Waveguide structure and preparation method thereof, interlayer coupling device and preparation method thereof

Abstract

The invention relates to the technical field of optical devices, and discloses a waveguide structure and a preparation method thereof, and an interlayer coupling device and a preparation method thereof. The preparation method of the waveguide structure comprises the following steps: forming a first lower cladding on a substrate layer; the first lower cladding layer forms a first groove comprising a first strip-shaped groove and a first tapered groove, and the section width of the first tapered groove is gradually reduced and gradually approaches to a preset width; a second lower cladding layer with a second groove is conformally formed on the first lower cladding layer, the second groove extends into the first groove and comprises a second strip-shaped groove and a second tapered groove, and the section width of the second tapered groove is gradually reduced and gradually approaches zero; and forming a waveguide core conformal with the second groove in the second groove. According to the interlayer coupling device formed by the preparation method of the waveguide structure, the coupling efficiency and the integration degree can be improved, the transmission loss is reduced, and a high-resolution photoetching process is not needed.

Description

Technical Field

[0001] The present invention relates to the technical field of optical devices, and in particular to a waveguide structure and a preparation method thereof, an interlayer coupling device and a preparation method thereof. Background Art

[0002] In order to meet the requirements of low power consumption, multifunctionality and high-density integration of photonic integrated circuits, photonic integration technology is developing from planar technology to three-dimensional compact integration technology. Based on this, the interference-free and low-loss transmission of optical signals between different devices and different levels plays an important role in the design and practical application of integrated optical chips. The interlayer coupler composed of two inverted tapered waveguides in different levels is a simple and effective structure to achieve optical signal coupling between different levels.

[0003] The tapered waveguide in the related art achieves a gradual width change through photolithography and etching processes, but due to the limitation of photolithography resolution, the end of the tapered waveguide still has a certain width, which makes it easy to generate reflection and resonance at the end of the tapered waveguide during light coupling, thereby affecting the coupling efficiency and transmission loss of the device. In order to improve the coupling efficiency and transmission loss of the interlayer coupler, two methods are usually used: one is to make the end narrower, but this method requires higher photolithography resolution, high process requirements, and high preparation difficulty; the other is to increase the distance between the two tapered waveguide ends, but this method will increase the overall size of the device, which is not conducive to the integration of the device. Summary of the invention

[0004] In view of this, the present invention provides a waveguide structure and a preparation method thereof, an interlayer coupling device and a preparation method thereof, so as to solve the problems of high requirements on the preparation process and poor integration of the existing interlayer coupling devices.

[0005] In a first aspect, the present invention provides a method for preparing a waveguide structure, comprising:

[0006] forming a first lower cladding layer on the substrate layer;

[0007] A first groove is formed in the first lower cladding layer at a side away from the substrate layer, the first groove includes a first strip groove and a first tapered groove that are connected to each other, and a cross-sectional width of the first tapered groove gradually decreases from an end connected to the first strip groove toward an end away from the first strip groove, and gradually approaches a preset width;

[0008] A second lower cladding is conformally formed on a side of the first lower cladding away from the substrate layer, the second lower cladding having a second groove extending into the first groove, the second groove comprising a second strip groove and a second tapered groove connected to each other, and a cross-sectional width of the second tapered groove gradually decreases from an end connected to the second strip groove toward an end away from the second strip groove and gradually approaches zero;

[0009] A waveguide core is formed in the second groove, and the waveguide core includes a strip portion and a tapered portion; in a direction from an end connected to the strip portion toward an end away from the strip portion, the cross-sectional width of the tapered portion gradually decreases and gradually approaches zero, and the surface of the waveguide core is flush with the port of the second groove.

[0010] Beneficial effects: The preparation method of the waveguide structure of the present invention is compatible with the conventional scheme to form a first lower cladding with a first groove, and then form a second lower cladding by conformal forming, further reducing the width of the first groove, and simply and quickly forming a second groove with a precise sharp end suitable for accommodating the waveguide core material; finally, a waveguide core with a precise sharp end can be obtained by simple filling. The groove with a sharp end for accommodating the waveguide core and the waveguide core are formed conformally in two steps, and a waveguide core structure with a sharp end of the waveguide core is obtained simply and quickly, which helps to improve the coupling efficiency and integration and reduce the transmission loss, and does not require a high-resolution lithography process, the process difficulty is low, the material selection is not restricted, and the application range is wide.

[0011] In an optional embodiment, the cross-sectional width of the first tapered groove decreases linearly in a direction from an end connected to the first strip groove toward an end away from the first strip groove.

[0012] Beneficial effects: The width of the first tapered groove is linearly reduced, the first tapered groove is simple to form, the linearly changing wall surface is highly consistent, and the surface performance is excellent, which is conducive to the conformal formation of the second tapered groove of the second groove.

[0013] In an optional embodiment, the cross-sectional width of the first tapered groove decreases nonlinearly in a direction from an end connected to the first strip groove toward an end away from the first strip groove.

[0014] Beneficial effect: The width of the first tapered groove decreases nonlinearly and may include a smooth curved surface with both sides concave inward or a smooth curved surface with both sides convex outward. In this embodiment, a smooth curved surface with both sides concave inward is selected. When the second lower cladding is conformally formed, it is easier to quickly form a sharp end at the tip, and the formed end is sharper, which helps to further improve the coupling efficiency and reduce the transmission loss.

[0015] In an optional embodiment, the second lower cladding layer is made of the same material as the first lower cladding layer.

[0016] Beneficial effect: Selecting the same material for the first lower cladding layer and the second lower cladding layer is conducive to conformal deposition, and for the formed second groove, it is more conducive to forming a smooth and consistent inner wall surface, thereby improving the molding quality of the waveguide core.

[0017] In an optional embodiment, forming a waveguide core in the second groove includes:

[0018] A first initial waveguide layer is formed on the entire surface of the second lower cladding layer on one side away from the substrate layer, wherein the thickness of the first initial waveguide layer in the second groove is greater than or equal to the depth of the second groove;

[0019] The portion of the first initial waveguide layer protruding from the end of the second groove is removed by grinding to obtain a waveguide core located in the second groove and flush with the end of the second groove.

[0020] Beneficial effect: The first initial waveguide layer is deposited on the entire surface of one side of the upper surface of the second lower cladding layer, and then the excess portion is removed by grinding to form the first waveguide core. The thickness of the first initial waveguide layer in the second groove is set to be greater than or equal to the depth of the second groove, which can effectively prevent the waveguide core material in the second groove from being accidentally removed during the subsequent grinding process, thereby causing damage to the waveguide core molding, ensuring that the first initial waveguide layer material in the second groove is fully filled, and finally ensuring the conformal formation of the waveguide core in the second groove.

[0021] In an optional implementation, the depth of the second groove is set to be greater than the width of the second groove, and the thickness of the first initial waveguide layer is greater than or equal to half of the width of the second groove.

[0022] Beneficial effect: The speed at which the second groove narrows is approximately twice the speed at which the second groove shallows. When the depth of the second groove is greater than half the width of the second groove, it is only necessary to deposit a first initial waveguide layer with a thickness of half the width of the second groove to fill the second groove, that is, it is not necessary to deposit a first initial waveguide layer with a thickness exceeding the depth of the second groove, which helps to accurately determine the thickness of the first initial waveguide layer and reduce unnecessary material waste.

[0023] In an optional embodiment, after the waveguide core is formed in the second groove, the method further includes: forming a first upper cladding on a surface of the second lower cladding facing away from the substrate layer, wherein the first upper cladding covers the second lower cladding and the waveguide core.

[0024] Beneficial effect: On the one hand, the first upper cladding layer can realize external protection for the waveguide core, and on the other hand, by adjusting its own thickness, it can adjust the distance between another waveguide core subsequently arranged thereon, so as to improve the coupling efficiency between waveguides of different levels and reduce transmission loss.

[0025] In a second aspect, the present invention further provides a waveguide structure, which is manufactured by the above-mentioned method for manufacturing the waveguide structure and is suitable for being arranged on a substrate layer; the waveguide structure comprises: a first lower cladding, a second lower cladding and a waveguide core, wherein the first lower cladding is located on a side surface of the substrate layer, and a first groove is provided on a side of the first lower cladding away from the substrate layer, wherein the first groove comprises a first strip groove and a first tapered groove which are connected to each other, and the cross-sectional width of the first tapered groove gradually decreases from an end connected to the first strip groove toward an end away from the first strip groove and gradually approaches a preset width; the second lower cladding is located on a side of the first lower cladding away from the substrate layer The second lower cladding is conformally arranged with the first lower cladding, the second lower cladding has a second groove extending into the first groove, the second groove includes a second strip groove and a second tapered groove that are connected to each other, and the cross-sectional width of the second tapered groove gradually decreases and gradually approaches zero from the end connected to the second strip groove toward the end away from the second strip groove; the waveguide core is located in the second groove, the waveguide core includes a strip portion and a tapered portion, and the cross-sectional width of the tapered portion gradually decreases and gradually approaches zero from the end connected to the strip portion toward the end away from the strip portion, and the surface of the waveguide core is flush with the port of the second groove.

[0026] Beneficial effects: The waveguide structure of the present invention is manufactured based on the above-mentioned waveguide structure preparation method. The waveguide structure has a high-precision sharp end, which can effectively improve the interlayer coupling efficiency and device integration and reduce transmission loss. In addition, the surface of the waveguide core is flush with the port of the second groove, which can effectively avoid unnecessary damage to the edge and further ensure the integrity and coupling performance of the waveguide core.

[0027] In a third aspect, the present invention provides a method for preparing an interlayer coupling device, comprising:

[0028] providing a substrate layer;

[0029] A first waveguide structure is formed on one side surface of the substrate layer, wherein the first waveguide structure includes a first waveguide core having a first strip-shaped portion and a first tapered portion;

[0030] A second waveguide structure is formed on a side of the first waveguide structure away from the substrate layer; the second waveguide structure comprises a second waveguide core having a second strip-shaped portion and a second tapered portion;

[0031] In forming the first waveguide structure and forming the second waveguide structure, at least one of them adopts the above-mentioned method for preparing the waveguide structure; the cross-sectional width of one end of the first tapered portion away from the first strip portion and / or one end of the second tapered portion away from the second strip portion gradually approaches zero; one end of the first tapered portion away from the first strip portion and one end of the second tapered portion away from the first strip portion are arranged opposite to each other, and the first tapered portion and the second tapered portion at least partially overlap.

[0032] Beneficial effect: The method for preparing an interlayer coupling device of the present invention comprises stacking a first waveguide structure and a second waveguide structure on a substrate layer, and in the two steps of forming the first waveguide structure and forming the second waveguide structure, at least one of the two steps adopts the method for preparing the waveguide structure to ensure that at least one of the waveguide structures forms a precise sharp end, does not require an excessively high photolithography resolution, has low preparation difficulty, has a wide range of applications, and can improve the coupling efficiency and integration of the interlayer coupling device while reducing transmission losses.

[0033] In an optional embodiment, a first waveguide structure is formed on one side surface of the substrate layer by using the above-mentioned method for preparing a waveguide structure, the first waveguide structure comprising a first lower cladding, a second lower cladding and a first waveguide core; the first waveguide core is located in the second groove, the first waveguide core comprising a first strip portion and a first tapered portion; in a direction from an end connected to the first strip portion toward an end away from the first strip portion, a cross-sectional width of the first tapered portion gradually decreases, and a cross-sectional width of an end of the first tapered portion away from the first strip portion gradually approaches zero, and a surface of the waveguide core is flush with a port of the second groove;

[0034] The first waveguide structure further includes: a first upper cladding layer formed on a surface of the second lower cladding layer facing away from the substrate layer; and a second waveguide structure formed on a side of the first waveguide structure facing away from the substrate layer, including:

[0035] A third groove is formed in the first upper cladding layer at a side away from the substrate layer, the third groove includes a third strip groove and a third tapered groove that are connected to each other, and the cross-sectional width of the third tapered groove gradually decreases from an end connected to the third strip groove toward an end away from the third strip groove, and gradually approaches a preset width;

[0036] A second upper cladding layer is conformally formed on a side of the first upper cladding layer away from the substrate layer, the second upper cladding layer has a fourth groove extending into the third groove, the fourth groove includes a fourth strip groove and a fourth tapered groove that are connected, and the cross-sectional width of the fourth tapered groove gradually decreases in a direction from an end connected to the fourth strip groove toward an end away from the fourth strip groove, and the cross-sectional width of the fourth tapered groove at an end away from the fourth strip groove gradually approaches zero;

[0037] A second waveguide core is formed in the fourth groove, the second waveguide core includes a second strip portion and a second tapered portion; the cross-sectional width of the second tapered portion gradually decreases in a direction from an end connected to the second strip portion toward an end away from the second strip portion, and the cross-sectional width of the end of the second tapered portion away from the second strip portion gradually approaches zero, and the surface of the second waveguide core is flush with the port of the fourth groove.

[0038] Beneficial effect: The first waveguide structure and the second waveguide structure are both made by the above-mentioned waveguide structure preparation method, and the waveguide cores of the two waveguide structures both have sharp ends with a cross-sectional width approaching zero. That is, through two layers of conformal films, the width of the groove formed for the first time in the conventional scheme is narrowed, and then a waveguide core with an end cross-sectional width gradually approaching zero is formed simply and quickly, which can improve the integration of the device, contribute to the coupling effect of the second waveguide structure and the first waveguide structure and the integration of the interlayer coupling device.

[0039] In an optional embodiment, after forming the second waveguide core in the fourth groove, the method further includes: forming a third upper cladding on a surface of the second upper cladding facing away from the substrate layer, wherein the third upper cladding covers the second upper cladding and the second waveguide core.

[0040] Beneficial effect: On the one hand, the third upper cladding layer can realize external protection for the second waveguide core, and on the other hand, by adjusting its own thickness, it can adjust the distance between another waveguide core subsequently arranged thereon, so as to improve the coupling efficiency between waveguides of different levels and reduce transmission loss.

[0041] In an optional embodiment, projections of the axis of the first waveguide core and the axis of the second waveguide core on the substrate layer are collinear.

[0042] Beneficial effect: The projections of the axis of the first waveguide core and the axis of the second waveguide core on the substrate layer are collinear, which can ensure that the tip of the first waveguide core is accurately aligned with the tip of the second waveguide core and partially overlaps, thereby ensuring efficient coupling effect and reducing transmission loss.

[0043] In a fourth aspect, the present invention provides an interlayer coupling device, which is manufactured by the above-mentioned method for manufacturing an interlayer coupling device, and includes: a substrate layer, a first waveguide structure and a second waveguide structure, the first waveguide structure and the second waveguide structure are stacked on the substrate layer, the first waveguide structure includes a first waveguide core having a first strip portion and a first tapered portion; the second waveguide structure includes a second waveguide core having a second strip portion and a second tapered portion; the cross-sectional width of an end of the first tapered portion away from the first strip portion and / or an end of the second tapered portion away from the second strip portion gradually approaches zero; an end of the first tapered portion away from the first strip portion and an end of the second tapered portion away from the first strip portion are arranged opposite to each other, and the first tapered portion and the second tapered portion at least partially overlap.

[0044] Beneficial effects: The interlayer coupling device of the present invention includes a first waveguide structure and a second waveguide structure stacked on a substrate layer, and at least one of the first waveguide structure and the second waveguide structure has a precise sharp end, which helps to improve the coupling efficiency and integration of the interlayer coupling device while reducing transmission loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 is a schematic flow chart of a method for preparing a waveguide structure according to an embodiment of the present invention;

[0047] Figure 2 is a schematic top view of an embodiment of the present invention when the width of the first tapered groove is nonlinearly reduced;

[0048] Figure 3 is a schematic top view of an embodiment of the present invention when the width of the first tapered groove decreases linearly;

[0049] Figure 4 is based on Figure 2 or Figure 3 A schematic cross-sectional view of the A1-A1 section;

[0050] Figure 5 is a schematic top view of the second tapered groove of the embodiment of the present invention when the width is nonlinearly reduced;

[0051] Figure 6 is a schematic top view of the second tapered groove according to the embodiment of the present invention when the width is linearly reduced;

[0052] Figure 7 is based on Figure 5 or Figure 6 A schematic cross-sectional view of the section A2-A2;

[0053] Figure 8 is a schematic top view of a waveguide core according to an embodiment of the present invention when the width of the tapered portion decreases nonlinearly;

[0054] Fig. 9 is a schematic top view of a waveguide core according to an embodiment of the present invention when the width of the tapered portion decreases linearly;

[0055] Fig.10 is based on Figure 8 or Fig. 9 A schematic cross-sectional view of A3-A3 in the middle;

[0056] Fig.11 is a schematic diagram of the structure after the initial first waveguide layer is set in an embodiment of the present invention;

[0057] Fig.12 is a schematic structural diagram of a waveguide structure after a first upper cladding layer is provided in an embodiment of the present invention;

[0058] Fig.13 is a schematic flow chart of a method for preparing an interlayer coupling device according to an embodiment of the present invention;

[0059] Fig.14 is a schematic top view of an interlayer coupling device according to an embodiment of the present invention after forming a first waveguide structure;

[0060] Fig.15 is based on Fig.14 Schematic diagram of the cross section at B1-B1;

[0061] Fig.16 is a schematic top view of a first upper cladding layer after a third groove is formed in the first upper cladding layer according to an embodiment of the present invention;

[0062] Fig.17 is based on Fig.16 A schematic cross-sectional view of the B2-B2 section;

[0063] Fig.18 is a schematic top view of an embodiment of the present invention after a fourth groove is formed in the second upper cladding layer;

[0064] Fig.19 is based on Fig.18 A schematic cross-sectional view of the B3-B3 section;

[0065] Fig. 20 is a schematic top view of a second waveguide core disposed in a fourth groove of a second upper cladding layer according to an embodiment of the present invention;

[0066] Fig.21 is based on Fig. 20 A schematic cross-sectional view of the B4-B4 section;

[0067] Fig. 22 is a schematic diagram of the structure after the initial second waveguide layer is set in an embodiment of the present invention;

[0068] Fig.23 It is a schematic structural diagram of an interlayer coupling device after a third upper cladding layer is provided according to an embodiment of the present invention.

[0069] Description of reference numerals:

[0070] 1. Substrate layer;

[0071] 2. first lower cladding layer; 21. first groove; 211. first strip groove; 212. first tapered groove;

[0072] 3. second lower cladding layer; 31. second groove; 311. second strip groove; 312. second tapered groove;

[0073] 4. waveguide core; 41. strip-shaped portion; 42. tapered portion; 400a. first initial waveguide layer;

[0074] 401, first waveguide core; 4011, first strip portion; 4012, first tapered portion; 402, second waveguide core; 4021, second strip portion; 4022, second tapered portion; 400b, second initial waveguide layer;

[0075] 5. first upper cladding layer; 51. third groove; 511. third strip groove; 512. third tapered groove;

[0076] 6. second upper cladding layer; 61. fourth groove; 611. fourth strip groove; 612. fourth tapered groove;

[0077] 7. The third upper cladding. DETAILED DESCRIPTION

[0078] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only some structures related to the present invention are shown in the accompanying drawings, rather than all structures. In the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention. Various structural schematic diagrams according to embodiments of the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified for the purpose of clear expression, and some details may be omitted. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships between them are only exemplary, and may be deviated due to manufacturing tolerances or technical limitations in practice, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs. In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. In addition, if one layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element.

[0079] The tapered waveguide in the related art realizes a gradual width change through photolithography and etching processes, but due to the limitation of photolithography resolution, the end of the tapered waveguide still has a certain width, which makes it easy to generate reflection and resonance at the end of the tapered waveguide during light coupling, thereby affecting the coupling efficiency and transmission loss of the device. To improve this situation, two methods are usually used: one is to make the end narrower, but this method requires higher photolithography resolution, has high process requirements, and is difficult to prepare; or a tapered mask is used to cover part of the epitaxial film layer, and the unshielded epitaxial film layer is thermally oxidized, and then the thermally oxidized epitaxial film layer and the tapered mask are etched to remove, thereby obtaining a tapered waveguide core, but this requires that the material of the epitaxial film layer has thermal oxidizability, and at the same time, the tapered mask and the oxidized epitaxial film layer have a high etching selectivity for the unoxidized epitaxial film layer, so there are great restrictions on the material of the epitaxial film layer (i.e., the tapered waveguide core), and the scope of application is small; the other is to increase the distance between the two ends of the tapered waveguide, but this method will increase the overall size of the device, which is not conducive to the integration of the device. Based on this, there is an urgent need for a method for preparing an optical waveguide structure and an interlayer coupling device that has low preparation difficulty, a wide range of applications and can improve integration.

[0080] Therefore, reference Figures 1 to 12 This embodiment provides a method for preparing a waveguide structure. Figure 1 1 is a schematic flow chart of a method for preparing a waveguide structure, the method comprising the following steps:

[0081] Step S101 : forming a first lower cladding layer 2 on a substrate layer 1 .

[0082] Exemplarily, the substrate layer 1 may be a silicon wafer, and the first lower cladding layer 2 may be silicon dioxide with a thickness of 2 μm to 20 μm.

[0083] In step S102, a first groove 21 is formed in the first lower cladding layer 2 on a side facing away from the substrate layer 1. The first groove 21 includes a first strip groove 211 and a first tapered groove 212 that are connected to each other. From an end connected to the first strip groove 211 toward an end away from the first strip groove 211, the cross-sectional width of the first tapered groove 212 gradually decreases and gradually approaches a preset width.

[0084] refer to Figures 2 to 4 , a first groove 21 is etched on the upper surface of the first lower cladding layer 2. By way of example, the width gradient of the first tapered groove 212 of the first groove 21 can be linear or nonlinear, but the first tapered groove 212 of the first groove 21 still has a certain width at one end away from the first strip groove 211. Therefore, the requirement for lithography resolution does not need to be particularly high, it is compatible with conventional lithography resolution, and the process difficulty is low.

[0085] In step S103, a second lower cladding 3 is conformally formed on the side of the first lower cladding 2 facing away from the substrate layer 1. The second lower cladding 3 has a second groove 31 extending into the first groove 21. The second groove 31 includes a second strip groove 311 and a second tapered groove 312 that are connected to each other. From an end connected to the second strip groove 311 toward an end away from the second strip groove 311, the cross-sectional width of the second tapered groove 312 gradually decreases and gradually approaches zero.

[0086] refer to Figures 5 to 7 , a second lower cladding 3 is conformally formed on the upper side of the first lower cladding 2 by a thin film deposition process such as chemical vapor deposition (CVD) and atomic layer deposition (ALD). Due to the conformal formation, the second lower cladding 3 forms a second groove 31 extending into the first groove 21. The thickness of the second lower cladding 3 located at the side wall and the bottom of the first groove 21 is equal. The groove width of the second strip groove 311 of the second groove 31 is equal to the groove width of the first strip groove 211 of the first groove 21 minus twice the thickness of the second lower cladding 3. The depth of the second groove 31 is equal to the depth of the first groove 21, so that the formed second groove 31 has the same shape as the first groove 21, thereby ensuring the morphological characteristics of the formed waveguide core 4; as the thickness of the second lower cladding 3 increases, the width of the first tapered groove 212 of the first groove 21 of the first lower cladding 2 at one end away from the first strip groove 211 gradually narrows and gradually approaches zero, providing a basis for forming a tapered waveguide core 4 with a precise sharp end.

[0087] Step S104, forming a waveguide core 4 in the second groove 31, the waveguide core 4 includes a strip portion 41 and a tapered portion 42; from the end connected to the strip portion 41 toward the end away from the strip portion 41, the cross-sectional width of the tapered portion 42 gradually decreases and gradually approaches zero, and the surface of the waveguide core 4 is flush with the port of the second groove 31.

[0088] refer to Figures 8 to 10 The waveguide core 4 is filled in the second groove 31 formed in the second lower cladding layer 3, and the thickness of the waveguide core 4 is set to be equal to the depth of the second groove 31, that is, the surface of the waveguide core 4 is flush with the end of the second groove 31, to ensure that the waveguide core 4 having a strip portion 41 and a tapered portion 42 that is completely consistent with the second groove 31 is formed in one piece, and the end of the tapered portion 42 away from the strip portion 41 is accurately formed into a sharp end with a width approaching zero.

[0089] In this embodiment, the first lower cladding 2 is first formed and the first groove 21 is formed in the first lower cladding 2. There is no strict requirement for the width of the tapered portion of the first groove 21, that is, the end of the first tapered groove 212 away from the first strip groove 211, and a certain width is allowed. Then, the second lower cladding 3 is formed conformally, and a second groove 31 narrower than the first groove 21 is formed in the second lower cladding 3 corresponding to the first groove 21. The width of the second tapered groove 312 of the second groove 31 away from the first strip groove 211 is even close to zero. Then, a tapered waveguide core 4 with a precise sharp end is formed by filling the second groove 31 with waveguide core 4 material.

[0090] In summary, the preparation method of the waveguide structure of the present embodiment is compatible with the conventional scheme to form the first lower cladding 2 with the first groove 21, and then the second lower cladding 3 is formed by conformal forming, the width of the first groove 21 is further reduced, and the thickness of the second lower cladding 3 located in the first groove 21 is equal at all places, ensuring that the second groove 31 is consistent with the shape of the first groove 21, and the second groove 31 with a precise sharp end suitable for accommodating the waveguide core 4 material is formed simply and quickly, and the inner wall morphology of the second groove 31 is good; finally, the waveguide core 4 with a precise sharp end can be obtained by simple filling. The second groove 31 with a sharp end for accommodating the waveguide core 4 and the waveguide core 4 are conformally formed in two steps, and the waveguide core 4 structure with a sharp end of the waveguide core 4 is obtained simply and quickly, which is helpful to improve the coupling efficiency and integration and reduce the transmission loss, and does not require a high-resolution photolithography process, the process difficulty is low, the material selection is not limited, and the application range is wide.

[0091] In an optional embodiment, reference Figure 3 The cross-sectional width of the first tapered groove 212 decreases linearly in a direction from an end connected to the first strip groove 211 toward an end away from the first strip groove 211 .

[0092] Combination Figure 6 and Figure 7 As shown, the second lower cladding layer 3 is formed conformally to the first lower cladding layer 2. Therefore, for the second groove 31, the cross-sectional width of the second tapered groove 312 decreases linearly from the end connected to the second strip groove 311 toward the end away from the second strip groove 311. Similarly, Figures 8 to 10 As shown, for the waveguide core 4 filled and formed in the second groove 31, the cross-sectional width of the tapered portion 42 decreases linearly from the end connected to the strip portion 41 toward the end away from the strip portion 41, as shown in FIG. Fig. 9 In this embodiment, the width of the first tapered groove 212 is linearly reduced, the first tapered groove 212 is simple to form, the linearly changing wall surface is highly consistent, and the surface performance is excellent, which is conducive to the conformal formation of the second tapered groove 312 of the second groove 31 in the subsequent process.

[0093] In another optional embodiment, reference Figure 2 The cross-sectional width of the first tapered groove 212 decreases nonlinearly in a direction from an end connected to the first strip groove 211 toward an end away from the first strip groove 211 .

[0094] Similarly, at this time, since the second lower cladding layer 3 is formed conformally to the first lower cladding layer 2, for the second groove 31, the cross-sectional width of the second tapered groove 312 decreases nonlinearly from the end connected to the second strip groove 311 toward the end away from the second strip groove 311, as shown in FIG. Figure 5 Similarly, for the waveguide core 4 filled in the second groove 31, the cross-sectional width of the tapered portion 42 decreases nonlinearly from the end connected to the strip portion 41 toward the end away from the strip portion 41, as shown in FIG. Figure 8 In this embodiment, the width of the first tapered groove 212 decreases nonlinearly, and may include a smooth curved surface with both sides concave inward or a smooth curved surface with both sides convex outward. In this embodiment, a smooth curved surface with both sides concave inward is selected. When the second lower cladding layer 3 is conformally formed, it is easier to quickly form a sharp end at the tip, and the formed end is sharper, which helps to further improve the coupling efficiency and reduce the transmission loss.

[0095] In an optional embodiment, the second lower cladding layer 3 is made of the same material as the first lower cladding layer 2 .

[0096] Exemplarily, both the first lower cladding 2 and the second lower cladding 3 are made of silica material. Using the same material for the first lower cladding 2 and the second lower cladding 3 is conducive to conformal deposition, and for the formed second groove 31, it is more conducive to forming a smooth and consistent inner wall surface, thereby improving the molding quality of the waveguide core 4.

[0097] In one embodiment, the above step S104 includes step S1041 and step S1042:

[0098] Step S1041 , forming a first initial waveguide layer 400 a on the entire surface of the second lower cladding layer 3 facing away from the substrate layer 1 , wherein the thickness of the first initial waveguide layer 400 a in the second groove 31 is greater than or equal to the depth of the second groove 31 .

[0099] refer to Fig.11, a first initial waveguide layer 400a is deposited on the entire surface of one side of the upper surface of the second lower cladding layer 3. For example, the first initial waveguide layer 400a can be made of silicon nitride, amorphous silicon or other materials having a refractive index greater than that of the first lower cladding layer 2 and the second lower cladding layer 3. The thickness of the first initial waveguide layer 400a in the second groove 31 is set to be greater than or equal to the depth of the second groove 31, so as to avoid the material of the waveguide core 4 in the second groove 31 being accidentally removed during the subsequent grinding process, thereby causing damage to the forming of the waveguide core 4, and to ensure that the material of the first initial waveguide layer 400a in the second groove 31 is fully filled, and finally to ensure conformal formation of the waveguide core 4 in the second groove 31.

[0100] Step S1042 , grinding and removing a portion of the first initial waveguide layer 400 a protruding from the end of the second groove 31 , so as to obtain a waveguide core 4 located in the second groove 31 and flush with the end of the second groove 31 .

[0101] Exemplarily, the first initial waveguide layer 400 a outside the second groove 31 is removed by a chemical mechanical planarization (CMP) process, so that a waveguide core 4 flush with the end of the second groove 31 is formed in the second groove 31 .

[0102] In one embodiment, the depth of the second groove 31 is set to be greater than the width of the second groove 31 , and the thickness of the first initial waveguide layer 400 a is greater than or equal to half of the width of the second groove 31 .

[0103] When depositing the material of the first initial waveguide layer 400a, the first initial waveguide layer 400a is deposited on two opposite side walls of the second groove 31 at the same time to narrow the second groove 31. The first initial waveguide layer 400a is deposited on the bottom of the second groove 31 to shallow the second groove 31. Therefore, the speed at which the second groove 31 narrows is about twice the speed at which the second groove 31 shallows. When the depth of the second groove 31 is greater than half the width of the second groove 31, it is only necessary to deposit the first initial waveguide layer 400a with a thickness of half the width of the second groove 31 to fill the second groove 31. That is, it is not necessary to deposit the first initial waveguide layer 400a with a thickness exceeding the depth of the second groove 31, which helps to accurately determine the thickness of the first initial waveguide layer 400a and reduce unnecessary material waste.

[0104] In one embodiment, reference Fig.12 , after step S104 of forming the waveguide core 4 in the second groove 31, further comprising:

[0105] Step S105 , forming a first upper cladding layer 5 on a surface of the second lower cladding layer 3 facing away from the substrate layer 1 , wherein the first upper cladding layer 5 covers the second lower cladding layer 3 and the waveguide core 4 .

[0106] Exemplarily, the material of the first upper cladding layer 5 can also be silicon dioxide. The thickness of the first upper cladding layer 5 ranges from 0.1 μm to 10 μm. On the one hand, the first upper cladding layer 5 can realize external protection for the waveguide core 4. On the other hand, by adjusting its own thickness, it can adjust the distance between another waveguide core 4 subsequently arranged thereon, so as to improve the coupling efficiency between waveguides of different levels and reduce transmission losses.

[0107] like Fig.10 As shown, the present embodiment further provides a waveguide structure, which is manufactured by the above-mentioned method for manufacturing the waveguide structure and is suitable for being arranged on the substrate layer 1; it comprises: a first lower cladding layer 2, a second lower cladding layer 3 and a waveguide core 4, the first lower cladding layer 2 is located on one side surface of the substrate layer 1, the first lower cladding layer 2 has a first groove 21 on the side away from the substrate layer 1, the first groove 21 comprises a first strip groove 211 and a first tapered groove 212 which are connected, and the cross-sectional width of the first tapered groove 212 gradually decreases from the end connected to the first strip groove 211 toward the end away from the first strip groove 211, and gradually approaches a preset width; the second lower cladding layer 3 is located on the side of the first lower cladding layer 2 which is away from the substrate layer 1, and the second lower cladding layer 3 is located on the side of the first lower cladding layer 2 which is away from the substrate layer 1, and the second lower cladding layer 3 is located on the side of the first lower cladding layer 2 which is away from the substrate layer 1, and the first lower cladding layer 21 comprises a first strip groove 211 and a first tapered groove 212 which are connected to each other. The layer 3 is conformally arranged with the first lower cladding layer 2, and the second lower cladding layer 3 has a second groove 31 extending into the first groove 21, and the second groove 31 includes a second strip groove 311 and a second tapered groove 312 that are connected to each other. From the end connected to the second strip groove 311 toward the end away from the second strip groove 311, the cross-sectional width of the second tapered groove 312 gradually decreases and gradually approaches zero; the waveguide core 4 is located in the second groove 31, and the waveguide core 4 includes a strip portion 41 and a tapered portion 42. From the end connected to the strip portion 41 toward the end away from the strip portion 41, the cross-sectional width of the tapered portion 42 gradually decreases and gradually approaches zero, and the surface of the waveguide core 4 is flush with the port of the second groove 31.

[0108] The waveguide structure of this embodiment is manufactured based on the above-mentioned waveguide structure preparation method. The waveguide structure has a high-precision sharp end, which can effectively improve the interlayer coupling efficiency and device integration and reduce transmission loss. In addition, the surface of the waveguide core 4 is flush with the port of the second groove 31, which can effectively avoid unnecessary damage to the edge and further ensure the integrity and coupling performance of the waveguide core 4.

[0109] Further, refer to Fig.12 In the waveguide structure of this embodiment, a first upper cladding layer 5 is formed on the surface of the second lower cladding layer 3 facing away from the substrate layer 1 , and the first upper cladding layer 5 covers the second lower cladding layer 3 and the waveguide core 4 .

[0110] The thickness of the first upper cladding layer 5 is set in the range of 0.1μm to 10μm. On the one hand, the first upper cladding layer 5 can realize external protection for the waveguide core 4. On the other hand, by adjusting its own thickness, it can adjust the distance between another waveguide core 4 subsequently set thereon, so as to improve the coupling efficiency between waveguides of different levels and reduce transmission loss.

[0111] Further, refer to Figures 13 to 23 This embodiment also provides a method for preparing an interlayer coupling device. Fig.13 The figure is a flow chart of a method for preparing an interlayer coupling device, and the method comprises the following steps:

[0112] Step S1301, providing a substrate layer 1.

[0113] Exemplarily, the substrate layer 1 may be a silicon wafer, and its size is set as required and is not specifically limited.

[0114] Step S1302 : forming a first waveguide structure on one side surface of the substrate layer 1 , wherein the first waveguide structure includes a first waveguide core 401 having a first strip portion 4011 and a first tapered portion 4012 .

[0115] Exemplarily, the first waveguide structure can be prepared by the above-mentioned waveguide structure preparation method, including a first lower cladding 2 having a first groove 21, a second lower cladding 3 having a second groove 31 and formed conformally with the first lower cladding 2, and a first waveguide core 401; of course, the first waveguide structure can also be a structure in which the conventional scheme only includes the first lower cladding 2 and a conventional waveguide core arranged in the first groove 21 of the first lower cladding 2, or a structure in which the first lower cladding 2 without the first groove 21 and a conventional waveguide core formed on the first lower cladding 2 by thin film deposition, photolithography, and etching. It can be known that the conventional waveguide core obtained by the above-mentioned conventional scheme does not have a high-precision sharp end.

[0116] Step S1303, forming a second waveguide structure on a side of the first waveguide structure away from the substrate layer 1, the second waveguide structure comprising a second waveguide core 402 having a second strip portion 4021 and a second tapered portion 4022. In forming the first waveguide structure and forming the second waveguide structure, at least one of the above-mentioned waveguide structure preparation method is used; the cross-sectional width of one end of the first tapered portion 4012 away from the first strip portion 4011 and / or one end of the second tapered portion 4022 away from the second strip portion 4021 gradually approaches zero; one end of the first tapered portion 4012 away from the first strip portion 4011 and one end of the second tapered portion 4022 away from the first strip portion 4011 are arranged opposite to each other, and the first tapered portion 4012 and the second tapered portion 4022 at least partially overlap.

[0117] Similarly, the second waveguide structure can be obtained by the preparation method of the above-mentioned waveguide structure, and illustratively includes a first upper cladding 5 having a third groove 51, a second upper cladding 6 having a fourth groove 61 and formed conformally with the first upper cladding 5, and a second waveguide core 402; of course, the second waveguide structure can also be a structure in which the conventional scheme only includes the first upper cladding 5 and a conventional waveguide core arranged in the third groove 51 of the first upper cladding 5, or a structure in which the second waveguide structure only includes the first upper cladding 5 without the third groove 51 and a conventional waveguide core formed on the first upper cladding 5 by thin film deposition, photolithography, and etching. It can be known that the conventional waveguide core obtained by the above-mentioned conventional scheme does not have a high-precision sharp end. It should be noted that, in the present embodiment, at least one of the first waveguide structure and the second waveguide structure is manufactured by the above-mentioned waveguide structure manufacturing method to ensure that one of the first waveguide core 401 or the second waveguide core 402, or both the first waveguide core 401 and the second waveguide core 402 have precise sharp ends, wherein the sharp ends are the portion where the first tapered portion 4012 gradually approaches zero at one end away from the first strip portion 4011, or the portion where the second tapered portion 4022 gradually approaches zero at one end away from the second strip portion 4021. The projections of the first tapered portion 4012 of the first waveguide structure and the second tapered portion 4022 of the second waveguide structure on the horizontal plane partially overlap, and the overlapping portion at least includes the above-mentioned sharp ends.

[0118] The preparation method of the interlayer coupling device of the present embodiment includes stacking a first waveguide structure and a second waveguide structure on a substrate layer 1, and in the two steps of forming the first waveguide structure and forming the second waveguide structure, at least one of the two steps adopts the preparation method of the waveguide structure to ensure that at least one of the waveguide structures forms a precise sharp end, does not require an excessively high lithography resolution, has low preparation difficulty, a wide range of applications, and can improve the coupling efficiency and integration of the interlayer coupling device while reducing transmission losses.

[0119] Specifically in this embodiment, the first waveguide structure and the second waveguide structure are both made by the above-mentioned waveguide structure preparation method, and the first waveguide core 401 and the second waveguide core 402 of the two waveguide structures both have sharp ends with a cross-sectional width approaching zero. That is, through two layers of conformal films, the width of the groove formed for the first time in the conventional solution is narrowed, thereby forming a waveguide core with an end cross-sectional width gradually approaching zero in a simple and quick manner.

[0120] On the one hand, a first waveguide structure is formed on one side surface of the substrate layer 1 by adopting the above-mentioned method for preparing the waveguide structure, wherein the first waveguide structure comprises a first lower cladding 2, a second lower cladding 3 and a first waveguide core 401; the first waveguide core 401 is located in the second groove 31, and the first waveguide core 401 comprises a first strip portion 4011 and a first tapered portion 4012; from the end connected to the first strip portion 4011 toward the end away from the first strip portion 4011, the cross-sectional width of the first tapered portion 4012 gradually decreases and gradually approaches zero, and the surface of the first waveguide core 401 is flush with the port of the second groove 31.

[0121] See also Fig.14 and Fig.15 On the basis of the above scheme, the first waveguide structure further includes: a first upper cladding layer 5 formed on the surface of the second lower cladding layer 3 facing away from the substrate layer 1. The thickness range of the first upper cladding layer 5 is set to 0.1 μm to 10 μm. At this time, the first upper cladding layer 5 adjusts its own thickness to adjust the distance between the first waveguide core 401 of the first waveguide structure and the second waveguide core 402 in the second waveguide structure to ensure a better coupling effect.

[0122] On the basis of the above solution, a second waveguide structure is formed on a surface of the first waveguide structure facing away from the substrate layer 1, specifically comprising the following steps:

[0123] In step S1303a, a third groove 51 is formed in the first upper cladding layer 5 on a side facing away from the substrate layer 1. The third groove 51 includes a third strip groove 511 and a third tapered groove 512 that are connected to each other. From an end connected to the third strip groove 511 toward an end away from the third strip groove 511, a cross-sectional width of the third tapered groove 512 gradually decreases and gradually approaches a preset width.

[0124] refer to Fig.16 and Fig.17 , a third groove 51 is etched on the upper surface of the first upper cladding layer 5. By way of example, the width gradient of the third tapered groove 512 of the third groove 51 can be linear or nonlinear, but the third tapered groove 512 of the third groove 51 still has a certain width at one end away from the third strip groove 511. Therefore, the requirement for lithography resolution does not need to be particularly high, it is compatible with conventional lithography resolution, and the process difficulty is low.

[0125] In step S1303b, a second upper cladding 6 is conformally formed on the side of the first upper cladding 5 facing away from the substrate layer 1. The second upper cladding 6 has a fourth groove 61 extending into the third groove 51. The fourth groove 61 includes a fourth strip groove 611 and a fourth tapered groove 612 that are connected to each other. From an end connected to the fourth strip groove 611 toward an end away from the fourth strip groove 611, the cross-sectional width of the fourth tapered groove 612 gradually decreases and gradually approaches zero.

[0126] refer to Fig.18 and Fig.19 The second upper cladding 6 is conformally formed on the upper side of the first upper cladding 5. Due to the conformal formation, a fourth groove 61 extending into the third groove 51 is simultaneously formed when the second upper cladding 6 is formed. The groove width of the fourth strip groove 611 of the fourth groove 61 is equal to the groove width of the third strip groove 511 of the third groove 51 minus twice the thickness of the second upper cladding 6. The depth of the fourth groove 61 is equal to the depth of the third groove 51. As the thickness of the second upper cladding 6 increases, the width of the third tapered groove 512 of the third groove 51 of the first upper cladding 5 away from the third strip groove 511 gradually narrows and gradually approaches zero, providing a basis for forming a second waveguide core 402 with a precise sharp end.

[0127] Step S1303c, forming a second waveguide core 402 in the fourth groove 61, the second waveguide core 402 includes a second strip portion 4021 and a second tapered portion 4022; from the end connected to the second strip portion 4021 toward the end away from the second strip portion 4021, the cross-sectional width of the second tapered portion 4022 gradually decreases, and the cross-sectional width of the end of the second tapered portion 4022 away from the second strip portion 4021 gradually approaches zero, and the surface of the second waveguide core 402 is flush with the end of the fourth groove 61.

[0128] refer to Fig. 20 and Fig.21 The second waveguide core 402 is filled in the fourth groove 61 formed in the second upper cladding layer 6, and the thickness of the second waveguide core 402 is set to be equal to the depth of the fourth groove 61, that is, the surface of the second waveguide core 402 is flush with the end of the fourth groove 61, to ensure that the second waveguide core 402 having the second strip portion 4021 and the second tapered portion 4022 that is completely consistent with the fourth groove 61 is formed in one piece, and the second tapered portion 4022 is precisely formed into a sharp end with a width approaching zero at one end away from the second strip portion 4021.

[0129] In the method for preparing the interlayer coupling device of the present embodiment, the first upper cladding 5 of the first waveguide structure is used as the first bottom cladding of the second waveguide structure, and the third groove 51 of the second waveguide structure is directly etched on the first upper cladding 5, which further improves the integration of the device and contributes to the coupling effect between the second waveguide core 402 and the first waveguide core 401.

[0130] Of course, the widths of the second strip portion 4021 of the second waveguide core 402 and the first strip portion 4011 of the first waveguide core 401 may be the same or different, and may be determined according to actual needs, as long as the sharp ends of the two have overlapping portions.

[0131] Similarly, in this embodiment, when forming the second waveguide core 402 of the second waveguide structure, it includes:

[0132] refer to Fig. 22 First, a second initial waveguide layer 400 b is formed on the entire surface of the second upper cladding layer 6 facing away from the substrate layer 1 , and the thickness of the second initial waveguide layer 400 b in the fourth groove 61 is greater than or equal to the depth of the fourth groove 61 .

[0133] The second initial waveguide layer 400b is deposited on the entire surface of one side of the upper surface of the second upper cladding layer 6. For example, the second initial waveguide layer 400b can also be made of silicon nitride, amorphous silicon, or other materials having a refractive index greater than that of the first upper cladding layer 5 and the second upper cladding layer 6. The thickness of the second initial waveguide layer 400b in the fourth groove 61 is set to be greater than or equal to the depth of the fourth groove 61 to prevent the second waveguide core 402 material in the fourth groove 61 from being accidentally removed during the subsequent grinding process, thereby causing damage to the molding of the second waveguide core 402, ensuring that the second initial waveguide layer 400b material in the fourth groove 61 is fully filled, and finally ensuring conformal formation of the second waveguide core 402 in the fourth groove 61.

[0134] Afterwards, a portion of the second initial waveguide layer 400 b protruding from the end of the fourth groove 61 is removed by grinding to obtain a second waveguide core 402 located in the fourth groove 61 and flush with the end of the fourth groove 61 .

[0135] Exemplarily, the second initial waveguide layer 400 b outside the fourth groove 61 is removed by a chemical mechanical planarization (CMP) process, so that a second waveguide core 402 flush with the end of the fourth groove 61 is formed in the fourth groove 61 .

[0136] refer to Fig.23 , after step S1303c of forming the second waveguide core 402 in the fourth groove 61, further comprising:

[0137] Step S1303 d , forming a third upper cladding layer 7 on a surface of the second upper cladding layer 6 facing away from the substrate layer 1 , wherein the third upper cladding layer 7 covers the second upper cladding layer 6 and the second waveguide core 402 .

[0138] Exemplarily, the material of the third upper cladding layer 7 can be the same silicon dioxide as the first upper cladding layer 5 and the second upper cladding layer 6. The thickness of the third upper cladding layer 7 ranges from 0.1 μm to 10 μm. On the one hand, the third upper cladding layer 7 can realize external protection for the second waveguide core 402. On the other hand, by adjusting its own thickness, it can adjust the distance between another waveguide core subsequently arranged thereon, so as to improve the coupling efficiency between waveguides of different levels and reduce transmission loss.

[0139] In one embodiment, reference Fig. 20 The projections of the axis of the first waveguide core 401 and the axis of the second waveguide core 402 on the substrate layer 1 are collinear, so as to ensure that the tip of the first waveguide core 401 and the tip of the second waveguide core 402 are accurately aligned and partially overlapped, thereby ensuring efficient coupling effect and reducing transmission loss.

[0140] refer to Fig. 20 and Fig.21 This embodiment also provides an interlayer coupling device, which is manufactured by the above-mentioned method for manufacturing an interlayer coupling device, and includes: a substrate layer 1, a first waveguide structure and a second waveguide structure, the first waveguide structure and the second waveguide structure are stacked on the substrate layer 1, the first waveguide structure includes a first waveguide core 401 having a first strip portion 4011 and a first tapered portion 4012; the second waveguide structure includes a second waveguide core 402 having a second strip portion 4021 and a second tapered portion 4022; the cross-sectional width of an end of the first tapered portion 4012 away from the first strip portion 4011 and / or an end of the second tapered portion 4022 away from the second strip portion 4021 gradually approaches zero; an end of the first tapered portion 4012 away from the first strip portion 4011 and an end of the second tapered portion 4022 away from the first strip portion 4011 are arranged opposite to each other, and the first tapered portion 4012 and the second tapered portion 4022 at least partially overlap.

[0141] The interlayer coupling device of this embodiment includes a first waveguide structure and a second waveguide structure stacked on a substrate layer 1, and at least one of the first waveguide structure and the second waveguide structure has a precise sharp end, which helps to improve the coupling efficiency and integration of the interlayer coupling device while reducing transmission loss.

[0142] In addition, if Fig.23 As shown, the above-mentioned interlayer coupling device further includes a third upper cladding layer 7 arranged on the upper side of the second upper cladding layer 6 .

[0143] The further functional description of each of the above modules is the same as that of the above corresponding embodiments and will not be repeated here.

[0144] In the above description, the technical details of the patterning and etching of each layer are not described in detail. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of desired shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not completely the same as the methods described above. In addition, although the various embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage.

[0145] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for preparing a waveguide structure, characterized in that: include: forming a first lower cladding layer on the substrate layer; A first groove is formed in the first lower cladding layer at a side away from the substrate layer, the first groove comprises a first strip groove and a first tapered groove that are connected to each other, and a cross-sectional width of the first tapered groove gradually decreases from an end connected to the first strip groove toward an end away from the first strip groove, and gradually approaches a preset width; A second lower cladding layer is conformally formed on a side of the first lower cladding layer away from the substrate layer, the second lower cladding layer has a second groove extending into the first groove, the second groove includes a second strip groove and a second tapered groove that are connected, and the cross-sectional width of the second tapered groove gradually decreases from an end connected to the second strip groove toward an end away from the second strip groove and gradually approaches zero; A waveguide core is formed in the second groove, and the waveguide core includes a strip portion and a tapered portion; from an end connected to the strip portion toward an end away from the strip portion, the cross-sectional width of the tapered portion gradually decreases and gradually approaches zero, and the surface of the waveguide core is flush with the port of the second groove.

2. The method for preparing a waveguide structure according to claim 1, characterized in that: The cross-sectional width of the first tapered groove decreases linearly in a direction from an end connected to the first strip groove toward an end away from the first strip groove.

3. The method for preparing a waveguide structure according to claim 1, characterized in that: The cross-sectional width of the first tapered groove decreases nonlinearly in a direction from an end connected to the first strip groove toward an end away from the first strip groove.

4. The method for preparing a waveguide structure according to any one of claims 1 to 3, characterized in that: The second lower cladding layer is made of the same material as the first lower cladding layer.

5. The method for preparing a waveguide structure according to claim 4, characterized in that: The forming of a waveguide core in the second groove comprises: forming a first initial waveguide layer on the entire surface of the second lower cladding layer on one side away from the substrate layer, wherein the thickness of the first initial waveguide layer in the second groove is greater than or equal to the depth of the second groove; The portion of the first initial waveguide layer protruding from the end of the second groove is removed by grinding to obtain a waveguide core located in the second groove and flush with the end of the second groove.

6. The method for preparing a waveguide structure according to claim 5, characterized in that: The depth of the second groove is set to be greater than the width of the second groove, and the thickness of the first initial waveguide layer is greater than or equal to half of the width of the second groove.

7. The method for preparing a waveguide structure according to claim 6, characterized in that: After forming the waveguide core in the second groove, the method further comprises: A first upper cladding layer is formed on a surface of the second lower cladding layer facing away from the substrate layer, and the first upper cladding layer covers the second lower cladding layer and the waveguide core.

8. A waveguide structure, manufactured by the method for manufacturing a waveguide structure according to any one of claims 1 to 7, suitable for being arranged on a substrate layer; characterized in that: include: A first lower cladding layer is located on one side surface of the substrate layer; a first groove is provided in the first lower cladding layer on a side away from the substrate layer, the first groove includes a first strip groove and a first tapered groove that are connected to each other, and a cross-sectional width of the first tapered groove gradually decreases from an end connected to the first strip groove toward an end away from the first strip groove, and gradually approaches a preset width; A second lower cladding layer is located on a side of the first lower cladding layer away from the substrate layer, and the second lower cladding layer is arranged conformally with the first lower cladding layer; the second lower cladding layer has a second groove extending into the first groove, the second groove includes a second strip groove and a second tapered groove that are connected, and the cross-sectional width of the second tapered groove gradually decreases from an end connected to the second strip groove toward an end away from the second strip groove, and gradually approaches zero; A waveguide core is located in the second groove, and the waveguide core includes a strip portion and a tapered portion; from an end connected to the strip portion toward an end away from the strip portion, the cross-sectional width of the tapered portion gradually decreases and gradually approaches zero, and the surface of the waveguide core is flush with the port of the second groove.

9. A method for preparing an interlayer coupling device, characterized in that: include: providing a substrate layer; A first waveguide structure is formed on a surface of one side of the substrate layer, wherein the first waveguide structure includes a first waveguide core having a first strip-shaped portion and a first tapered portion; A second waveguide structure is formed on a side of the first waveguide structure away from the substrate layer; the second waveguide structure comprises a second waveguide core having a second strip-shaped portion and a second tapered portion; In forming the first waveguide structure and forming the second waveguide structure, at least one of them adopts the method for preparing a waveguide structure described in any one of claims 1 to 7; the cross-sectional width of an end of the first tapered portion away from the first strip portion and / or an end of the second tapered portion away from the second strip portion gradually approaches zero; an end of the first tapered portion away from the first strip portion and an end of the second tapered portion away from the first strip portion are arranged opposite to each other, and the first tapered portion and the second tapered portion at least partially overlap.

10. The method for preparing an interlayer coupling device according to claim 9, characterized in that: A first waveguide structure is formed on one side surface of the substrate layer by using the method for preparing a waveguide structure according to any one of claims 1 to 7, wherein the first waveguide structure comprises a first lower cladding, a second lower cladding and a first waveguide core; the first waveguide core is located in the second groove, and the first waveguide core comprises a first strip portion and a first tapered portion; in a direction from an end connected to the first strip portion toward an end away from the first strip portion, a cross-sectional width of the first tapered portion gradually decreases, and a cross-sectional width of an end of the first tapered portion away from the first strip portion gradually approaches zero, and a surface of the waveguide core is flush with a port of the second groove; The first waveguide structure further includes: a first upper cladding layer formed on a surface of the second lower cladding layer facing away from the substrate layer; and a second waveguide structure formed on a side of the first waveguide structure facing away from the substrate layer, including: A third groove is formed in the first upper cladding layer at a side away from the substrate layer, the third groove comprises a third strip groove and a third tapered groove which are connected to each other, and a cross-sectional width of the third tapered groove gradually decreases from an end connected to the third strip groove toward an end away from the third strip groove, and gradually approaches a preset width; A second upper cladding layer is conformally formed on a side of the first upper cladding layer away from the substrate layer, the second upper cladding layer has a fourth groove extending into the third groove, the fourth groove includes a fourth strip groove and a fourth tapered groove that are connected, and the cross-sectional width of the fourth tapered groove gradually decreases in a direction from an end connected to the fourth strip groove toward an end away from the fourth strip groove, and the cross-sectional width of the fourth tapered groove at an end away from the fourth strip groove gradually approaches zero; A second waveguide core is formed in the fourth groove, the second waveguide core comprising a second strip portion and a second tapered portion; a cross-sectional width of the second tapered portion gradually decreases in a direction from an end connected to the second strip portion toward an end away from the second strip portion, and a cross-sectional width of the second tapered portion at an end away from the second strip portion gradually approaches zero, and a surface of the second waveguide core is flush with a port of the fourth groove.

11. The method for preparing an interlayer coupling device according to claim 10, characterized in that: After forming the second waveguide core in the fourth groove, the method further includes: A third upper cladding layer is formed on a surface of the second upper cladding layer facing away from the substrate layer, and the third upper cladding layer covers the second upper cladding layer and the second waveguide core.

12. The method for preparing an interlayer coupling device according to claim 11, characterized in that: Projections of an axis of the first waveguide core and an axis of the second waveguide core on the substrate layer are collinear.

13. An interlayer coupling device, manufactured by the method for manufacturing an interlayer coupling device according to any one of claims 9 to 12, characterized in that: include: substrate layer; A first waveguide structure and a second waveguide structure are stacked on the substrate layer; the first waveguide structure comprises a first waveguide core having a first strip portion and a first tapered portion; the second waveguide structure comprises a second waveguide core having a second strip portion and a second tapered portion; The cross-sectional width of one end of the first tapered portion away from the first strip portion and / or one end of the second tapered portion away from the second strip portion gradually approaches zero; one end of the first tapered portion away from the first strip portion and one end of the second tapered portion away from the first strip portion are arranged opposite to each other, and the first tapered portion and the second tapered portion at least partially overlap.

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