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

Abstract

The invention discloses a three-dimensional optical filter device capable of realizing light vertical coupling and a preparation method and system thereof, and the device comprises a first straight waveguide which extends along a first direction; the resonant micro-ring waveguide is arranged on one side of the first straight waveguide in the third direction; the axial direction of the resonant micro-ring 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; a second straight waveguide extending in a third direction; the distance from the circle center of the circular section of the resonant micro-ring waveguide to the first straight waveguide is equal to the distance from the circle center to the second straight waveguide; the distance between the end face of one side, close to the first straight waveguide, of the second straight waveguide and the first straight waveguide is smaller than (R1 + R2) / 3, R1 is the inner ring radius of the resonant micro-ring waveguide, and R2 is the outer ring radius of the resonant micro-ring waveguide. The three-dimensional optical filter provided by the invention is high in integration level, reduces the number of devices in a three-dimensional photoelectric system, and is beneficial to realizing large-scale optical communication.

Description

Technical Field

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

[0002] In the context of the rapid development of big data centers and high-performance computing technologies, due to the limitation of the electronic bottleneck, the traditional on-chip electrical interconnection technology is gradually unable to meet the requirements in terms of bandwidth and speed. In contrast, the on-chip optical interconnection technology exhibits great potential due to its advantages such as high speed, low power consumption, strong anti-interference ability, and high-density integration. In an on-chip optoelectronic integration system, three-dimensional on-chip optical interconnection can flexibly arrange optical devices between different layers, support complex routing layouts and dynamic configurations, and has higher integration, stronger adaptability, and broader application prospects.

[0003] In the design of three-dimensional on-chip electrical interconnection, the combination of TSV (through-silicon via), BGA (ball grid array), and microstrip lines can be used to meet the electrical interconnection communication between different layers. In the design of three-dimensional on-chip optical interconnection, when the transmission direction of light waves needs to change between layers, an interconnection structure with an optical vertical coupling function needs to be introduced. In an on-chip optoelectronic integration system, most of the methods for optical wave coupling and filtering are achieved by combining a grating with an optical via hole, or for optical wave coupling transmission, by coupling a grating with a grating in a three-dimensional layer. All of these methods for optical signal transmission in a three-dimensional layer introduce a grating structure, which occupies a large area on the chip and is not suitable for large-scale optical communication. For a three-dimensional optoelectronic hybrid system, the research on using a silicon substrate and an optical vertical coupling structure with appropriate size and applicable to inter-layer optical interconnection is crucial for improving the integration and communication capabilities of the system.

[0004] An optical filter is a key device in a three-dimensional optoelectronic integration system. Currently, the research on optical filters mainly focuses on two-dimensional planes, with emphasis on high-precision regulation, high-narrowband filtering, and integrated miniaturization design. During the design process of an optical interconnection structure, an optical vertical coupling device needs to be introduced again. For a three-dimensional integration system, reducing the number of involved devices is of great significance for improving the integration of the system, promoting the miniaturization of the system, and enhancing the overall performance of the system. At the same time, in a three-dimensional integration system, there are few implementation process schemes for three-dimensional optical interconnection structures and the difficulty is high, which further restricts the development of optical filters in three-dimensional integration systems.

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

[0006] The object of the present invention is to overcome the deficiencies of the above-mentioned prior art, and to provide a three-dimensional optical filtering device capable of realizing optical vertical coupling, a preparation method thereof, and a system. The technical problems to be solved by the present invention are realized through the following technical solutions: In a first aspect, the present invention provides a three-dimensional optical filtering device capable of realizing optical vertical coupling, comprising: a first straight waveguide extending along a first direction; a resonant micro-ring waveguide disposed on one side of the first straight waveguide along a third direction, the third direction being the normal extension direction of the first straight waveguide; the axial direction of the resonant micro-ring waveguide is parallel to a second direction; the second direction and the first direction are perpendicular to each other, and both are perpendicular to the third direction; a second straight waveguide extending along the third direction; the distance from the center of the circular cross-section of the resonant micro-ring waveguide to the first straight waveguide is equal to the distance from the center of the circular cross-section of the resonant micro-ring waveguide to the second straight waveguide; the distance between the end face on the side of the second straight waveguide close 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 micro-ring waveguide and R2 is the outer ring radius of the resonant micro-ring waveguide.

[0007] In an embodiment of the present invention, the materials of the first straight waveguide, the resonant micro-ring waveguide, and the second straight waveguide are a first material, and the first straight waveguide, the resonant micro-ring waveguide, and the second straight waveguide are all coated with a second material; the refractive index of the first material is greater than the refractive index of the second material.

[0008] In an embodiment of the present invention, the first material is a silicon material, and the second material is a silica material.

[0009] In a second aspect, the present invention provides a three-dimensional optoelectronic integration system, at least comprising a first device layer and a second device layer stacked, and optical interconnection is realized between the first device layer and the second device layer through at least one three-dimensional optical filtering device capable of realizing optical vertical coupling described in the first aspect above.

[0010] In an embodiment of the present invention, the first device layer includes a first silicon substrate and a plurality of three-dimensional optical filtering devices disposed on one side of the first silicon substrate; the second device layer includes a second silicon substrate, and a photoreceiver and a light emitter disposed on the side of the second silicon substrate close to the three-dimensional optical filtering device; at least one of the photoreceiver and the light emitter is optically interconnected with the second straight waveguide in the three-dimensional optical filtering device.

[0011] Thirdly, the present invention provides a method for manufacturing the above-mentioned three-dimensional optical filtering device capable of realizing optical vertical coupling, including manufacturing a resonant micro-ring waveguide in a manufacturing area corresponding to the resonant micro-ring waveguide to be manufactured; wherein, manufacturing a resonant micro-ring waveguide in a manufacturing area corresponding to the resonant micro-ring waveguide to be manufactured includes: S1. Obtain a silicon substrate and form a first protective layer on one side of the silicon substrate; S2. Form a first trench pair corresponding to the resonant micro-ring waveguide to be manufactured in the manufacturing area, the first trench pair includes two first trenches arranged in parallel; wherein, along the axial direction parallel to the resonant micro-ring waveguide to be manufactured, the size of the first trench is greater than the width of the resonant micro-ring waveguide to be manufactured; the depth of the first trench on the silicon substrate is at least 3×R2', the distance between the two first trenches is greater than 3×R2', and the R2' is the outer ring radius of the resonant micro-ring waveguide to be manufactured; S3. Form a second protective layer on the side walls of the two first trenches, and the second protective layer exposes the bottom of the first trench; S4. Perform isotropic etching on the bottoms of the two first trenches to form a first bottom chamber; S5. Perform the first thermal oxidation to oxidize the silicon between the two first bottom chambers of the first trench pair, so that the silicon between the two first bottom chambers of the first trench pair is oxidized into silicon dioxide; S6. Remove the first protective layer and the second protective layer; S7. Perform the second thermal oxidation, so that the silicon material between the two first trenches of the first trench pair is partially oxidized into silicon dioxide, and the remaining silicon material forms a silicon core column, the axis of the silicon core column coincides with the axis of the resonant micro-ring waveguide to be manufactured, and the diameter of the silicon core column is the same as the inner ring diameter of the resonant micro-ring waveguide to be manufactured; S8. In the manufacturing area, remove the silicon dioxide to expose the silicon core column; S9. Perform the third thermal oxidation on the manufacturing area, so that the silicon core column is oxidized into a silicon dioxide core column; S10. Form a silicon filling body that completely covers the silicon dioxide core column in the manufacturing area, the minimum distance between the surface of the silicon filling body and the silicon dioxide core column is 1.5 times the thickness of the resonant micro-ring waveguide to be manufactured, and the thickness of the resonant micro-ring waveguide to be manufactured is (R2'-R1'), wherein, R1' is the inner ring radius size of the resonant micro-ring waveguide to be manufactured; S11. Sequentially form a third protective layer in the manufacturing area corresponding to the resonant micro-ring waveguide to be manufactured; S12. Manufacture a silicon core ring surrounding the silicon dioxide core column; the axis of the silicon core ring coincides with the axis of the resonant micro-ring waveguide to be manufactured, and the outer ring diameter of the silicon core ring is the same as the outer ring diameter of the resonant micro-ring waveguide to be manufactured; S13. Fill the preparation area with silicon dioxide to form a silicon dioxide filling surrounding the outside of the silicon core ring; etch 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.

[0012] In an embodiment of the present invention, in step S12, preparing a silicon core ring surrounding the silicon dioxide core column includes the following steps: S1201. Form a second trench pair in the preparation area corresponding to the resonant microring waveguide to be prepared. The second trench pair includes two second trenches arranged in parallel; along the axial direction parallel to the resonant microring waveguide to be prepared, the size of the second trench is larger than the width of the resonant microring waveguide to be prepared; the depth of the second trench on the silicon filling body is at least 3×R2', and the distance between the two second trenches is greater than 3×R2'; S1202. Form a fourth protective layer in the preparation area. The fourth protective layer covers the side walls of the second trenches and exposes the bottoms of the second trenches; S1203. Perform isotropic etching on the bottoms of the two second trenches to form a second bottom chamber; S1204. Perform a fourth thermal oxidation to oxidize the silicon between the two second bottom chambers of the second trench pair, so that the silicon between the two second bottom chambers of the second trench pair is oxidized into silicon dioxide; S1205. Remove the third protective layer and the fourth protective layer; S1206. Perform a fifth thermal oxidation, so that the silicon material between the two second trenches of the second trench pair is partially oxidized into silicon dioxide, and the remaining silicon material forms a silicon core ring.

[0013] In an embodiment of the present invention, it further includes forming a first straight waveguide and forming a second straight waveguide after forming the resonant microring waveguide; The forming of the second straight waveguide includes: forming a through hole in the silicon dioxide filled in step S13 according to the size of the second straight waveguide, and growing silicon material in the through hole to form a second straight waveguide; The forming of the first straight waveguide includes: performing surface planarization on the side of the silicon substrate away from the resonant microring waveguide by using a chemical mechanical polishing process to form a planarized surface, wherein the planarized surface completely exposes the silicon dioxide layer in the stacked area with the resonant microring waveguide; Form a silicon material layer on the planarized surface, and form a silicon dioxide layer on the side of the silicon material layer away from the resonant microring waveguide; Lithographically form a second straight waveguide according to the preset size of the second straight waveguide; Wherein, the distance from the center of the circular cross-section of the resonant micro-ring waveguide to the first straight waveguide is equal to the distance from the center of the circular cross-section of the resonant micro-ring waveguide to the second straight waveguide; the distance between the surface of the second straight waveguide close to the first straight waveguide and the first straight waveguide is less than (R1'+R2') / 3.

[0014] In an embodiment of the present invention, the depth of the first trench in the silicon substrate is 3×R2' to 6×R2'; the distance between the two first trenches is 3×R2' to 6×R2'; The depth of the second trench in the silicon filling is 3×R2' to 6×R2'; the distance along between the two second trenches is 3×R2' to 6×R2'; The distance between the surface of the silicon filling and the silica core column is 1.5 times to 3 times the thickness of the to-be-prepared resonant micro-ring waveguide, and the thickness of the to-be-prepared resonant micro-ring waveguide is (R2'-R1').

[0015] In an embodiment of the present invention, both the first protective layer and the third protective layer include a silicon nitride layer and a tetraethyl orthosilicate layer stacked in sequence, and the tetraethyl orthosilicate layer is located on the side of the silicon nitride layer away from the silicon substrate; a silica layer is provided between the first protective layer and the silicon substrate, and between the third protective layer and the silicon filling; The second protective layer and the fourth protective layer are silicon nitride layers.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The three-dimensional optical filtering device provided by the present invention places the second straight waveguide vertically above the first straight waveguide, and the process of realizing the transmission of the optical signal from the first straight waveguide to the second straight waveguide is the process of completing optical vertical coupling. The three-dimensional optical filtering device uses a resonant micro-ring waveguide vertically placed above the first straight waveguide, and based on the micro-ring resonance principle, realizes resonant filtering, so that the three-dimensional optical filtering device integrates the functions of optical vertical coupling and optical signal filtering in the three-dimensional space. The three-dimensional optical filtering device has a high integration degree, does not need to set an additional coupling connection structure, reduces the number of devices in the three-dimensional optoelectronic system, improves the integration degree of the optical interconnection system, and is convenient for realizing large-scale optical communication.

[0017] 2. The preparation method of the three-dimensional optical filtering device provided by the present invention constructs a vertical resonant micro-ring waveguide in the three-dimensional space through multiple thermal oxidations, etching and growth of the required material layers, and integrates it with the first straight waveguide and the second straight waveguide to realize 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.

[0018] 3. In the preparation method provided by the present invention, the thermal oxidation stress plasticity and epitaxial growth processes are adopted for preparing the silica core column and the silicon core ring, which reduces the etching difficulty, improves the roundness consistency and dimensional accuracy of the prepared resonant micro-ring waveguide, and further improves the transmission performance of the three-dimensional optoelectronic integration system.

[0019] The present invention will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present invention, and are used together with the specification to explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0021] Figure 1 It is a schematic three-dimensional structure diagram of a three-dimensional optical filtering device capable of realizing optical vertical coupling in an embodiment of the present invention; Figure 2 It is a schematic cross-sectional structure diagram corresponding to step S1 in the preparation method of the three-dimensional optical filtering device capable of realizing optical vertical coupling provided by the embodiment of the present invention; Figure 3 It is a schematic cross-sectional structure diagram corresponding to preparation step S2 in the preparation method of the three-dimensional optical filtering device capable of realizing optical vertical coupling provided by the embodiment of the present invention; Figure 4 It is a schematic cross-sectional structure diagram corresponding to step S3 in the preparation method of the three-dimensional optical filtering device capable of realizing optical vertical coupling provided by the embodiment of the present invention; Figure 5 It is a schematic cross-sectional structure diagram corresponding to step S4 in the preparation method of the three-dimensional optical filtering device capable of realizing optical vertical coupling provided by the embodiment of the present invention; Figure 6 It is a schematic cross-sectional structure diagram corresponding to step S5 in the preparation method of the three-dimensional optical filtering device capable of realizing optical vertical coupling provided by the embodiment of the present invention; Figure 7 It is a schematic cross-sectional structure diagram corresponding to step S6 in the preparation method of the three-dimensional optical filtering device capable of realizing optical vertical coupling provided by the embodiment of the present invention; Figure 8 It is a schematic cross-sectional structure diagram corresponding to step S7 in the preparation method of the three-dimensional optical filtering device capable of realizing optical vertical coupling provided by the embodiment of the present invention; Figure 9 It is a schematic cross-sectional structure diagram corresponding to step S8 in the preparation method of the three-dimensional optical filtering device capable of realizing optical vertical coupling provided by the embodiment of the present invention; Figure 10Schematic cross-sectional structure diagram corresponding to step S9 in the preparation method of a three-dimensional optical filtering device capable of realizing optical vertical coupling provided by an embodiment of the present invention; Figure 11 Schematic cross-sectional structure diagram corresponding to step S10 in the preparation method of a three-dimensional optical filtering device capable of realizing optical vertical coupling provided by an embodiment of the present invention; Figure 12 Schematic cross-sectional structure diagram corresponding to step S11 in the preparation method of a three-dimensional optical filtering device capable of realizing optical vertical coupling provided by an embodiment of the present invention; Figure 13 Schematic cross-sectional structure diagram corresponding to step S12 in the preparation method of a three-dimensional optical filtering device capable of realizing optical vertical coupling provided by an embodiment of the present invention; Figure 14 Schematic three-dimensional structure diagram corresponding to step S131 in the preparation method of a three-dimensional optical filtering device capable of realizing optical vertical coupling provided by an embodiment of the present invention; Figure 15 Schematic three-dimensional structure diagram corresponding to step S132 in the preparation method of a three-dimensional optical filtering device capable of realizing optical vertical coupling provided by an embodiment of the present invention; Figure 16 Schematic three-dimensional structure diagram corresponding to step S133 in the preparation method of a three-dimensional optical filtering device capable of realizing optical vertical coupling provided by an embodiment of the present invention; Figure 17 Schematic three-dimensional structure diagram corresponding to step S134 in the preparation method of a three-dimensional optical filtering device capable of realizing optical vertical coupling provided by an embodiment of the present invention; Figure 18 Schematic structure diagram of a three-dimensional optoelectronic integration system in an embodiment of the present invention; Figure 19 Schematic diagram of a three-dimensional optical filtering device capable of realizing optical vertical coupling in an embodiment of the present invention; Figure 20 Output power spectrum diagram of a three-dimensional optical filtering device in an embodiment of the present invention.

[0022] Reference numerals are as follows: 1 - First straight waveguide, 2 - Resonant micro-ring waveguide, 3 - Second straight waveguide, 4 - Silicon substrate, 10 - First silicon dioxide layer, 11 - First protective layer, 12 - First trench, 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 trench, 24 - Second bottom chamber, 25 - Fifth protective layer, 30 - Optical transmitter, 40 - Optical receiver, MRR1 - First three-dimensional optical filtering device, MRR2 - Second three-dimensional optical filtering device, X1 - First direction, X2 - Second direction, X3 - Third direction. Detailed implementation manners

[0023] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. Like reference numerals in the figures denote like or similar structures, and thus their detailed description will be omitted. In addition, the drawings are only schematic illustrations of the present invention and are not necessarily drawn to scale.

[0024] The terms "a", "the", "said", and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "comprising" and "having" are used to mean an open inclusion and mean that there may be additional elements / components / etc. in addition to the listed elements / components / etc.; the terms "first", "second", "third", etc. are used only as labels and are not a limitation on the quantity of their objects.

[0025] The meaning of the term "the normal extension direction of the first straight waveguide" is: 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.

[0026] The meaning of "the width of the resonant micro-ring waveguide" is: the axial dimension along the resonant micro-ring waveguide.

[0027] An embodiment of the present invention provides a three-dimensional optical filtering device capable of realizing optical vertical coupling, as Figure 1 shown. The three-dimensional optical filtering device includes: a first straight waveguide 1 extending along a first direction X1; a resonant micro-ring waveguide 2 disposed on one side of the first straight waveguide 1 along a third direction X3, and the third direction X3 is the normal extension direction of the first straight waveguide 1; the axis of the resonant micro-ring waveguide 2 is parallel to a second direction X2; the second direction X2 and the first direction X1 are perpendicular to each other and both are perpendicular to the third direction X3; a second straight waveguide 3 extending along the third direction X3. Wherein, 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 distance between the end face of the second straight waveguide 3 on the side close to the first straight waveguide 1 and the first straight waveguide 1 is less than (R1 + R2) / 3, where 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.

[0028] That is to say, the three-dimensional optical filtering device includes a first straight waveguide 1 at the bottom, a resonant micro-ring waveguide 2 vertically arranged above the first straight waveguide, and the circular section of the resonant micro-ring waveguide 2 is perpendicular to the upper surface of the first straight waveguide; and a second straight waveguide 3 vertically arranged above the first straight waveguide 1 and beside the resonant micro-ring waveguide 2. The bottom of the second straight waveguide 3 does not intersect with the first straight waveguide 1, which is beneficial to reducing optical loss during optical signal transmission. When the first straight waveguide 1 transmits an optical signal, optical coupling is carried out with the resonant micro-ring waveguide 2 within a very small wavelength range, and the optical signal is coupled into the micro-ring. When the three-dimensional optical filtering device transmits an optical signal, when the micro-ring resonance principle is satisfied, by designing the radius size of the resonant micro-ring waveguide 2, light waves of the required wavelength can be obtained, and the frequency selection and filtering function of the optical signal can be completed. The second straight waveguide 3 can carry out optical coupling with the resonant micro-ring waveguide 2 within a very small wavelength range, transfer the filtered optical wavelength in the resonant micro-ring waveguide 2 to the second straight waveguide 3, and then transmit it to the optical receiving end. In this way, when the three-dimensional optical filtering device vertically places the second straight waveguide 3 above the first straight waveguide 1, the process of realizing the transmission of the optical signal from the first straight waveguide 1 to the second straight waveguide 3 is the process of completing the turning of the optical path from the horizontal direction to the vertical direction. The three-dimensional optical filtering device uses the resonant micro-ring waveguide 2 vertically placed above the first straight waveguide 1, and based on the micro-ring resonance principle, completes resonant filtering, enabling the three-dimensional optical filtering device to integrate the optical vertical coupling function and the optical signal filtering function in the three-dimensional space.

[0029] In this embodiment, the second straight waveguide 3 is equivalent to an optical TSV, an optical through-hole for transmitting light. In actual design, according to the micro-ring resonance principle, by adjusting the size of the resonant micro-ring, an efficient optical filtering function and an optical turning function can be realized. In this way, the three-dimensional optical filtering device provided by the embodiment of the present invention breaks through the design limitations of traditional two-dimensional planar optical filters, integrates optical vertical coupling and optical filtering functions in the three-dimensional space, reduces the number of devices in the three-dimensional optoelectronic system, improves the integration degree of the system, and is convenient for large-scale optical communication.

[0030] In one example, according to the micro-ring resonance formula: , the radius of the resonant micro-ring waveguide 2 can be determined, where is the effective refractive index of the resonant micro-ring waveguide 2, is the radius of the resonant micro-ring waveguide 2, , is the resonant wavelength ， is the micro-ring resonance order ( ). In this way, according to the filtering wavelength, the radius of the resonant micro-ring waveguide 2 that meets the requirements can be selected to realize optical filtering and optical turning.

[0031] Exemplarily, the height of the first straight waveguide 1 in the third direction X3 is 0.34 micrometers, and the width of the first straight waveguide 1 in the second direction X2 is 0.32 micrometers; the width of the second straight waveguide 3 in the second direction X2 is 0.32 micrometers, and the height of the second straight waveguide 3 in the first direction X1 is 0.34 micrometers. The micro-ring radius of the circular cross-section of the resonant micro-ring waveguide 2 is 1.467 micrometers, the width of the resonant micro-ring waveguide 2 in the second direction X2 is 0.04 micrometers, and the micro-ring resonance order is 16; the distance from the outer ring edge of the circular cross-section of the resonant micro-ring waveguide 2 to the first straight waveguide 1 and the distance from the outer ring edge of the circular cross-section of the resonant micro-ring waveguide 2 to the second straight waveguide 3 are both 0.04 micrometers; the distance between the end face of the second straight waveguide 3 close to the first straight waveguide 1 and the first straight waveguide 1 is 0.978 micrometers.

[0032] In an embodiment of the present invention, the materials of the first straight waveguide 1, the resonant micro-ring waveguide 2, and the second straight waveguide 3 are the first material; the outer surfaces of the first straight waveguide 1, the resonant micro-ring waveguide 2, and the second straight waveguide 3 are all coated with the second material; the refractive index of the first material is greater than that of the second material. It should be noted that Figure 1 only the first straight waveguide 1, the resonant micro-ring waveguide 2, and the second straight waveguide 3 are schematically shown, and the coating of the second material on the outer surfaces of the first straight waveguide 1, the resonant micro-ring waveguide 2, and the second straight waveguide 3 is not schematically shown.

[0033] Exemplarily, the first material is a silicon material, and the second material is a silicon dioxide (SiO2) material.

[0034] The embodiment of the present invention also provides a preparation method for the above-mentioned three-dimensional optical filtering device capable of realizing optical vertical coupling, as Figures 2 - 14 shown, including preparing a resonant micro-ring waveguide in the preparation area corresponding to the resonant micro-ring waveguide to be prepared; wherein, preparing a resonant micro-ring waveguide in the preparation area corresponding to the resonant micro-ring waveguide to be prepared includes: S1, as Figure 2 shown, obtaining a silicon substrate 4 and forming a first protective layer 11 on one side of the silicon substrate 4.

[0035] Exemplarily, the first protective layer 11 includes a silicon nitride layer (SiN) and a tetraethyl orthosilicate (TEOS) layer that are sequentially stacked on one side of the silicon substrate 4. Further, a first silicon dioxide layer 10 is provided between the first protective layer 11 and the silicon substrate 4. The thermal expansion coefficients of SiN and the silicon substrate 4 differ greatly, and directly depositing SiN may cause interfacial stress, resulting in cracking or warping. The thermal expansion coefficient of SiO2 is between that of Si and SiN and can be used as a buffer layer to reduce stress.

[0036] S2, as Figure 3As shown, a first trench pair corresponding to the resonant micro-ring waveguide to be fabricated is formed in the fabrication region. The first trench pair includes two first trenches 12 arranged in parallel; wherein, along the axial direction parallel to the resonant micro-ring waveguide to be fabricated, the size of the first trench 12 is greater than the width of the resonant micro-ring waveguide to be fabricated; the depth of the first trench 12 on the silicon substrate 4 is at least 3×R2', and the distance between the two first trenches 12 is greater than 3×R2', where R2' is the outer ring radius of the resonant micro-ring waveguide to be fabricated.

[0037] In S2, as Figure 3 shown, the distance between the two first trenches 12 is L, and L is the thickness of the silicon material between the two first trenches 12. Considering that a margin should be left for the thermal oxidation process in the subsequent process, L should be at least greater than three times the outer ring radius of the resonant micro-ring waveguide to be fabricated. Further, 3×R2' < L < 6×R2'.

[0038] In one example, the depth of the first trench 12 on the silicon substrate 4 is 3×R2' to 6×R2'.

[0039] Preferably, along the axial direction parallel to the resonant micro-ring waveguide to be fabricated, the size of the first trench 12 is 4×W1, where W1 is the width of the resonant micro-ring waveguide to be fabricated in the axial direction; the depth of the first trench 12 on the silicon substrate 4 is 4×R2'; the distance L between the two first trenches 12 is 4×R2'.

[0040] S3, as Figure 4 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.

[0041] S4, as Figure 5 shown, isotropic etching is performed on the bottoms of the two first trenches 12 to form a first bottom chamber 14.

[0042] S5, referring to Figure 6 , a first thermal oxidation is carried out to oxidize the silicon between the two first bottom chambers 14 of the first trench pair, so that the silicon between the two first bottom chambers 14 of the first trench pair is oxidized to silicon dioxide. In this step, the first thermal oxidation uses the dry oxygen oxidation method to oxidize the silicon between the two first bottom chambers 14 at the bottom of the first trench 12 to silicon dioxide, so that two adjacent grooves are laterally connected to form a continuous insulating layer, providing a basis for the preparation of the subsequent columnar silicon structure. The SiO2 generated by the dry oxygen oxidation method has a high density and few interface defects, and an insulating SiO2 can be formed in the bottom groove region by controlling the oxidation time.

[0043] S6, referring to Figure 7 , remove the first protective layer 11 and the second protective layer 13; S7. Refer to Figure 8 and perform a second thermal oxidation so that the silicon material between the two first trenches 12 of the first trench pair is partially oxidized to 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 micro-ring waveguide to be fabricated, and the diameter of the silicon core column 15 is the same as the inner ring diameter of the resonant micro-ring waveguide to be fabricated. The second thermal oxidation in this step can use dry oxygen oxidation or wet oxygen oxidation. Utilizing the volume expansion effect during the silicon thermal oxidation process (when silicon is converted to silicon dioxide, the volume expands by more than 2 times), the convex structure between the two first trenches 12 can obtain a cylindrical shape plastically, and the diameter of the silicon core column 15 formed by the remaining silicon material can be precisely adjusted by the oxidation time, improving the dimensional accuracy of the fabricated resonant micro-ring waveguide.

[0044] S8. Refer to Figure 9 and remove the silicon dioxide in the fabrication area to expose the silicon core column 15.

[0045] S9. Refer to Figure 10 and perform a third thermal oxidation on the fabrication area so that the silicon core column 15 is oxidized to a silicon dioxide core column 16.

[0046] S10. As shown in Figure 11 , form a silicon filling body that completely coats the silicon dioxide core column 16 in the fabrication area. The minimum distance between the surface of the silicon filling body and the silicon dioxide core column 16 is 1.5 times the thickness of the resonant micro-ring waveguide to be fabricated. The thickness of the resonant micro-ring waveguide to be fabricated is (R2' - R1'), where R1' is the inner ring radius dimension of the resonant micro-ring waveguide to be fabricated.

[0047] In this step, a flat surface is formed by the silicon filling body, and the silicon filling body is used to form the resonant micro-ring waveguide. To facilitate the subsequent formation of a silicon material ring through thermal oxidation, a margin needs to be left for the thickness of the silicon material. The distance between the surface of the silicon filling body and the silicon dioxide core column 16 is at least 1.5 times the thickness of the resonant micro-ring waveguide 2. Further, the distance between the surface of the silicon filling body and the silicon dioxide core column 16 is 1.5 - 3 times the thickness of the resonant micro-ring waveguide 2.

[0048] S11. As shown in Figure 12 , form a third protective layer 21 in the fabrication area corresponding to the resonant micro-ring waveguide to be fabricated. Exemplarily, the third protective layer 21 includes a silicon nitride layer (SiN) and a tetraethyl orthosilicate (TEOS) layer that are sequentially stacked on the side of the surface of the silicon filling body away from the silicon substrate 4. Further, a second silicon dioxide layer 20 is provided between the third protective layer 21 and the surface of the silicon filling body.

[0049] S12. As shown in Figure 13 (Cross-sectional view) and Figure 14(As shown in the perspective view), a silicon core ring surrounding the silica core column 16 is prepared; the axis of the silicon core ring coincides with the axis of the resonant micro-ring waveguide to be prepared, and the outer diameter of the outer ring of the silicon core ring is the same as the outer diameter of the outer ring of the resonant micro-ring waveguide to be prepared.

[0050] In one example, a silicon core ring surrounding the silica core column 16 is formed by thermal oxidation. Specifically, it includes the following steps S1201 to S1206.

[0051] S1201. A second trench pair is formed in the preparation area corresponding to the resonant micro-ring waveguide to be prepared. The second trench pair includes two second trenches 23 arranged in parallel; along the axial direction parallel to the resonant micro-ring waveguide to be prepared, the size of the second trench 23 is larger than the width of the resonant micro-ring waveguide to be prepared; the depth of the second trench 23 on the silicon filling body is at least 3×R2', and the distance between the two second trenches 23 is greater than 3×R2'. It can be understood that a partition wall is formed between the two second trenches 23, and the silica core column 16 is located inside the partition wall, and the distance between the two second trenches 23 is the thickness of the partition wall between the two second trenches 23.

[0052] Furthermore, the depth of the second trench 23 on the silicon filling body is 3×R2' to 6×R2'; the distance between the two second trenches 23 is 3×R2' to 6×R2'.

[0053] S1202. A fourth protective layer is formed in the preparation area. The fourth protective layer covers the side walls of the second trenches 23 and exposes the bottom of the second trenches 23. Exemplarily, the fourth protective layer is a silicon nitride layer.

[0054] S1203. Isotropic etching is performed on the bottoms of the two second trenches 23 to form a second bottom chamber 24.

[0055] S1204. The fourth thermal oxidation is performed to oxidize the silicon between the two second bottom chambers 24 of the second trench pair, so that the silicon between the two second bottom chambers 24 of the second trench pair is oxidized into silica.

[0056] S1205. The third protective layer 21 and the fourth protective layer are removed.

[0057] S1206. The fifth thermal oxidation is performed, so that the silicon material between the two second trenches 23 of the second trench pair is partially oxidized into silica, and the remaining silicon material forms a silicon core ring 22.

[0058] S13. The preparation area is filled with silica, so that the filled silica surrounding the silicon core ring is formed; according to the preset width of the micro-ring waveguide, the preparation area is etched, so that the silicon core ring is cut off to form a resonant micro-ring waveguide.

[0059] In one example, step S13 includes steps S131 - S134.

[0060] 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 silicon dioxide material. Define the silicon dioxide surrounding the outside of the silicon core ring as the filled silicon dioxide.

[0061] 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 the size of the fifth protective layer 25.

[0062] Exemplarily, the fifth protective layer 25 can be a SiN layer.

[0063] 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.

[0064] 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

[0065] the right - hand view of

[0066] 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. S200. Form a silicon material layer on the planarized surface and form a silicon dioxide layer on the side of the silicon material layer away from the resonant micro - ring waveguide 2; S300. Lithographically form the second straight waveguide 3 according to the preset size of the second straight waveguide. Wherein, the distance from the center of the circular cross-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 cross-section of the resonant micro-ring waveguide 2 to the second straight waveguide 3; the distance between the surface of the second straight waveguide 3 close to the first straight waveguide 1 and the first straight waveguide 1 is less than (R1'+R2') / 3.

[0067] The embodiment of the present invention also provides a three-dimensional optoelectronic integration system, as Figure 18 shown, the system at least includes a first device layer and a second device layer arranged in a stacked manner, and optical interconnection is realized between the first device layer and the second device layer through at least one of the above three-dimensional optical filtering devices.

[0068] In one embodiment, the first device layer includes a first silicon substrate and a plurality of three-dimensional optical filtering devices arranged on one side of the first silicon substrate. The second device layer includes a second silicon substrate and at least a group of optical receivers 40 and optical transmitters 30 arranged on the side of the second silicon substrate close to the three-dimensional optical filtering devices. At least one of the optical receivers 40 and the optical transmitters 30 is optically interconnected with the second straight waveguide in the three-dimensional optical filtering device.

[0069] In one example, as Figure 18 shown, the three-dimensional optoelectronic integration system includes a first silicon substrate and a second silicon substrate; a control circuit module and a plurality of three-dimensional optical filtering devices are arranged on one side of the first silicon substrate; the second silicon substrate is arranged on the side of the three-dimensional optical filtering device away from the first silicon substrate, a signal storage and processing unit, an optical receiver 40, and an optical transmitter 30 are arranged on the side of the second silicon substrate close to the first silicon substrate, and multiple groups of circuit units are arranged on the side of the second silicon substrate away from the first silicon substrate. Each group of circuit units includes a first circuit unit and a second circuit unit. For the design of CMOS (Complementary Metal Oxide Semiconductor) circuits, different types of circuit types are formed between different dies. For example, as Figure 18 shown, the first circuit unit can be a digital circuit module, and the second circuit unit can be a second analog circuit module; or the first circuit unit can be a three-dimensional integrated circuit module, and the second circuit unit can be a first analog circuit module. It should be noted that Figure 18 In order to more clearly show the setting manner of the three-dimensional optical filtering device in the three-dimensional optoelectronic integration system, only part of the structure is schematically shown on the first silicon substrate.

[0070] Taking the signal transmission process from a three-dimensional integrated circuit module to a first analog circuit module as an example, the signal transmission process is illustrated. The data signal to be transmitted first vertically transmits from the three-dimensional integrated circuit module to the signal storage and processing unit on the back of the second silicon substrate through a through-silicon via (TSV). The signal storage and processing unit encodes and modulates the signal to be transmitted to form an electrical signal that drives the optical transmitter 30. The electrical signal transmits to the optical transmitter 30, and the optical transmitter 30 converts the electrical signal into an optical signal with a specific wavelength and emits it to the second straight waveguide 3 of the first three-dimensional optical filtering device MRR1, and is coupled and transmitted to the resonant micro-ring waveguide 2 of the first three-dimensional optical filtering device MRR1. In the resonant micro-ring waveguide 2, the optical signal with the specific wavelength is transmitted to the first straight waveguide 1 of the first three-dimensional optical filtering device MRR1 through resonance. Transmitting counterclockwise in the first straight waveguide 1, when the optical signal reaches the receiving end, it resonantly filters through the resonant micro-ring waveguide 2 of the second three-dimensional optical filtering device MRR2 again, is coupled into the second straight waveguide 3 of the second three-dimensional optical filtering device MRR2, and is turned and 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 integration system can simultaneously realize the optical vertical coupling and optical path filtering functions of the optical interconnection device, with high integration and being convenient for large-scale optical path design.

[0071] The filtering function and turning function of the three-dimensional optical filtering device provided by the present invention are further illustrated through specific embodiments below.

[0072] As Figure 19As shown in the figure, the three-dimensional micro-ring resonator optical filtering device performs simulation detection on the 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 micro-ring 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 micro-ring waveguide 2 and R2 is the outer ring radius of the resonant micro-ring waveguide 2. The resonance order is taken as 16, and the width of the resonant micro-ring 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 distance 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 distance 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 coated with silica material with a refractive index n2 of 1.444. As Figure 19 shown, 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 through port of the transmitted optical signal of the first straight waveguide 1 to detect the optical signal not absorbed by the resonant micro-ring waveguide 2; a detector Monitor 7 is set at the drop port of the resonant optical signal of the second straight waveguide 3 to detect the optical signal matching the wavelength of the resonant micro-ring waveguide 2. Simulation is carried out in the frequency domain, and the output power spectrogram obtained by simulation is as Figure 20 shown.

[0073] 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 satisfied, 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) in the first straight waveguide 1. That is, this structure is similar to a band-pass filter near the resonance frequency and has a frequency selection filtering function. And, from Figure 20The insertion loss (LS) generated at a wavelength of 1.55 μm can be obtained to be only 2.51 dB. The absorption wavelengths of two adjacent resonant peaks are 1.49 μm and 1.55 μm respectively, that is, its free spectral range (FSR) reaches 0.055 μm. Taking the detection data at a wavelength of 1.55 μm for calculation, the extinction ratio (ER) reaches 8.38 dB, the 3 dB bandwidth (BW) is about 0.014 μm, and the obtained Q value (quality factor) is about 110.7.

[0074] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope 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 the direction in which the normal of the first straight waveguide (1) extends; 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 end face of the second straight waveguide (3) close to one side of the first straight waveguide (1) is at a distance less than (R1+R2) / 3 from the first straight waveguide (1), 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 the first material; the first straight waveguide (1), the resonant microring waveguide (2) and the second straight waveguide (3) are all coated with the second material; and 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 a silicon material, and the second material is a silicon dioxide material.

4. A three-dimensional optoelectronic integrated system, characterized in that: At least comprises 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 as claimed in 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 transmitters (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 filtering device.

6. A method for preparing a three-dimensional optical filter device capable of realizing vertical optical coupling according to any one of claims 1 to 3, characterized in that: The method comprises preparing a resonant micro-ring waveguide (2) in a preparation area corresponding to the resonant micro-ring waveguide to be prepared; wherein preparing the resonant micro-ring waveguide (2) in the preparation area corresponding to the resonant micro-ring waveguide to be prepared comprises: S1, obtaining a silicon substrate (4), and forming 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', the distance between the two first grooves (12) is greater than 3×R2', and R2' is the outer ring radius of the resonant microring waveguide to be prepared; S3, forming a second protective layer (13) on the side walls of the two first trenches (12), wherein the second protective layer (13) exposes the bottom of the first trenches (12); S4, isotropically etching the bottoms of the two first grooves (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 body that completely covers the silicon dioxide core column (16) in the preparation area, wherein the minimum distance between the surface of the silicon filler body 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, characterized in that: In step S12, preparing a silicon core ring (22) surrounding the silicon dioxide core column (16) comprises 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, isotropically etching the bottoms of the two second grooves (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, characterized in that: The method also 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 the silicon substrate (4) on a side away from the resonant microring waveguide (2) to form a flattened surface, wherein the stacking area between the flattened surface and the resonant microring waveguide (2) completely exposes the silicon dioxide layer; 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 realizing vertical optical coupling according to claim 8, characterized in that: 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, characterized in that: The first protective layer (11) and the third protective layer (21) both comprise a silicon nitride layer and an ethyl orthosilicate layer which are 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 disposed 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.

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