Waveguide structure and method of manufacturing the same, interlayer coupling device and method of manufacturing the same

Abstract

The present application relates to the technical field of optical devices, and discloses a waveguide structure, a preparation method thereof, 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 layer on a substrate layer; the first lower cladding layer forms a first groove comprising a first strip-shaped groove and a first tapered groove, the cross-sectional width of the first tapered groove gradually decreases and gradually approaches a preset width; a second lower cladding layer with a second groove is formed on the first lower cladding layer in a conformal manner, the second groove extends into the first groove, comprises a second strip-shaped groove and a second tapered groove, the cross-sectional width of the second tapered groove gradually decreases and gradually approaches zero; a waveguide core conformal to the second groove is formed in the second groove. The interlayer coupling device formed by the preparation method of the waveguide structure can improve the coupling efficiency and integration, reduce the transmission loss, and does not require a high-resolution photolithography process.

Description

TECHNICAL FIELD

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

[0002] To meet the requirements of low power consumption, multi-function 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 realization of non-interference 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 for realizing the coupling of optical signals between different levels.

[0003] The tapered waveguide in the related art realizes the gradual change of width through photolithography and etching process, but due to the limitation of photolithography resolution, the end of the tapered waveguide still has a certain width, which makes it easy to produce reflection and resonance at the position of the end of the tapered waveguide during optical 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 narrow, but this way requires higher photolithography resolution, high process requirement and large preparation difficulty; the other is to increase the distance between the two ends of the tapered waveguide, but this way will increase the overall size of the device, which is not conducive to the integration of the device. SUMMARY

[0004] Therefore, the present application provides a waveguide structure and a preparation method thereof, and an interlayer coupling device and a preparation method thereof, to solve the problems of high preparation process requirement and poor integration of the existing interlayer coupling device.

[0005] In a first aspect, the present application provides a preparation method of a waveguide structure, comprising:

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

[0007] forming a first recess on the side of the first lower cladding layer away from the substrate layer, the first recess comprising a first strip-shaped groove and a first tapered groove connected in communication, the cross-sectional width of the first tapered groove gradually decreases in the direction from the end connected with the first strip-shaped groove to the end away from the first strip-shaped groove, and gradually approaches a preset width;

[0008] forming a second lower cladding layer conformally on the side of the first lower cladding layer away from the substrate layer, the second lower cladding layer having a second recess extending into the first recess, the second recess comprising a second strip-shaped groove and a second tapered groove connected in communication, the cross-sectional width of the second tapered groove gradually decreases in the direction from the end connected with the second strip-shaped groove to the end away from the second strip-shaped groove, and gradually approaches zero;

[0009] The waveguide core is formed in the second groove, and the waveguide core comprises a strip-shaped part and a tapered part; from the end connected with the strip-shaped part to the end away from the strip-shaped part, the cross-sectional width of the tapered part 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 is compatible with the conventional scheme to form a first lower cladding layer with a first groove, then a second lower cladding layer is formed by conformal deposition, the width of the first groove is further reduced, and a second groove with a precise sharp end suitable for accommodating a waveguide core material is simply and quickly formed; finally, a waveguide core with a precise sharp end is obtained by simple filling. The groove with a sharp end for accommodating the waveguide core and the waveguide core are formed by two-step conformal deposition, and the waveguide core structure with a sharp end of the waveguide core is simply and quickly obtained, which helps to improve the coupling efficiency and integration and reduce the transmission loss, and does not require high-resolution photolithography process, has low process difficulty, is not limited in material selection, and has wide application range.

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

[0012] Beneficial effects: the first tapered groove has linearly reduced width, the first tapered groove is simple to form, the wall surface with linear change has high consistency, and the surface performance is superior, which helps to conformally form the second tapered groove of the second groove.

[0013] In an optional embodiment, from the end connected with the first strip-shaped groove to the end away from the first strip-shaped groove, the cross-sectional width of the first tapered groove non-linearly decreases.

[0014] Beneficial effects: the first tapered groove has non-linearly reduced width, which can include two smooth curved surfaces concave inward or two smooth curved surfaces convex outward, in this embodiment, the two smooth curved surfaces concave inward are selected, the sharp end is more easily and quickly formed at the sharp end when the second lower cladding layer is conformally deposited, and the formed end has higher sharpness, which helps to further improve the coupling efficiency and reduce the transmission loss.

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

[0016] Beneficial effects: the same material of the first lower cladding layer and the second lower cladding layer helps to conformally deposit, and is more conducive to forming a smooth and consistent inner wall surface for the formed second groove, thereby improving the forming quality of the waveguide core.

[0017] In an optional embodiment, the waveguide core is formed in the second groove, comprising:

[0018] The first initial waveguide layer is formed on the entire surface of the side of the second lower cladding layer away from the substrate layer, and 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 first initial waveguide layer protruding from the port of the second groove is removed by grinding to obtain a waveguide core located in the second groove and flush with the port of the second groove.

[0020] Beneficial effects: The first initial waveguide layer is deposited on the entire surface of the upper surface of the second lower cladding layer, and then the excess part is removed by grinding to form the first waveguide core. The thickness of the first initial waveguide layer in the second groove is greater than or equal to the depth of the second groove, which can effectively avoid the waveguide core material in the second groove being inadvertently removed in the subsequent grinding process, thereby preventing the waveguide core from being damaged during the forming process, 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 embodiment, the depth of the second groove is greater than the width of the second groove, and the thickness of the first initial waveguide layer is greater than or equal to half the width of the second groove.

[0022] Beneficial effects: The second groove narrows at a speed that is about twice the speed at which the second groove becomes shallower. When the depth of the second groove is greater than half the width of the second groove, only the first initial waveguide layer with a thickness of half the width of the second groove is needed to fill the second groove, i.e., it is not necessary to deposit the first initial waveguide layer with a thickness greater than the depth of the second groove, which helps to accurately determine the thickness of the first initial waveguide layer and reduces unnecessary material waste.

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

[0024] Beneficial effects: The first upper cladding layer can provide external protection for the waveguide core, and by adjusting its thickness, the distance between the waveguide core and another waveguide core arranged thereon can be adjusted to improve the coupling efficiency between waveguides at different levels and reduce transmission loss.

[0025] In a second aspect, the present application also provides a waveguide structure prepared by the preparation method of the waveguide structure, and suitable for being arranged on a substrate layer, comprising: a first lower cladding layer, a second lower cladding layer and a waveguide core, the first lower cladding layer is located on one side surface of the substrate layer, the first lower cladding layer has a first recess on the side away from the substrate layer, the first recess comprises a first strip-shaped groove and a first tapered groove connected in communication, the cross-sectional width of the first tapered groove gradually decreases from the end connected with the first strip-shaped groove to the end away from the first strip-shaped groove, and gradually approaches a preset width; the second lower cladding layer is located on the side of the first lower cladding layer away from the substrate layer, the second lower cladding layer is conformally arranged with the first lower cladding layer, the second lower cladding layer has a second recess extending into the first recess, the second recess comprises a second strip-shaped groove and a second tapered groove connected in communication, the cross-sectional width of the second tapered groove gradually decreases from the end connected with the second strip-shaped groove to the end away from the second strip-shaped groove, and gradually approaches zero; the waveguide core is located in the second recess, the waveguide core comprises a strip-shaped part and a tapered part, the cross-sectional width of the tapered part gradually decreases from the end connected with the strip-shaped part to the end away from the strip-shaped part, and gradually approaches zero, and the surface of the waveguide core is flush with the port of the second recess.

[0026] Beneficial effects: the waveguide structure of the present application is prepared based on the preparation method of the waveguide structure, the waveguide structure has a high-precision sharp end, which can effectively improve the interlayer coupling efficiency and device integration, and reduce the transmission loss; in addition, the surface of the waveguide core is flush with the port of the second recess, 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 application provides a preparation method of an interlayer coupling device, comprising:

[0028] providing a substrate layer;

[0029] forming a first waveguide structure on one side surface of the substrate layer, the first waveguide structure comprises a first waveguide core having a first strip-shaped part and a first tapered part;

[0030] forming a second waveguide structure on the 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 part and a second tapered part;

[0031] in at least one of the forming of the first waveguide structure and the forming of the second waveguide structure, the preparation method of the waveguide structure is adopted; the cross-sectional width of the end of the first tapered part away from the first strip-shaped part and / or the end of the second tapered part away from the second strip-shaped part gradually approaches zero; the end of the first tapered part away from the first strip-shaped part is arranged opposite to the end of the second tapered part away from the first strip-shaped part, and the first tapered part and the second tapered part at least partially overlap.

[0032] Beneficial effects: the preparation method of the interlayer coupling device, including layering the first waveguide structure and the second waveguide structure on the substrate layer, and at least one of the two steps of forming the first waveguide structure and forming the second waveguide structure adopts the preparation method of the waveguide structure, to ensure that at least one of the waveguide structures forms a precise sharp end, without high photolithography resolution, low preparation difficulty, wide application range, and can improve the coupling efficiency and integration of the interlayer coupling device, while reducing the transmission loss.

[0033] In an optional embodiment, the preparation method of the waveguide structure is used to form the first waveguide structure on one side surface of the substrate layer, the first waveguide structure includes a first lower cladding layer, a second lower cladding layer and a first waveguide core; the first waveguide core is located in the second groove, and the first waveguide core includes a first strip part and a first tapered part; from one end connected with the first strip part to the direction away from the first strip part, the cross-sectional width of the first tapered part gradually decreases, and the cross-sectional width of the first tapered part away from the first strip part gradually approaches zero, and the surface of the waveguide core is flush with the port of the second groove;

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

[0035] A third groove is formed in the first upper cladding layer away from the substrate layer, the third groove includes a third strip groove and a third tapered groove connected in communication, from one end connected with the third strip groove to the direction away from the third strip groove, the cross-sectional width of the third tapered groove gradually decreases, and gradually approaches a preset width;

[0036] A second upper cladding layer is conformally formed on the 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 connected in communication, from one end connected with the fourth strip groove to the direction away from the fourth strip groove, the cross-sectional width of the fourth tapered groove gradually decreases, and the cross-sectional width of the fourth tapered groove 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 part and a second tapered part; from one end connected with the second strip part to the direction away from the second strip part, the cross-sectional width of the second tapered part gradually decreases, and the cross-sectional width of the second tapered part away from the second strip part gradually approaches zero, and the surface of the second waveguide core is flush with the port of the fourth groove.

[0038] Beneficial effects: the first waveguide structure and the second waveguide structure are both prepared by the preparation method of the waveguide structure, and the waveguide cores of the two waveguide structures both have sharp end portions with a cross-sectional width gradually approaching zero. That is, by narrowing the width of the groove formed for the first time in the conventional scheme through the two conformal films, the waveguide core with the end portion cross-sectional width gradually approaching zero is simply and quickly formed, which can improve the integration of the device and help the coupling effect of the second wave structure and the first wave structure and the integration of the interlayer coupling device.

[0039] In an optional embodiment, after the second waveguide core is formed in the fourth groove, the method further comprises: forming a third upper cladding layer on a side surface of the second upper cladding layer away from the substrate layer, the third upper cladding layer covering the second upper cladding layer and the second waveguide core.

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

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

[0042] Beneficial effects: the axis of the first waveguide core and the axis of the second waveguide core are collinear in projection on the substrate layer, which can ensure that the sharp end of the first waveguide core and the sharp end of the second waveguide core are accurately aligned and partially overlapped, guaranteeing efficient coupling effect and reducing transmission loss.

[0043] In a fourth aspect, the present application provides an interlayer coupling device prepared by the preparation method of the interlayer coupling device, comprising: a substrate layer, a first waveguide structure and a second waveguide structure, the first waveguide structure and the second waveguide structure being arranged in layers on the substrate layer, the first waveguide structure comprising a first waveguide core with a first strip portion and a first tapered portion; the second waveguide structure comprising a second waveguide core with a second strip portion and a second tapered portion; the cross-sectional width of the end of the first tapered portion away from the first strip portion and / or the end of the second tapered portion away from the second strip portion gradually approaches zero; the end of the first tapered portion away from the first strip portion and the end of the second tapered portion away from the first strip portion are arranged in opposite directions, and the first tapered portion and the second tapered portion at least partially overlap.

[0044] Beneficial effects: the interlayer coupling device of the present application comprises the first waveguide structure and the second waveguide structure arranged in layers on the substrate layer, and at least one of the first waveguide structure and the second waveguide structure has a sharp end portion, which helps to improve the coupling efficiency and integration of the interlayer coupling device and reduce transmission loss. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the drawings needed to be used in the specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0046] Figure 1 is a flowchart of the preparation method of the waveguide structure of the embodiment of the present application;

[0047] Figure 2 is a top view schematic diagram of the first gradually tapered slot width linear reduction of the embodiment of the present application;

[0048] Figure 3 is a top view schematic diagram of the first gradually tapered slot width linear reduction of the embodiment of the present application;

[0049] Figure 4 is a cross-sectional schematic diagram according to A1-A1 in Figure 2 or Figure 3 ;

[0050] Figure 5 is a top view schematic diagram of the second gradually tapered slot width linear reduction of the embodiment of the present application;

[0051] Figure 6 is a top view schematic diagram of the second gradually tapered slot width linear reduction of the embodiment of the present application;

[0052] Figure 7 is a cross-sectional schematic diagram according to A2-A2 in Figure 5 or Figure 6 ;

[0053] Figure 8 is a top view schematic diagram of the gradually tapered slot width linear reduction of the waveguide core of the embodiment of the present application;

[0054] Figure 9 is a top view schematic diagram of the gradually tapered slot width linear reduction of the waveguide core of the embodiment of the present application;

[0055] Figure 10 is a cross-sectional schematic diagram according to A3-A3 in Figure 8 or Figure 9 ;

[0056] Figure 11 is a schematic diagram of the structure after setting the initial first waveguide layer of the embodiment of the present application;

[0057] Figure 12 is a schematic diagram of the waveguide structure after setting the first upper cladding layer of the embodiment of the present application;

[0058] Figure 13 is a flowchart of a preparation method of an interlayer coupling device according to an embodiment of the present application;

[0059] Figure 14 is a top view schematic diagram of the interlayer coupling device after a first waveguide structure is formed according to an embodiment of the present application;

[0060] Figure 15 is a cross-sectional view schematic diagram at B1-B1 in Figure 14

[0061] Figure 16 is a top view schematic diagram of the interlayer coupling device after a third groove is formed on the first upper cladding layer according to an embodiment of the present application;

[0062] Figure 17 is a cross-sectional view schematic diagram at B2-B2 in Figure 16

[0063] Figure 18 is a top view schematic diagram of the interlayer coupling device after a fourth groove is formed on the second upper cladding layer according to an embodiment of the present application;

[0064] Figure 19 is a cross-sectional view schematic diagram at B3-B3 in Figure 18

[0065] Figure 20 is a top view schematic diagram of the interlayer coupling device after a second waveguide core is arranged in the fourth groove of the second upper cladding layer according to an embodiment of the present application;

[0066] Figure 21 is a cross-sectional view schematic diagram at B4-B4 in Figure 20

[0067] Figure 22 is a structure schematic diagram of the interlayer coupling device after an initial second waveguide layer is arranged according to an embodiment of the present application;

[0068] Figure 23 is a structure schematic diagram of the interlayer coupling device after a third upper cladding layer is arranged according to an embodiment of the present application.

[0069] Explanation of reference signs:

[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 part; 42, tapered part; 400a, first initial waveguide layer; ​​​​

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

[0075] 5, first upper cladding layer; 51, third groove; 511, third bar-shaped groove; 512, third tapered groove;

[0076] 6, second upper cladding layer; 61, fourth groove; 611, fourth bar-shaped groove; 612, fourth tapered groove;

[0077] 7, third upper cladding layer. DETAILED DESCRIPTION

[0078] The application will be further described below in conjunction with the drawings and embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. It is also to be understood that, for the purpose of explanation, only the parts of the structures related to the present application are shown in the drawings and not all the parts. In the following description, the description of the well-known structures and techniques is omitted to avoid unnecessary confusion of the concept of the present application. In the drawings, various structural diagrams according to the embodiments of the present application are shown. These diagrams are not drawn to scale, in which some details are exaggerated for the purpose of clarity and some details can be omitted. The shapes of the various regions, layers, and the relative size and position relationship between them shown in the drawings are merely exemplary, and in practice, they can be deviated due to manufacturing tolerance or technical limitation, and a person skilled in the art can additionally design regions / layers with different shapes, sizes, and relative positions according to the actual needs. In the context of the present application, when a layer / element is referred to as being located "on" another layer / element, the layer / element can be directly located on the other layer / element, or there can be an intermediate layer / element between them. In addition, if a layer / element is located "on" another layer / element in one orientation, it can be located "under" the other layer / element when the orientation is reversed.

[0079] The tapered waveguide in the related art is realized by photolithography and etching process, but is limited by the resolution of photolithography, and the tapered waveguide end still has a certain width, so that reflection and resonance are easily generated at the tapered waveguide end position when light is coupled, thereby affecting the coupling efficiency and transmission loss of the device. To improve this situation, two methods are usually adopted: one is to make the end narrow, but this way requires higher photolithography resolution, has high process requirement and is difficult to prepare; or a tapered mask is used to shield part of the epitaxial film layer, and after the epitaxial film layer not shielded is subjected to thermal oxidation, the epitaxial film layer after thermal oxidation and the tapered mask are etched to remove, so as to obtain a tapered waveguide core, but this requires the material of the epitaxial film layer to have thermal oxidation property, and the tapered mask and the oxidized epitaxial film layer have high etching selectivity to the epitaxial film layer not oxidized, so the material of the epitaxial film layer (i.e. the tapered waveguide core) is greatly limited, and the application range is small; the other way is to increase the distance between the two tapered waveguide ends, but this way will increase the overall size of the device, which is not conducive to the integration of the device. Therefore, there is an urgent need for an optical waveguide structure and a preparation method of an interlayer coupling device which has low preparation difficulty, wide application range and can improve the integration.

[0080] Therefore, with reference to Figures 1 to 12 , the embodiment provides a preparation method of a waveguide structure, Figure 1 is a flowchart of the preparation method of the waveguide structure, which comprises the following steps:

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

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

[0083] Step S102, forming a first recess 21 in the first lower cladding layer 2 away from the substrate layer 1, the first recess 21 comprising a first strip-shaped groove 211 and a first tapered groove 212 connected in series, the cross-sectional width of the first tapered groove 212 gradually decreases in the direction from the end connected with the first strip-shaped groove 211 to the end away from the first strip-shaped groove 211, and gradually approaches a preset width.

[0084] With reference to Figures 2 to 4 , the first recess 21 is etched on the upper surface of the first lower cladding layer 2, exemplarily, the width of the first tapered groove 212 of the first recess 21 can be linear or nonlinear, but the end of the first tapered groove 212 away from the first strip-shaped groove 211 still has a certain width, so the requirement for the resolution of photolithography is not particularly high, which is compatible with the conventional resolution of photolithography and has low process difficulty.

[0085] Step S103, a second lower cladding layer 3 is conformally formed on the side of the first lower cladding layer 2 away from the substrate layer 1, the second lower cladding layer 3 has a second recess 31 extending into the first recess 21, the second recess 31 includes a second strip groove 311 and a second tapered groove 312 connected in sequence, the cross-sectional width of the second tapered groove 312 gradually decreases from the end connected with the second strip groove 311 to the end away from the second strip groove 311, and gradually approaches zero.

[0086] Reference Figures 5 to 7 The second lower cladding layer 3 is conformally formed on the upper side of the first lower cladding layer 2 by a thin film deposition process such as chemical vapor deposition (CVD), atomic layer deposition (ALD), etc. Due to the conformal formation, the second lower cladding layer 3 forms the second recess 31 extending into the first recess 21, the thickness of the second lower cladding layer 3 at each of the side wall and the bottom of the first recess 21 is equal, the inner width of the second strip groove 311 of the second recess 31 is equal to the inner width of the first strip groove 211 of the first recess 21 minus twice the thickness of the second lower cladding layer 3, and the depth of the second recess 31 is equal to the depth of the first recess 21, so that the formed second recess 31 has the same shape as the first recess 21, thereby ensuring the topography characteristics of the formed waveguide core 4; as the thickness of the second lower cladding layer 3 increases, the width of the first tapered groove 212 of the first recess 21 away from the end of 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 recess 31, the waveguide core 4 includes a strip portion 41 and a tapered portion 42; the cross-sectional width of the tapered portion 42 gradually decreases from the end connected with the strip portion 41 to the end away from the strip portion 41, and gradually approaches zero, and the surface of the waveguide core 4 is flush with the port of the second recess 31.

[0088] Reference Figures 8 to 10 The waveguide core 4 is filled and formed in the second recess 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 recess 31, that is, the surface of the waveguide core 4 is flush with the port of the second recess 31, ensuring that the waveguide core 4 with the strip portion 41 and the tapered portion 42 is integrally formed and completely consistent with the second recess 31, and the end of the tapered portion 42 away from the strip portion 41 is precisely formed as a sharp end with a width approaching zero.

[0089] In this embodiment, first, the first lower cladding layer 2 is formed, and the first recess 21 is formed in the first lower cladding layer 2. The tapering portion of the first recess 21, i.e., the first tapered groove 212, is not strictly required to have a width that decreases away from the end of the first strip groove 211, and is allowed to have a certain width. Then, the second lower cladding layer 3 is formed by conformal formation, and the second recess 31 having a width that is narrower than that of the first recess 21 is formed in the second lower cladding layer 3 corresponding to the first recess 21. The second tapered groove 312 of the second recess 31 has a width that even approaches zero away from one end of the first strip groove 211. Then, the waveguide core 4 having a tapering shape with a sharp end is formed by filling the waveguide core 4 material in the second recess 31.

[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 layer 2 having the first recess 21. Then, the second lower cladding layer 3 is formed by conformal formation, further reducing the width of the first recess 21, and the thickness of the second lower cladding layer 3 at each position in the first recess 21 is equal, ensuring that the second recess 31 is consistent with the shape of the first recess 21. The second recess 31 having a sharp end suitable for accommodating the waveguide core 4 material is simply and quickly formed, and the inner wall of the second recess 31 has a good appearance. Finally, the waveguide core 4 having a sharp end is obtained by simple filling. The second recess 31 having a sharp end for accommodating the waveguide core 4 and the waveguide core 4 are formed by two-step conformal formation, which is simple and fast to obtain the waveguide core 4 structure with a sharp end of the waveguide core 4, which helps to improve the coupling efficiency and integration and reduce the transmission loss. Moreover, the high-resolution photolithography process is not required, the process difficulty is low, the material selection is not limited, and the application range is wide.

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

[0092] As shown in Figure 6 and Figure 7 , the second lower cladding layer 3 is conformally formed on the first lower cladding layer 2. Therefore, for the second recess 31, the cross-sectional width of the second tapered groove 312 linearly decreases in the direction from the end connected to the second strip groove 311 to the end away from the second strip groove 311. Similarly, as shown in Figures 8 to 10 , for the waveguide core 4 formed by filling in the second recess 31, the cross-sectional width of the tapered portion 42 linearly decreases in the direction from the end connected to the strip portion 41 to the end away from the strip portion 41, as shown in Figure 9 . In this embodiment, the width of the first tapered groove 212 linearly decreases, the first tapered groove 212 is simple to form, the wall has high consistency in linear change, and the surface performance is superior, which helps the conformal formation of the second tapered groove 312 of the second recess 31 in the subsequent process.

[0093] In another alternative embodiment, referring to Figure 2 , the cross-sectional width of the first tapered groove 212 decreases non-linearly from the end connected to the first strip groove 211 towards the end away from the first strip groove 211.

[0094] Similarly, at this time, since the second lower cladding layer 3 is conformally formed on the first lower cladding layer 2, for the second groove 31, the cross-sectional width of the second tapered groove 312 decreases non-linearly from the end connected to the second strip groove 311 towards the end away from the second strip groove 311, as shown in Figure 5 Similarly, for the waveguide core 4 formed by filling the second groove 31, the cross-sectional width of the tapered portion 42 decreases non-linearly from the end connected to the strip portion 41 towards the end away from the strip portion 41, as shown in Figure 8 In this embodiment, the non-linear decrease in the width of the first tapered groove 212 can include two smooth curves concave inward or two smooth curves convex outward. In the present embodiment, the two smooth curves concave inward are selected, which makes it easier to quickly form a sharp end at the tip when conformally forming the second lower cladding layer 3, and the formed end is more sharp, which helps to further improve the coupling efficiency and reduce the transmission loss.

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

[0096] For example, the first lower cladding layer 2 and the second lower cladding layer 3 are both made of silica material. The use of the same material for the first lower cladding layer 2 and the second lower cladding layer 3 helps conformal deposition, and for the second groove 31 formed, it is more helpful to form a smooth and consistent inner wall surface, thereby improving the forming 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 400a on the entire surface of the side of the second lower cladding layer 3 away from the substrate layer 1, the thickness of the first initial waveguide layer 400a in the second groove 31 is greater than or equal to the depth of the second groove 31.

[0099] Referring to Figure 11The first initial waveguide layer 400a is deposited on the upper surface of the second lower cladding layer 3. The first initial waveguide layer 400a can be made of silicon nitride, amorphous silicon or other material with 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 greater than or equal to the depth of the second groove 31, so as to avoid the waveguide core 4 material in the second groove 31 from being removed by mistake in the subsequent grinding process, thereby ensuring that the first initial waveguide layer 400a material sufficiently fills the second groove 31, and finally ensuring the conformal formation of the waveguide core 4 in the second groove 31.

[0100] In step S1042, the portion of the first initial waveguide layer 400a protruding from the port of the second groove 31 is removed by grinding, so as to obtain the waveguide core 4 located in the second groove 31 and flush with the port of the second groove 31.

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

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

[0103] When the material of the first initial waveguide layer 400a is deposited, the second groove 31 narrows due to the simultaneous deposition of the first initial waveguide layer 400a on the opposite two side walls of the second groove 31, and the second groove 31 becomes shallower due to the deposition of the first initial waveguide layer 400a at the bottom of the second groove 31. Therefore, the narrowing speed of the second groove 31 is about twice the shallowing speed of the second groove 31. When the depth of the second groove 31 is greater than half the width of the second groove 31, the first initial waveguide layer 400a with a thickness of half the width of the second groove 31 is sufficient to fill the second groove 31, that is, the first initial waveguide layer 400a with a thickness greater than the depth of the second groove 31 is not necessary. This helps to accurately determine the thickness of the first initial waveguide layer 400a and reduces unnecessary material waste.

[0104] In an embodiment, referring to Figure 12 After the step S104 of forming the waveguide core 4 in the second groove 31, the method further includes:

[0105] In step S105, a first upper cladding layer 5 is formed on the surface of the second lower cladding layer 3 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.

[0106] Exemplarily, the first upper cladding layer 5 can also be silicon dioxide, and the thickness of the first upper cladding layer 5 ranges from 0.1 μm to 10 μm. On one hand, the first upper cladding layer 5 can protect the waveguide core 4 from the outside. On the other hand, by adjusting the thickness of the first upper cladding layer 5, the distance between the waveguide core 4 and another waveguide core 4 arranged thereon can be adjusted, so as to improve the coupling efficiency between waveguides of different levels and reduce the transmission loss.

[0107] As shown in Figure 10 , the embodiment also provides a waveguide structure, which is prepared by using the preparation method of the waveguide structure and is suitable to be arranged on the substrate layer 1. The waveguide structure 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 recess 21 on the side away from the substrate layer 1. The first recess 21 comprises a first strip-shaped groove 211 and a first tapered groove 212 connected in series. The cross-sectional width of the first tapered groove 212 gradually decreases from the end connected with the first strip-shaped groove 211 to the end away from the first strip-shaped 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 away from the substrate layer 1. The second lower cladding layer 3 is conformally arranged with the first lower cladding layer 2. The second lower cladding layer 3 has a second recess 31 extending into the first recess 21. The second recess 31 comprises a second strip-shaped groove 311 and a second tapered groove 312 connected in series. The cross-sectional width of the second tapered groove 312 gradually decreases from the end connected with the second strip-shaped groove 311 to the end away from the second strip-shaped groove 311, and gradually approaches zero. The waveguide core 4 is located in the second recess 31. The waveguide core 4 comprises a strip-shaped portion 41 and a tapered portion 42. The cross-sectional width of the tapered portion 42 gradually decreases from the end connected with the strip-shaped portion 41 to the end away from the strip-shaped portion 41, and gradually approaches zero. The surface of the waveguide core 4 is flush with the port of the second recess 31.

[0108] The waveguide structure of the embodiment is prepared by using the preparation method of the waveguide structure. The waveguide structure has a high-precision sharp end, which can effectively improve the interlayer coupling efficiency and device integration and reduce the transmission loss. In addition, the surface of the waveguide core 4 is flush with the port of the second recess 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, with reference to Figure 12 , the waveguide structure of the embodiment further comprises a first upper cladding layer 5 formed on the side surface of the second lower cladding layer 3 away from the substrate layer 1. 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 0.1 μm to 10 μm. The first upper cladding layer 5 can protect the waveguide core 4 from the outside, and can adjust the distance between the waveguide core 4 and another waveguide core 4 arranged thereon by adjusting the thickness of the first upper cladding layer 5, so as to improve the coupling efficiency between waveguide cores of different levels and reduce the transmission loss.

[0111] Further, with reference to Figures 13 to 23 , the embodiment also provides a preparation method of the interlayer coupling device, Figure 13 The preparation method of the interlayer coupling device is shown in the flowchart, and the preparation method comprises the following steps.

[0112] In step S1301, a substrate layer 1 is provided.

[0113] Exemplarily, the substrate layer 1 can be a silicon wafer, and the size of the silicon wafer is set according to the needs, which is not specifically limited.

[0114] In step S1302, a first waveguide structure is formed on one side surface of the substrate layer 1, and the first waveguide structure comprises a first waveguide core 401 with a first bar-shaped portion 4011 and a first tapered portion 4012.

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

[0116] In step S1303, a second waveguide structure is formed on the side of the first waveguide structure away from the substrate layer 1, and the second waveguide structure comprises a second waveguide core 402 with a second bar-shaped portion 4021 and a second tapered portion 4022. In the formation of the first waveguide structure and the formation of the second waveguide structure, at least one of them adopts the preparation method of the waveguide structure; the cross-sectional width of the first tapered portion 4012 away from the one end of the first bar-shaped portion 4011 and / or the cross-sectional width of the second tapered portion 4022 away from the one end of the second bar-shaped portion 4021 gradually approaches zero; the one end of the first tapered portion 4012 away from the first bar-shaped portion 4011 is arranged opposite to the one end of the second tapered portion 4022 away from the first bar-shaped portion 4011, and the first tapered portion 4012 and the second tapered portion 4022 at least partially overlap.

[0117] Similarly, the second waveguide structure can be prepared by the above-mentioned preparation method of waveguide structure, and exemplarily include the first upper cladding layer 5 with the third groove 51, the second upper cladding layer 6 with the fourth groove 61 and conformally formed with the first upper cladding layer 5, and the second waveguide core 402; of course, the second waveguide structure can also be a conventional structure including only the first upper cladding layer 5 and a conventional waveguide core arranged in the third groove 51 of the first upper cladding layer 5, or a structure including only the first upper cladding layer 5 without the third groove 51 and a conventional waveguide core formed on the first upper cladding layer 5 by thin film deposition, photolithography and etching, and it can be known that the conventional waveguide core obtained by the above-mentioned conventional structure does not have a high-precision sharp end. It should be noted that at least one of the first waveguide structure and the second waveguide structure in the embodiment is prepared by the above-mentioned preparation method of waveguide structure, so as 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 a precise sharp end, wherein the sharp end refers to the part of the first tapered portion 4012 far away from the first bar-shaped portion 4011 gradually approaching to zero, or the part of the second tapered portion 4022 far away from the second bar-shaped portion 4021 gradually approaching to zero, the projection 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 has a partial overlap, and the overlapping part at least includes the above-mentioned sharp end.

[0118] The preparation method of the interlayer coupling device of the embodiment includes stacking the first waveguide structure and the second waveguide structure on the substrate layer 1, and at least one of the two steps of forming the first waveguide structure and forming the second waveguide structure adopts the above-mentioned preparation method of waveguide structure, so as to ensure that at least one of the waveguide structures has a precise sharp end, without high photolithography resolution, low preparation difficulty, wide application range, and can improve the coupling efficiency and integration of the interlayer coupling device, while reducing the transmission loss.

[0119] In the embodiment, the first waveguide structure and the second waveguide structure are both prepared by the above-mentioned preparation method of waveguide structure, and the first waveguide core 401 and the second waveguide core 402 of the two waveguide structures both have a sharp end with a cross-sectional width approaching to zero. That is, by two layers of conformal films, the width of the groove formed in the conventional scheme is narrowed, and then a waveguide core with an end cross-sectional width gradually approaching to zero is simply and quickly formed.

[0120] In one aspect, the preparation method of the above waveguide structure is used to form a first waveguide structure on one side surface of the substrate layer 1, the first waveguide structure comprising a first lower cladding layer 2, a second lower cladding layer 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-shaped portion 4011 and a first tapered portion 4012; from one end connected to the first strip-shaped portion 4011 to the direction away from the first strip-shaped 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] Referring to Figure 14 and Figure 15 On the basis of the above scheme, the first waveguide structure further comprises: a first upper cladding layer 5 formed on the side surface of the second lower cladding layer 3 away from the substrate layer 1. The thickness of the first upper cladding layer 5 is set to be in the range of 0.1 μm to 10 μm, and at this time, the first upper cladding layer 5 adjusts the distance between the first waveguide core 401 of the first waveguide structure and the second waveguide core 402 in the second waveguide structure by adjusting its own thickness, so as to ensure better coupling effect.

[0122] On the basis of the above scheme, the second waveguide structure is formed on the side surface of the first waveguide structure away from the substrate layer 1, and specifically comprises the following steps:

[0123] Step S1303a, a third groove 51 is formed in the first upper cladding layer 5 away from the substrate layer 1, the third groove 51 comprises a third strip-shaped groove 511 and a third tapered groove 512 connected in communication, from one end connected to the third strip-shaped groove 511 to the direction away from the third strip-shaped groove 511, the cross-sectional width of the third tapered groove 512 gradually decreases and gradually approaches a preset width.

[0124] Referring to Figure 16 and Figure 17 The third groove 51 is etched on the upper surface of the first upper cladding layer 5, and the width 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 away from the third strip-shaped groove 511 still has a certain width, so the requirement for the lithography resolution is not particularly high, and the process difficulty is low.

[0125] Step S1303b, a second upper cladding layer 6 is conformally formed on the side of the first upper cladding layer 5 away from the substrate layer 1, and the second upper cladding layer 6 has a fourth groove 61 extending into the third groove 51, the fourth groove 61 comprises a fourth strip-shaped groove 611 and a fourth tapered groove 612 connected in communication, from one end connected to the fourth strip-shaped groove 611 to the direction away from the fourth strip-shaped groove 611, the cross-sectional width of the fourth tapered groove 612 gradually decreases and gradually approaches zero.

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

[0127] In step S1303c, the second waveguide core 402 is formed in the fourth groove 61. The second waveguide core 402 includes a second strip portion 4021 and a second tapered portion 4022. The cross-sectional width of the second tapered portion 4022 gradually decreases from one end connected to the second strip portion 4021 to the direction away from the one end of the second strip portion 4021, and the cross-sectional width of the one end of the second tapered portion 4022 away from the second strip portion 4021 gradually approaches zero. The surface of the second waveguide core 402 is flush with the port of the fourth groove 61.

[0128] Reference Figure 20 and Figure 21 The second waveguide core 402 is filled and formed in the fourth groove 61 formed by 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 port of the fourth groove 61. This ensures that the second waveguide core 402 with the second strip portion 4021 and the second tapered portion 4022 is integrally formed and completely consistent with the fourth groove 61, and the one end of the second tapered portion 4022 away from the second strip portion 4021 is precisely formed with a sharp end with a width approaching zero.

[0129] The preparation method of the interlayer coupling device of the embodiment further improves the integration of the device and helps the coupling effect of the second waveguide core 402 and the first waveguide core 401, because the first upper cladding layer 5 of the first waveguide structure is used as the first layer bottom cladding layer of the second waveguide structure, and the third groove 51 of the second waveguide structure is etched directly on the first upper cladding layer 5.

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

[0131] Similarly, in the embodiment, when the second waveguide core 402 is formed, the following steps are included:

[0132] Referring to Figure 22 First, a second initial waveguide layer 400b is formed on the entire surface of the side of the second upper cladding layer 6 away from the substrate layer 1, and the thickness of the second initial waveguide layer 400b 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 the upper surface of the second upper cladding layer 6. Exemplarily, the second initial waveguide layer 400b can also be made of a material with a refractive index greater than the materials of the first upper cladding layer 5 and the second upper cladding layer 6, such as silicon nitride or amorphous silicon. The thickness of the second initial waveguide layer 400b in the fourth groove 61 is greater than or equal to the depth of the fourth groove 61, so as to avoid that the material of the second waveguide core 402 in the fourth groove 61 is removed by mistake in the subsequent grinding process, and thus the formation of the second waveguide core 402 is damaged. The material of the second initial waveguide layer 400b in the fourth groove 61 is fully filled, and finally the conformal formation of the second waveguide core 402 in the fourth groove 61 is ensured.

[0134] Then, the part of the second initial waveguide layer 400b protruding from the port of the fourth groove 61 is removed by grinding, so as to obtain the second waveguide core 402 located in the fourth groove 61 and flush with the port of the fourth groove 61.

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

[0136] Referring to Figure 23 After the step S1303c of forming the second waveguide core 402 in the fourth groove 61, the following steps are further included:

[0137] In step S1303d, a third upper cladding layer 7 is formed on the side surface of the second upper cladding layer 6 away from the substrate layer 1, and 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 the thickness of the third upper cladding layer 7, the distance between the third upper cladding layer 7 and another waveguide core arranged thereon can be adjusted, so as to improve the coupling efficiency between waveguides at different levels and reduce the transmission loss.

[0139] In one embodiment, referring to Figure 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 to ensure that the tip of the first waveguide core 401 and the tip of the second waveguide core 402 are precisely aligned and partially overlap, ensuring efficient coupling effect and reducing transmission loss.

[0140] Referring to Figure 20 and Figure 21 , the embodiment also provides an interlayer coupling device, which is prepared by the preparation method of the interlayer coupling device described above, 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-shaped portion 4011 and a first tapered portion 4012; the second waveguide structure includes a second waveguide core 402 having a second strip-shaped portion 4021 and a second tapered portion 4022; the cross-sectional width of the first tapered portion 4012 away from the first strip-shaped portion 4011 and / or the cross-sectional width of the second tapered portion 4022 away from the second strip-shaped portion 4021 gradually approaches zero; the end of the first tapered portion 4012 away from the first strip-shaped portion 4011 and the end of the second tapered portion 4022 away from the first strip-shaped portion 4011 are oppositely arranged, and the first tapered portion 4012 and the second tapered portion 4022 at least partially overlap.

[0141] The interlayer coupling device of the embodiment includes the first waveguide structure and the second waveguide structure stacked on the 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, as shown in Figure 23 , the interlayer coupling device described above further includes a third upper cladding layer 7 arranged on the upper side of the second upper cladding layer 6.

[0143] The further function description of each module is the same as that of the corresponding embodiment described above, and will not be described here.

[0144] In the above description, the technical details such as the patterning and etching of each layer are not described in detail. However, those skilled in the art should understand that the layers, regions, etc. of the required shape can be formed by various technical means. In addition, those skilled in the art can also design methods that are not exactly the same as the methods described above in order to form the same structure. In addition, although each embodiment is described above, this does not mean that the measures in each embodiment cannot be used advantageously in combination.

[0145] While embodiments of the application have been described in connection with the preferred embodiments of the various figures, those of ordinary skill in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the application, and that such modifications and changes fall within the scope of the appended claims.

Claims

1. A method of fabricating a waveguide structure, characterized by, Comprising: forming a first lower cladding layer on a substrate layer; forming a first recess in the first lower cladding layer, the first recess comprising a first bar-shaped groove and a first tapered groove connected in series, the cross-sectional width of the first tapered groove gradually decreases and gradually approaches a preset width from a first end connected to the first bar-shaped groove to a second end away from the first bar-shaped groove; forming a second lower cladding layer conformally on the side of the first lower cladding layer away from the substrate layer, the second lower cladding layer having a second recess extending into the first recess, the second recess comprising a second bar-shaped groove and a second tapered groove connected in series, the cross-sectional width of the second tapered groove gradually decreases and gradually approaches zero from a first end connected to the second bar-shaped groove to a second end away from the second bar-shaped groove; the second lower cladding layer is made of the same material as the first lower cladding layer; forming a waveguide core in the second recess, comprising: forming a first initial waveguide layer on the entire surface of the side of the second lower cladding layer away from the substrate layer, the thickness of the first initial waveguide layer in the second recess being greater than or equal to the depth of the second recess; grinding to remove part of the first initial waveguide layer protruding from the port of the second recess to obtain a waveguide core located in the second recess and flush with the port of the second recess, the waveguide core comprising a bar-shaped portion and a tapered portion, the cross-sectional width of the tapered portion gradually decreases and gradually approaches zero from a first end connected to the bar-shaped portion to a second end away from the bar-shaped portion.

2. The method of claim 1, wherein The cross-sectional width of the first tapered groove linearly decreases from a first end connected to the first bar-shaped groove to a second end away from the first bar-shaped groove.

3. The method of claim 1, wherein the method further comprises: The cross-sectional width of the first tapered groove non-linearly decreases from a first end connected to the first bar-shaped groove to a second end away from the first bar-shaped groove.

4. The method of claim 1, wherein The depth of the second recess is greater than the width of the second recess, and the thickness of the first initial waveguide layer is greater than or equal to half the width of the second recess.

5. The method of claim 4, wherein the method further comprises: After forming the waveguide core in the second recess, further comprising: forming a first upper cladding layer on the surface of the side of the second lower cladding layer away from the substrate layer, the first upper cladding layer covering the second lower cladding layer and the waveguide core.

6. A waveguide structure, prepared by the method of any one of claims 1 to 5, adapted to be disposed on a substrate layer; characterized in that, Comprising: a first lower cladding layer on the surface of the side of the substrate layer, the first lower cladding layer having a first recess on the side away from the substrate layer, the first recess comprising a first bar-shaped groove and a first tapered groove connected in series, the cross-sectional width of the first tapered groove gradually decreases and gradually approaches a preset width from a first end connected to the first bar-shaped groove to a second end away from the first bar-shaped groove; A second lower cladding layer is located on the side of the first lower cladding layer away from the substrate layer, and is conformally arranged with the first lower cladding layer; the second lower cladding layer has a second recess extending into the first recess, and the second recess comprises a second strip-shaped groove and a second tapered groove connected in communication; the cross-sectional width of the second tapered groove gradually decreases from the end connected with the second strip-shaped groove to the end away from the second strip-shaped groove, and gradually approaches zero; A waveguide core is located in the second recess, and comprises a strip-shaped portion and a tapered portion; the cross-sectional width of the tapered portion gradually decreases from the end connected with the strip-shaped portion to the end away from the strip-shaped portion, and gradually approaches zero; the surface of the waveguide core is flush with the port of the second recess.

7. A method of fabricating an interlayer coupling device, characterized by, Comprising: providing a substrate layer; forming a first waveguide structure on one side surface of the substrate layer, the first waveguide structure comprising a first waveguide core having a first strip-shaped portion and a first tapered portion; forming a second waveguide structure on the 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 at least one of the forming of the first waveguide structure and the forming of the second waveguide structure, the preparation method of the waveguide structure according to any one of claims 1-5 is adopted; the cross-sectional width of the end of the first tapered portion away from the first strip-shaped portion and / or the cross-sectional width of the end of the second tapered portion away from the second strip-shaped portion gradually approaches zero; the end of the first tapered portion away from the first strip-shaped portion is arranged opposite to the end of the second tapered portion away from the first strip-shaped portion, and the first tapered portion and the second tapered portion at least partially overlap.

8. The method of claim 7, wherein the method further comprises: The preparation method of the waveguide structure according to any one of claims 1-5 is adopted to form a first waveguide structure on one side surface of the substrate layer, the first waveguide structure comprising a first lower cladding layer, a second lower cladding layer and a first waveguide core; the first waveguide core is located in the second recess, and the first waveguide core comprises a first strip-shaped portion and a first tapered portion; the cross-sectional width of the first tapered portion gradually decreases from the end connected with the first strip-shaped portion to the end away from the first strip-shaped portion, and the cross-sectional width of the end of the first tapered portion away from the first strip-shaped portion gradually approaches zero; the surface of the waveguide core is flush with the port of the second recess; The first waveguide structure further comprises: a first upper cladding layer formed on the side surface of the second lower cladding layer away from the substrate layer; a second waveguide structure is formed on the side of the first waveguide structure away from the substrate layer, comprising: a third recess is formed in the first upper cladding layer away from the substrate layer, and the third recess comprises a third strip-shaped groove and a third tapered groove connected in communication; the cross-sectional width of the third tapered groove gradually decreases from the end connected with the third strip-shaped groove to the end away from the third strip-shaped groove, and gradually approaches a preset width; forming a second upper cladding layer conformally on a side of the first upper cladding layer facing away from the substrate layer, the second upper cladding layer having a fourth recess extending into the third recess, the fourth recess comprising a fourth strip-shaped slot and a fourth tapered slot connected in communication, a cross-sectional width of the fourth tapered slot gradually decreasing from an end connected to the fourth strip-shaped slot toward an end of the fourth tapered slot facing away from the fourth strip-shaped slot, and the cross-sectional width of the end of the fourth tapered slot facing away from the fourth strip-shaped slot gradually approaching zero; forming a second waveguide core in the fourth recess, the second waveguide core comprising a second strip-shaped portion and a second tapered portion, a cross-sectional width of the second tapered portion gradually decreasing from an end connected to the second strip-shaped portion toward an end of the second tapered portion facing away from the second strip-shaped portion, and the cross-sectional width of the end of the second tapered portion facing away from the second strip-shaped portion gradually approaching zero, a surface of the second waveguide core being flush with a port of the fourth recess.

9. The method of claim 8, wherein the method further comprises: after forming the second waveguide core in the fourth recess, further comprising: forming a third upper cladding layer on a side surface of the second upper cladding layer facing away from the substrate layer, the third upper cladding layer covering the second upper cladding layer and the second waveguide core.

10. The method of claim 9, wherein the method further comprises: projections of an axis of the first waveguide core and an axis of the second waveguide core on the substrate layer are collinear.

11. An interlayer coupling device produced by the production method of any one of claims 7 to 10, characterized by comprising: a substrate layer; a first waveguide structure and a second waveguide structure stacked on the substrate layer, the first waveguide structure comprising a first waveguide core having a first strip-shaped portion and a first tapered portion, the second waveguide structure comprising a second waveguide core having a second strip-shaped portion and a second tapered portion; a cross-sectional width of the first tapered portion away from an end of the first strip-shaped portion and / or a cross-sectional width of the second tapered portion away from an end of the second strip-shaped portion gradually approaching zero, the end of the first tapered portion away from the first strip-shaped portion being disposed opposite the end of the second tapered portion away from the first strip-shaped portion, and the first tapered portion and the second tapered portion at least partially overlapping.

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