Three-dimensional waveguide crossing structure, preparation method and optical communication system
By adjusting the position of the waveguide layer in the three-dimensional waveguide cross structure to ensure that its power coupling completes an integer multiple of the coupling period, the problems of loss and crosstalk in three-dimensional wiring are solved, realizing high-density wiring and compatible fabrication processes, which are suitable for optical communication systems.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUHAN POST & TELECOMM RES INST CO LTD
- Filing Date
- 2026-04-20
- Publication Date
- 2026-06-05
AI Technical Summary
In three-dimensional routing, when the waveguide layer spacing is small, the three-dimensional cross structure leads to a significant increase in loss and crosstalk due to enhanced coupling, which limits the expansion of port size.
By adjusting the position of the first material waveguide layer relative to the second material waveguide layer in the three-dimensional waveguide cross structure, the power coupling at the cross port completes an integer multiple of the coupling period during propagation, thereby reducing loss and crosstalk.
It effectively reduces losses and crosstalk caused by enhanced coupling, supports the expansion of on-chip optical switching/interconnects from two-dimensional topology to three-dimensional topology, improves the wiring and device layout density per unit area, and the fabrication process is compatible with common silicon photonics/silicon nitride processes, making it suitable for wafer-level mass production.
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Figure CN122151284A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of integrated optics and silicon photonics, specifically to a three-dimensional waveguide cross structure, its fabrication method, and an optical communication system. Background Technology
[0002] With the development of data centers, high-performance computing, and on-chip optical switching and interconnects, silicon-based photonics integration has become an important platform due to its high integration density and compatibility with CMOS processes. In large-scale optical switching and dense cabling scenarios, two-dimensional planar waveguides inevitably generate a large number of waveguide crossings. Crossing insertion loss and crosstalk accumulate after multiple cascades, limiting the expansion of port size. Three-dimensional cabling can reduce the number of planar crossings through vertical layering.
[0003] However, when the waveguide layer spacing is small during three-dimensional wiring (e.g., less than 500 nm), the three-dimensional cross structure will result in a significant increase in loss and crosstalk due to enhanced coupling. Summary of the Invention
[0004] This invention provides a three-dimensional waveguide cross structure, a fabrication method, and an optical communication system, which can solve the problem that when the spacing between waveguide layers is small during three-dimensional wiring, the loss and crosstalk of the three-dimensional cross structure will increase significantly due to enhanced coupling.
[0005] In a first aspect, embodiments of the present invention provide a three-dimensional waveguide cross structure, comprising: Buried oxygen layer; A first material waveguide layer is disposed on one side of the buried oxide layer; A first silicon oxide capping layer is disposed on the side of the first material waveguide layer away from the buried oxide layer; A second material waveguide layer is disposed on the side of the first silicon oxide capping layer away from the first material waveguide layer; A second silicon oxide capping layer is disposed on the side of the second material waveguide layer away from the first silicon oxide capping layer; The effective coupling length of the overlapping region of the projection of the first material waveguide layer onto the second material waveguide layer satisfies:
[0006] In the formula: Indicates the effective coupling length. This represents the coupling wavelength, and the range of values for n is... to ,in It is an integer. It is a constant less than 1.
[0007] In conjunction with the first aspect, in one embodiment, the effective coupling length of the overlapping region of the projection of the first material waveguide layer onto the second material waveguide layer is calculated according to the following formula:
[0008] In the formula, Indicates the effective coupling length. This indicates the width of the first material waveguide layer. This represents the angle between the first material waveguide layer and the line perpendicular to the second material waveguide layer. This indicates the spacing between the first material waveguide layer and the second material waveguide layer. This indicates the thickness of the first material waveguide layer. This indicates the thickness of the second material waveguide layer.
[0009] In conjunction with the first aspect, in one embodiment, the angle between the first material waveguide layer and the straight line perpendicular to the second material waveguide layer is 60° to 80°.
[0010] In conjunction with the first aspect, in one embodiment, it further includes: a substrate disposed on the side of the buried oxide layer away from the first material waveguide layer.
[0011] In conjunction with the first aspect, in one embodiment, the effective refractive index of the first material waveguide layer and the second material waveguide layer is greater than the effective refractive index of the first silicon oxide capping layer.
[0012] In conjunction with the first aspect, in one embodiment, the first material waveguide layer is a silicon waveguide layer; and the second material waveguide layer is a silicon nitride waveguide layer.
[0013] In conjunction with the first aspect, in one embodiment, the thickness of the first material waveguide layer is 220 nm; the thickness of the second material waveguide layer is 400 nm to 800 nm.
[0014] In conjunction with the first aspect, in one embodiment, the spacing between the first material waveguide layer and the second material waveguide layer is between 150 nm and 500 nm.
[0015] Secondly, embodiments of the present invention provide a method for fabricating a three-dimensional waveguide cross structure, comprising the following steps: A first material waveguide layer is deposited on the buried oxide layer in a first preset shape; A first silicon oxide capping layer of a predetermined thickness is deposited on the first material waveguide layer to cover the first material waveguide layer; A second material waveguide layer is deposited on the first silicon oxide capping layer in a second preset shape; A second silicon oxide capping layer of a predetermined thickness is deposited on the second material waveguide layer to cover the second material waveguide layer.
[0016] Thirdly, embodiments of the present invention provide an optical communication system including the aforementioned three-dimensional waveguide cross structure.
[0017] The beneficial effects of the technical solutions provided by the embodiments of the present invention include: This invention discloses a three-dimensional waveguide cross structure, comprising: a buried oxide layer; a first material waveguide layer disposed on one side of the buried oxide layer; a first silicon oxide capping layer disposed on the side of the first material waveguide layer away from the buried oxide layer; a second material waveguide layer disposed on the side of the first silicon oxide capping layer away from the first material waveguide layer; and a second silicon oxide capping layer disposed on the side of the second material waveguide layer away from the first silicon oxide capping layer; wherein the effective coupling length of the overlapping region of the projection of the first material waveguide layer onto the second material waveguide layer satisfies: In the formula: λ represents the effective coupling length, and λ represents the coupling wavelength. Take the integer part. This invention adjusts the position of the first material waveguide layer relative to the second material waveguide layer so that the power coupling at the cross port of the three-dimensional waveguide cross structure completes an integer multiple of the coupling period during propagation, thereby reducing losses and crosstalk caused by enhanced coupling. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 This is a multi-angle simulation structure and cross-sectional schematic diagram of an embodiment of the three-dimensional waveguide cross structure of the present invention; Figure 2 This is a schematic diagram illustrating the design theory of the three-dimensional waveguide cross structure of the present invention; Figure 3 This is a top view of an embodiment of the three-dimensional waveguide cross structure of the present invention.
[0020] In the figure: 10, first material waveguide layer; 20, second material waveguide layer; 30, buried oxide layer; 40, first silicon oxide capping layer; 50, second silicon oxide capping layer; 60, substrate. Detailed Implementation
[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] In large-scale optical switching and dense cabling scenarios, existing technologies utilize three-dimensional optical cross-connect structures. Compared to two-dimensional planar structures, three-dimensional structures effectively avoid the intersection of different waveguide materials in a two-dimensional plane. However, if the spacing between different waveguide materials is too small, the coupling enhancement will lead to a significant increase in loss and crosstalk; while increasing the interlayer spacing between waveguide materials will introduce additional losses in interlayer transition or transition structures and reduce cabling space density.
[0023] like Figure 1 As shown, this embodiment of the invention discloses a three-dimensional waveguide cross structure, including: a buried oxide layer 30; a first material waveguide layer 10 disposed on one side of the buried oxide layer 30; a first silicon oxide capping layer 40 disposed on the side of the first material waveguide layer 10 away from the buried oxide layer 30; a second material waveguide layer 20 disposed on the side of the first silicon oxide capping layer 40 away from the first material waveguide layer 10; and a second silicon oxide capping layer 50 disposed on the side of the second material waveguide layer 20 away from the first silicon oxide capping layer 40. The effective coupling length of the overlapping region of the projection of the first material waveguide layer 10 onto the second material waveguide layer 20 satisfies: (Formula 1) In the formula: Indicates the effective coupling length. This represents the coupling wavelength, and the range of values for n is... to ,in It is an integer. It is a constant less than 1.
[0024] further, .
[0025] When the thickness between the first material waveguide layer 10 and the second material waveguide layer 20 in a three-dimensional waveguide cross structure is fixed, and the interlayer spacing between the first material waveguide layer 10 and the second material waveguide layer 20 is also fixed, the overlapping area of the projection of the first material waveguide layer 10 onto the second material waveguide layer 20 can be changed by adjusting the relative positions of the first material waveguide layer 10 and the second material waveguide layer 20. This changes the effective coupling length of the overlapping area of the projection of the first material waveguide layer 10 onto the second material waveguide layer 20.
[0026] Since the loss and crosstalk of the waveguide crossover structure are also slightly affected by other factors, such as the process tolerance of waveguide manufacturing, the value of n in Formula 1 will be an integer due to the influence of other factors. The value of n fluctuates around the value of n. Furthermore, the value of n in Formula 1 is... to Between, and This ensures that the power coupling at the cross-port completes an integer number of coupling cycles during propagation and suppresses crosstalk.
[0027] Furthermore, under the same coupling conditions, the fewer the number of coupling periods, the lower the loss. That is, assuming that the three-dimensional waveguide cross structure can be manufactured, the smaller the value of n, the lower the loss.
[0028] This invention adjusts the position of the first material waveguide layer relative to the second material waveguide layer to enable the power coupling at the cross port of the three-dimensional waveguide cross structure to complete an integer multiple of the coupling period during propagation, thereby reducing losses and crosstalk caused by enhanced coupling.
[0029] like Figure 2 , 3 As shown, in one embodiment, the effective coupling length of the projected overlapping region of the first material waveguide layer 10 on the second material waveguide layer 20 is calculated according to the following formula: (Formula 2) In the formula, Indicates the effective coupling length. This indicates the width of the first material waveguide layer. This represents the angle between the first material waveguide layer and the line perpendicular to the second material waveguide layer. This indicates the spacing between the first material waveguide layer and the second material waveguide layer. This indicates the thickness of the first material waveguide layer. This indicates the thickness of the second material waveguide layer.
[0030] It represents the length of the projection overlap region of the first material waveguide layer 10 on the second material waveguide layer 20 along the light propagation direction in the second material waveguide layer 20.
[0031] Changing the effective coupling length is mainly achieved by altering the length of the overlapping region of the projection of the first material waveguide layer 10 onto the second material waveguide layer 20 along the light propagation direction within the second material waveguide layer 20, such as... Figure 3 As shown, the width of the first material waveguide layer 10 Once determined, when the position of the first material waveguide layer 10, which is disposed in the two parallel layers, rotates relative to the second material waveguide layer 20, the angle between the first material waveguide layer and the straight line perpendicular to the second material waveguide layer is determined. It will change, corresponding It will also change; the effective coupling length can be seen from Formula 2. It will also change. When adjusted When Equation 1 is satisfied, the effective coupling length of the intersection region of the three-dimensional waveguide intersection structure can be achieved. ,satisfy .
[0032] Specifically, the first waveguide layer 10 is made of silicon, and the second waveguide layer 20 is made of silicon nitride. When light propagates in the second waveguide layer 20, because the effective refractive index of silicon is much greater than that of silicon nitride, when the interlayer spacing between the first waveguide layer 10 and the second waveguide layer 20 is less than 500 nm, the light propagating in the second waveguide layer 20 will exhibit significant evanescent wave coupling at the three-dimensional waveguide intersection, resulting in substantial loss and crosstalk. Conversely, due to the huge difference in effective refractive index, when light propagates in the silicon waveguide, the influence of the silicon nitride waveguide at the three-dimensional intersection on the light in the silicon waveguide is very small. Therefore, formulas 1 and 2 are for the case when light propagates in silicon nitride.
[0033] This invention adjusts the angle between the first material waveguide layer and the straight line perpendicular to the second material waveguide layer in the three-dimensional waveguide cross structure to ensure that the power coupling at the cross port completes an integer number of coupling cycles during propagation and suppresses crosstalk.
[0034] In one embodiment, the angle between the first material waveguide layer 10 and the line perpendicular to the second material waveguide layer 20 is 60° to 80°.
[0035] The angle between the first material waveguide layer 10 and the line perpendicular to the second material waveguide layer 20 is a variable value. Once the thickness and width of the first material waveguide layer 10 and the second material waveguide layer 20, as well as the interlayer spacing between the first material waveguide layer 10 and the second material waveguide layer 20, are determined, the specific value of the angle between the first material waveguide layer 10 and the line perpendicular to the second material waveguide layer 20 can be determined according to Formula 1 and Formula 2.
[0036] like Figure 1As shown, in one embodiment, it further includes a substrate 60, which is disposed on the side of the buried oxide layer 30 away from the first material waveguide layer 10.
[0037] The substrate 60 is disposed on one side of the buried oxide layer 30 to provide a stable and flat substrate for the three-dimensional waveguide cross structure, ensuring the physical integrity of the structure during manufacturing and operation.
[0038] In one embodiment, the effective refractive index of the first material waveguide layer 10 and the second material waveguide layer 20 is greater than the effective refractive index of the first silicon oxide capping layer 40.
[0039] The propagation of light in the first material waveguide layer 10 and the second material waveguide layer 20 depends on total internal reflection at the core-cladding interface. Total internal reflection requires that light travel from the high-refractive-index medium (i.e., the first material waveguide layer 10 and the second material waveguide layer 20) to the low-refractive-index medium (the first silicon oxide capping layer 40 and the second silicon oxide capping layer 50) at an angle of incidence greater than the critical angle.
[0040] In one embodiment, the first material waveguide layer 10 is a silicon waveguide layer; the second material waveguide layer 20 is a silicon nitride waveguide layer.
[0041] Furthermore, in the three-dimensional waveguide cross structure, the first material waveguide layer 10 and the second material waveguide layer 20 can also be made of materials other than silicon and silicon nitride. As long as the effective refractive indices of the first material waveguide layer 10 and the second material waveguide layer 20 are different, and under the condition of satisfying Formula 1 and Formula 2, the loss and crosstalk of the waveguide cross can be reduced.
[0042] In one embodiment, the thickness of the first material waveguide layer 10 is 220 nm; the thickness of the second material waveguide layer 20 is 400 nm to 800 nm.
[0043] The thicknesses of the first material waveguide layer 10 and the second material waveguide layer 20 are selected based on the mature technical parameters currently used by optical chip fabrication manufacturers. Furthermore, the thicknesses of the first material waveguide layer 10 and the second material waveguide layer 20 can also be other values, as long as they are convenient for manufacturing.
[0044] In one embodiment, the spacing between the first material waveguide layer 10 and the second material waveguide layer 20 is between 150 nm and 500 nm.
[0045] Specifically, in order to increase the density of waveguide layers in a three-dimensional waveguide cross structure, in a specific three-dimensional optical cross structure, the spacing between the first material waveguide layer 10 and the second material waveguide layer 20 is... The wavelength is between 150nm and 500nm. The first material waveguide layer 10 is a silicon waveguide layer with a thickness of... The width of the first material waveguide layer 10 is 220nm. The wavelength range is 400nm to 700nm. The second material waveguide layer 20 is a silicon nitride waveguide layer with a thickness of... The width of the second material waveguide layer 20 is 400nm to 800nm. The range is from 1 μm to 3.5 μm.
[0046] Preferably, to adapt to current processing platforms, the spacing between the first material waveguide layer 10 and the second material waveguide layer 20 is... It can be between 250nm and 400nm.
[0047] When the spacing between the first material waveguide layer 10 and the second material waveguide layer 20 When the wavelength is 250nm, the first material waveguide layer 10 is a silicon waveguide layer with a width of... It is 700nm thick. The wavelength is 220 nm, and the second material waveguide layer 20 is a silicon nitride waveguide layer with a width of 220 nm. The thickness is 3000nm (i.e., 3μm). The value is 400nm. In the C-band (1550 nm) scenario of optical communication, the value can be calculated by combining formulas 1 and 2. The value of is approximately in the range of 50° to 80°. Furthermore, to reduce insertion loss and crosstalk, The value is between 70° and 80°, more preferably, The value is 78°.
[0048] Of course, the above The value range is determined after specifying the spacing between the first material waveguide layer 10 and the second material waveguide layer 20, as well as the width and thickness of the first and second material waveguide layers. When the spacing between the first material waveguide layer 10 and the second material waveguide layer 20, as well as the width and thickness of the first and second material waveguide layers, change... The value of will also change. yes , , , , The selection is coordinated to reduce coupling in the cross-section.
[0049] This invention also discloses a method for fabricating a three-dimensional waveguide cross structure, comprising the following steps: depositing a first material waveguide layer 10 on a buried oxide layer 30 in a first preset shape; depositing a first silicon oxide capping layer 40 of a preset thickness on the first material waveguide layer 10 to cover the first material waveguide layer 10; depositing a second material waveguide layer 20 on the first silicon oxide capping layer 40 in a second preset shape; and depositing a second silicon oxide capping layer 50 of a preset thickness on the second material waveguide layer 20 to cover the second material waveguide layer 20.
[0050] The fabrication process can be as follows: a buried oxide layer 30 is formed on a substrate 60; a first silicon waveguide layer 10 is deposited and etched on the buried oxide layer 30 according to a first preset shape as required by the design; then a silicon dioxide capping layer is deposited according to the preset thickness of the first silicon oxide capping layer 40 as required by the design to cover the first waveguide layer 10 and CMP planarization is performed to the target. A second silicon nitride waveguide layer 20 is formed by depositing and etching a second preset shape on the silicon dioxide capping layer according to the design requirements; finally, a silicon dioxide capping layer is deposited according to the preset thickness of the second silicon dioxide capping layer 50 in the design requirements to complete the encapsulation. The above process steps can be implemented based on existing CMOS compatible process lines.
[0051] During the deposition and etching of the first material waveguide layer 10 and the second material waveguide layer 20, it is possible to... Adjust the relative positions of the first material waveguide layer 10 and the second material waveguide layer 20.
[0052] When the thickness between the first material waveguide layer 10 and the second material waveguide layer 20 in the three-dimensional waveguide cross structure is fixed, and the interlayer spacing between the first material waveguide layer 10 and the second material waveguide layer 20 is also fixed, the result can be calculated using formulas 1 and 2. The relative positions between the first material waveguide layer 10 and the second material waveguide layer 20 are adjusted. This configuration of the first material waveguide layer 10 and the second material waveguide layer 20 satisfies the effective coupling length of the intersection region of the three-dimensional waveguide cross structure. ,satisfy This ensures that the power coupling at the cross-port completes an integer number of coupling cycles during propagation and suppresses crosstalk.
[0053] This invention adjusts the position of the first material waveguide layer relative to the second material waveguide layer to enable the power coupling at the cross port of the three-dimensional waveguide cross structure to complete an integer multiple of the coupling period during propagation, thereby reducing losses and crosstalk caused by enhanced coupling.
[0054] The present invention also discloses an optical communication system, including the aforementioned three-dimensional waveguide cross structure.
[0055] The three-dimensional waveguide cross structure includes: a buried oxide layer 30; a first material waveguide layer 10, the first material waveguide layer 10 being disposed on one side of the buried oxide layer 30; a first silicon oxide capping layer 40, the first silicon oxide capping layer 40 being disposed on the side of the first material waveguide layer 10 away from the buried oxide layer 30; a second material waveguide layer 20, the second material waveguide layer 20 being disposed on the side of the first silicon oxide capping layer 40 away from the first material waveguide layer 10; and a second silicon oxide capping layer 50, the second silicon oxide capping layer 50 being disposed on the side of the second material waveguide layer 20 away from the first silicon oxide capping layer 40; the effective coupling length of the overlapping region of the projection of the first material waveguide layer 10 onto the second material waveguide layer 20 satisfies: (Formula 1) In the formula: Indicates the effective coupling length. Indicates the coupling wavelength. Take the integer part.
[0056] When the thickness between the first material waveguide layer 10 and the second material waveguide layer 20 in a three-dimensional waveguide cross structure is fixed, and the interlayer spacing between the first material waveguide layer 10 and the second material waveguide layer 20 is also fixed, the overlapping area of the projection of the first material waveguide layer 10 onto the second material waveguide layer 20 can be changed by adjusting the relative positions between the first material waveguide layer 10 and the second material waveguide layer 20. This changes the effective coupling length of the overlapping area of the projection of the first material waveguide layer 10 onto the second material waveguide layer 20.
[0057] When the effective coupling length satisfies Equation 1, the effective coupling length of the intersection region of the three-dimensional waveguide cross structure is... ,satisfy This ensures that the power coupling at the cross-port completes an integer number of coupling cycles during propagation and suppresses crosstalk.
[0058] This invention adjusts the position of the first material waveguide layer relative to the second material waveguide layer to enable the power coupling at the cross port of the three-dimensional waveguide cross structure to complete an integer multiple of the coupling period during propagation, thereby reducing losses and crosstalk caused by enhanced coupling.
[0059] The present invention has the following beneficial effects: 1. Significantly suppresses cross-coupling and reduces cross-loss and crosstalk under conditions of small interlayer spacing; 2. Supports extending on-chip optical switching / interconnection from two-dimensional topology to three-dimensional topology, improving wiring and device density per unit area; 3. The fabrication process is compatible with common silicon photonics / silicon nitride processes, making it suitable for wafer-level mass production and migration across multiple material platforms.
[0060] In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.
[0061] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0062] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.
Claims
1. A three-dimensional waveguide cross structure, characterized in that, include: Buried oxygen layer (30); A first material waveguide layer (10) is disposed on one side of the buried oxide layer (30); A first silicon oxide capping layer (40) is disposed on the side of the first material waveguide layer (10) away from the buried oxide layer (30); The second material waveguide layer (20) is disposed on the side of the first silicon oxide capping layer (40) away from the first material waveguide layer (10); A second silicon oxide capping layer (50) is disposed on the side of the second material waveguide layer (20) away from the first silicon oxide capping layer (40); The effective coupling length of the overlapping region of the projection of the first material waveguide layer (10) onto the second material waveguide layer (20) satisfies: In the formula: Indicates the effective coupling length. This represents the coupling wavelength, and the range of values for n is... to ,in It is an integer. It is a constant less than 1.
2. The three-dimensional waveguide cross structure according to claim 1, characterized in that, The effective coupling length of the projected overlapping region of the first material waveguide layer (10) on the second material waveguide layer (20) is calculated using the following formula: In the formula, Indicates the effective coupling length. This indicates the width of the first material waveguide layer. This represents the angle between the first material waveguide layer and the line perpendicular to the second material waveguide layer. This indicates the spacing between the first material waveguide layer and the second material waveguide layer. Indicates the thickness of the first material waveguide layer. This indicates the thickness of the second material waveguide layer.
3. The three-dimensional waveguide cross structure according to claim 2, characterized in that, The angle between the first material waveguide layer (10) and the straight line perpendicular to the second material waveguide layer (20) is 60° to 80°.
4. The three-dimensional waveguide cross structure according to claim 1, characterized in that, Also includes: Substrate (60), the substrate (60) is disposed on the side of the buried oxide layer (30) away from the first material waveguide layer (10).
5. The three-dimensional waveguide cross structure according to claim 1, characterized in that: The effective refractive index of the first material waveguide layer (10) and the second material waveguide layer (20) is greater than the effective refractive index of the first silicon oxide capping layer (40).
6. The three-dimensional waveguide cross structure according to claim 5, characterized in that: The first material waveguide layer (10) is a silicon waveguide layer; The second material waveguide layer (20) is a silicon nitride waveguide layer.
7. The three-dimensional waveguide cross structure according to claim 6, characterized in that: The thickness of the first material waveguide layer (10) is 220 nm; The thickness of the second material waveguide layer (20) is 400 nm to 800 nm.
8. The three-dimensional waveguide cross structure according to claim 1, characterized in that: The spacing between the first material waveguide layer (10) and the second material waveguide layer (20) is between 150 nm and 500 nm.
9. A method for preparing the three-dimensional waveguide cross structure according to any one of claims 1-8, characterized in that, Includes the following steps: A first material waveguide layer (10) is deposited on the buried oxide layer (30) in a first preset shape; A first silicon oxide capping layer (40) of a predetermined thickness is deposited on the first material waveguide layer (10) to cover the first material waveguide layer (10). A second material waveguide layer (20) is deposited on the first silicon oxide capping layer (40) in a second preset shape. A second silicon oxide capping layer (50) of a predetermined thickness is deposited on the second material waveguide layer (20) to cover the second material waveguide layer (20).
10. An optical communication system, characterized in that, Includes the three-dimensional waveguide cross structure as described in any one of claims 1-8.