Piezoelectrically driven silicon optical resonator and system, method of manufacture and method of wavelength tuning

Abstract

This application discloses a piezoelectric-driven silicon photonic resonator and its system, fabrication method, and wavelength tuning method, applicable to the field of silicon-based optoelectronics. The device includes: an SOI substrate, a silicon photonic resonant waveguide, a dielectric isolation layer, and a piezoelectric driving component arranged sequentially upwards. The piezoelectric driving component includes a lower electrode layer, a piezoelectric functional layer, and an upper electrode layer arranged sequentially upwards, and is divided into a first side region and a second side region along the radial direction of the silicon photonic resonant waveguide. The first side region has a mechanical continuity control structure to change the spatial distribution of inverse piezoelectric strain in the silicon photonic resonant waveguide. The second side region maintains a complete and continuous support structure. The two together form an asymmetric mechanical boundary along the radial direction of the silicon photonic resonant waveguide. Thus, the mechanical continuity control structure and the complete and continuous support structure arranged on both sides along the radial direction form an asymmetric mechanical boundary, reconstructing the spatial distribution of inverse piezoelectric strain in the silicon photonic resonant waveguide and improving the wavelength tuning efficiency of the piezoelectric-driven silicon photonic resonator.

Description

Technical Field

[0001] This application relates to the field of silicon-based optoelectronics technology, and in particular to a piezoelectrically driven silicon optical resonator and its system, fabrication method and wavelength tuning method. Background Technology

[0002] Silicon photonic resonators are widely used in optical filtering, wavelength division multiplexing, optical switching, and reconfigurable photonic integrated circuits due to their small size, high quality factor, and low power consumption. However, in practical applications, manufacturing errors, ambient temperature, and device aging can all cause the resonant wavelength of silicon photonic resonators to shift. Therefore, the industry commonly uses wavelength tuning structures to compensate for and continuously adjust the resonant wavelength in real time.

[0003] The current mainstream wavelength tuning method uses piezoelectric materials to drive silicon photonic resonators for wavelength tuning. This is achieved by the piezoelectric material generating an inverse piezoelectric effect under an applied electric field, and then coupling mechanical strain to the silicon photonic waveguide via a dielectric layer. The effective refractive index of the waveguide is altered through the photoelastic effect, thus achieving wavelength tuning. Existing piezoelectric-driven silicon photonic resonators generally employ a mechanically continuous and approximately symmetrical device structure. The piezoelectric driving component has a symmetrical mechanical boundary along the radial direction of the resonant waveguide, lacking differentiated mechanical constraints. After mechanical strain is generated in the piezoelectric layer, the stress easily diffuses to the device periphery and the substrate. Mechanical energy is significantly lost due to substrate constraints, making it impossible to actively control the spatial distribution of strain within the silicon photonic resonant waveguide, resulting in a low effective variable coupled to the waveguide region. Furthermore, under symmetrical boundary conditions, the contributions of the effective refractive index change induced by mechanical strain and the change in the resonant cavity geometry to the resonant wavelength tend to cancel each other out, further reducing the piezoelectric tuning efficiency.

[0004] Therefore, how to improve the wavelength tuning efficiency of piezoelectric-driven silicon photonic resonators is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] Based on the above problems, this application provides a piezoelectric-driven silicon photonic resonator and its system, fabrication method and wavelength tuning method. By setting a mechanical continuity control structure and a complete continuous support structure on both sides of the radial direction of the piezoelectric driving component to form an asymmetric mechanical boundary, the spatial distribution of inverse piezoelectric strain in the silicon photonic resonant waveguide is reconstructed, thereby improving the wavelength tuning efficiency of the piezoelectric-driven silicon photonic resonator.

[0006] In a first aspect, embodiments of this application provide a piezoelectric-driven silicon photonic resonator, comprising: an SOI substrate, a silicon photonic resonant waveguide, a dielectric isolation layer, and a piezoelectric driving component arranged sequentially from bottom to top; the piezoelectric driving component comprises a lower electrode layer, a piezoelectric functional layer, and an upper electrode layer arranged sequentially from bottom to top. Along the radial direction of the silicon photonic resonant waveguide, the piezoelectric drive assembly is divided into a first side region and a second side region arranged opposite to each other; The first side region is provided with a mechanical continuity control structure that disrupts the lateral mechanical continuity of the piezoelectric drive assembly to reduce local stiffness; The second side region maintains a complete and continuous support structure; The mechanical continuity control structure, together with the complete continuous support structure, forms an asymmetric mechanical boundary along the radial direction of the silicon photonic resonant waveguide.

[0007] Optionally, the mechanical continuity control structure is disposed outside the effective optical mode distribution region of the silicon photonic resonant waveguide.

[0008] Optionally, the mechanical continuity control structure is formed by at least one of the following processes: local grooving, local removal, local film thinning, local structure release, and local cavity formation.

[0009] Optionally, the mechanical continuity control structure is an air gap groove; the air gap groove penetrates the upper electrode layer, the piezoelectric functional layer and the lower electrode layer along the direction perpendicular to the substrate, and the bottom end of the air gap groove extends downward and is embedded in the interior of the dielectric isolation layer.

[0010] Optionally, the lateral spacing between the air gap slot and the fundamental mode energy center of the silicon photonic resonant waveguide is such that the light intensity of the boundary evanescent field of the silicon photonic resonant waveguide is attenuated to less than 1 / e² of the maximum value at the inner wall of the air gap slot.

[0011] Optionally, the projection of the bottom contour of the air gap groove in the direction perpendicular to the SOI substrate and the outer edge of the silicon optical bus waveguide next to the silicon optical resonant waveguide maintain a preset lateral distance, which constitutes a safe clearance to prevent cutting off the silicon optical bus waveguide. And / or, an etching barrier layer is provided locally inside or on the surface of the dielectric isolation layer corresponding to the air gap groove to prevent alignment deviations during the dry etching process from cutting off the silicon optical bus waveguide. Its advantages are: it can provide sufficient process tolerance in the complex continuous dry etching process of piezoelectric thin films and metal stacks. By physically avoiding the layout dimensions or using a high etching selectivity of the barrier layer material, abnormal over-etching trends are forcibly terminated, preventing accidental cutting off of the bottom silicon optical bus waveguide due to etching alignment deviations during multi-layer patterning. This fundamentally ensures the optical yield and overall device reliability of wafer-level heterogeneous integration fabrication.

[0012] Optionally, the material of the etching barrier layer includes one of aluminum oxide, aluminum nitride, or dense silicon nitride. Optionally, the lateral width of the piezoelectric drive component in the first side region is smaller than the lateral width of the piezoelectric drive component in the second side region. The solid width of the first upper electrode layer in the first side region and the solid width of the second upper electrode layer in the second side region satisfy a preset expression; the preset expression is: ; In the formula The solid width of the first upper electrode layer. The solid width of the second upper electrode layer.

[0013] Optionally, the first side region is located radially outside the silicon photonic resonant waveguide away from the center of the resonant cavity, and the second side region is located radially inside the silicon photonic resonant waveguide toward the center of the resonant cavity, so that the effective refractive index change induced by the applied driving voltage and the change in the geometric dimensions of the resonant cavity can adjust the resonant wavelength by redshifting or blueshifting in the same direction.

[0014] Optionally, the change in the resonant cavity geometry includes: a change in the resonant cavity radius of the silicon photonic resonant waveguide, and / or a change in the optical perimeter of the resonant cavity.

[0015] Optionally, the piezoelectric functional layer is composed of at least one material selected from lead zirconate titanate, aluminum nitride, scandium-doped aluminum nitride, thin-film lithium niobate, thin-film lithium tantalate, and barium titanate.

[0016] Optionally, the silicon photonic resonant waveguide is at least one of a microring resonator, a racetrack resonator, and a microdisk resonator.

[0017] Secondly, embodiments of this application provide a dual-timescale co-tuning system, including the piezoelectrically driven silicon photonic resonator described above; The silicon photonic resonant waveguide integrates a fast actuator for realizing high-speed electro-optic modulation. The fast actuator includes a PN junction modulation structure integrated in the core region of the silicon photonic resonant waveguide through ion implantation, and a radio frequency drive electrode connected to the PN junction modulation structure. The dual-timescale coordinated tuning system is configured to: perform slow piezoelectric stress bias control through the piezoelectric drive component to achieve athermal wavelength locking, and perform high-speed optical signal modulation or optical path switching through the PN junction modulation structure driven by the RF drive electrode, so as to construct a dual-actuator closed-loop control architecture based on the complementary coordination of piezoelectric strain and carrier effect.

[0018] Thirdly, embodiments of this application provide a method for fabricating a piezoelectrically driven silicon optical resonator, including: A silicon optical resonant waveguide is fabricated on an SOI substrate, and a dielectric isolation layer is deposited on the surface of the silicon optical resonant waveguide. A lower electrode layer, a piezoelectric functional layer, and an upper electrode layer are sequentially fabricated on the surface of the dielectric isolation layer to form an integrally covered piezoelectric drive assembly; The piezoelectric drive component is radially differentiated by patterning photolithography and dry etching processes. A mechanical continuity control structure is prepared in the first side region, and a complete and continuous support structure is maintained in the second side region, so that the piezoelectric drive component forms a radially asymmetric mechanical boundary, thereby obtaining a piezoelectric driven silicon photonic resonator.

[0019] Fourthly, embodiments of this application provide a wavelength tuning method for a piezoelectrically driven silicon optical resonator, the wavelength tuning method being used in the piezoelectrically driven silicon optical resonator as described above, comprising: An optical signal is input into the silicon photonic resonant waveguide, causing the piezoelectric drive silicon photonic resonator to establish an initial resonance state. Apply a driving voltage to the piezoelectric drive component to induce inverse piezoelectric strain in the piezoelectric functional layer; The propagation path of the mechanical strain generated by the inverse piezoelectric strain is adjusted by utilizing asymmetric mechanical boundaries; The mechanical strain causes a change in the effective refractive index and a change in the geometric dimensions of the silicon optical resonant waveguide, thereby causing a change in the resonant wavelength of the piezoelectrically driven silicon optical resonator. Adjusting the driving voltage allows for continuous tuning of the resonant wavelength.

[0020] As can be seen from the above technical solutions, compared with the prior art, this application has the following advantages: This application provides a piezoelectric-driven silicon photonic resonator, comprising, from bottom to top, an SOI substrate, a silicon photonic resonant waveguide, a dielectric isolation layer, and a piezoelectric driving component. The piezoelectric driving component, from bottom to top, includes a lower electrode layer, a piezoelectric functional layer, and an upper electrode layer. Along the radial direction of the silicon photonic resonant waveguide, the piezoelectric driving component is divided into a first side region and a second side region arranged opposite each other. The first side region has a mechanical continuity control structure that disrupts the lateral mechanical continuity of the piezoelectric driving component to reduce local stiffness. The second side region maintains a complete and continuous support structure. The mechanical continuity control structure and the complete and continuous support structure cooperate to form an asymmetric mechanical boundary along the radial direction of the silicon photonic resonant waveguide. Thus, by setting the mechanical continuity control structure and the complete and continuous support structure on both sides of the radial direction of the piezoelectric driving component to form an asymmetric mechanical boundary, the spatial distribution of inverse piezoelectric strain within the silicon photonic resonant waveguide is reconstructed, improving the wavelength tuning efficiency of the piezoelectric-driven silicon photonic resonator. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of a piezoelectric-driven silicon photonic resonator provided in an embodiment of this application; Figure 2 A schematic diagram of a piezoelectrically driven silicon photonic resonator based on a single-sided air gap groove is provided in an embodiment of this application; Figure 3 A schematic diagram of a dual-mechanism cooperative principle corresponding to redshift is provided in an embodiment of this application; Figure 4 A schematic diagram of a dual-mechanism collaborative principle corresponding to blue shift is provided in an embodiment of this application; Figure 5 A schematic diagram of a piezoelectrically driven silicon photonic resonator based on asymmetric width is provided for an embodiment of this application; Figure 6 A schematic diagram of finite element stress distribution simulation results for an asymmetric electrode width structure provided in this application embodiment; Figure 7 A flowchart illustrating a wavelength tuning method for a piezoelectric-driven silicon optical resonator provided in this application embodiment; Figure 8 A flowchart illustrating a method for fabricating a piezoelectrically driven silicon photonic resonator, provided in an embodiment of this application; Figure 9 This is a schematic diagram of the architecture and cross-section of a dual-timescale collaborative tuning system provided in an embodiment of this application.

[0023] Explanation of reference numerals in the attached figures: 010 - First side region; 011 - Mechanical continuity control structure; 020 - Second side region; 100 - SOI substrate; 110 - Silicon substrate; 120 - Buried oxide layer; 130 - Top silicon layer; 200 - Silicon optical resonant waveguide; 201 - RF driving electrode; 210 - Silicon optical bus waveguide; 300 - Dielectric isolation layer; 310 - Etching barrier layer; 400 - Piezoelectric driving component; 410 - Lower electrode layer; 411 - First lower electrode layer; 412 - Second lower electrode layer; 420 - Piezoelectric functional layer; 421 - First piezoelectric functional layer; 422 - Second piezoelectric functional layer; 430 - Upper electrode layer; 431 - First upper electrode layer; 432 - Second upper electrode layer. Detailed Implementation

[0024] As mentioned earlier, existing piezoelectric-driven silicon photonic resonators (PSRs) have low wavelength tuning efficiency. Specifically, existing PSRs generally employ a mechanically continuous and approximately symmetrical device structure. The piezoelectric driving component has a symmetrical mechanical boundary along the resonant waveguide radial direction, lacking differentiated mechanical constraint structures. After mechanical strain is generated in the piezoelectric layer, the stress easily diffuses to the device periphery and substrate. Mechanical energy is significantly lost due to substrate constraints, making it impossible to actively control the spatial distribution of strain within the silicon photonic resonant waveguide, resulting in low effective variables coupled to the waveguide region. Furthermore, under symmetrical boundary conditions, the contributions of the effective refractive index change synchronously induced by mechanical strain and the resonant cavity geometry change to the resonant wavelength tend to cancel each other out, further reducing the piezoelectric tuning efficiency.

[0025] To address the aforementioned issues, this application provides a piezoelectric-driven silicon photonic resonator, comprising, from bottom to top, an SOI substrate, a silicon photonic resonant waveguide, a dielectric isolation layer, and a piezoelectric driving component; the piezoelectric driving component, from bottom to top, includes a lower electrode layer, a piezoelectric functional layer, and an upper electrode layer; along the radial direction of the silicon photonic resonant waveguide, the piezoelectric driving component is divided into a first side region and a second side region arranged opposite to each other; the first side region is provided with a mechanical continuity control structure that disrupts the lateral mechanical continuity of the piezoelectric driving component to reduce local stiffness; the second side region maintains a complete and continuous support structure; the mechanical continuity control structure and the complete and continuous support structure cooperate to form an asymmetric mechanical boundary along the radial direction of the silicon photonic resonant waveguide.

[0026] Thus, by setting up a mechanical continuity control structure and a complete continuous support structure on both sides of the piezoelectric drive component to form an asymmetric mechanical boundary, the spatial distribution of inverse piezoelectric strain in the silicon photonic resonant waveguide is reconstructed, thereby improving the wavelength tuning efficiency of the piezoelectric-driven silicon photonic resonator.

[0027] It should be noted that the piezoelectric-driven silicon optical resonator and its system, fabrication method, and wavelength tuning method provided in this application can be applied to the field of silicon-based optoelectronic technology. The above are merely examples and do not limit the application areas of the piezoelectric-driven silicon optical resonator and its system, fabrication method, and wavelength tuning method provided in this application.

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0029] Figure 1 This is a schematic diagram of a piezoelectrically driven silicon photonic resonator provided as an embodiment of this application. (Combined with...) Figure 1 As shown, the piezoelectric driven silicon photonic resonator includes, from bottom to top, an SOI substrate 100, a silicon photonic resonant waveguide 200, a dielectric isolation layer 300, and a piezoelectric driving component 400; the piezoelectric driving component includes, from bottom to top, a lower electrode layer 410, a piezoelectric functional layer 420, and an upper electrode layer 430. Along the radial direction of the silicon photonic resonant waveguide 200, the piezoelectric drive assembly 400 is divided into a first side region 010 and a second side region 020 arranged opposite to each other. The first side region 010 is provided with a mechanical continuity control structure 011 that disrupts the lateral mechanical continuity of the piezoelectric drive assembly 400 to reduce local stiffness; The second side region 020 maintains a complete and continuous support structure; The mechanical continuity control structure 011 cooperates with the complete continuous support structure to form an asymmetric mechanical boundary along the radial direction of the silicon photonic resonant waveguide 200.

[0030] Furthermore, the first side region 010 is located on the radially outer side of the silicon photonic resonant waveguide 200 away from the center of the resonant cavity, and the second side region 020 is located on the radially inner side of the silicon photonic resonant waveguide 200 toward the center of the resonant cavity, so that the effective refractive index change induced by the applied driving voltage and the change in the geometric dimensions of the resonant cavity can adjust the resonant wavelength by redshifting or blueshifting in the same direction. The changes in the geometric dimensions of the resonant cavity include: changes in the resonant cavity radius of the silicon photonic resonant waveguide 200, and / or changes in the optical perimeter of the resonant cavity.

[0031] Specifically, this application provides a piezoelectric-driven silicon photonic resonator, which comprises, from bottom to top, an SOI substrate 100, a silicon photonic resonant waveguide 200, a dielectric isolation layer 300, and a piezoelectric driving component 400. The SOI substrate 100 serves as the mechanical support substrate and silicon photonic integration platform for the entire device, including a bottom silicon substrate 110, a buried oxide layer 120 disposed on the silicon substrate 110, and a top silicon layer 130 disposed above the buried oxide layer 120. The buried oxide layer 120 has a thickness of approximately 1-3 micrometers and is used to achieve optical and electrical isolation, reduce the leakage of optical modes towards the silicon substrate 110, and provide a low-loss optical propagation environment for the upper silicon photonic resonant waveguide 200. The top silicon layer 130 has a thickness of approximately 220 nanometers and is used to form the silicon photonic resonant waveguide 200. The dielectric isolation layer 300 is made of silicon dioxide, and its thickness is designed to be synergistically optimized according to the mechanical strain transfer efficiency and the optical loss requirements of the evanescent field, typically ranging from 100nm to 2μm. This ensures electrical insulation between the piezoelectric drive component 400 and the bottom silicon optical resonant waveguide 200, preventing the high-voltage drive electrode from directly contacting the top silicon 130 optical waveguide and guaranteeing the device's breakdown life. Simultaneously, as a rigid mechanical strain transfer medium, it efficiently transfers the mechanical strain generated by the piezoelectric functional layer 420 downwards to the silicon optical resonant waveguide 200 region. It also participates in forming the mechanical boundary conditions of the piezoelectric drive region, regulating the distribution of internal residual stress and drive stress by altering the local mechanical continuity. The piezoelectric drive component 400 contains a lower electrode layer 410, a piezoelectric functional layer 420, and an upper electrode layer 430 stacked from bottom to top. When voltage is applied to the upper and lower electrodes, a vertical electric field is formed within the piezoelectric functional layer 420, exciting the piezoelectric material to produce the inverse piezoelectric effect and output mechanical strain. The piezoelectric drive component 400 is radially divided into a first side region 010 and a second side region 020 arranged opposite each other along the silicon photonic resonant waveguide 200. The first side region 010 is located radially outward of the silicon photonic resonant waveguide 200 away from the center of the resonant cavity, and is equipped with a mechanical continuity control structure 011 that disrupts the lateral mechanical continuity of the piezoelectric drive component 400 to reduce local stiffness. The second side region 020 is located radially inward of the silicon photonic resonant waveguide 200 towards the center of the resonant cavity, and retains a complete continuous support structure. The combination of the two can form an asymmetric mechanical boundary distributed radially along the waveguide. This structure can change the spatial distribution of inverse piezoelectric strain within the silicon photonic resonant waveguide 200, allowing the mechanical strain generated by piezoelectricity to simultaneously induce changes in the effective refractive index of the waveguide and the geometric dimensions of the resonant cavity, avoiding the defects of strain dispersion loss and easy cancellation of the two tuning effects in traditional symmetrical structures. It can be understood that the asymmetric mechanical boundary formed by the combination of the mechanical continuity control structure 011 and the complete continuous support structure can guide the strain to act directionally and concentrated on the silicon photonic resonant waveguide 200, improving stress coupling efficiency.Furthermore, this asymmetric mechanical boundary enables the effective refractive index change induced by the applied driving voltage to produce a redshift or blueshift in the same direction as the resonant wavelength change (ensuring that the contribution directions of the effective refractive index change and the resonant cavity geometry change to the resonant wavelength are consistent). The resonant cavity geometry change is specifically manifested as a change in the resonant cavity radius and / or a change in the resonant cavity optical perimeter. The two tuning effects are superimposed in the same direction, further improving the overall wavelength tuning efficiency of the device. The overall structure is simple and can be integrated through thin film deposition, photolithography, and dry etching processes compatible with silicon-based photonics, facilitating large-scale photonics integration applications.

[0032] As one implementation, regarding the design of the piezoelectric functional layer 420, the piezoelectric functional layer 420 is composed of at least one material selected from lead zirconate titanate, aluminum nitride, scandium-doped aluminum nitride, thin-film lithium niobate, thin-film lithium tantalate, and barium titanate.

[0033] Specifically, the piezoelectric functional layer 420, as the core functional layer generating inverse piezoelectric strain in the piezoelectric drive component 400, can be prepared using at least one of lead zirconate titanate, aluminum nitride, scandium-doped aluminum nitride, thin-film lithium niobate, thin-film lithium tantalate, and barium titanate. As an example, the piezoelectric functional layer 420 can be made of lead zirconate titanate (PZT) thin film, which has excellent high electrical conductivity and piezoelectric response characteristics, typically with a thickness of 100 nm-2 μm. This is because PZT thin film material has extremely high piezoelectric response charge constants (such as...). The piezoelectric coefficient (Pt) can generate a large transverse inverse piezoelectric strain under the action of an external bias voltage, making it very suitable for achieving wide-range silicon photonic resonant wavelength tuning under extremely low driving voltages. Correspondingly, the upper electrode layer 430 and the lower electrode layer 410 adopt metal electrode materials with high crystal orientation matching with the growth of lead zirconate titanate thin films and excellent conductivity, such as Pt, Au, Ti / Pt, or Ti / Au layered composite structures. All of the above-mentioned piezoelectric materials are compatible with silicon-based wafer heterogeneous integration processes and can be directly grown / bonded to the surface of the silicon dioxide dielectric isolation layer 300, exhibiting good compatibility with CMOS silicon photonic manufacturing processes. It is understood that this application does not impose a single limitation on the material of the piezoelectric functional layer 420, and can flexibly select it according to the actual needs of device tuning range, operating voltage, and fabrication process cost to adapt to various application scenarios such as optical communication and optical computing.

[0034] As one implementation method, regarding how to design the silicon photonic resonant waveguide 200, the silicon photonic resonant waveguide 200 is at least one of a micro-ring resonator, a racetrack resonator, and a micro-disk resonator.

[0035] Specifically, in the piezoelectric-driven silicon optical resonator provided in this application, the silicon optical resonant waveguide 200 is at least one of a micro-ring resonator, a racetrack-shaped resonator, and a micro-disk resonator. Taking the silicon optical resonant waveguide 200 as a micro-ring resonator as an example, it can include a ring resonant waveguide and an input / output bus waveguide coupled to the ring resonant waveguide, which can be used to form an optical resonant cavity, and to achieve the enhancement and selection of specific wavelength optical signals through the cyclic propagation of optical signals in the micro-ring.

[0036] As one implementation method, the mechanical continuity control structure 011 is formed by at least one of the following processes: local grooving, local removal, local thin film thinning, local structure release, and local cavity formation.

[0037] Specifically, the mechanical continuity control structure 011 is disposed on the radially outer or radially inner side of the silicon photonic resonant waveguide 200 to change the mechanical constraint conditions of the first side region 010 of the piezoelectric drive component 400. It can be formed through at least one of the following processes: local grooving, local removal, local thin film thinning, local structure release, local cavity formation, and local material replacement. Grooving, removal, thin film thinning, structure release, and cavity formation can be completed simultaneously with the rest of the device structure through photolithography etching, without requiring additional complex process steps. Local material replacement can be achieved using corresponding deposition and etching processes according to actual design requirements. By mechanically weakening the first side region 010 in the above manner, the mechanical stiffness of this region can be flexibly changed, thereby precisely controlling the propagation path and distribution state of the inverse piezoelectric strain, ensuring the construction effect of the asymmetric mechanical boundary, and achieving effective adjustment of the strain field inside the silicon photonic resonant waveguide 200.

[0038] As one implementation, regarding the design of the mechanical continuity control structure 011, the aforementioned mechanical continuity control structure 011 is an air gap groove; the air gap groove penetrates the upper electrode layer 430, the piezoelectric functional layer 420 and the lower electrode layer 410 along the direction perpendicular to the substrate, and the bottom end of the air gap groove extends downward and is embedded in the interior of the dielectric isolation layer 300.

[0039] Furthermore, the mechanical continuity control structure 011 is disposed outside the effective optical mode distribution region of the silicon photonic resonant waveguide 200; The lateral spacing between the air gap slot and the fundamental mode energy center of the silicon photonic resonant waveguide 200 causes the light intensity of the boundary evanescent field of the guided wave of the silicon photonic resonant waveguide 200 to attenuate to less than 1 / e² of the maximum value at the inner wall of the air gap slot.

[0040] Furthermore, the projection of the bottom contour of the air gap groove in the direction perpendicular to the SOI substrate and the outer edge of the silicon optical bus waveguide next to the silicon optical resonant waveguide maintain a preset lateral distance, which constitutes a safe clearance to prevent cutting off the silicon optical bus waveguide. And / or, the dielectric isolation layer corresponding to the air gap groove is provided with an etching barrier layer inside or on the surface to prevent alignment deviations in the dry etching process from cutting off the silicon photonic bus waveguide.

[0041] The material of the etching barrier layer includes one of aluminum oxide, aluminum nitride, or dense silicon nitride.

[0042] Specifically, the mechanical continuity control structure 011 can be configured as an air gap slot. Continuing with the example of the silicon photonic resonant waveguide 200 as a microring resonator, this air gap slot is located in the radially outer region of the microring resonant waveguide and is continuously arranged in a concentric arc along the extension direction of the microring resonant waveguide (i.e., the circumferential direction of the microring). Simultaneously, to avoid introducing additional mode scattering loss, a specific preset distance is maintained between the air gap slot and the microring resonant waveguide, ensuring that the air gap slot is completely outside the effective distribution area of ​​the optical modes in the microring resonant waveguide. It can be understood that the inner edge of the air gap slot maintains sufficient lateral spatial isolation from the core maximum field distribution area (fundamental mode energy center) of the microring resonant waveguide, enabling the boundary evanescent field intensity of the guided wave to be reduced to its maximum value at its inner wall. The following spatial separation design effectively prevents the sidewall roughness caused by slotting from disturbing the guided wave mode, thereby reducing the additional optical scattering loss to a negligible level. Figure 2 This is a schematic diagram of a piezoelectrically driven silicon photonic resonator based on a single-sided air gap groove, provided as an embodiment of this application. (Combined with...) Figure 2 As shown, the air gap groove extends downward along a longitudinal direction perpendicular to the surface of the silicon substrate 110. When processed using a wafer-level high aspect ratio etching process, the air gap groove vertically and continuously penetrates the upper electrode layer 430, the piezoelectric functional layer 420, and the lower electrode layer 410, and further extends downward into the interior of the dielectric isolation layer 300. The bottom of the groove ends inside the dielectric isolation layer 300, and can optionally abut against the surface of the buried oxide layer 120 or cut into the interior of the buried oxide layer 120.

[0043] In practical semiconductor heterogeneous integration manufacturing, continuous dry etching processes (such as ICP-RIE) for multilayer piezoelectric stacks (e.g., complex structures with alternating bilayer piezoelectric materials and metal electrodes) are extremely challenging, often accompanied by intense plasma bombardment and chemical reactions. If etching alignment misalignment occurs during the fabrication of air gap trenches, excessively deep etch trenches can easily laterally sever the silicon optical bus waveguide 210 adjacent to the microring resonant waveguide. This physical breakage can lead to the device performing normally in independent piezoelectric electrical parameter verification and single-layer SOI microring optical performance testing, but its overall optical integration testing may face the risk of complete failure.

[0044] To mitigate this wafer-level manufacturing defect, this embodiment incorporates anti-cut-off margin design in the layout and thin-film structure. Specifically, the bottom contour of the air gap trench and the underlying silicon photonic bus waveguide 210 maintain a preset safe clearance distance D on the vertical projection plane. The specific value of this safe clearance distance is determined based on the photolithography overlay accuracy and dry etching sidewall tilt angle deviation in the manufacturing process, typically ranging from 500 nm to 2 μm. If the distance is less than 500 nm, photolithography alignment errors may still cause the deep trench to cut into the evanescent field region of the bus waveguide or even physically cut off the waveguide; if the distance is too large, it will increase the chip size and reduce the layout integration density.

[0045] Alternatively, an etching barrier layer 310 with high selectivity for dry etching gases (such as fluorine- or chlorine-containing gases) can be pre-embedded inside the dielectric isolation layer 300, near the bottom of the air gap groove. The etching barrier layer 310 is made of materials such as alumina (Al2O3), aluminum nitride (AlN), or dense silicon nitride (Si3N4), and its thickness is typically 20 nm to 100 nm. This barrier layer effectively intercepts over-etching damage caused by deep trench etching, ensuring the structural integrity of the silicon optical bus waveguide 210, without significantly negatively interfering with the overall stress distribution transmitted from the piezoelectric drive component to the resonant waveguide.

[0046] Thus, through the deep three-dimensional trench design, a local mechanical release region is formed in the first side region 010 of the piezoelectric drive component 400. The first side region 010, due to the complete break in lateral solid continuity at the air contact surface, forms a region with low mechanical impedance and no clamping, constituting a free deformation release boundary. Meanwhile, the second side region 020 retains a seamless, continuous silicon dioxide solid and a complete metal layer, forming a region with high mechanical impedance and maintaining mechanical continuity under the anchoring effect of a rigid substrate, constituting a strong solid constraint boundary. Because the air gap trench breaks the spatial uniformity of mechanical impedance, the outer low-constraint end possesses extremely high deformation freedom, allowing lateral elastic release and local displacement of the inverse piezoelectric strain; while the inner strong solid constraint end strongly restricts mechanical displacement. Due to the air gap trench in the first side region 010, the interface mechanical impedance is significantly reduced, decreasing the degree of mechanical constraint and equivalent mechanical stiffness in this region. This forces the principal stress lines of the strain generated by the inverse piezoelectricity to deflect and converge towards the high-impedance, high-mechanical-continuity second-side solid medium, thereby achieving directional focusing of strain towards the silicon photonic resonant waveguide region. In this embodiment, the air gap groove is embedded downwards into the dielectric isolation layer, with the insertion depth being 30%-100% of the total thickness of the dielectric isolation layer. Alternatively, it can be over-etched downwards to a distance of 50nm-200nm from the surface of the buried oxide layer. Based on the multiphysics phonon energy flow distribution principle, this asymmetric mechanical boundary forces a significant deflection and reconstruction of the propagation path of the transverse internal mechanical stress. The mechanical strain tends to concentrate towards the inner continuous dielectric direction with high mechanical impedance and strong constraint. Through this path redirection, the inverse piezoelectric strain changes from a traditional isotropic "divergent diffusion distribution" to a "locally enhanced distribution" that is directionally focused towards the silicon photonics microring resonant waveguide region, effectively increasing the strain acting on the resonant waveguide and improving the device's wavelength tuning efficiency.

[0047] Figure 3 This is a schematic diagram of a dual-mechanism cooperative principle corresponding to redshift provided in an embodiment of this application. Figure 4 This application provides a schematic diagram of a dual-mechanism collaborative principle for blue shift. Combined with... Figure 3 and Figure 4As shown, continuing with the example of a silicon photonic resonant waveguide 200 as a microring resonator, when the mechanical continuity control structure 011 is specifically set as an air gap slot, the working process and strain limiting principle of this piezoelectric-driven silicon photonic resonator are as follows: The input optical signal is coupled into the silicon photonic resonant waveguide 200 via a bus waveguide. An external driving voltage is applied through the upper electrode layer 430 and the lower electrode layer 410, which can excite a longitudinal or transverse driving electric field in the piezoelectric functional layer 420. Under the action of the inverse piezoelectric effect, the piezoelectric functional layer 420 generates mechanical strain, which in turn generates piezoelectric stress. Since the first side region 010 is provided with an air gap slot, the mechanical constraint on this side is greatly weakened, and the mechanical strain is forced to preferentially propagate to the complete continuous support structure of the high-stiffness second side region 020, and highly concentratedly coupled to the vicinity of the silicon photonic resonant waveguide 200, significantly optimizing the stress field distribution in the waveguide region. In addition, the silicon photonic microring resonator satisfies the basic resonance condition. In the formula Represents the order of the resonant optical mode. This represents the current resonant wavelength of the device. The effective refractive index represents the silicon optical resonant waveguide 200. The optical perimeter of the microring resonator is represented by the microring perimeter. , Let be the equivalent radius of the microring resonator; differentiating this formula yields the basic relationship for the change in resonant wavelength. In the formula The first term represents the offset caused by the resonant wavelength. The effective refractive index change caused by stress optical effects. It is the change in effective refractive index caused by stress, the second term. The geometric deformation (equivalent radius change) of the micro-ring cavity caused by the inverse piezoelectric effect corresponds to the change in the resonant cavity radius. This represents the deformation change of the equivalent radius of the microring. In traditional symmetrical support structures, the contribution of effective refractive index change and geometric deformation to the resonant wavelength often cancel each other out. However, the asymmetric mechanical boundary constructed in this scheme can achieve both red-shift synergy and blue-shift synergy dual-mechanism co-directional tuning effects under specific driving polarities. In the red-shift synergy mode, mechanical strain increases the internal stress of the silicon photonic resonant waveguide 200. In the photoelastic effect branch, the photoelastic effect leads to an increase in the effective refractive index ( Simultaneously, in the geometric deformation branch, mechanical geometric deformation drives the microring to undergo radial deformation, resulting in an increase in the equivalent radius of the microring. Both changes in effective refractive index and geometric dimensions contribute positively to the resonant wavelength (synergistic effect), resulting in a superimposed redshift of the resonant wavelength, significantly increasing the wavelength shift per unit driving voltage and improving tuning efficiency. In the blueshift synergistic mode, mechanical strain alters the internal stress of the silicon photonic resonant waveguide 200. In the photoelastic effect branch, the photoelastic effect leads to a decrease in effective refractive index. Simultaneously, in the geometric deformation branch, mechanical geometric deformation drives the microring to undergo radial inward deformation, resulting in a reduction in the equivalent radius of the microring. The effective refractive index change and geometric size change both contribute negatively to the resonant wavelength (synergistic effect), resulting in a superimposed blue shift of the resonant wavelength, which can also significantly increase the wavelength shift per unit driving voltage and improve tuning efficiency.

[0048] Furthermore, the precise excitation of the aforementioned dual-mechanism synergistic tuning mode of "co-direction redshift" and "co-direction blueshift" is highly dependent on the material crystal orientation of the piezoelectric functional layer 420 and the relative physical relationship between its internal spontaneous polarization direction and the direction of the applied driving electric field. Specifically, the sign of the transverse mechanical strain (i.e., the generation of tensile or compressive stress) is jointly determined by the piezoelectric charge tensor coefficient of the piezoelectric material (such as the transverse piezoelectric coefficient d31) and the direction of the applied driving electric field Ez (satisfying the basic relationship εx = d31·Ez).

[0049] In the actual device fabrication and design, taking lead zirconate titanate (PZT) or Z-cut lithium niobate (Z-cut LNOI) as the piezoelectric functional layer 420 as an example: when the direction of the applied driving electric field is aligned with the polarization direction of the piezoelectric material, the piezoelectric functional layer will experience lateral contraction or expansion in a specific direction within the plane due to the influence of the d31 coefficient sign. This lateral mechanical stress is transmitted to the silicon photonic resonant waveguide via the asymmetric boundary unique to this application, resulting in the effective refractive index change (Δneff) and the equivalent radius change (ΔR) having the same sign, i.e., satisfying the algebraic product formula: Δneff × ΔR > 0. At this time, the physical contribution directions of the two to the resonant wavelength drift are completely consistent. Specifically, when the induced mechanical stress causes Δneff < 0 and ΔR < 0, the device precisely excites the "co-directional blue shift" synergistic mode; conversely, when the induced mechanical stress causes Δneff > 0 and ΔR > 0, the device precisely excites the "co-directional red shift" synergistic mode.

[0050] If the polarity of the applied driving voltage is reversed during operation (making the applied electric field opposite to the spontaneous polarization direction), or if a piezoelectric thin film stack with opposite crystal orientation is pre-selected during the wafer heterogeneous integration stage (e.g., using -Z-cut lithium niobate thin film instead of Z-cut), the piezoelectric functional layer 420 will output mechanical strain with opposite signs. At this time, the system still satisfies the cooperative boundary condition Δneff × ΔR > 0, but the device's tuning state will precisely switch between "co-directional redshift" and "co-directional blueshift" modes. Therefore, this application not only proposes an asymmetric mechanical boundary on a macroscopic level, but also provides a rigorous, quantitative, and highly controllable foundation for "dual-mechanism co-directional cooperative" tuning from the perspective of microscopic crystal physics and algebraic governing equations.

[0051] As another implementation, regarding how to design the mechanical continuity control structure 011, the lateral width of the piezoelectric drive component 400 in the first side region 010 is smaller than the lateral width of the piezoelectric drive component 400 in the second side region 020. The solid width of the first upper electrode layer 431 in the first side region 010 and the solid width of the second upper electrode layer 432 in the second side region 020 satisfy a preset expression; the preset expression is: ; In the formula The solid width of the first upper electrode layer 431 The solid width of the second upper electrode layer 432.

[0052] Figure 5 This is a schematic diagram of a piezoelectrically driven silicon photonic resonator based on asymmetric width, provided as an embodiment of this application. (Combined with...) Figure 5 As shown, and The piezoelectric-driven silicon photonic resonator, represented by the bias voltage and ground voltage, consists of a silicon substrate 110, a 1-3 μm buried oxide layer 120, a 220 nm silicon photonic resonant waveguide 200, a 100 nm-2 μm dielectric isolation layer 300, and a piezoelectric driving component 400 stacked sequentially from bottom to top. The piezoelectric driving component 400 is patterned along the radial direction of the silicon photonic resonant waveguide 200, dividing it into a first side region 010 and a second side region 020. The lateral width of the piezoelectric driving component 400 in the first side region 010 is smaller than that in the second side region 020, forming a mechanical continuity control structure 011. The second side region 020 maintains a complete and continuous support structure, and the two together form an asymmetric mechanical boundary. Specifically, taking the piezoelectric drive assembly 400 in the first side region 010 corresponding to the first upper electrode layer 431, the first piezoelectric functional layer 421, and the first lower electrode layer 411, and the piezoelectric drive assembly 400 in the second side region 020 corresponding to the second upper electrode layer 432, the second piezoelectric functional layer 422, and the second lower electrode layer 412 as examples, the solid width of the first upper electrode layer 431 needs to be set. Smaller than the solid width of the second upper electrode layer 432 Normally, take Furthermore, the first piezoelectric functional layer 421 and the second piezoelectric functional layer 422 respectively correspond to the same constant first spatial widening amount at the edge of the corresponding upper electrode layer 430. The solid width of the first piezoelectric functional layer 421 is... The solid width of the second piezoelectric functional layer 422 ,in Furthermore, the first lower electrode layer 411 and the second lower electrode layer 412 can each correspond to the same constant second spatial widening amount at the edge of the corresponding piezoelectric functional layer 420. The solid width of the first lower electrode layer 411 The solid width of the second lower electrode layer 412 ,in (like Figure 5 (as shown in b in the diagram). Alternatively, as another layout configuration, only the solid width of the first upper electrode layer 431 can be set. Smaller than the solid width of the second upper electrode layer 432 This causes the corresponding piezoelectric functional layer 420 and lower electrode layer 410 to simultaneously expand outwards with the same constant spatial widening (e.g. Figure 5(As shown in a). Thus, by graphically cutting the inner and outer active stacks, the piezoelectric drive component 400 is divided into a first side region 010 and a second side region 020 arranged opposite to each other, forming a concentric annular three-dimensional gap G between them. This gap is the layout pattern boundary interval, which longitudinally penetrates the active stack (piezoelectric drive component 400) and terminates at the surface of the dielectric isolation layer 300. In this embodiment, mechanical weakening is not achieved by relying on this gap, but by setting the overall width of the piezoelectric drive component 400 in the first side region 010 to be significantly smaller than that in the second side region 020, the local equivalent mechanical stiffness of the first side region 010 is reduced, thereby constructing a radially asymmetric mechanical boundary. This structure does not require deep etching and slotting of the piezoelectric drive component 400. The inverse piezoelectric strain propagation path can be controlled by the layout pattern size design, causing stress to converge at the silicon photonic resonant waveguide 200 and improving the device wavelength tuning efficiency.

[0053] Figure 6 This is a schematic diagram of the finite element stress distribution simulation results for an asymmetric electrode width structure provided in this application embodiment. Combined with... Figure 6As shown, continuing with the example of a silicon photonic resonant waveguide 200 as a microring resonator, the piezoelectric functional layer 420 uses lead zirconate titanate (PZT) thin film. A radially asymmetric mechanical boundary is constructed by setting the overall width of the piezoelectric drive component 400 in the first side region 010 to be significantly smaller than that in the second side region 020. The principal stress (σxx) distribution in the X direction is shown in the enlarged views on the regions near the first and second upper electrodes, respectively, on the left and right sides, illustrating the effect of the asymmetric electrode width on the spatial distribution of the stress field and the stress tensor. The refractive indices at 0V and 10V are 2.464635 and 2.465202, respectively. Thus, by locally removing the electrodes and the piezoelectric functional layer 420 stacked material, a locally thinned structure is formed. Relying on the transverse mechanical impedance discontinuity, the stress optical effect and geometric deformation are synergistically tuned through positive superposition in the same direction. When a uniform tuning drive voltage V=10V is applied between the upper electrode layer 430 and the lower electrode layer 410, a multi-physics cascade response is induced inside the device due to the volume and stiffness defects of the active entities on both sides of the silicon photonic resonant waveguide 200. First, a stress tensor space shift occurs. The widths of the upper electrode layer 430, piezoelectric functional layer 420, and lower electrode layer 410 integrated on the silicon photonic resonant waveguide 200 are not equal on both sides. This satisfies the condition that the overall width W1 of the piezoelectric drive component 400 in the first side region 010 is less than the overall width W2 of the piezoelectric drive component 400 in the second side region 020. The transverse stress (σxx) is balanced, and the width of the stress drive device on the inner diameter side of the microring is greater than that on the outer diameter side of the microring. Second, stress optical effect components are generated. Under the condition of applying a 10V drive voltage, the reconstructed transverse compressive stress penetrates unidirectionally into the core of the single-crystal silicon waveguide, compressing the atomic lattice spacing and increasing the electron cloud polarization, causing a positive step change in the effective refractive index. In the simulation, the compressive stress on the microring waveguide is approximately -60 MPa, corresponding to an effective refractive index of 2.464635 at the center of the microring at 0 V and 2.465202 at the center of the microring at 10 V. The change in effective refractive index is then obtained. , Subsequently, a geometric deformation effect component is generated. Under the action of a 10V voltage, the horizontal compressive stress of the non-uniform strain field drives the microring waveguide to undergo centrifugal expansion, resulting in an increase in the equivalent radius of the microring and an increase in the optical physical perimeter (0.108nm / V), satisfying... ,correspond The total differential governing equation for the relative drift of the microring resonant wavelength is as follows: ; Since the refractive index change term and the perimeter change term both contribute positive values, the dual mechanism achieves positive superposition in both physical direction and sign, driving the resonant wavelength to achieve high-efficiency linear tuning. In this embodiment, the micro-ring radius of the simulation model is 15μm, and the working wavelength is 1550nm. The calculation process for the tuning efficiency in the simulation is as follows: [The remaining text appears to be incomplete and requires further context.] Operating wavelength Group refractive index The wavelength shift contributed by the photoelastic effect was calculated. ,for ,Right now Geometric deformation causes a change in radius. relative radius change Geometric deformation contributes to wavelength deviation Combining the two contributions, the final result was... .

[0054] In summary, this application provides a piezoelectric-driven silicon photonic resonator, comprising, from bottom to top, an SOI substrate, a silicon photonic resonant waveguide, a dielectric isolation layer, and a piezoelectric driving component. The piezoelectric driving component, from bottom to top, includes a lower electrode layer, a piezoelectric functional layer, and an upper electrode layer. Along the radial direction of the silicon photonic resonant waveguide, the piezoelectric driving component is divided into a first side region and a second side region arranged opposite each other. The first side region has a mechanical continuity control structure that disrupts the lateral mechanical continuity of the piezoelectric driving component to reduce local stiffness. The second side region maintains a complete and continuous support structure. The mechanical continuity control structure and the complete and continuous support structure cooperate to form an asymmetric mechanical boundary along the radial direction of the silicon photonic resonant waveguide. Thus, by setting the mechanical continuity control structure and the complete and continuous support structure on both sides of the radial direction of the piezoelectric driving component to form an asymmetric mechanical boundary, the spatial distribution of inverse piezoelectric strain within the silicon photonic resonant waveguide is reconstructed, improving the wavelength tuning efficiency of the piezoelectric-driven silicon photonic resonator.

[0055] This application employs an asymmetric boundary structure with weakened support on one side and complete anchoring on the other. Specifically, the complete and continuous support structure retained in the second-side region not only provides the necessary high mechanical impedance boundary for the directional transmission of inverse piezoelectric strain to the silicon photonic resonant waveguide, but also constructs a large-area, high-efficiency solid-state heat dissipation channel extending downwards to the SOI substrate on one side of the device. Compared to the shortcomings of traditional cantilever beam MEMS microring resonators, such as poor heat dissipation, high thermal noise, and easy structural breakage due to the suspended structure, the semi-anchored design of this structure can rapidly conduct and dissipate heat generated by ambient temperature fluctuations or the device itself.

[0056] More importantly, this large-area, high-efficiency solid-state heat dissipation feature is deeply compatible with the physical characteristics of piezoelectric functional layers (such as PZT thin films) that rely on electric field driving and have extremely low static leakage current. The efficient heat dissipation channel effectively suppresses local heat accumulation, while the piezoelectric drive itself has near-zero static power consumption. The combination of the two forms the key foundation for achieving "ultra-low static power consumption operation" and "thermostatic wavelength stability" of piezoelectric-driven silicon photonic resonators at the physical structure level. This greatly improves the reliability of the device in complex temperature environments and high-density photonic integration scenarios, thus completely overcoming the bottlenecks of high power consumption and susceptibility to temperature interference in traditional thermo-optical tuning mechanisms.

[0057] Figure 7 A flowchart illustrating a wavelength tuning method for a piezoelectrically driven silicon optical resonator provided in this application embodiment. (In conjunction with...) Figure 7 As shown, this method is used for the aforementioned piezoelectric-driven silicon optical resonator, and includes: S701: Input an optical signal into the silicon photonic resonant waveguide to enable the piezoelectric drive silicon photonic resonator to establish its initial resonance state.

[0058] In practical applications, continuous light is output from an external light source and fed into the silicon optical resonant waveguide on the SOI substrate via on-chip coupling structures such as edge couplers and grating couplers. The light then enters an optical resonant cavity in the form of a microring, racetrack, or microdisk. When light propagation satisfies the resonance formula... At this point, the device forms a stable initial resonance. Then, using an output photodetector and a spectrum analyzer, the positions of the resonance peaks / valleys are read to determine the initial operating wavelength, providing a reference for subsequent piezoelectric tuning. This step can accurately lock the initial resonance point of the device, improving the accuracy of subsequent wavelength tuning and closed-loop locking. Among these steps... The optical mode order. , , These are the initial resonant wavelength, initial effective refractive index, and initial optical path of the resonant cavity, respectively.

[0059] S702: Apply a driving voltage to the piezoelectric drive component to cause the piezoelectric functional layer to generate inverse piezoelectric strain.

[0060] In practical applications, the upper and lower electrode layers of the piezoelectric drive component are connected to an external drive power supply and a tuning voltage V is input. A driving electric field is generated inside the piezoelectric functional layer along a direction perpendicular to the substrate. This electric field satisfies… ,in The thickness of the piezoelectric functional layer is given. When the piezoelectric material is excited by an electric field, it exhibits the inverse piezoelectric effect and generates planar mechanical strain. The radial strain conforms to... ,in To correspond to the radial piezoelectric coefficient, this mechanical strain is the driving force for changing the optical properties of the silicon waveguide. Relying on the inverse piezoelectric effect to generate deformation, it has the advantages of fast response and low static power consumption, and can realize high-speed and low-power adjustment of the resonant wavelength.

[0061] S703: Adjust the propagation path of mechanical strain generated by the inverse piezoelectric strain using asymmetric mechanical boundaries.

[0062] In practical applications, the mechanical strain generated by the piezoelectric functional layer would normally diffuse uniformly in all directions. However, because the piezoelectric drive component has a mechanical continuity control structure arranged radially along the silicon photonic resonant waveguide, one side weakens the mechanical constraint and reduces stiffness through methods such as slotting, thinning, and creating air gaps, while the other side maintains a complete and continuous support structure to form a strong constraint. This creates a radially asymmetric mechanical boundary, changing the direction of strain diffusion. Furthermore, by adjusting the position, size, shape, and release degree of the mechanical continuity control structure, the distribution of mechanical strain in the silicon photonic resonant waveguide region can be altered, resulting in a stress distribution with a preset direction and intensity in the silicon photonic resonant waveguide region. Thus, this structure can reduce unnecessary strain loss and significantly improve effective stress utilization and wavelength tuning efficiency.

[0063] S704: The mechanical strain simultaneously causes a change in the effective refractive index of the silicon photonic resonant waveguide and a change in the geometric dimensions of the resonant cavity, so as to change the resonant wavelength of the piezoelectrically driven silicon photonic resonator.

[0064] In practical applications, the mechanical stress after directional transmission through the asymmetric mechanical boundary acts on the silicon photonic resonant waveguide. On the one hand, the photoelastic effect of silicon material changes the stress components in different directions inside the waveguide. , , This leads to a change in the effective refractive index. On the other hand, mechanical strain can directly stretch or compress the resonant cavity, causing changes in its geometric dimensions. This causes a change in the effective optical path length of the resonant cavity. The combined effect of these two changes alters the resonant wavelength of the device, as shown in the wavelength change formula. Thus, this scheme utilizes asymmetric boundaries to allow the wavelength tuning effects of refractive index changes and cavity size changes to be superimposed in the same direction, avoiding the problem of the two tuning effects canceling each other out in traditional symmetrical structures, and significantly improving the wavelength tuning amplitude per unit voltage.

[0065] S705: Adjust the driving voltage to achieve continuous tuning of the resonant wavelength.

[0066] In practical applications, the current operating wavelength of the device is acquired by a spectral detection module and compared with a preset target wavelength to obtain the wavelength error. .in, For the target wavelength, The operating wavelength is determined by this error. The amplitude and / or polarity of the piezoelectric drive voltage are dynamically adjusted based on this error, thereby changing the magnitude of the mechanical strain output by the piezoelectric functional layer. This, in turn, alters the stress state on the silicon photonic resonant waveguide, achieving continuous adjustment of the resonant wavelength. This method allows for flexible and continuous change of the output wavelength and can also compensate for wavelength drift caused by temperature and process variations, ensuring the stability of the tuning operation.

[0067] In summary, this application provides a wavelength tuning method for a piezoelectric-driven silicon optical resonator. This method, applied to the aforementioned piezoelectric-driven silicon optical resonator, first inputs an optical signal into the silicon optical resonant waveguide to establish an initial resonant state. Then, a driving voltage is applied to the piezoelectric driving component, causing inverse piezoelectric strain in the piezoelectric functional layer. An asymmetric mechanical boundary is used to adjust the propagation path of the mechanical strain generated by the inverse piezoelectric strain. Finally, the mechanical strain simultaneously causes changes in the effective refractive index of the silicon optical resonant waveguide and the geometric dimensions of the resonant cavity, thereby changing the resonant wavelength of the piezoelectric-driven silicon optical resonator. This allows for adjustment of the driving voltage, achieving continuous tuning of the resonant wavelength. Thus, by setting a mechanical continuity control structure and a complete continuous support structure on both radial sides of the piezoelectric driving component to form an asymmetric mechanical boundary, the spatial distribution of inverse piezoelectric strain within the silicon optical resonant waveguide is reconstructed, improving the wavelength tuning efficiency of the piezoelectric-driven silicon optical resonator.

[0068] Figure 8 This is a flowchart illustrating a method for fabricating a piezoelectrically driven silicon photonic resonator, provided as an embodiment of this application. (Combined with...) Figure 8 As shown, the method may include: S801: A silicon photonic resonant waveguide is fabricated on an SOI substrate, and a dielectric isolation layer is deposited on the surface of the silicon photonic resonant waveguide.

[0069] In practical applications, silicon photonic resonant waveguides are fabricated on the top silicon film of an SOI substrate. The target structure of the silicon photonic resonant waveguide can be obtained by performing standard high-resolution photolithography and dry etching on the top silicon. After fabrication, a dielectric isolation layer is deposited on its surface. This dielectric isolation layer electrically isolates the underlying silicon photonic resonant waveguide from the upper piezoelectric drive component, preventing short circuits between the electrodes of the piezoelectric drive component and the silicon photonic resonant waveguide. It also acts as a stress transfer medium, efficiently transferring the inverse piezoelectric strain generated by the piezoelectric drive component to the silicon photonic resonant waveguide. Furthermore, the dielectric isolation layer protects the silicon photonic resonant waveguide, reducing damage caused by subsequent thin film deposition and etching processes, ensuring excellent optical transmission performance.

[0070] S802: A lower electrode layer, a piezoelectric functional layer, and an upper electrode layer are sequentially prepared on the surface of the dielectric isolation layer to form an overall covered piezoelectric drive assembly.

[0071] In practical applications, a lower electrode layer, a piezoelectric functional layer, and a top electrode layer are sequentially fabricated on the surface of the dielectric isolation layer to form a piezoelectric driving component that covers the entire structure. The lower and upper electrode layers are respectively positioned on the upper and lower sides of the piezoelectric functional layer, serving as conductive electrodes to apply a driving voltage to the piezoelectric functional layer. When a voltage is applied to the upper and lower electrodes, the piezoelectric functional layer undergoes mechanical deformation due to the inverse piezoelectric effect. The lower electrode layer, piezoelectric functional layer, and top electrode layer can be fabricated using thin-film deposition and patterning processes, respectively, and then stacked to completely cover the dielectric isolation layer. This stacked structure allows the mechanical deformation generated by the piezoelectric functional layer to be fully transferred to the lower dielectric isolation layer, and then further conducted to the silicon photonic resonant waveguide, providing a driving source for wavelength tuning of the device.

[0072] S803: The piezoelectric drive component is radially differentiated through patterned photolithography and dry etching processes. A mechanical continuity control structure is prepared in the first side region, and a complete and continuous support structure is maintained in the second side region, so that the piezoelectric drive component forms a radially asymmetric mechanical boundary, thereby obtaining a piezoelectric driven silicon photonic resonator.

[0073] In practical applications, the piezoelectric drive component is partitioned along the radial direction of the silicon photonic resonant waveguide, dividing it into a first side region and a second side region. Here, the radial direction is the radiation direction from the center of the silicon photonic resonant waveguide to the outer edge of the ring. The first side region and the second side region correspond to the outer and inner parts of the piezoelectric drive component relative to the resonant waveguide, respectively.

[0074] Next, the piezoelectric driving component is radially differentiated using patterned photolithography and dry etching processes. A mechanical continuity control structure is set in the first side region, while the second side region maintains a complete and continuous support structure, creating a radially asymmetric mechanical boundary for the piezoelectric driving component, ultimately resulting in a piezoelectric-driven silicon photonic resonator. The mechanical continuity control structure alters the mechanical constraints of the first side region, reducing its mechanical stiffness; while the thin film stack in the second side region remains intact and uninterrupted, maintaining higher mechanical stiffness. This creates a differentiated mechanical boundary in the radial direction of the piezoelectric driving component, with one side having weak constraints and the other side having strong constraints. This asymmetric boundary can change the propagation direction of piezoelectric deformation stress, reducing the dissipation of driving stress into the unconstrained outer region and allowing more mechanical stress to be transferred to the silicon photonic resonant waveguide. This improves stress coupling and enhances the device's wavelength tuning performance with almost no additional optical loss.

[0075] In summary, this application provides a method for fabricating a piezoelectric-driven silicon photonic resonator. First, a silicon photonic resonant waveguide is formed on an SOI substrate, and a dielectric isolation layer is deposited on the surface of the waveguide. Then, a lower electrode layer, a piezoelectric functional layer, and an upper electrode layer are sequentially fabricated on the surface of the dielectric isolation layer to form an integrally covered piezoelectric driving component. Finally, the piezoelectric driving component is radially differentiated using patterned photolithography and dry etching processes. A mechanically continuous control structure is fabricated in the first side region, while a complete and continuous support structure is maintained in the second side region, thus forming a radially asymmetric mechanical boundary for the piezoelectric driving component, resulting in the piezoelectric-driven silicon photonic resonator. In this way, by setting a mechanically continuous control structure and a complete and continuous support structure on both radially sides of the piezoelectric driving component to form an asymmetric mechanical boundary, the spatial distribution of inverse piezoelectric strain within the silicon photonic resonant waveguide is reconstructed, improving the wavelength tuning efficiency of the piezoelectric-driven silicon photonic resonator.

[0076] In addition, this application provides a dual time-scale coordinated tuning system, which includes the piezoelectric driven silicon photonic resonator described above. The silicon photonic resonant waveguide integrates a fast actuator for realizing high-speed electro-optic modulation. The fast actuator includes a PN junction modulation structure integrated in the core region of the silicon photonic resonant waveguide through an ion implantation process, and a radio frequency driving electrode connected to the PN junction modulation structure. The dual-timescale coordinated tuning system is configured to: perform slow piezoelectric stress bias control through the piezoelectric drive component to achieve athermal wavelength locking, and perform high-speed optical signal modulation or optical path switching through the PN junction modulation structure driven by the RF drive electrode, so as to construct a dual-actuator closed-loop control architecture based on the complementary coordination of piezoelectric strain and carrier effect.

[0077] Specifically, for high-capacity optical interconnects and optical cross-connect nodes (OXCs) in applications such as high-density AI data center networks and scalable computing clusters, relying solely on a single tuning mechanism is insufficient to simultaneously achieve low power consumption and high speed. Therefore, the piezoelectric-driven silicon photonic resonator of this application can serve as a core device to construct a dual-timescale collaborative tuning system. Figure 9 This is a schematic diagram of the architecture and cross-section of a dual-timescale collaborative tuning system provided for embodiments of this application. Combined with... Figure 9As shown, in this coordinated tuning system, the piezoelectric drive component 400 acts as a "slow actuator," driven by a low-frequency piezoelectric bias output from a low-frequency bias voltage source. Meanwhile, the silicon photonic resonant waveguide 200 (e.g., a micro-ring waveguide region) can be further integrated with a PN junction composed of P-regions and N-regions via ion implantation, acting as a "fast actuator" based on carrier dissipation effects. RF drive electrodes 201 are configured at both ends of the PN junction, with an RF drive signal source providing the drive input, ultimately outputting a high-speed optical signal. During system operation, the piezoelectric drive component applies a low-frequency bias voltage for slow piezoelectric stress bias control, offsetting ambient temperature drift and manufacturing process errors, achieving ultra-low static power consumption and non-thermal wavelength stabilization (thermal wavelength locking). Simultaneously, an RF drive signal is applied to the PN junction integrated in the core region of the silicon photonic waveguide, driven by the RF drive electrode 201, enabling nanosecond-level or even picosecond-level rapid electro-optic modulation or optical path switching.

[0078] Through this dual-actuator closed-loop control architecture, slow piezoelectric strain and rapid carrier effects are heterogeneously integrated in physical space and complemented and coordinated on a time scale. This not only solves the bottlenecks of excessive power consumption and thermal crosstalk in traditional thermo-optical tuning, but also greatly expands the application potential of piezoelectrically driven silicon photonic resonators in high-speed native optical I / O interfaces, large-scale optical neural network (ONN) weight updates, and broadband wavelength-locked loops.

[0079] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A piezoelectrically driven silicon optical resonator, characterized in that, include: The SOI substrate, silicon photonic resonant waveguide, dielectric isolation layer, and piezoelectric drive assembly are arranged sequentially from bottom to top. The piezoelectric drive assembly comprises, from bottom to top, a lower electrode layer, a piezoelectric functional layer, and an upper electrode layer; Along the radial direction of the silicon photonic resonant waveguide, the piezoelectric drive assembly is divided into a first side region and a second side region arranged opposite to each other; The first side region is provided with a mechanical continuity control structure that disrupts the lateral mechanical continuity of the piezoelectric drive assembly to reduce local stiffness. The second side region maintains a complete and continuous support structure; The mechanical continuity control structure, together with the complete continuous support structure, forms an asymmetric mechanical boundary along the radial direction of the silicon photonic resonant waveguide.

2. The piezoelectrically driven silicon optical resonator according to claim 1, characterized in that, The mechanical continuity control structure is located outside the effective optical mode distribution region of the silicon photonic resonant waveguide.

3. The piezoelectrically driven silicon optical resonator according to claim 1, characterized in that, The mechanical continuity control structure is formed by at least one of the following processes: local grooving, local removal, local film thinning, local structure release, and local cavity formation.

4. The piezoelectrically driven silicon optical resonator according to claim 1, characterized in that, The mechanical continuity control structure is an air gap groove; the air gap groove penetrates the upper electrode layer, the piezoelectric functional layer and the lower electrode layer along the direction perpendicular to the substrate, and the bottom end of the air gap groove extends downward and is embedded in the interior of the dielectric isolation layer.

5. The piezoelectrically driven silicon photonic resonator according to claim 4, characterized in that, The lateral spacing between the air gap slot and the fundamental mode energy center of the silicon photonic resonant waveguide causes the light intensity of the boundary evanescent field of the silicon photonic resonant waveguide to attenuate to less than 1 / e² of the maximum value at the inner wall of the air gap slot.

6. The piezoelectrically driven silicon optical resonator according to any one of claims 4 or 5, characterized in that, The projection of the bottom contour of the air gap groove in the direction perpendicular to the SOI substrate and the outer edge of the silicon optical bus waveguide next to the silicon optical resonant waveguide maintain a preset lateral distance. The lateral distance constitutes a safe clearance to prevent cutting off the silicon optical bus waveguide. And / or, the dielectric isolation layer corresponding to the air gap groove is provided with an etching barrier layer inside or on the surface to prevent alignment deviations in the dry etching process from cutting off the silicon photonic bus waveguide.

7. The piezoelectrically driven silicon optical resonator according to claim 6, characterized in that, The material of the etching barrier layer includes one of aluminum oxide, aluminum nitride, or dense silicon nitride.

8. The piezoelectrically driven silicon optical resonator according to claim 1, characterized in that, The lateral width of the piezoelectric drive component in the first side region is smaller than the lateral width of the piezoelectric drive component in the second side region; The solid width of the first upper electrode layer in the first side region and the solid width of the second upper electrode layer in the second side region satisfy a preset expression; the preset expression is: ; In the formula The solid width of the first upper electrode layer. The solid width of the second upper electrode layer.

9. The piezoelectrically driven silicon optical resonator according to claim 1, characterized in that, The first side region is located on the radially outer side of the silicon photonic resonant waveguide away from the center of the resonant cavity, and the second side region is located on the radially inner side of the silicon photonic resonant waveguide toward the center of the resonant cavity, so that the effective refractive index change induced by the applied driving voltage and the change in the geometric dimensions of the resonant cavity can adjust the resonant wavelength by redshifting or blueshifting in the same direction.

10. The piezoelectrically driven silicon optical resonator according to claim 9, characterized in that, The changes in the resonant cavity geometry include: changes in the resonant cavity radius of the silicon photonic resonant waveguide, and / or changes in the optical perimeter of the resonant cavity.

11. The piezoelectrically driven silicon optical resonator according to claim 1, characterized in that, The piezoelectric functional layer is composed of at least one material selected from lead zirconate titanate, aluminum nitride, scandium-doped aluminum nitride, thin-film lithium niobate, thin-film lithium tantalate, and barium titanate.

12. The piezoelectrically driven silicon optical resonator according to claim 1, characterized in that, The silicon photonic resonant waveguide is at least one of a microring resonator, a racetrack resonator, and a microdisk resonator.

13. A dual-timescale coordinated tuning system, characterized in that, Includes a piezoelectrically driven silicon optical resonator as described in any one of claims 1-12; The silicon photonic resonant waveguide integrates a fast actuator for realizing high-speed electro-optic modulation. The fast actuator includes a PN junction modulation structure integrated in the core region of the silicon photonic resonant waveguide through ion implantation, and a radio frequency drive electrode connected to the PN junction modulation structure. The dual-timescale coordinated tuning system is configured to: perform slow piezoelectric stress bias control through the piezoelectric drive component to achieve athermal wavelength locking, and perform high-speed optical signal modulation or optical path switching through the PN junction modulation structure driven by the RF drive electrode, so as to construct a dual-actuator closed-loop control architecture based on the complementary coordination of piezoelectric strain and carrier effect.

14. A method for fabricating a piezoelectrically driven silicon optical resonator, characterized in that, include: A silicon optical resonant waveguide is fabricated on an SOI substrate, and a dielectric isolation layer is deposited on the surface of the silicon optical resonant waveguide. A lower electrode layer, a piezoelectric functional layer, and an upper electrode layer are sequentially fabricated on the surface of the dielectric isolation layer to form an integrally covered piezoelectric drive assembly; The piezoelectric drive component is radially differentiated by patterning photolithography and dry etching processes. A mechanical continuity control structure is prepared in the first side region, and a complete and continuous support structure is maintained in the second side region, so that the piezoelectric drive component forms a radially asymmetric mechanical boundary, thereby obtaining a piezoelectric driven silicon photonic resonator.

15. A wavelength tuning method for a piezoelectrically driven silicon optical resonator, characterized in that, The wavelength tuning method is used in the piezoelectrically driven silicon optical resonator as described in any one of claims 1-12, comprising: An optical signal is input into the silicon photonic resonant waveguide, causing the piezoelectric drive silicon photonic resonator to establish an initial resonance state. Apply a driving voltage to the piezoelectric drive component to induce inverse piezoelectric strain in the piezoelectric functional layer; The propagation path of the mechanical strain generated by the inverse piezoelectric strain is adjusted by utilizing asymmetric mechanical boundaries; The mechanical strain causes a change in the effective refractive index and a change in the geometric dimensions of the silicon optical resonant waveguide, thereby causing a change in the resonant wavelength of the piezoelectrically driven silicon optical resonator. Adjusting the driving voltage allows for continuous tuning of the resonant wavelength.

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