using a complementary metal oxide semiconductor process to form a metal ridge waveguide 32, combined with Figure 3 As shown in Figure g, the metal ridge waveguide 32 and the middle section 312 of the silicon waveguide 31 are equidistantly arranged, d=70nm, S8, growing cladding 2, using chemical vapor deposition CVD method, placing the wafer in the reaction chamber, heating the wafer, introducing reaction gas into the reaction chamber for thin film deposition, thereby completing the growth of the thin film, the growing part is the new layer 202, combined with Figure 3 Understanding of the h diagram, S9, etching the air cavity 33, etching between the silicon waveguide 31 and the metal ridge waveguide 32, etching away a part of the new layer 202, and combining Figure 3 Chinese picture understanding, S10, after the etching is completed, the air cavity 33 is inflated and covered with a silicon dioxide film, and finally completed. Figure 3 As shown in Figure j.

[0037] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. An on-chip frequency-stabilizing gas chamber of a surface plasmon waveguide structure, characterized in that: include: an air chamber structure (3) and a cladding layer (2) located around the air chamber structure (3), The air chamber structure (3) comprises: a silicon waveguide (31), a metal ridge waveguide (32) and an air cavity (33); the middle section (312) of the silicon waveguide (31) and the metal ridge waveguide (32) are arranged in an equidistant physical arrangement; the air cavity (33) is located between the silicon waveguide (31) and the metal ridge waveguide (32); and the longitudinal cross section of the air cavity (33) is rectangular. The front end of the middle section (312) is connected to the front connecting section (311), and the rear end is connected to the rear connecting section (313); the front connecting section (311) and the rear connecting section (313) both present a single-sided conical structure, and the conical side is respectively close to the metal ridge waveguide (32); the width of the single-sided conical structure in the front connecting section (311) and the rear connecting section (313) gradually increases from the inside to the outside.

2. The on-chip frequency-stabilizing gas chamber of the surface plasmon waveguide structure according to claim 1, characterized in that: The equidistant distance between the silicon waveguide (31) and the metal ridge waveguide (32) is d, and the front connecting section (311) and the rear connecting section (313) are projected to the left side in the form of a single-sided conical structure portion, and the projection width of the single-sided conical structure portion is D, where D≥d.

3. The on-chip frequency-stabilizing gas chamber of the surface plasmon waveguide structure according to claim 2, characterized in that: The gas cavity (33) is filled with acetylene gas, and the optical path length of the gas cavity (33) is 20 mm.

4. The on-chip frequency-stabilizing gas chamber of the surface plasmon waveguide structure according to claim 3, characterized in that: The middle section (312) and the metal ridge waveguide (32) are designed to form a serpentine structure.

5. The on-chip frequency-stabilizing gas chamber of the surface plasmon waveguide structure according to claim 4, characterized in that: The bending radius of the serpentine structure is 20 μm.

6. The on-chip frequency-stabilizing gas chamber of the surface plasmon waveguide structure according to claim 1, characterized in that: The cladding (2) comprises an original layer (201) and a new layer (202), wherein the original layer (201) is located below the air chamber structure (3), and the new layer (202) is located around and above the same layer of the air chamber structure (3).

7. The on-chip frequency-stabilizing gas chamber of the surface plasmon waveguide structure according to claim 1, characterized in that: The two ends of the silicon waveguide (31) respectively establish an optical transmission path with a pattern spot converter (315) through a straight waveguide (314), and the pattern spot converter (315) is in a trident structure.

8. The on-chip frequency-stabilizing gas chamber of the surface plasmon waveguide structure according to claim 1, characterized in that: Also includes: A semiconductor refrigerator TEC is arranged below the air cavity (33).

9. A method for preparing an on-chip frequency stabilizing gas chamber, characterized in that: It is prepared using a method that is compatible with silicon photonics technology and complementary metal oxide semiconductor processes.

10. The method for preparing an on-chip frequency stabilizing gas chamber according to claim 9, characterized in that: Here are the steps: S1. Substrate preparation: Si-SiO2-Si three-layer structure substrate is obtained by dissociation, cleaning and drying. S2, coating photoresist, coating a layer of photoresist on the upper surface of the substrate, removing the solvent in the photoresist to solidify it, S3, alignment and exposure, transfer the pattern designed on the mask to the photoresist, S4, development, remove unnecessary photoresist according to the design pattern of the mask, leaving only the photoresist at the position corresponding to the design pattern of the mask. S5, etching, removing the area not covered by photoresist from the upper layer of the substrate, S6, remove the photoresist, and the silicon waveguide (31) structure is formed. S7, forming a metal ridge waveguide (32), using a complementary metal oxide semiconductor process to form the metal ridge waveguide (32), S8, growing the cladding (2), using a chemical vapor deposition method, placing the wafer in a reaction chamber, heating the wafer, and introducing a reaction gas into the reaction chamber for thin film deposition, thereby completing the growth of the thin film, S9, etching the air cavity (33) to etch away the space between the silicon waveguide (31) and the metal ridge waveguide (32). S10, after the etching is completed, the air cavity (33) is inflated to form an air cavity, and a silicon dioxide film is covered on the air cavity (33).

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