Three-dimensional optical filter device capable of realizing vertical optical coupling and preparation method and system thereof

Abstract

The present invention discloses a three-dimensional optical filter device capable of achieving vertical optical coupling, and a method and system for preparing the same. The device comprises: a first straight waveguide extending in a first direction; a resonant microring waveguide disposed on one side of the first straight waveguide along a third direction; the axial direction of the resonant microring waveguide is parallel to a second direction; the second direction and the first direction are mutually perpendicular and both perpendicular to the third direction; a second straight waveguide extending in the third direction; the distance from the center of a circular cross-section of the resonant microring waveguide to the first straight waveguide is equal to the distance from the center of the circular cross-section of the resonant microring waveguide to the second straight waveguide; and the distance between the end face of the second straight waveguide on the side closest to the first straight waveguide and the first straight waveguide is less than (R1+R2) / 3, where R1 is the inner ring radius of the resonant microring waveguide and R2 is the outer ring radius of the resonant microring waveguide. The three-dimensional optical filter device provided by the present invention has a high degree of integration, reduces the number of components in a three-dimensional optoelectronic system, and facilitates the implementation of large-scale optical communications.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor optical filtering technology, and in particular to a three-dimensional optical filter device capable of realizing vertical optical coupling, and a preparation method and system thereof. Background Art

[0002] Amid the rapid development of big data centers and high-performance computing, traditional on-chip electrical interconnect technologies are increasingly unable to meet bandwidth and speed demands due to electronic bottlenecks. In contrast, on-chip optical interconnect technologies, with their advantages of high speed, low power consumption, strong anti-interference capabilities, and high-density integration, demonstrate tremendous potential. In on-chip optoelectronic integrated systems, three-dimensional on-chip optical interconnects enable flexible placement of optical devices across different layers, supporting complex routing layouts and dynamic configurations. These interconnects offer higher integration, greater adaptability, and broader application prospects.

[0003] In the design of three-dimensional on-chip electrical interconnects, the electrical interconnection and communication between different layers can be met by combining TSV (through silicon via), BGA (ball grid array) and microstrip lines. In the design of three-dimensional on-chip optical interconnects, when the transmission direction of light waves needs to change between layers, an interconnection structure with optical vertical coupling function needs to be introduced. In on-chip optoelectronic integrated systems, most of them use a method of combining gratings with optical through holes to perform light wave coupling filtering or a method of coupling gratings with gratings in three-dimensional layers to perform light wave coupling transmission. All of the above methods of transmitting optical signals between three-dimensional layers introduce grating structures, which occupy a large area on the chip and are not suitable for large-scale optical communications. For three-dimensional optoelectronic hybrid systems, it is crucial to study optical vertical coupling structures that use silicon substrates, are of appropriate size, and can be applied to interlayer optical interconnects to improve the system's integration and communication capabilities.

[0004] Optical filters are key components in three-dimensional optoelectronic integrated systems. Currently, research on optical filters primarily focuses on two-dimensional surfaces, with a focus on high-precision control, high-narrowband filtering, and integrated miniaturized design. In the design process of optical interconnect structures, it is necessary to introduce optical vertical coupling devices. For three-dimensional integrated systems, reducing the number of components involved is crucial for increasing system integration, promoting system miniaturization, and enhancing overall system performance. At the same time, the limited number of process solutions for implementing three-dimensional optical interconnect structures in three-dimensional integrated systems presents significant challenges, further limiting the development of optical filters in these systems.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of the above-mentioned prior art and provide a three-dimensional optical filter device capable of achieving vertical optical coupling, and a method and system for its preparation. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a three-dimensional optical filter device capable of realizing vertical optical coupling, comprising:

[0008] a first straight waveguide extending along a first direction;

[0009] A resonant microring waveguide is arranged on one side of the first straight waveguide along a third direction, wherein the third direction is a normal extension direction of the first straight waveguide; the axial direction of the resonant microring waveguide is parallel to the second direction; the second direction and the first direction are perpendicular to each other and are both perpendicular to the third direction;

[0010] a second straight waveguide extending along a third direction;

[0011] The distance from the center of the circular section of the resonant microring waveguide to the first straight waveguide is equal to the distance from the center of the circular section of the resonant microring waveguide to the second straight waveguide;

[0012] The end face of the second straight waveguide close to the first straight waveguide is less than (R1+R2) / 3 from the first straight waveguide, where R1 is the inner ring radius of the resonant microring waveguide and R2 is the outer ring radius of the resonant microring waveguide.

[0013] In one embodiment of the present invention, the materials of the first straight waveguide, the resonant microring waveguide, and the second straight waveguide are the first material, and the first straight waveguide, the resonant microring waveguide, and the second straight waveguide are all coated with the second material; the refractive index of the first material is greater than the refractive index of the second material.

[0014] In one embodiment of the present invention, the first material is a silicon material, and the second material is a silicon dioxide material.

[0015] In a second aspect, the present invention provides a three-dimensional optoelectronic integrated system, comprising at least a first device layer and a second device layer stacked together, wherein the first device layer and the second device layer are optically interconnected via at least one three-dimensional optical filter device capable of vertical optical coupling as described in the first aspect above.

[0016] In one embodiment of the present invention, the first device layer includes a first silicon substrate, and a plurality of three-dimensional optical filter devices disposed on one side of the first silicon substrate;

[0017] The second device layer includes a second silicon substrate, and a light receiver and a light emitter arranged on a side of the second silicon substrate close to the three-dimensional optical filter device;

[0018] At least one of the optical receiver and the optical transmitter is optically interconnected with the second straight waveguide in the three-dimensional optical filtering device.

[0019] In a third aspect, the present invention provides a method for preparing the above-mentioned three-dimensional optical filter device capable of realizing vertical optical coupling, comprising preparing a resonant microring waveguide in a preparation area corresponding to the resonant microring waveguide to be prepared; wherein preparing the resonant microring waveguide in the preparation area corresponding to the resonant microring waveguide to be prepared comprises:

[0020] S1. Obtain a silicon substrate and form a first protective layer on one side of the silicon substrate;

[0021] S2. Forming a first groove pair corresponding to the resonant microring waveguide to be prepared in the preparation area, the first groove pair including two first grooves arranged in parallel; wherein, along the axial direction parallel to the resonant microring waveguide to be prepared, the size of the first groove is greater than the width of the resonant microring waveguide to be prepared; the depth of the first groove on the silicon substrate is at least 3×R2′, and the distance between the two first grooves is greater than 3×R2′, where R2′ is the outer ring radius of the resonant microring waveguide to be prepared;

[0022] S3, forming a second protective layer on the sidewalls of the two first trenches, wherein the second protective layer exposes the bottom of the first trenches;

[0023] S4, performing isotropic etching on the bottoms of the two first trenches to form a first bottom cavity;

[0024] S5, performing a first thermal oxidation to oxidize the two first bottom cavities, so that the silicon between the two first bottom cavities of the first trench pair is oxidized into silicon dioxide;

[0025] S6, removing the first protective layer and the second protective layer;

[0026] S7. Perform a second thermal oxidation to partially oxidize the silicon material between the two first trenches of the first trench pair into silicon dioxide, and the remaining silicon material forms a silicon core column, wherein the axis of the silicon core column coincides with the axis of the resonant microring waveguide to be prepared, and the diameter of the silicon core column is the same as the inner ring diameter of the resonant microring waveguide to be prepared;

[0027] S8, in the preparation area, removing silicon dioxide to expose the silicon core column;

[0028] S9, performing a third thermal oxidation on the preparation area, so that the silicon core column is oxidized into a silicon dioxide core column;

[0029] S10, forming a silicon filler that completely covers the silicon dioxide core column in the preparation area, wherein the minimum distance between the surface of the silicon filler and the silicon dioxide core column is 1.5 times the thickness of the resonant microring waveguide to be prepared, and the thickness of the resonant microring waveguide to be prepared is (R2'-R1'), wherein R1' is the inner ring radius of the resonant microring waveguide to be prepared;

[0030] S11, sequentially forming a third protective layer in the preparation area corresponding to the resonant microring waveguide to be prepared;

[0031] S12, preparing a silicon core ring surrounding the silicon dioxide core column; the axis of the silicon core ring coincides with the axis of the resonant microring waveguide to be prepared, and the outer ring diameter of the silicon core ring is the same as the outer ring diameter of the resonant microring waveguide to be prepared;

[0032] S13, filling the preparation area with silicon dioxide to form a filling silicon dioxide surrounding the outside of the silicon core ring; etching the preparation area according to the preset width of the microring waveguide, so that the silicon core ring is cut off to form a resonant microring waveguide.

[0033] In one embodiment of the present invention, in step S12, preparing a silicon core ring surrounding the silicon dioxide core column comprises the following steps:

[0034] S1201, forming a second groove pair in a preparation area corresponding to the resonant microring waveguide to be prepared, the second groove pair including two second grooves arranged in parallel; along an axial direction parallel to the resonant microring waveguide to be prepared, the size of the second groove is greater than the width of the resonant microring waveguide to be prepared; the depth of the second groove on the silicon filling body is at least 3×R2′, and the distance between the two second grooves is greater than 3×R2′;

[0035] S1202, forming a fourth protective layer in the preparation area, wherein the fourth protective layer covers the sidewalls of the second trench and exposes the bottom of the second trench;

[0036] S1203, performing isotropic etching on the bottoms of the two second trenches to form a second bottom cavity;

[0037] S1204, performing a fourth thermal oxidation to oxidize the two second bottom cavities, so that the silicon between the two second bottom cavities of the second trench pair is oxidized into silicon oxide;

[0038] S1205, removing the third protective layer and the fourth protective layer;

[0039] S1206 , performing a fifth thermal oxidation, so that the silicon material between the two second trenches of the second trench pair is partially oxidized into silicon oxide, and the remaining silicon material forms a silicon core ring.

[0040] In one embodiment of the present invention, the method further includes forming a first straight waveguide and forming a second straight waveguide after forming the resonant microring waveguide;

[0041] The forming of the second straight waveguide comprises: filling silicon dioxide in step S13 to form a through hole according to the size of the second straight waveguide, and growing silicon material in the through hole to form the second straight waveguide;

[0042] The forming of the first straight waveguide includes: using a chemical mechanical polishing process to flatten the surface of the silicon substrate away from the resonant microring waveguide to form a flattened surface, wherein the silicon dioxide layer is completely exposed in the stacking area of the flattened surface and the resonant microring waveguide;

[0043] forming a silicon material layer on the planarized surface, and forming a silicon dioxide layer on a side of the silicon material layer away from the resonant microring waveguide;

[0044] forming the second straight waveguide by photolithography according to a preset size of the second straight waveguide;

[0045] The distance from the center of the circular section of the resonant microring waveguide to the first straight waveguide is equal to the distance from the center of the circular section of the resonant microring waveguide to the second straight waveguide; the second straight waveguide is close to the surface of the first straight waveguide, and the distance between the second straight waveguide and the first straight waveguide is less than (R1'+R2') / 3.

[0046] In one embodiment of the present invention, the depth of the first trench on the silicon substrate is 3×R2′ to 6×R2′; the distance between two first trenches is 3×R2′ to 6×R2′;

[0047] The depth of the second trench on the silicon filling body is 3×R2′ to 6×R2′; the distance between two second trenches is 3×R2′ to 6×R2′;

[0048] The distance between the surface of the silicon filler and the silicon dioxide core column is 1.5 to 3 times the thickness of the resonant micro-ring waveguide to be prepared, and the thickness of the resonant micro-ring waveguide to be prepared is (R2'-R1').

[0049] In one embodiment of the present invention, the first protective layer and the third protective layer each include a silicon nitride layer and an ethyl orthosilicate layer stacked in sequence, the ethyl orthosilicate layer being located on a side of the silicon nitride layer away from the silicon substrate; a silicon dioxide layer is disposed between the first protective layer and the silicon substrate, and between the third protective layer and the silicon filler;

[0050] The second protective layer and the fourth protective layer are silicon nitride layers.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1. The three-dimensional optical filter device provided by the present invention vertically positions a second straight waveguide above a first straight waveguide. The process of transmitting an optical signal from the first straight waveguide to the second straight waveguide is the process of achieving vertical optical coupling. The three-dimensional optical filter device utilizes a resonant microring waveguide vertically positioned above the first straight waveguide. Based on the principle of microring resonance, resonant filtering is achieved, enabling the three-dimensional optical filter device to integrate vertical optical coupling and optical signal filtering functions in three dimensions. The three-dimensional optical filter device has a high degree of integration, eliminating the need for additional coupling connection structures. This reduces the number of components in the three-dimensional optoelectronic system, improves the integration of the optical interconnect system, and facilitates large-scale optical communications.

[0053] 2. The method for preparing a three-dimensional optical filter device provided by the present invention constructs a vertical resonant microring waveguide in a three-dimensional space through multiple thermal oxidation, etching and growth of the required material layers, and integrates it with the first straight waveguide and the second straight waveguide to achieve the filtering and coupling functions of the optical signal, providing a new idea for the preparation method of the three-dimensional optical interconnection device structure.

[0054] 3. In the preparation method provided by the present invention, thermal oxidation stress plasticity and epitaxial growth processes are used to prepare the silica core column and the silicon core ring, which reduces the difficulty of etching, improves the roundness consistency and dimensional accuracy of the prepared resonant microring waveguide, and thus improves the transmission performance of the three-dimensional optoelectronic integrated system.

[0055] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The accompanying drawings are incorporated into and constitute a part of this specification, illustrate embodiments consistent with the present invention, and together with the description, serve to explain the principles of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and it is clear that those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0057] Figure 1 This is a schematic diagram of the three-dimensional structure of a three-dimensional optical filter device capable of achieving vertical light coupling in one embodiment of the present invention;

[0058] Figure 2 A schematic cross-sectional structure diagram corresponding to step S1 in a method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0059] Figure 3 A schematic cross-sectional structure diagram corresponding to step S2 of the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0060] Figure 4A schematic cross-sectional structure diagram corresponding to step S3 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0061] Figure 5 A schematic cross-sectional structure diagram corresponding to step S4 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0062] Figure 6 A schematic cross-sectional structure diagram corresponding to step S5 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0063] Figure 7 A schematic cross-sectional structure diagram corresponding to step S6 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0064] Figure 8 A schematic cross-sectional structure diagram corresponding to step S7 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0065] Figure 9 A schematic cross-sectional structure diagram corresponding to step S8 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0066] Figure 10 A schematic cross-sectional structure diagram corresponding to step S9 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0067] Figure 11 A schematic cross-sectional structure diagram corresponding to step S10 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0068] Figure 12 A schematic cross-sectional structure diagram corresponding to step S11 in a method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0069] Figure 13 A schematic cross-sectional structure diagram corresponding to step S12 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0070] Figure 14 A schematic diagram of the three-dimensional structure corresponding to step S131 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0071] Figure 15 A schematic diagram of the three-dimensional structure corresponding to step S132 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0072] Figure 16 A schematic diagram of the three-dimensional structure corresponding to step S133 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0073] Figure 17 A schematic diagram of the three-dimensional structure corresponding to step S134 in the method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling provided by an embodiment of the present invention;

[0074] Figure 18 A schematic structural diagram of a three-dimensional optoelectronic integrated system in one embodiment of the present invention;

[0075] Figure 19 This is a schematic diagram of a three-dimensional optical filter device capable of achieving vertical optical coupling in one embodiment of the present invention;

[0076] Figure 20 This is an output power spectrum diagram of a three-dimensional optical filter device in one embodiment of the present invention.

[0077] The reference numerals are as follows:

[0078] 1-first straight waveguide, 2-resonant microring waveguide, 3-second straight waveguide, 4-silicon substrate, 10-first silicon dioxide layer, 11-first protective layer, 12-first groove, 13-second protective layer, 14-first bottom chamber, 15-silicon core column, 16-silicon dioxide core column, 20-second silicon dioxide layer, 21-third protective layer, 22-silicon core ring, 23-second groove, 24-second bottom chamber, 25-fifth protective layer, 30-optical transmitter, 40-optical receiver, MRR1-first three-dimensional optical filter device, MRR2-second three-dimensional optical filter device, X1-first direction, X2-second direction, X3-third direction. DETAILED DESCRIPTION

[0079] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent identical or similar structures, and thus their detailed description will be omitted. Furthermore, the figures are merely schematic illustrations of the present invention and are not necessarily drawn to scale.

[0080] The terms "a", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express open-ended inclusion and mean that additional elements / components / etc. may be present in addition to the listed elements / components / etc.; the terms "first", "second" and "third" etc. are used only as labels and are not intended to limit the quantity of their objects.

[0081] The term “normal extension direction of the first straight waveguide” means: perpendicular to the upper surface of the first straight waveguide in the present invention and perpendicular to the light propagation direction of the first straight waveguide.

[0082] The term “width of the resonant microring waveguide” means the axial dimension of the resonant microring waveguide.

[0083] The embodiment of the present invention provides a three-dimensional optical filter device capable of realizing vertical light coupling, such as Figure 1 As shown, the three-dimensional optical filter device includes: a first straight waveguide 1 extending along a first direction X1; a resonant microring waveguide 2 disposed on one side of the first straight waveguide 1 along a third direction X3, the third direction X3 being the normal extension direction of the first straight waveguide 1; the axial direction of the resonant microring waveguide 2 is parallel to the second direction X2; the second direction X2 and the first direction X1 are perpendicular to each other and both perpendicular to the third direction X3; and a second straight waveguide 3 extending along the third direction X3. The distance from the center of the circular cross section of the resonant microring waveguide 2 to the first straight waveguide 1 is equal to the distance from the center of the circular cross section of the resonant microring waveguide 2 to the second straight waveguide 3; the end face of the second straight waveguide 3 on the side close to the first straight waveguide 1 is less than (R1+R2) / 3 from the first straight waveguide 1, where R1 is the inner ring radius of the resonant microring waveguide 2 and R2 is the outer ring radius of the resonant microring waveguide 2.

[0084] Specifically, the three-dimensional optical filter device includes a first straight waveguide 1 at the bottom, a resonant microring waveguide 2 vertically disposed above the first straight waveguide, with the circular cross-section of the resonant microring waveguide 2 perpendicular to the upper surface of the first straight waveguide; and a second straight waveguide 3 vertically disposed above the first straight waveguide 1 and adjacent to the resonant microring waveguide 2. The bottom of the second straight waveguide 3 does not intersect with the first straight waveguide 1, which helps reduce optical loss during optical transmission. When transmitting an optical signal, the first straight waveguide 1 couples the optical signal into the microring by optically coupling with the resonant microring waveguide 2 within a very narrow wavelength range. When transmitting an optical signal, the three-dimensional optical filter device, by designing the radius of the resonant microring waveguide 2 to meet the microring resonance principle, can generate a light wave of the desired wavelength, thereby achieving frequency-selective filtering of the optical signal. The second straight waveguide 3 can optically couple with the resonant microring waveguide 2 within a very narrow wavelength range, transferring the filtered light wavelength in the resonant microring waveguide 2 to the second straight waveguide 3 for transmission to the optical receiving end. In this way, the 3D optical filter device vertically positions the second straight waveguide 3 above the first straight waveguide 1. Transmitting the optical signal from the first straight waveguide 1 to the second straight waveguide 3 effectively transforms the optical path from horizontal to vertical. The 3D optical filter device utilizes a resonant microring waveguide 2 vertically positioned above the first straight waveguide 1. Based on the principle of microring resonance, resonant filtering is achieved, enabling the 3D optical filter device to integrate vertical optical coupling and optical signal filtering in three dimensions.

[0085] In this embodiment, the second straight waveguide 3 acts as an optical TSV, a through-hole for transmitting light. In practical designs, efficient optical filtering and steering can be achieved by adjusting the size of the resonant microring based on the principle of microring resonance. Thus, the three-dimensional optical filtering device provided by the embodiments of the present invention transcends the design limitations of traditional two-dimensional planar optical filters, integrating vertical optical coupling and optical filtering in three dimensions. This reduces the number of components in a three-dimensional optoelectronic system, improves system integration, and facilitates large-scale optical communications.

[0086] In one example, the microring resonance formula can be used: , determine the radius of the resonant microring waveguide 2, where is the effective refractive index of the resonant microring waveguide 2, is the radius of the resonant microring waveguide 2, , is the resonant wavelength ， is the microring resonance order ( In this way, the radius of the resonant micro-ring waveguide 2 can be selected according to the filtering wavelength to achieve light filtering and light steering.

[0087] For example, the height of the first straight waveguide 1 in the third direction X3 is 0.34 microns, and the width of the first straight waveguide 1 in the second direction X2 is 0.32 microns. The width of the second straight waveguide 3 in the second direction X2 is 0.32 microns, and the height of the second straight waveguide 3 in the first direction X1 is 0.34 microns. The microring radius of the circular cross-section of the resonant microring waveguide 2 is 1.467 microns, the width of the resonant microring waveguide 2 in the second direction X2 is 0.04 microns, and the number of microring resonances is 16. The distance from the outer edge of the circular cross-section of the resonant microring waveguide 2 to the first straight waveguide 1 and the distance from the outer edge of the circular cross-section of the resonant microring waveguide 2 to the second straight waveguide 3 are both 0.04 microns. The second straight waveguide 3 is close to the end face of the first straight waveguide 1, and the distance between the second straight waveguide 3 and the first straight waveguide 1 is 0.978 microns.

[0088] In one embodiment of the present invention, the first straight waveguide 1, the resonant microring waveguide 2, and the second straight waveguide 3 are made of a first material; the first straight waveguide 1, the resonant microring waveguide 2, and the second straight waveguide 3 are all covered with a second material; and the refractive index of the first material is greater than the refractive index of the second material. It should be noted that Figure 1 Only the first straight waveguide 1, the resonant microring waveguide 2, and the second straight waveguide 3 are illustrated, and the first straight waveguide 1, the resonant microring waveguide 2, and the second straight waveguide 3 are not illustrated as being covered with the second material.

[0089] Exemplarily, the first material is silicon material, and the second material is silicon dioxide (SiO 2 ) material.

[0090] The embodiment of the present invention also provides a method for preparing the above-mentioned three-dimensional optical filter device capable of realizing vertical optical coupling, such as Figure 2-Figure 14 As shown, the method includes preparing a resonant microring waveguide in a preparation area corresponding to the resonant microring waveguide to be prepared; wherein the method includes:

[0091] S1, such as Figure 2 As shown, a silicon substrate 4 is obtained, and a first protective layer 11 is formed on one side of the silicon substrate 4 .

[0092] Exemplarily, the first protective layer 11 includes a silicon nitride (SiN) layer and a tetraethyl orthosilicate (TEOS) layer stacked sequentially on one side of the silicon substrate 4. Furthermore, a first silicon dioxide layer 10 is disposed between the first protective layer 11 and the silicon substrate 4. The thermal expansion coefficients of SiN and the silicon substrate 4 differ significantly, and direct deposition of SiN may cause interfacial stress, leading to cracking or warping. The thermal expansion coefficient of SiO2 is between that of Si and SiN, and thus serves as a buffer layer to reduce stress.

[0093] S2, such as Figure 3As shown, a first groove pair corresponding to the resonant microring waveguide to be prepared is formed in the preparation area, and the first groove pair includes two first grooves 12 arranged in parallel; wherein, along the axial direction parallel to the resonant microring waveguide to be prepared, the size of the first groove 12 is greater than the width of the resonant microring waveguide to be prepared; the depth of the first groove 12 on the silicon substrate 4 is at least 3×R2', and the distance between the two first grooves 12 is greater than 3×R2', where R2' is the outer ring radius of the resonant microring waveguide to be prepared.

[0094] In S2, as Figure 3 As shown, the distance between the two first trenches 12 is L, where L is the thickness of the silicon material between the two first trenches 12. To allow for margin in the subsequent thermal oxidation process, L should be at least three times the outer ring radius of the resonant microring waveguide to be fabricated. Furthermore, 3×R2′<L<6×R2′.

[0095] In one example, the depth of the first trench 12 on the silicon substrate 4 is 3×R2′ to 6×R2′.

[0096] Preferably, along the axial direction parallel to the resonant microring waveguide to be prepared, the size of the first groove 12 is 4×W1, where W1 is the width of the resonant microring waveguide to be prepared in the axial direction; the depth of the first groove 12 on the silicon substrate 4 is 4×R2′; and the distance L between the two first grooves 12 is 4×R2′.

[0097] S3, such as Figure 4 As shown, a second protective layer 13 is formed on the sidewalls of the two first trenches 12, and the second protective layer 13 exposes the bottom of the first trench 12. Exemplarily, the second protective layer 13 is a silicon nitride layer.

[0098] S4, such as Figure 5 As shown, the bottoms of the two first trenches 12 are isotropically etched to form a first bottom cavity 14 .

[0099] S5, see Figure 6 , a first thermal oxidation is performed to oxidize the two first bottom cavities 14, so that the silicon between the two first bottom cavities 14 of the first trench pair is oxidized to silicon dioxide. In this step, the first thermal oxidation uses dry oxygen oxidation to oxidize the silicon between the two first bottom cavities 14 at the bottom of the first trench 12 to silicon dioxide, thereby laterally connecting the two adjacent grooves and forming a continuous insulating layer, which provides a foundation for the subsequent preparation of the columnar silicon structure. The SiO2 generated by the dry oxygen oxidation method has high density and few interface defects. By controlling the oxidation time, insulating SiO2 can be formed in the bottom groove area.

[0100] S6, see Figure 7 , removing the first protective layer 11 and the second protective layer 13;

[0101] S7, see Figure 8 , a second thermal oxidation is performed so that the silicon material between the two first grooves 12 of the first groove pair is partially oxidized into silicon dioxide, and the remaining silicon material forms a silicon core column 15. The axis of the silicon core column 15 coincides with the axis of the resonant microring waveguide to be prepared, and the diameter of the silicon core column 15 is the same as the inner ring diameter of the resonant microring waveguide to be prepared. The second thermal oxidation in this step can be dry oxygen oxidation or wet oxygen oxidation. By utilizing the volume expansion effect of silicon during thermal oxidation (silicon is converted into silicon dioxide, and the volume expansion is greater than 2 times), the protruding structure between the two first grooves 12 plastically obtains a cylindrical shape. The diameter of the silicon core column 15 formed by the remaining silicon material can be accurately adjusted by the oxidation time, thereby improving the dimensional accuracy of the prepared resonant microring waveguide.

[0102] S8, see Figure 9 In the preparation area, the silicon dioxide is removed to expose the silicon core column 15.

[0103] S9, see Figure 10 , the prepared area is thermally oxidized for the third time, so that the silicon core column 15 is oxidized into a silicon dioxide core column 16.

[0104] S10, such as Figure 11 As shown, a silicon filler that completely covers the silicon dioxide core column 16 is formed in the preparation area, and the minimum distance between the surface of the silicon filler and the silicon dioxide core column 16 is 1.5 times the thickness of the resonant microring waveguide to be prepared. The thickness of the resonant microring waveguide to be prepared is (R2'-R1'), where R1' is the inner ring radius size of the resonant microring waveguide to be prepared.

[0105] In this step, a flat surface is formed by the silicon filler, which is used to form a resonant microring waveguide. To facilitate the subsequent formation of a silicon ring by thermal oxidation, the thickness of the silicon material needs to be left with a margin. The distance between the surface of the silicon filler and the silica core 16 is at least 1.5 times the thickness of the resonant microring waveguide 2 to be prepared. Furthermore, the distance between the surface of the silicon filler and the silica core 16 is 1.5 to 3 times the thickness of the resonant microring waveguide 2 to be prepared.

[0106] S11, such as Figure 12 As shown, a third protective layer 21 is formed in the preparation area corresponding to the resonant microring waveguide to be prepared. Exemplarily, the third protective layer 21 includes a silicon nitride layer (SiN) and a tetraethyl orthosilicate (TEOS) layer stacked sequentially on the surface of the silicon filler away from the silicon substrate 4. Furthermore, a second silicon dioxide layer 20 is provided between the third protective layer 21 and the surface of the silicon filler.

[0107] S12, such as Figure 13(Sectional view) and Figure 14 As shown in (stereoscopic view), a silicon core ring is prepared surrounding the silicon dioxide core column 16; the axis of the silicon core ring coincides with the axis of the resonant microring waveguide to be prepared, and the outer ring diameter of the silicon core ring is the same as the outer ring diameter of the resonant microring waveguide to be prepared.

[0108] In one example, thermal oxidation is used to form a silicon core ring surrounding the silicon dioxide core column 16. The process specifically includes the following steps S1201 to S1206.

[0109] S1201. Form a second trench pair in a preparation area corresponding to the resonant microring waveguide to be prepared. The second trench pair includes two parallel second trenches 23. Along an axial direction parallel to the resonant microring waveguide to be prepared, the second trenches 23 are larger than the width of the resonant microring waveguide to be prepared. The depth of the second trenches 23 on the silicon filler is at least 3×R2′, and the distance between the two second trenches 23 is greater than 3×R2′. It is understood that a partition wall is formed between the two second trenches 23, the silica core 16 is located within the partition wall, and the distance between the two second trenches 23 is equal to the thickness of the partition wall between the two second trenches 23.

[0110] Furthermore, the depth of the second trench 23 on the silicon filling body is 3×R2′ to 6×R2′; and the distance between two second trenches 23 is 3×R2′ to 6×R2′.

[0111] S1202: Form a fourth protective layer in the preparation area, where the fourth protective layer covers the sidewalls of the second trench 23 and exposes the bottom of the second trench 23. Exemplarily, the fourth protective layer is a silicon nitride layer.

[0112] S1203 , performing isotropic etching on the bottoms of the two second trenches 23 to form a second bottom cavity 24 .

[0113] S1204 , performing a fourth thermal oxidation to oxidize the two second bottom cavities 24 , so that the silicon between the two second bottom cavities 24 of the second trench pair is oxidized into silicon dioxide.

[0114] S1205 , removing the third protective layer 21 and the fourth protective layer.

[0115] S1206 , performing a fifth thermal oxidation, so that the silicon material between the two second trenches 23 of the second trench pair is partially oxidized into silicon dioxide, and the remaining silicon material forms the silicon core ring 22 .

[0116] S13, filling the preparation area with silicon dioxide to form a filling silicon dioxide surrounding the silicon core ring; etching the preparation area according to the preset width of the microring waveguide so that the silicon core ring is cut off to form a resonant microring waveguide.

[0117] In one example, step S13 includes steps S131 - S134.

[0118] S131. Refer to Figure 14 , fill the second trench 23 and the second bottom chamber 24 in the preparation area, so that the outside of the silicon core ring is all made of silica material. Define the silica surrounding the outside of the silicon core ring as the filled silica.

[0119] S132. Refer to Figure 15 , deposit the fifth protective layer 25 in the preparation area according to the width of the resonant micro - ring waveguide to be prepared. That is, along the axial extension direction of the resonant micro - ring waveguide to be prepared, the size of the resonant micro - ring waveguide 2 is the same as that of the fifth protective layer 25.

[0120] Exemplarily, the fifth protective layer 25 can be a SiN layer.

[0121] S133. Refer to Figure 16 , perform anisotropic etching on the preparation area, so that the silicon core ring 22 is cut off to obtain the resonant micro - ring waveguide 2 with the required size.

[0122] S134. Refer to Figure 17 , remove the fifth protective layer; at the axial two ends of the resonant micro - ring waveguide 2, grow SiO2 ( Figure 17 not shown in Figure 16 ). That is, after the etching in step S133, refer to

[0123] the right - hand view of

[0124] is in a "ji" - shaped form. A protrusion is formed in the width area of the resonant micro - ring waveguide 2, and steps are formed at the axial two ends of the resonant micro - ring waveguide 2. After removing the fifth protective layer in step S134, SiO2 is grown at the steps, so that the upper plane of the steps is flush with the upper surface of the width area of the resonant micro - ring waveguide 2.

[0125] In one embodiment of the present invention, it further includes forming the first straight waveguide 1 and forming the second straight waveguide 3 after forming the resonant micro - ring waveguide 2. Forming the second straight waveguide 3 includes: according to the size of the second straight waveguide 3, form through - holes in the filled silica in step S13, and grow silicon material in the through - holes to form the second straight waveguide 3.

[0126] Forming the first straight waveguide 1 includes the following steps: S100. Use a chemical - mechanical polishing process to perform surface planarization on the side of the silicon substrate 4 away from the resonant micro - ring waveguide 2 to form a planarized surface. Among them, the planarized surface and the stacked area of the resonant micro - ring waveguide are completely exposed to the silica layer; that is, after grinding off the silicon material in the stacked corresponding area of the resonant micro - ring waveguide 2, a flat silica surface (planarized surface) is exposed in the stacked area of the resonant micro - ring waveguide 2;

[0127] S200. Form a silicon material layer on the planarized surface, and form a silica layer on the side of the silicon material layer away from the resonant micro - ring waveguide 2;

[0126] S300, forming a second straight waveguide 3 by photolithography according to a preset size of the second straight waveguide;

[0127] The distance from the center of the circular section of the resonant microring waveguide 2 to the first straight waveguide 1 is equal to the distance from the center of the circular section of the resonant microring waveguide 2 to the second straight waveguide 3; the second straight waveguide 3 is close to the surface of the first straight waveguide 1, and the distance between the second straight waveguide 3 and the first straight waveguide 1 is less than (R1'+R2') / 3.

[0128] The embodiment of the present invention also provides a three-dimensional optoelectronic integrated system, such as Figure 18 As shown, the system comprises at least a first device layer and a second device layer which are stacked, and the first device layer and the second device layer are optically interconnected via at least one of the above-mentioned three-dimensional optical filter devices.

[0129] In one embodiment, the first device layer includes a first silicon substrate and multiple three-dimensional optical filter devices disposed on one side of the first silicon substrate. The second device layer includes a second silicon substrate and at least one set of optical receivers 40 and optical transmitters 30 disposed on a side of the second silicon substrate proximal to the three-dimensional optical filter devices. At least one of the optical receivers 40 and optical transmitters 30 is optically interconnected with a second straight waveguide in the three-dimensional optical filter device.

[0130] In one example, Figure 18 As shown, the three-dimensional optoelectronic integrated system includes a first silicon substrate and a second silicon substrate; a control circuit module and multiple three-dimensional optical filter devices are provided on one side of the first silicon substrate; the second silicon substrate is provided on the side of the three-dimensional optical filter device away from the first silicon substrate, and a signal storage and processing unit, an optical receiver 40, and an optical transmitter 30 are provided on the side of the second silicon substrate close to the first silicon substrate. Multiple groups of circuit units are provided on the side of the second silicon substrate away from the first silicon substrate, each group of circuit units including a first circuit unit and a second circuit unit. In the design of CMOS (complementary metal oxide semiconductor) circuits, different types of circuit types are formed between different bare chips. For example, Figure 18 As shown, the first circuit unit may be a digital circuit module, and the second circuit unit may be a second analog circuit module; or the first circuit unit may be a three-dimensional integrated circuit module, and the second circuit unit may be a first analog circuit module. Figure 18 In order to more clearly demonstrate the arrangement of the three-dimensional optical filter device in the three-dimensional optoelectronic integrated system, only a partial structure is schematically shown on the first silicon substrate.

[0131] The signal transmission process is described by taking the signal transmission process from the three-dimensional integrated circuit module to the first analog circuit module as an example. The data signal to be transmitted is first vertically transmitted from the three-dimensional integrated circuit module through a through-silicon via (TSV) to a signal storage and processing unit on the back side of the second silicon substrate. The signal storage and processing unit encodes and modulates the signal to be transmitted to form an electrical signal for driving the optical transmitter 30. The electrical signal is transmitted to the optical transmitter 30, which converts the electrical signal into an optical signal of a specific wavelength and transmits it to the second straight waveguide 3 of the first three-dimensional optical filter device MRR1. The optical signal is then coupled to the resonant microring waveguide 2 of the first three-dimensional optical filter device MRR1, where the optical signal of the specific wavelength is transmitted to the first straight waveguide 1 of the first three-dimensional optical filter device MRR1 through resonance. The optical signal is transmitted counterclockwise in the first straight waveguide 1 and reaches the receiving end. The optical signal is then resonated and filtered again by the resonant microring waveguide 2 of the second three-dimensional optical filter device MRR2, coupled into the second straight waveguide 3 of the second three-dimensional optical filter device MRR2, and then transmitted to the optical receiver 40. The optical receiver 40 converts the received optical signal into an electrical signal and outputs it to the first analog circuit module, completing the signal transmission. In this way, the entire three-dimensional optoelectronic integrated system can simultaneously realize the optical vertical coupling and optical path filtering functions of optical interconnect devices, with high integration and convenient for large-scale optical path design.

[0132] The filtering function and steering function of the three-dimensional optical filter device provided by the present invention are further described below through specific embodiments.

[0133] like Figure 19As shown, a three-dimensional microring resonant optical filter device was simulated and tested for steering efficiency and optical filtering efficiency based on a central wavelength of 1.550 microns and a resonance order of 16. In this embodiment, the width W1 of the first straight waveguide 1 in the second direction X2 is 0.32 microns, and the height H1 of the first straight waveguide 1 in the third direction X3 is 0.34 microns. The width W2 of the second straight waveguide 3 in the second direction X2 is 0.32 microns, and the height H2 of the second straight waveguide 3 in the first direction X1 is 0.34 microns. The radius R of the resonant microring waveguide 2 is set to 1.467 microns, R = R1 + (R2 - R1) / 2 = 0.5 × (R1 + R2), where R1 is the inner ring radius of the resonant microring waveguide 2 and R2 is the outer ring radius of the resonant microring waveguide 2. The resonance order is 16, and the width of the resonant microring waveguide 2 (the dimension in the second direction X2) is the same as the height H1 of the first straight waveguide 1 in the third direction X3. The gap Gap between the outer ring surface of the resonant micro-ring waveguide 2 and the upper surface of the first straight waveguide 1 is 0.04 microns, and the gap Gap between the outer ring surface of the resonant micro-ring waveguide 2 and the second straight waveguide 3 is 0.04 microns. The distance between the bottom surface of the second straight waveguide 3 and the upper surface of the first straight waveguide 1 is one-third of the diameter of the resonant micro-ring waveguide 2 (the diameter is 2R, 2R=R1+R2). The first straight waveguide 1, the resonant micro-ring waveguide 2, and the second straight waveguide 3 are made of silicon material with a refractive index n1 of 3.476. The outer sides of the first straight waveguide 1, the resonant micro-ring waveguide 2, and the second straight waveguide 3 are all covered with silicon dioxide material with a refractive index n2 of 1.444. Figure 19 As shown in FIG, a detector Monitor 5 is set at the input port of the input optical signal of the first straight waveguide 1 to detect the input optical signal; a detector Monitor 6 is set at the output port of the transmitted optical signal of the first straight waveguide 1 to detect the optical signal not absorbed by the resonant microring waveguide 2; a detector Monitor 7 is set at the output port of the resonant optical signal of the second straight waveguide 3 to detect the optical signal with a wavelength matching the resonant microring waveguide 2. The simulation is performed in the frequency domain, and the output power spectrum obtained by the simulation is shown in FIG. Figure 20 shown.

[0134] from Figure 20 It can be observed that there is an absorption peak near the central wavelength λ of 1.55 microns. When the resonance condition is not met, the light intensity at the output end (drop port) of the second straight waveguide 3 (optical TSV) is lower than the light intensity at the output end (through port) of the first straight waveguide 1. That is, the structure is similar to a bandpass filter near the resonance frequency and has a frequency-selective filtering function. Figure 20The insertion loss (LS) at a wavelength of 1.55 μm is only 2.51 dB. The two adjacent resonant peak absorption wavelengths are 1.49 μm and 1.55 μm, respectively, resulting in a free spectrum width (FSR) of 0.055 μm. Calculations based on test data at 1.55 μm reveal an extinction ratio (ER) of 8.38 dB, a 3dB bandwidth (BW) of approximately 0.014 μm, and a Q (quality factor) of approximately 110.7.

[0135] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A three-dimensional optical filter device capable of realizing vertical optical coupling, characterized in that: include: A first straight waveguide (1) extending along a first direction (X1); A resonant micro-ring waveguide (2) is arranged on one side of the first straight waveguide (1) along a third direction (X3), wherein the third direction (X3) is a normal extension direction of the first straight waveguide (1); the axial direction of the resonant micro-ring waveguide (2) is parallel to the second direction (X2); the second direction (X2) and the first direction (X1) are perpendicular to each other and are both perpendicular to the third direction (X3); a second straight waveguide (3) extending along a third direction (X3); The distance from the center of the circular section of the resonant micro-ring waveguide (2) to the first straight waveguide (1) is equal to the distance from the center of the circular section of the resonant micro-ring waveguide (2) to the second straight waveguide (3); The second straight waveguide (3) is close to the end face of one side of the first straight waveguide (1), and the distance between the second straight waveguide (3) and the first straight waveguide (1) is less than (R1+R2) / 3, wherein R1 is the inner ring radius of the resonant micro-ring waveguide (2), and R2 is the outer ring radius of the resonant micro-ring waveguide (2).

2. The three-dimensional optical filter device capable of realizing vertical optical coupling according to claim 1, characterized in that: The materials of the first straight waveguide (1), the resonant microring waveguide (2), and the second straight waveguide (3) are a first material, and the first straight waveguide (1), the resonant microring waveguide (2), and the second straight waveguide (3) are all coated with a second material; the refractive index of the first material is greater than the refractive index of the second material.

3. The three-dimensional optical filter device capable of realizing vertical optical coupling according to claim 2, characterized in that: The first material is silicon material, and the second material is silicon dioxide material.

4. A three-dimensional optoelectronic integrated system, characterized in that: The device comprises at least a first device layer and a second device layer which are stacked, wherein the first device layer and the second device layer are optically interconnected via at least one three-dimensional optical filter device capable of realizing vertical optical coupling according to any one of claims 1 to 3.

5. The three-dimensional optoelectronic integrated system according to claim 4, characterized in that: The first device layer includes a first silicon substrate, and a plurality of three-dimensional optical filter devices arranged on one side of the first silicon substrate; The second device layer includes a second silicon substrate, and at least one group of light receivers (40) and light emitters (30) arranged on a side of the second silicon substrate close to the three-dimensional optical filter device; At least one of the optical receiver (40) and the optical transmitter (30) is optically interconnected with the second straight waveguide (3) in the three-dimensional optical filter device.

6. A method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling according to any one of claims 1 to 3, characterized in that: The method comprises preparing a resonant microring waveguide (2) in a preparation area corresponding to the resonant microring waveguide to be prepared; wherein preparing the resonant microring waveguide (2) in the preparation area corresponding to the resonant microring waveguide to be prepared comprises: S1. Obtain a silicon substrate (4), and form a first protective layer (11) on one side of the silicon substrate (4); S2. forming a first groove pair corresponding to the resonant microring waveguide to be prepared in the preparation area, the first groove pair comprising two first grooves (12) arranged in parallel; wherein, along the axial direction parallel to the resonant microring waveguide to be prepared, the size of the first groove (12) is greater than the width of the resonant microring waveguide to be prepared; the depth of the first groove (12) on the silicon substrate (4) is at least 3×R2′, and the distance between the two first grooves (12) is greater than 3×R2′, where R2′ is the outer ring radius of the resonant microring waveguide to be prepared; S3, forming a second protective layer (13) on the sidewalls of the two first trenches (12), wherein the second protective layer (13) exposes the bottom of the first trench (12); S4, isotropically etching the bottoms of the two first trenches (12) to form a first bottom chamber (14); S5, performing a first thermal oxidation to oxidize the two first bottom chambers (14), so that the silicon between the two first bottom chambers (14) of the first trench pair is oxidized into silicon dioxide; S6, removing the first protective layer (11) and the second protective layer (13); S7, performing a second thermal oxidation, so that the silicon material between the two first grooves (12) of the first groove pair is partially oxidized into silicon dioxide, and the remaining silicon material forms a silicon core column (15), the axis of the silicon core column (15) coincides with the axis of the resonant microring waveguide to be prepared, and the diameter of the silicon core column (15) is the same as the inner ring diameter of the resonant microring waveguide to be prepared; S8, in the preparation area, removing silicon dioxide to expose the silicon core column (15); S9, performing a third thermal oxidation on the preparation area, so that the silicon core column (15) is oxidized into a silicon dioxide core column (16); S10, forming a silicon filler that completely covers the silicon dioxide core column (16) in the preparation area, wherein the minimum distance between the surface of the silicon filler and the silicon dioxide core column (16) is 1.5 times the thickness of the resonant micro-ring waveguide to be prepared, and the thickness of the resonant micro-ring waveguide to be prepared is (R2'-R1'), wherein R1' is the inner ring radius size of the resonant micro-ring waveguide to be prepared; S11, sequentially forming a third protective layer (21) in the preparation area corresponding to the resonant microring waveguide to be prepared; S12, preparing a silicon core ring (22) surrounding the silicon dioxide core column (16); the axis of the silicon core ring (22) coincides with the axis of the resonant microring waveguide to be prepared, and the outer ring diameter of the silicon core ring (22) is the same as the outer ring diameter of the resonant microring waveguide to be prepared; S13, filling the preparation area with silicon dioxide to form a filling silicon dioxide surrounding the outside of the silicon core ring (22); etching the preparation area according to the preset width of the microring waveguide, so that the silicon core ring (22) is cut off to form a resonant microring waveguide (2).

7. The method for preparing a three-dimensional optical filter device capable of realizing vertical optical coupling according to claim 6, wherein: In step S12, preparing a silicon core ring (22) surrounding the silicon dioxide core column (16) includes the following steps: S1201, forming a second groove pair in a preparation area corresponding to the resonant microring waveguide to be prepared, the second groove pair comprising two second grooves (23) arranged in parallel; along an axial direction parallel to the resonant microring waveguide to be prepared, the size of the second groove (23) is greater than the width of the resonant microring waveguide to be prepared; the depth of the second groove (23) on the silicon filling body is at least 3×R2′, and the distance between the two second grooves (23) is greater than 3×R2′; S1202, forming a fourth protective layer in the preparation area, wherein the fourth protective layer covers the sidewalls of the second trench (23) and exposes the bottom of the second trench (23); S1203, performing isotropic etching on the bottoms of the two second trenches (23) to form a second bottom chamber (24); S1204, performing a fourth thermal oxidation to oxidize the two second bottom chambers (24), so that the silicon between the two second bottom chambers (24) of the second trench pair is oxidized into silicon oxide; S1205, removing the third protective layer (21) and the fourth protective layer; S1206, performing a fifth thermal oxidation, so that the silicon material between the two second trenches (23) of the second trench pair is partially oxidized into silicon oxide, and the remaining silicon material forms a silicon core ring (22).

8. The method for preparing a three-dimensional optical filter device capable of realizing vertical optical coupling according to claim 7, wherein: The method further includes forming a first straight waveguide (1) and a second straight waveguide (3) after forming the resonant microring waveguide (2); The forming of the second straight waveguide (3) comprises: filling silicon dioxide in step S13 to form a through hole according to the size of the second straight waveguide (3), and growing silicon material in the through hole to form the second straight waveguide (3); The forming of the first straight waveguide (1) comprises: using a chemical mechanical polishing process to flatten the surface of a silicon substrate (4) on a side away from the resonant microring waveguide (2) to form a flattened surface, wherein the silicon dioxide layer is completely exposed in the stacking area between the flattened surface and the resonant microring waveguide (2); forming a silicon material layer on the flattened surface, and forming a silicon dioxide layer on a side of the silicon material layer away from the resonant microring waveguide (2); Photolithographically forming the second straight waveguide (3) according to a preset size of the second straight waveguide (3); The distance from the center of the circular section of the resonant micro-ring waveguide (2) to the first straight waveguide (1) is equal to the distance from the center of the circular section of the resonant micro-ring waveguide (2) to the second straight waveguide (3); the second straight waveguide (3) is close to the surface of the first straight waveguide (1), and the distance between the second straight waveguide (3) and the first straight waveguide (1) is less than (R1'+R2') / 3.

9. The method for preparing a three-dimensional optical filter device capable of achieving vertical optical coupling according to claim 8, wherein: The depth of the first groove (12) on the silicon substrate (4) is 3×R2′ to 6×R2′; the distance between two first grooves (12) is 3×R2′ to 6×R2′; The depth of the second groove (23) on the silicon filling body is 3×R2′ to 6×R2′; the distance between two second grooves (23) is 3×R2′ to 6×R2′; The distance between the surface of the silicon filler and the silicon dioxide core column (16) is 1.5 to 3 times the thickness of the resonant micro-ring waveguide to be prepared, and the thickness of the resonant micro-ring waveguide to be prepared is (R2'-R1').

10. The method for preparing a three-dimensional optical filter device capable of realizing vertical optical coupling according to claim 8, wherein: The first protective layer (11) and the third protective layer (21) both comprise a silicon nitride layer and an ethyl orthosilicate layer stacked in sequence, the ethyl orthosilicate layer being located on a side of the silicon nitride layer away from the silicon substrate (4); a silicon dioxide layer is provided between the first protective layer (11) and the silicon substrate (4), and between the third protective layer (21) and the silicon filler; The second protective layer (13) and the fourth protective layer are silicon nitride layers.

Images