A synaesthesia integrated optical chip based on hybrid resonance and its preparation method

Abstract

The present invention discloses a hybrid resonance-based integrated optical chip and a preparation method, and relates to the field of optoelectronic integration technology. The present invention comprises a silicon substrate, a buried oxide layer is deposited on the top of the silicon substrate, a multilayer rectangular waveguide is installed above the buried oxide layer, one end of the multilayer rectangular waveguide is kept flush with the buried oxide layer, and a silicon rectangular waveguide is installed on the other end, the end of the multilayer rectangular waveguide facing the center of the buried oxide layer is provided with a reverse tapered portion, and the end of the silicon rectangular waveguide away from the center of the buried oxide layer is provided with a forward tapered portion. The present invention realizes the hybrid integration of a dielectric-metal hybrid resonant cavity with on-chip silicon and ordinary dielectric waveguides based on on-chip optical interconnection, and utilizes the strong coupling between optical and plasma modes to excite quasi-continuous spectrum bound states, which can not only realize high-sensitivity on-chip optical sensing, but also greatly improve the quality factor and have low transmission loss.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic integration technology, and in particular to a hybrid resonance-based synaesthesia integrated optical chip and a preparation method thereof. Background Art

[0002] In recent years, plasmonic structures have been increasingly used in SOI-based on-chip optical sensors, breaking the diffraction limit and improving sensitivity. However, traditional plasmonic structures are limited by large mode losses and small quality factors, making it difficult to meet the current needs of high-integration, high-sensitivity on-chip optical sensing. In this context, building on-chip optical interconnects based on Si waveguides, leveraging the inherent high quality factor advantages of quasi-continuum bound states, combined with the small size and high sensitivity of plasmons, has become an important means to break through the current plasmon bottleneck.

[0003] A 2017 Nature report noted that within a submicron-scale dielectric resonant cavity, the coupling of transverse and longitudinal modes can generate quasi-continuum bound states with extremely high quality factors. This optical resonant structure is known as a supercavity. Despite its numerous advantages, supercavities still face challenges in structure, testing, and sensing. Quasi-continuum bound states in a supercavity can generally only be excited near the resonance avoidance intersection of the dispersion range, placing stringent requirements on the cavity's cross-sectional aspect ratio and the material's refractive index. This, to a certain extent, limits supercavity design and complicates its hybrid integration with different units.

[0004] Taking all of the above factors into consideration, this patent, based primarily on the theory of strong coupling of optical modes, develops a dielectric-metal hybrid resonant cavity similar to a supercavity. Leveraging the high compatibility of the SOI platform, this patent combines Si waveguides to construct an on-chip photon-plasmonic hybrid optical circuit. The patent explores the excitation conditions for quasi-continuum bound states in hybrid optical-plasmonic modes and the on-chip optical interconnect integration of subwavelength plasma resonants, thereby addressing bottlenecks such as high plasma sensing losses, low integration density, and low quality factor. Furthermore, a novel on-chip mode-spot converter will be designed and fabricated to reduce the end-face coupling losses between Si waveguides and optical fibers, paving the way for the application of quasi-continuum bound state optical sensor chips in optical fiber systems. This patent significantly enhances the performance of on-chip optical sensing, providing a path to high-performance, low-cost integrated optical sensor chips.

[0005] To this end, we propose a quasi-continuous spectrum bound-state integrated optical sensor with a hybrid resonant cavity and its preparation method. Summary of the Invention

[0006] The purpose of the present invention is to provide a hybrid resonance-based integrated optical chip and its preparation method, and to design and implement an on-chip optical interconnection integration solution based on the excitation conditions of the optical-plasmon mode hybrid quasi-continuous spectrum bound state and the subwavelength plasma resonant cavity, thereby solving the problems of high plasma sensing loss, low integration and small quality factor.

[0007] According to a first aspect of the present invention, to achieve the above-mentioned objectives, the present invention provides the following technical solution: a hybrid resonance-based integrated optical chip comprising a silicon substrate, a buried oxide layer deposited on top of the silicon substrate, a multilayer rectangular waveguide mounted above the buried oxide layer, one end of the multilayer rectangular waveguide being flush with the buried oxide layer, and a silicon rectangular waveguide mounted on the other end, a reverse tapered portion being provided at one end of the multilayer rectangular waveguide facing the center of the buried oxide layer, and a forward tapered portion being provided at one end of the silicon rectangular waveguide away from the center of the buried oxide layer, the forward tapered portion being completely enclosed within the reverse tapered portion to form a directional coupling structure;

[0008] The multilayer rectangular waveguide and the silicon rectangular waveguide as a whole constitute a coupling unit, the number of the coupling units is at least two, and the two coupling units are symmetrically arranged along the length direction of the buried oxide layer with the center line of the buried oxide layer as the symmetry axis;

[0009] A gold resonant ring is installed in the center between the two coupling units. A hybrid resonant cavity is formed inside the gold resonant ring. Two openings are opened in the direction of the straight waveguide near the position of the gold resonant ring near the silicon rectangular waveguide, which are used for near-field coupling between the silicon rectangular waveguides on both sides and the hybrid resonant cavity.

[0010] A silicon disk is arranged inside the gold resonant ring, the center of the silicon disk coincides with the center of the gold resonant ring, and the silicon disk and the gold resonant ring are indirectly coupled.

[0011] Furthermore, the multilayer rectangular waveguide is integrally formed with the reverse tapered portion, and the multilayer rectangular waveguide is sequentially formed with a GaN layer, a Si3N4 layer and a SU-8 photoresist layer from bottom to top, and the refractive indices of the GaN layer, the Si3N4 layer and the SU-8 photoresist layer in the near-infrared band are 2.4, 2 and 1.53 respectively.

[0012] Furthermore, the thickness of the silicon rectangular waveguide is equal to the thickness of the hybrid resonant cavity, both being 220 nm.

[0013] Furthermore, the width of the reverse tapered portion gradually decreases along one side of the buried oxide layer toward the center;

[0014] The forward tapered portion is integrally formed with the silicon rectangular waveguide, and the forward tapered portion gradually decreases along the center of the buried oxide layer toward one side.

[0015] Furthermore, the thickness of the buried oxide layer is set to 2 μm.

[0016] Furthermore, the radius of the silicon disk is set to 390nm to 430nm, and the thickness of the silicon disk is set to 200nm to 220nm.

[0017] Furthermore, the inner and outer radii of the gold resonant ring are 1.4 μm to 1.6 μm and 1.7 μm to 1.9 μm respectively, and the width of the opening is 100 nm to 150 nm.

[0018] Furthermore, the center of the gold resonant ring coincides with the center point of the line connecting the centers of the silicon rectangular waveguides arranged on both sides, and there is a certain distance between the silicon rectangular waveguides on both sides and the openings on the gold resonant ring.

[0019] Furthermore, the silicon rectangular waveguide and the hybrid resonant cavity form an on-chip optical interconnection by near-field coupling, and the light field input into the second rectangular waveguide contacts and couples with the hybrid resonant cavity, thereby exciting a plasmon mode;

[0020] The silicon disk is used to excite the optical mode through indirect coupling with the gold resonant ring.

[0021] According to a second aspect of the present invention, a method for preparing a synaesthesia integrated optical chip based on hybrid resonance is provided, which is used to prepare the above-mentioned synaesthesia integrated optical chip based on hybrid resonance, and specifically comprises the following steps:

[0022] S1. First, a 350nm-thick layer of electron beam photoresist is laid on the top silicon layer of the silicon substrate. Silicon rectangular waveguides and silicon disks are then fabricated using electron beam lithography and dry etching.

[0023] S2. 100nm thick GaN and 100nm thick Si3N4 films were grown on a silicon substrate using PECVD. A 350nm thick electron beam photoresist layer was then deposited. The Si3N4 / GaN multilayer structure was fabricated using electron beam lithography and dry etching.

[0024] S3. Then, a 2.7 μm thick SU-8 photoresist was laid on the Si3N4 / GaN multilayer structure, and the SU-8 / Si3N4 / GaN multilayer waveguide was prepared by a one-time film-spinning, UV lithography, development, and curing process.

[0025] S4. Lay a 500nm thick layer of electron beam photoresist on the chip with the waveguide pattern, and then pattern the gold resonant ring and silicon disk by electron beam lithography;

[0026] S5. A 220nm thick gold layer is deposited on the electron beam photoresist patterned chip using a metal deposition process. After metal deposition, the chip is placed in an acetone solution and ultrasonically cleaned to remove the electron beam photoresist. Only the gold resonant ring and silicon disk directly deposited on the buried oxide layer remain, completing the preparation of the dielectric-metal hybrid resonant cavity.

[0027] S6. The patterned chip is cleaned a second time to remove all residual photoresist and complete the device preparation;

[0028] S7. Finally, the chip is packaged based on a light array system. The single-mode optical fiber and the multi-layer rectangular waveguide are end-face coupled and bonded with UV-curable adhesive to complete the optical packaging of the device.

[0029] The present invention has at least the following beneficial effects:

[0030] The present invention realizes the hybrid integration of dielectric-metal hybrid resonant cavity with on-chip silicon and ordinary dielectric waveguide based on on-chip optical interconnection, and utilizes the strong coupling between optical and plasma modes to excite quasi-continuous spectrum bound states, which can not only realize high-sensitivity on-chip optical sensing, but also greatly improve the quality factor and have low transmission loss.

[0031] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a three-dimensional schematic diagram of the overall structure of the present invention;

[0033] Figure 2 It is a top view schematic diagram of the overall structure of the present invention;

[0034] Figure 3 The on-chip spot converter of the present invention is composed of a multilayer rectangular waveguide and a silicon rectangular waveguide, wherein (a) is a three-dimensional structure diagram of the on-chip spot converter; (b) is a diagram showing the coupling efficiency between the spot converter and the silicon waveguide; (c) is a diagram showing the coupling efficiency between the spot converter and the single-mode optical fiber;

[0035] Figure 4 The simple harmonic oscillator oscillation model of the hybrid resonant cavity in the present invention, wherein (a) is a three-dimensional structure diagram of the resonant cavity; (b) is a top view of the resonant cavity; (c) is a schematic diagram of the simple harmonic oscillator model of the resonant cavity;

[0036] Figure 5 Schematic diagram of the quasi-continuous spectrum bound state mode excited by the hybrid resonant cavity in the present invention;

[0037] Figure 6This is an analysis of the refractive index sensing performance of the optical chip described in the present invention, where (a) is the output spectrum at different refractive indices; (b) is the relationship between the central wavelength of the quasi-continuous spectrum bound state resonance signal and the ambient refractive index.

[0038] Reference numerals:

[0039] 1. Silicon substrate; 2. Buried oxide layer; 3. Multilayer rectangular waveguide; 31. GaN layer; 32. Si3N4 layer; 33. SU-8 photoresist layer; 4. Reverse tapered portion; 5. Silicon rectangular waveguide; 6. Forward tapered portion; 7. Gold resonant ring; 8. Opening; 9. Silicon disk. DETAILED DESCRIPTION

[0040] The following will be combined with the accompanying drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the embodiments described are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present disclosure.

[0041] The present invention includes a silicon rectangular waveguide 5 and a SU-8 / Si3N4 / GaN multilayer rectangular waveguide. There is a tapered overlapping region between the silicon rectangular waveguide 5 and the SU-8 / Si3N4 / GaN multilayer rectangular waveguide for mode spot coupling; the number of the multilayer rectangular waveguide 3 and the silicon rectangular waveguide 5 is set to two, of which the two SU-8 / Si3N4 / GaN multilayer rectangular straight waveguides serve as input and output ports for direct end-face coupling with external single-mode optical fibers respectively; the two silicon rectangular straight waveguides are mainly divided into input and output parts, the silicon rectangular straight waveguide of the input part mainly introduces the input light signal into the dielectric-metal hybrid resonant cavity and excites the quasi-continuous spectrum bound state mode through near-field coupling, and the output silicon rectangular straight waveguide mainly derives the quasi-continuous spectrum bound state in the resonant cavity; the dielectric-metal hybrid resonant cavity serves as the core resonant unit, and its structure can not only simultaneously meet the excitation of plasma and traditional optical modes, but also enable strong coupling between the two modes, thereby exciting optical-plasmon hybrid quasi-continuous spectrum bound states.

[0042] See also Figures 1-6 The present invention provides a technical solution: a hybrid resonance-based integrated optical chip, comprising a silicon substrate 1, a buried oxide layer 2 deposited on the top of the silicon substrate 1, a multilayer rectangular waveguide 3 installed above the buried oxide layer 2, one end of the multilayer rectangular waveguide 3 being flush with the buried oxide layer 2, and a silicon rectangular waveguide 5 installed on the other end, a reverse tapered portion 4 being provided at one end of the multilayer rectangular waveguide 3 facing the center of the buried oxide layer 2, and a forward tapered portion 6 being provided at one end of the silicon rectangular waveguide 5 away from the center of the buried oxide layer 2, the forward tapered portion 6 being completely enclosed in the reverse tapered portion 4 to form a directional coupling structure;

[0043] The multilayer rectangular waveguide 3 and the silicon rectangular waveguide 5 constitute a coupling unit as a whole. The number of coupling units is at least two, and the two coupling units are symmetrically arranged along the length direction of the buried oxide layer 2 with the center line of the buried oxide layer 2 as the symmetry axis;

[0044] A gold resonant ring 7 is installed in the center between the two coupling units. A hybrid resonant cavity is formed inside the gold resonant ring 7. Two openings 8 are opened along the straight waveguide direction near the silicon rectangular waveguide 5 on the gold resonant ring 7 to achieve near-field coupling between the silicon rectangular waveguides 5 on both sides and the hybrid resonant cavity.

[0045] A silicon disk 9 is provided inside the gold resonant ring 7 . The center of the silicon disk 9 coincides with the center of the gold resonant ring 7 , and the silicon disk 9 and the gold resonant ring 7 are indirectly coupled.

[0046] According to the technical solution of this embodiment, the multilayer rectangular waveguide 3 serves as a secondary waveguide structure, one end of which is directly end-to-end connected to the single-mode optical fiber, thereby introducing the optical signal into the chip with a smaller coupling loss, and the other end is connected to the reverse tapered portion 4 of the silicon rectangular waveguide 5 to form a clad directional coupling structure, realizing template conversion and providing high-efficiency fiber-chip optical coupling. The multilayer rectangular waveguide 3 and the reverse tapered portion 4 are integrally formed, and the multilayer rectangular waveguide 3 is sequentially formed with a GaN layer 31, a Si3N4 layer 32 and a SU-8 photoresist layer 33 from bottom to top, and the refractive indices of the GaN layer 31, the Si3N4 layer 32 and the SU-8 photoresist layer 33 in the near-infrared band are 2.4, 2 and 1.53, respectively, where SU-8 is an epoxy resin polymer GM-1040 produced by Gerste ltec.

[0047] Furthermore, two symmetrical silicon rectangular waveguides 5 are the primary optical interconnection structure, which is mainly used for the transmission of on-chip optical signals. They can be near-field coupled with the hybrid resonant cavity as an excitation source for exciting plasma modes, and can also detect quasi-continuous spectrum bound state optical signals in the resonant cavity. The silicon rectangular waveguide 5 is made of silicon material, and the thickness of the silicon rectangular waveguide 5 is equal to the thickness of the hybrid resonant cavity, both of which are 220nm.

[0048] According to the technical solution of this embodiment, the width of the reverse tapered portion 4 gradually decreases along one side of the buried oxide layer 2 toward the center, the forward tapered portion 6 is integrally formed with the silicon rectangular waveguide 5, and the width of the forward tapered portion 6 gradually decreases along the center of the buried oxide layer 2 toward one side. The forward tapered portion 6 is completely covered by the GaN layer 31 and the Si3N4 layer 32 of the reverse tapered portion 4 to form a directional coupling structure, so that the mode spot size can be converted between the multilayer rectangular waveguide 3 and the silicon rectangular waveguide 5, as shown in FIG. Figure 3As shown, (a) is the structural diagram of the on-chip spot converter; (b) is the coupling efficiency diagram of the spot converter and the silicon waveguide; and (c) is the coupling efficiency diagram of the spot converter and the single-mode optical fiber.

[0049] According to the technical solution of this embodiment, the thickness of the buried oxide layer 2 deposited on the SOI silicon substrate 1 is set to 2μm, serving as the SiO2 lower cladding layer of the entire on-chip optical interconnection structure. It should be noted that the thickness of the buried oxide layer 2 is not specifically limited in this embodiment and can be selected according to actual needs.

[0050] According to the technical solution of this embodiment, the outer ring of the dielectric-metal hybrid resonant cavity is called a gold resonant ring 7 with symmetrical openings 8, and the resonant structure at the center of the resonant cavity is called a silicon disk 9. The gold resonant ring 7 completely wraps the silicon disk 9, and only two symmetrical openings 8 are opened near the silicon rectangular waveguide 5. The size of the opening 8 can be set to 100nm-150nm, and can be set to 100nm in this embodiment. The gold resonant ring 7 is directly coupled with the silicon rectangular waveguide 5 for near-field coupling to form an on-chip optical interconnection. Since the two are very close, near-field coupling is convenient. The light field input into the silicon rectangular waveguide 5 can directly contact and couple with the metal structure of the resonant cavity without undergoing a long distance of spatial divergence, thereby exciting a plasma mode; the optical mode in the silicon disk 9 structure can be excited by indirect coupling with the gold resonant ring 7, and the photon-plasma quasi-continuum bound state finally excited in the resonant cavity can be excited by indirect coupling with the gold resonant ring 7. The form of the evanescent field is coupled with the silicon rectangular waveguide 5 of the output part, thereby extracting the optical signal in the resonant cavity. The dielectric-metal hybrid resonant cavity serves as the core resonant unit. Its structure can simultaneously meet the excitation of plasma and traditional optical modes, and can make the two modes strongly coupled, thereby exciting the optical-plasma hybrid quasi-continuous spectrum bound state. Moreover, due to the compact structure and extremely small size of the resonant cavity, the plasma mode excited by the silicon rectangular waveguide 5 and the optical mode generated by indirect coupling are strongly coupled with each other, and then hybridized into a quasi-continuous spectrum bound state mode. Unlike the traditional supercavity and plasma quasi-continuous spectrum bound state modes, this optical-plasma hybrid quasi-continuous spectrum bound state not only has a large number of mode fields bound on the surface of the metal structure and is very sensitive to the refractive index of the surrounding environment, but also effectively reduces the negative impact of metal absorption on the mode, further reducing the overall loss of the chip.

[0051] It should be noted that plasma mode refers to the ability of a sensor, through specific design and processing, to generate a plasma effect when receiving light signals, thereby improving the signal-to-noise ratio, reducing noise, and enhancing detection performance. The plasma effect is an optical phenomenon in which light waves interact with matter, generating plasma regions of charged particles. These plasmas affect the propagation and reception of light. By controlling the formation and distribution of plasma regions, sensor performance can be optimized to a certain extent, achieving improved signal-to-noise ratios and detection capabilities across different wavelengths and conditions.

[0052] Furthermore, in on-chip optical sensors, generating optical modes refers to a mechanism that, through specific design and processing, enables the sensor to selectively respond to and absorb light within a specific wavelength or spectral range, thereby achieving specific functions and performance. Optical modes typically include aspects such as polarization state, vibration direction, band structure, and quantum coherence. Different optical modes can have a significant impact on the sensor's imaging quality, spectral response range, anti-interference ability, power consumption, and other performance. Therefore, by controlling and adjusting the combination and relative intensity of optical modes, on-chip optical sensors can be customized and optimized for different application scenarios.

[0053] Furthermore, the radius of the silicon disk 9 can be set to 390 nm to 430 nm, and the thickness of the silicon disk 9 can be set to 200 nm to 220 nm. This embodiment does not make specific limitations here, and can be selected according to actual needs.

[0054] Furthermore, the inner and outer radii of the gold resonant ring 7 are 1.4 μm to 1.6 μm and 1.7 μm to 1.9 μm, respectively. The center of the gold resonant ring 7 coincides with the center point of the line connecting the centers of the silicon rectangular waveguides 5 arranged on both sides. There is a certain distance between the silicon rectangular waveguides 5 on both sides and the openings 8 on the gold resonant ring 7. The distance can be set to 210 nm. This embodiment does not make any specific restrictions here and can be selected according to actual needs.

[0055] like Figure 4 As shown in (a) to (c), based on the simple harmonic oscillator coupling model, the resonant cavity designed in this embodiment can be divided into two structures: a plasma resonance structure and an optical resonance structure. The coupling between the two structures satisfies the following rules:

[0056]

[0057] Where x c , γ c and ω represent the resonance amplitude, damping coefficient and resonance frequency of the excited mode in the resonant cavity respectively; g in (ω) represents the near-field coupling coefficient between the input silicon waveguide and the dielectric-metal hybrid resonant cavity; here, the excitation light field satisfies: E(t) = E0e-iωt , the resonance amplitude of the mode: x c (t) = x c e -iωt .

[0058] At the output end, the silicon rectangular waveguide 5 can also couple with the dielectric-metal hybrid resonant cavity, thereby deriving the optical-plasmonic hybrid quasi-continuum bound state generated therein, and the output light field satisfies:

[0059]

[0060] Where x Si and γ Si represents the amplitude and attenuation coefficient of the transmitted light wave in the output silicon waveguide; g out (ω) is the near-field coupling coefficient between the output silicon waveguide and the dielectric-metal hybrid resonator; for most cases, γ c Much larger than γ Si , and g in (ω)≈g out (ω).

[0061] The hybrid resonance-based integrated optical chip provided in this embodiment mainly uses silicon waveguide near-field coupling to form on-chip optical interconnection, which is directly optically coupled with the dielectric-metal hybrid resonant cavity on the chip, making it easier to implement optoelectronic packaging of the chip; since no upper cladding layer is made, the dielectric-metal hybrid resonant cavity is directly exposed to the air and can be in direct contact with the surrounding environment; Figure 5 As shown, since the quasi-continuous spectrum bound state generated by the hybridization of optical mode and plasma mode is not mainly bound inside the material, a large number of mode fields are in the air layer, so it can respond to the refractive index changes of the surrounding environment in real time. That is, once the refractive index of the environment changes, the resonant characteristics of the plasma mode will also change, causing the resonant frequency to shift.

[0062] like Figure 6 As shown in (a) and (b), (a) is the output spectrum under different refractive indices; (b) is the relationship between the central wavelength of the quasi-continuous spectrum bound state resonance signal and the ambient refractive index. The hybrid resonant integrated optical sensor with integrated synaesthesia in this embodiment can achieve high-sensitivity refractive index detection for different ambient refractive indices (1.315-1.365). As the ambient refractive index increases, it can be seen that the resonance peak corresponding to the quasi-continuous spectrum bound state undergoes a significant red shift. The simulation results show that the wavelength of the resonance peak is linearly related to the refractive index of the surrounding environment. The calculated sensing sensitivity of the chip is approximately 300nm / RI U, which fully meets the requirements of high-performance on-chip optical sensing.

[0063] In summary, the present invention uses a dielectric-metal hybrid resonant cavity as the core component of the device, and a silicon rectangular waveguide 5 as the excitation and transmission unit of the on-chip optical signal. The optical signal of the external light source is transmitted through the silicon rectangular waveguide 5 at the input end for the excitation of the quasi-continuous spectrum bound state, while the silicon rectangular straight waveguide at the output end can derive the stable quasi-continuous spectrum bound state sensing signal in the resonant cavity through near-field coupling; the multilayer rectangular waveguide 3 serves as a secondary waveguide structure, which is coupled with the external single-mode optical fiber and the silicon rectangular waveguide 5 respectively to achieve template conversion and provide high-efficiency fiber-to-chip optical coupling;

[0064] Among them, the combination of the multilayer rectangular waveguide 3 and the silicon rectangular waveguide 5 constitutes an on-chip mode spot converter, and the large-sized multilayer rectangular waveguide 3 introduces the optical signal into the chip with a small coupling loss, further reducing the insertion loss of the chip, and utilizing the strong coupling between the optical mode and the plasma mode to excite the quasi-continuous spectrum bound state, it can also realize high-sensitivity on-chip optical sensing, greatly improving the quality factor.

[0065] Example 2:

[0066] The present invention provides a method for preparing a synaesthesia integrated optical chip based on hybrid resonance, which is used to prepare the above-mentioned synaesthesia integrated optical chip based on hybrid resonance, and specifically includes the following steps:

[0067] S1. First, a 350nm thick layer of electron beam photoresist is laid on the top silicon of the silicon substrate 1, and a silicon rectangular waveguide 5 and a silicon disk 9 are produced by electron beam lithography and dry etching;

[0068] S2. A 100nm thick GaN film and a 100nm thick Si3N4 film were grown on a silicon substrate 1 by PECVD, and then a 350nm thick electron beam photoresist layer was laid, and a Si3N4 / GaN multilayer structure was produced by electron beam lithography and dry etching;

[0069] S3. Then, a 2.7 μm thick SU-8 photoresist was laid on the Si3N4 / GaN multilayer structure, and the SU-8 / Si3N4 / GaN multilayer waveguide was prepared by a one-time film-spinning, UV lithography, development, and curing process.

[0070] S4. A 500nm thick layer of electron beam photoresist is laid on the chip with the waveguide pattern, and the pattern of the gold resonant ring 7 and the silicon disk 9 is formed by electron beam lithography;

[0071] S5. A 220 nm thick gold layer is deposited on the chip with the electron beam photoresist pattern using a metal deposition process. After the metal deposition is completed, the chip is placed in an acetone solution and the electron beam photoresist on the chip is removed by ultrasonic cleaning. At this time, only the gold resonant ring 7 and the silicon disk 9 directly deposited on the buried oxide layer 2 are retained, and the dielectric-metal hybrid resonant cavity preparation is completed.

[0072] S6. The patterned chip is cleaned a second time to remove all residual photoresist and complete the device preparation;

[0073] S7. Finally, the chip is packaged based on a light array system. The single-mode optical fiber and the multilayer rectangular waveguide 3 are end-face coupled and bonded with UV-curable adhesive to complete the optical packaging of the device. The entire manufacturing process is compatible with the current CMOS processing technology.

[0074] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0075] For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on", "installed on", "fixed on" or "set on" another element, it can be directly on the other element or there can be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there can be a central element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0076] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0077] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Claims

1. A hybrid resonance-based integrated optical chip, comprising a silicon substrate (1), characterized in that: A buried oxide layer (2) is deposited on the top of the silicon substrate (1), a multilayer rectangular waveguide (3) is installed above the buried oxide layer (2), one end of the multilayer rectangular waveguide (3) is kept flush with the buried oxide layer (2), and a silicon rectangular waveguide (5) is installed on the other end, a reverse tapered portion (4) is provided at one end of the multilayer rectangular waveguide (3) facing the center of the buried oxide layer (2), and a forward tapered portion (6) is provided at one end of the silicon rectangular waveguide (5) away from the center of the buried oxide layer (2), and the forward tapered portion (6) is completely covered in the reverse tapered portion (4) to form a directional coupling structure; The multilayer rectangular waveguide (3) and the silicon rectangular waveguide (5) integrally form a coupling unit, the number of the coupling units is at least two, and the two coupling units are symmetrically arranged along the length direction of the buried oxide layer (2) with the center line of the buried oxide layer (2) as the symmetry axis; A gold resonant ring (7) is installed at the center between the two coupling units, a hybrid resonant cavity is formed inside the gold resonant ring (7), and two openings (8) are provided in the gold resonant ring (7) near the silicon rectangular waveguide (5) along the straight waveguide direction, for near-field coupling between the silicon rectangular waveguides (5) on both sides and the hybrid resonant cavity; A silicon disk (9) is provided inside the gold resonant ring (7), the center of the silicon disk (9) coincides with the center of the gold resonant ring (7), and the silicon disk (9) and the gold resonant ring (7) are indirectly coupled; The multilayer rectangular waveguide (3) and the reverse tapered portion (4) are integrally formed, and the multilayer rectangular waveguide (3) is sequentially formed with a GaN layer (31), a Si3N4 layer (32), and a SU-8 photoresist layer (33) from bottom to top, wherein the forward tapered portion (6) in the silicon rectangular waveguide (5) is completely enclosed in the GaN layer (31) and the Si3N4 layer (32), and the refractive indices of the GaN layer (31), the Si3N4 layer (32), and the SU-8 photoresist layer (33) in the near-infrared band are 2.4, 2, and 1.53, respectively.

2. The hybrid resonance-based synaesthesia integrated optical chip according to claim 1, characterized in that: The thickness of the silicon rectangular waveguide (5) is equal to the thickness of the hybrid resonant cavity, both being 220 nm.

3. The hybrid resonance-based synaesthesia integrated optical chip according to claim 2, characterized in that: The width of the reverse tapered portion (4) gradually decreases along one side of the buried oxide layer (2) toward the center; The forward tapered portion (6) is integrally formed with the silicon rectangular waveguide (5), and the forward tapered portion (6) gradually decreases along the center of the buried oxide layer (2) toward one side.

4. The hybrid resonance-based synaesthesia integrated optical chip according to claim 3, characterized in that: The thickness of the buried oxide layer (2) is set to 2 μm.

5. The hybrid resonance-based synaesthesia integrated optical chip according to claim 4, characterized in that: The radius of the silicon disk (9) is set to 390 nm to 430 nm, and the thickness of the silicon disk (9) is set to 200 nm to 220 nm.

6. The hybrid resonance-based synaesthesia integrated optical chip according to claim 5, characterized in that: The inner and outer radii of the gold resonant ring (7) are 1.4 μm to 1.6 μm and 1.7 μm to 1.9 μm respectively, and the width of the opening (8) is 100 nm to 150 nm.

7. The hybrid resonance-based synaesthesia integrated optical chip according to claim 6, characterized in that: The center of the gold resonant ring (7) coincides with the center point of the center line connecting the silicon rectangular waveguides (5) arranged on both sides, and a certain distance exists between the silicon rectangular waveguides (5) on both sides and the openings (8) on the gold resonant ring (7).

8. The hybrid resonance-based synaesthesia integrated optical chip according to claim 7, characterized in that: The silicon rectangular waveguide (5) and the hybrid resonant cavity form an on-chip optical interconnection by means of near-field coupling, and the light field input into the second rectangular waveguide contacts and couples with the hybrid resonant cavity, thereby exciting a plasma mode; The silicon disk (9) is indirectly coupled with the gold resonant ring (7) to excite an optical mode.

9. A method for preparing a synaesthesia integrated optical chip based on hybrid resonance, for preparing the synaesthesia integrated optical chip based on hybrid resonance according to any one of claims 1 to 8, comprising: S1. First, a 350 nm thick layer of electron beam photoresist is laid on the top silicon of the silicon substrate (1), and a silicon rectangular waveguide (5) and a silicon disk (9) are produced by electron beam lithography and dry etching; S2. A 100 nm thick GaN film and a 100 nm thick Si3N4 film were grown on a silicon substrate (1) by PECVD, and then a 350 nm thick electron beam photoresist layer was laid, and a Si3N4 / GaN multilayer structure was produced by electron beam lithography and dry etching; S3. Then, a 2.7 μm thick SU-8 photoresist was laid on the Si3N4 / GaN multilayer structure, and the SU-8 / Si3N4 / GaN multilayer waveguide was prepared by a one-time film-spinning, UV lithography, development, and curing process. S4. A 500nm thick layer of electron beam photoresist is laid on the chip with the waveguide pattern, and the pattern of the gold resonant ring (7) and the silicon disk (9) is formed by electron beam photolithography; S5. A 220 nm thick gold layer is deposited on the chip with the electron beam photoresist pattern using a metal deposition process. After the metal deposition is completed, the chip is placed in an acetone solution and the electron beam photoresist on the chip is removed by ultrasonic cleaning. At this time, only the gold resonant ring (7) and silicon disk (9) directly deposited on the buried oxide layer (2) are retained, and the dielectric-metal hybrid resonant cavity is prepared; S6. The patterned chip is cleaned a second time to remove all residual photoresist and complete the device preparation; S7. Finally, the chip that has been prepared is packaged based on a light array system, the single-mode optical fiber is end-face coupled and docked with the multi-layer rectangular waveguide (3), and then bonded with ultraviolet curing glue to complete the optical packaging of the device.

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