Multi-dimensional wedge-shaped spot size converter and manufacturing method thereof

Abstract

The invention relates to the technical field of optical fiber communication, in particular to a multi-dimensional wedge-shaped spot size converter and a manufacturing method thereof. The spot size converter comprises a substrate layer, a first dielectric layer, a second dielectric layer and a third dielectric layer which are sequentially arranged from bottom to top in a longitudinal dimension, and the second dielectric layer adopts an inverted conical waveguide structure; the inverted-cone-shaped waveguide structure is a single-layer structure and is inverted-cone-shaped in the transverse dimension and the longitudinal dimension from the input end to the output end. The spot size converter can be directly and efficiently coupled with a standard single-mode fiber, and the manufacturing cost is low. According to the manufacturing method, an expensive electron beam exposure process is replaced by a mode of combining an ultraviolet lithography process and a wafer pretreatment process, and the inverted conical waveguide structure in the spot size converter can be processed.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber communication technology, in particular to a multi-dimensional wedge-shaped pattern spot converter and a manufacturing method thereof. Background Art

[0002] With the development of a new round of technological industry, the dependence of various fields on information and communication networks has been continuously strengthened, and optical fiber communication technology has become the focus and commanding heights of international high-tech intellectual property competition. Due to the large refractive index contrast between the core and cladding of the optical waveguide, although the overall size of the device is greatly reduced, there is also a very large mode mismatch between the waveguide and the standard single-mode fiber (SMF). This is because the mode field diameter of the standard single-mode fiber (SMF) is about 10μm, which is much larger than the mode spot size range of the optical waveguide (from a few tenths of a micron to several microns). In optical fiber communication systems, mode spot converters can be used to improve the quality and efficiency of signal transmission. It can adjust and optimize the mode of the light beam to better adapt it to the transmission conditions in the optical fiber, thereby improving the performance and stability of the communication system.

[0003] Researchers have adopted two optical coupler solutions: one is the grating coupler, which has the advantage of unlimited placement and no need for end face cutting and polishing, but its coupling efficiency with the optical fiber is not the highest and is very sensitive to polarization; another type of coupler commonly used for mode adaptation is the edge coupler. Compared with grating coupling, edge coupling has the advantages of high coupling efficiency, high bandwidth, and polarization insensitivity. The current mainstream edge couplers include cone-type mode spot converters, step-type mode spot converters, etc.

[0004] First, the spot converter cannot achieve efficient coupling with the standard single-mode fiber (SMF) due to its one-dimensional structural size change. Secondly, on the one hand, the conical spot converter uses the etching process to linearly widen or narrow the waveguide width in the lateral dimension, thereby changing the size of the spot diameter. The width of the tip cone area of ​​this type of spot converter is about 200nm, and the production often requires a higher precision electron beam exposure (EBL) process, which greatly increases the production cost of the device and is not conducive to marketization. On the other hand, the step spot converter uses the etching process to distribute the etching in the longitudinal dimension to form a series of step waveguides with height differences, thereby realizing fiber-waveguide mode matching. Although the production of such devices has the advantage of lower cost, the large loss caused by the destruction of the adiabatic mode cannot be avoided.

[0005] Therefore, it is necessary to design a spot mode converter that can not only couple with standard single-mode fiber (SMF) with high efficiency but also reduce the production cost. Summary of the invention

[0006] In view of the deficiency in the prior art that a mode spot converter capable of efficiently coupling with a standard single-mode optical fiber cannot be produced at low cost, the present invention proposes a multi-dimensional wedge-shaped mode spot converter and a manufacturing method thereof; the inverted tapered waveguide structure in the mode spot converter is a single-layer structure and is inverted tapered in both the lateral and longitudinal dimensions from the input end to the output end, and can be directly and efficiently coupled with a standard single-mode optical fiber, and the low-linewidth single-layer structure adopted can be processed by combining ultraviolet lithography technology and wafer pretreatment technology instead of expensive electron beam exposure technology, thereby reducing the manufacturing cost.

[0007] Firstly, the present invention proposes a multi-dimensional wedge-shaped pattern spot converter.

[0008] The multi-dimensional wedge-shaped pattern spot converter comprises, in the longitudinal dimension, a substrate layer, a first dielectric layer, a second dielectric layer, and a third dielectric layer which are sequentially arranged from bottom to top; from the input end to the output end, the second dielectric layer sequentially arranges a waveguide input region, a step transition region, and a wedge-shaped output region; the wedge-shaped output region has a single-layer inverted cone waveguide structure, and the line width of the inverted cone waveguide structure in both the transverse and longitudinal dimensions is linearly narrowed.

[0009] It should be noted that the "inverted cone" mentioned in the present invention is broad in meaning, and generally refers to a structure whose overall lateral and / or longitudinal dimensions gradually decrease from the input end to the output end: if the outer surface of the inverted cone structure is composed of several planes, it can be understood as a pyramidal structure or a quasi-pyramidal structure; if the outer surface of the inverted cone structure is composed of curved surfaces, it can be understood as a conical structure, a quasi-conical structure or a special-shaped structure. Based on this design idea, the pattern spot converter provided by the present invention has an inverted cone waveguide structure whose line width in both the lateral and longitudinal dimensions changes linearly, but the rate of change in the lateral dimension is not necessarily equal to the rate of change in the longitudinal dimension.

[0010] In some embodiments, the height of the wedge-shaped output region after being narrowed in the longitudinal dimension is set to 0-200 nm, and the width of the wedge-shaped output region after being narrowed in the transverse dimension is set to 100-600 nm.

[0011] In some embodiments, the waveguide input region is a ridge optical waveguide; the wedge-shaped output region includes a wedge-shaped ridge waveguide and a wedge-shaped slab waveguide, and the ridge of the wedge-shaped ridge waveguide and the wedge-shaped slab waveguide together constitute an inverted cone waveguide structure; the ridge optical waveguide and the wedge-shaped ridge waveguide have a preset step height difference in the longitudinal dimension, forming a step transition region.

[0012] In some embodiments, the absolute value of the length difference between the wedge-ridge waveguide and the wedge-slab waveguide in the lateral dimension does not exceed 500 μm.

[0013] In some embodiments, the linewidth of the slab portion of the wedge-ridge waveguide narrows linearly in the longitudinal dimension.

[0014] In some embodiments, the waveguide width of the waveguide input region is greater than 0.5 μm.

[0015] In some embodiments, the refractive index of the first medium layer and the refractive index of the third medium layer are both lower than the refractive index of the second medium layer.

[0016] In some embodiments, the material of the second dielectric layer is silicon, lithium niobate or indium phosphide; The material of the first dielectric layer is silicon dioxide, silicon nitride or silicon oxynitride; The material of the third dielectric layer is silicon dioxide, silicon nitride or silicon oxynitride.

[0017] In some embodiments, the third dielectric layer completely covers the second dielectric layer; Alternatively, the third dielectric layer only covers the waveguide input region and the wedge-shaped output region of the second dielectric layer but does not cover the step transition region.

[0018] Secondly, the present invention proposes a method for manufacturing a multi-dimensional wedge-shaped pattern spot converter, which is used to manufacture the multi-dimensional wedge-shaped pattern spot converter.

[0019] The manufacturing method processes the side cone surface configuration of the second dielectric layer through an ultraviolet photolithography process to achieve a taper change in the lateral dimension of the inverted cone waveguide structure; and also processes the top cone surface configuration of the second dielectric layer through a wafer pretreatment process to achieve a taper change in the longitudinal dimension of the inverted cone waveguide structure.

[0020] The present invention has the following beneficial effects.

[0021] (1) The multi-dimensional wedge-shaped spot converter disclosed in the present invention has an inverted tapered waveguide structure which is a single-layer structure and is inverted tapered in both the lateral and longitudinal dimensions from the input end to the output end, and can be directly and efficiently coupled with a standard single-mode optical fiber.

[0022] (2) The multi-dimensional wedge-shaped mode spot converter disclosed in the present invention is fabricated at the input / output waveguide of the photonic chip. Its mode field at the input end matches the optical fiber mode field, and its mode field at the output end matches the micro-nano waveguide mode field of the photonic chip, thereby realizing the conversion of the optical fiber mode field to the micro-nano waveguide mode field and increasing the coupling efficiency.

[0023] (3) The multi-dimensional wedge-shaped spot converter disclosed in the present invention has an inverted tapered waveguide structure with a low line width single-layer structure. The minimum size of the structure can be achieved through ultraviolet lithography, which is suitable for batch processing of 6-inch or 8-inch wafers and can effectively reduce process costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the three-dimensional structure of the multi-dimensional wedge-shaped pattern spot converter in the present invention.

[0025] Figure 2This is a schematic diagram of the three-dimensional structure of the multi-dimensional wedge-shaped spot converter of the present invention after the third dielectric layer is hidden.

[0026] Figure 3 for Figure 2 Corresponding right view.

[0027] Figure 4 for Figure 2 The corresponding main view.

[0028] Figure 5 This is a diagram showing the light transmission simulation effect of the multi-dimensional wedge-shaped pattern converter in the present invention.

[0029] Figure 6 This is a cross-sectional mode field diagram of the multi-dimensional wedge-shaped mode spot converter in the present invention.

[0030] Figure 7 This is a production flow chart of the multi-dimensional wedge-shaped pattern spot converter in the present invention.

[0031] Icons: 110, substrate layer; 120, first dielectric layer; 130, second dielectric layer; 131, waveguide input region; 132, step transition region; 133, wedge-shaped output region; 1331, wedge-shaped ridge waveguide; 1332, wedge-shaped slab waveguide; 140, third dielectric layer. DETAILED DESCRIPTION

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be understood that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, and therefore should not be regarded as limiting the scope of protection. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technical personnel in this field without making creative work are within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] Embodiment 1: At present, the core diameter of single-mode optical fiber is about 9μm; the waveguides of mainstream integrated photonic chips are relatively small, and the thickness and width of the waveguides are usually less than 1μm, which are often called micro-nano waveguides. There is a large mismatch between the mode field of these micro-nano waveguides and the mode field of single-mode optical fibers, resulting in large mode field mismatch losses when these photonic chips are coupled with single-mode optical fibers to realize the input / output of optical signals, which hinders the practical application of the chips. The mode spot converter is made at the input / output waveguide of the photonic chip. At the input end, its mode field matches the optical fiber mode field, and at the output end, its mode field matches the micro-nano waveguide mode field of the photonic chip, thereby realizing the conversion of the optical fiber mode field to the micro-nano waveguide mode field and increasing the coupling efficiency.

[0035] Most of the existing conical spot converters are based on a waveguide with a horizontal conical structure placed in the center of the converter. According to the position of the conical waveguide relative to the optical fiber, they are divided into two categories: the inverted conical spot converter and the positive inverted conical spot converter. In terms of structure, the positive conical spot converter is widely used because of its large line width and easy process implementation. However, the coupling efficiency of the positive conical spot converters reported so far is generally not as good as that of the inverted conical spot converter.

[0036] To achieve higher coupling efficiency, the width of the tapered waveguide at the input end of the inverted tapered spot converter should be as narrow as possible, usually required to be at least less than 200nm. It is generally implemented using the EBL process and should be placed in the center of the spot converter. However, the realization of this waveguide width and placement position places extremely high demands on process technology, requiring high-precision secondary alignment and EBL process technology, which results in a low device yield, greatly increases process cost and complexity, and makes it difficult to achieve mass processing of 6-inch or 8-inch wafers.

[0037] On the other hand, in the prior art, such as the mode spot converter disclosed in the Chinese invention patent with patent publication number CN114035269A, the mode spot converter is a double-layer widening type mode spot converter that diverges the horizontal component of the optical mode field, and then adds a high refractive index silicon waveguide in the longitudinal direction to widen the mode field size in the longitudinal direction. This type of mode spot converter involves multiple layers of materials and the horizontal and longitudinal mode field distribution is widened, which firstly increases the device length and is not conducive to system integration, and secondly increases the difficulty of the manufacturing process and is not conducive to cost control of mass production; moreover, the waveguide structure of this type of mode spot converter uses a stepped structure to perform mode field transition, which will destroy the adiabatic transmission condition.

[0038] This embodiment proposes a multi-dimensional wedge-shaped pattern spot converter. Figure 1 , Figure 3 As shown, the multi-dimensional wedge-shaped pattern spot converter includes a substrate layer 110, a first dielectric layer 120, a second dielectric layer 130, and a third dielectric layer 140 arranged in sequence from bottom to top in the longitudinal dimension. Figure 2 , Figure 4 As shown, from the input end to the output end, the second dielectric layer 130 sequentially provides a waveguide input region 131, a step transition region 132, and a wedge-shaped output region 133. The wedge-shaped output region 133 has a single-layer inverted tapered waveguide structure, and the line width of the inverted tapered waveguide structure in both the lateral and longitudinal dimensions is linearly narrowed.

[0039] First, in this embodiment, the waveguide structure of the wedge-shaped output region 133 is inverted-cone-shaped, and the inverted-cone-shaped waveguide structure is a narrowing structure in both the lateral dimension and the longitudinal dimension, so that the mode spot changes in two dimensions.

[0040] Secondly, compared with the waveguide structure in the prior art that uses a stepped structure to perform mode field transition, the line width of the inverted tapered waveguide structure in this embodiment is linearly narrowed in both the lateral and longitudinal dimensions, ensuring uniform change of the mode spot and further reducing coupling loss.

[0041] Furthermore, compared with a multi-layer structure using a variety of cladding and core materials, the waveguide structure of the wedge-shaped output region 133 in this embodiment is single-layer, which has obvious advantages in terms of performance stability and production cost control.

[0042] Another point is that in this embodiment, the second dielectric layer 130 is provided with a step transition area 132. After entering the step transition area 132, the mode field begins to slowly expand in the wedge-shaped output area 133, and finally achieves mode matching with the transmission optical fiber. The existence of the step can better control the total length of the wedge-shaped output area 133, and can also reduce the large device transmission loss caused by the long wedge length, and at the same time reserve sufficient grinding distance for the subsequent end face polishing process.

[0043] Based on the specific structure of the above-mentioned multi-dimensional wedge-shaped pattern spot converter, while improving product performance, it can also effectively reduce manufacturing difficulty and processing costs.

[0044] like Figure 1 As shown, the straight line X represents the horizontal dimension, and the straight line Y represents the vertical dimension. In this embodiment, the dimension corresponding to the spatial layout of the waveguide input area 131, the step transition area 132, and the wedge-shaped output area 133 in the horizontal direction is the horizontal dimension; and the dimension corresponding to the spatial layout of the substrate layer 110, the first dielectric layer 120, the second dielectric layer 130, and the third dielectric layer 140 in the vertical direction is the vertical dimension.

[0045] If the top surface of the first dielectric layer 120 is used as a reference plane in the horizontal direction, the direction perpendicular to the reference plane is recorded as the vertical direction; at this time, the spatial dimension of the inverted cone waveguide structure from the input end to the output end in the horizontal direction is the length, the spatial dimension perpendicular to the length is the width, and the spatial dimension of the inverted cone waveguide structure in the vertical direction is the height. Therefore, "the line width of the inverted cone waveguide structure in the lateral dimension and the longitudinal dimension are both linearly narrowed" is equivalent to the width and height of the inverted cone waveguide structure becoming smaller on the path where the optical signal is transmitted from the input end to the output end. At this time, the lateral dimension in the horizontal direction and the longitudinal dimension in the vertical direction of the inverted cone waveguide structure are both wedge-shaped. The concepts of lateral dimension, longitudinal dimension, horizontal direction, and vertical direction are not the improvement points of this embodiment, but are common knowledge in the art. This embodiment only describes the inverted cone waveguide structure by direction, so it will not be repeated.

[0046] In a specific embodiment, the inverted tapered waveguide structure has four tapered surfaces, wherein the bottom tapered surface contacts the first dielectric layer 120, the top tapered surface is opposite to the bottom tapered surface, and the two side surfaces between the top tapered surface and the bottom tapered surface are side tapered surfaces. Further, the top tapered surface and the side tapered surfaces are both planes.

[0047] Based on the multi-dimensional wedge-shaped pattern spot converter, the side cone surface configuration of the second dielectric layer 130 is processed by ultraviolet lithography to achieve the taper change of the inverted tapered waveguide structure in the lateral dimension; the top cone surface configuration of the second dielectric layer 130 is also processed by wafer pretreatment process to achieve the taper change of the inverted tapered waveguide structure in the longitudinal dimension. The ultraviolet lithography process is implemented by an i-line lithography machine.

[0048] The minimum structural size of this embodiment is greater than 500nm. On the one hand, only ultraviolet lithography is needed to achieve taper changes in the horizontal direction, and it can be formed in one step without special requirements for lithography alignment accuracy; on the other hand, in the vertical direction, a tapered slope can be formed through simple wafer pretreatment processes such as laser direct writing, wet etching, and chemical mechanical polishing. High-efficiency coupling from fiber to chip is achieved without adding new process steps and mask plates, and is suitable for batch processing of 6-inch or 8-inch wafers.

[0049] Embodiment 2: This embodiment is described based on Embodiment 1.

[0050] The height setting value of the wedge-shaped output area 133 after narrowing in the longitudinal dimension is 0-200nm, and the width setting value of the wedge-shaped output area 133 after narrowing in the transverse dimension is 100-600nm. It can be seen that since the acceptable range of the structural size in the transverse dimension is relatively large, the i-line lithography machine can be considered when making the transverse pattern, and the expensive EBL equipment can be avoided.

[0051] In some embodiments, Figure 2 , Figure 4 As shown, the wedge-shaped output region 133 includes a wedge-shaped ridge waveguide 1331 and a wedge-shaped slab waveguide 1332, and the ridge of the wedge-shaped ridge waveguide 1331 and the wedge-shaped slab waveguide 1332 together constitute an inverted cone waveguide structure. The line width of the inverted cone waveguide structure is linearly narrowed in both the transverse and longitudinal dimensions from the side connected to the step transition region 132 to the side away from the step transition region 132, that is, the wedge-shaped output region 133 has a wedge-shaped configuration with size changes in both the transverse and longitudinal dimensions. After entering the step transition region 132, the mode field begins to be slowly expanded in the wedge-shaped output region 133, and finally achieves mode matching with the transmission optical fiber. The step transition region 132 can effectively shorten the SSC length, thereby improving the system integration.

[0052] In some embodiments, the lengths of the wedge-shaped ridge waveguide 1331 and the wedge-shaped slab waveguide 1332 in the lateral dimension are similar or equal. Further, the absolute value of the length difference between the wedge-shaped ridge waveguide 1331 and the wedge-shaped slab waveguide 1332 does not exceed 500 μm.

[0053] In some embodiments, the waveguide input region 131 is a ridge optical waveguide. The waveguide width of the waveguide input region 131 is greater than 0.5 μm. The tip width of the inverted cone waveguide that has been reported is about 200 nm, which is generally achieved by expensive electron beam lithography. In this embodiment, the waveguide width of the waveguide input region 131 is set to be greater than 0.5 μm, at which time i-line ultraviolet lithography can achieve the waveguide line width size.

[0054] In some embodiments, the waveguide input region 131, the step transition region 132, and the wedge-shaped output region 133 of the entire second dielectric layer 130 are different parts of a whole, wherein the wedge-shaped output region 133 is further subdivided into a wedge-shaped ridge waveguide 1331 and a wedge-shaped slab waveguide 1332. There is a preset step height difference between the ridge optical waveguide of the waveguide input region 131 and the wedge-shaped ridge waveguide 1331 of the wedge-shaped output region 133 in the longitudinal dimension, forming the step transition region 132, so the step transition region 132 is actually a sudden change structure, and since the two optical waveguides forming the sudden change structure corresponding to the step transition region 132 are both ridge optical waveguides, the step transition region 132 can also be understood as a ridge optical waveguide.

[0055] In some embodiments, the line width of the planar portion of the wedge-ridge waveguide 1331 is linearly narrowed in the longitudinal dimension, thereby ensuring a uniform change in the mode spot and further reducing coupling loss.

[0056] The other parts of this embodiment are the same as those of Embodiment 1, and thus will not be described in detail.

[0057] Embodiment 3: This embodiment is further described based on the embodiment 1 or the embodiment 2.

[0058] This embodiment provides a multi-dimensional wedge-shaped spot converter, including a substrate layer 110 , a first dielectric layer 120 , a second dielectric layer 130 , and a third dielectric layer 140 .

[0059] The first dielectric layer 120 and the third dielectric layer 140 are made of low refractive index dielectric materials, and the second dielectric layer 130 is made of high refractive index dielectric materials. Generally, low refractive index dielectric materials refer to materials with a refractive index below 2, while high refractive index dielectric materials refer to materials with a refractive index of 2 or above.

[0060] These low refractive index materials can completely cover the wedge-shaped pattern spot converter made of the wedge-shaped high refractive index material, or can only cover the waveguide input area 131 and the wedge-shaped output area 133; the pattern spot converter structure formed by the third dielectric layer 140 and the second dielectric layer 130 can also be covered by another material with a lower refractive index or not covered. Figure 1 As shown, the third dielectric layer 140 completely covers the second dielectric layer 130 .

[0061] The low refractive index dielectric material includes but is not limited to silicon dioxide, silicon nitride, and silicon oxynitride. The high refractive index dielectric material includes but is not limited to silicon, lithium niobate, and indium phosphide.

[0062] In some embodiments, the substrate layer 110 is made of silicon, lithium niobate, quartz, lithium tantalate, etc. The first dielectric layer 120 is made of silicon dioxide, silicon nitride, or silicon oxynitride. The second dielectric layer 130 is made of silicon, lithium niobate, or indium phosphide. The third dielectric layer 140 is made of silicon dioxide, silicon nitride, or silicon oxynitride.

[0063] In some embodiments, the thickness of the first dielectric layer 120 is 1-10 μm, the thickness of the second dielectric layer 130 is 0.3-1 μm, and the thickness of the third dielectric layer 140 is 1-10 μm.

[0064] The other parts of this embodiment are the same as those of Embodiment 1 or Embodiment 2, and thus will not be described in detail.

[0065] Embodiment 4: This embodiment is further explained based on any one of Embodiments 1 to 3.

[0066] The substrate layer 110 is silicon, the first dielectric layer 120 is silicon dioxide, the second dielectric layer 130 is X-cut lithium niobate, and the third dielectric layer 140 is silicon dioxide. The thickness of the second dielectric layer 130 is 400nm, and the thickness of the third dielectric layer is 3um. Figure 5The propagation path diagram shows that the coupling efficiency of the TE fundamental mode and the standard single-mode fiber can reach 66% in Rsoft, Lumerical and other integrated optical simulation software, and the coupling loss can be as low as 1.8dB, which is much lower than the loss value of the direct coupling between the single-mode waveguide and the standard single-mode fiber (>10dB). The reduction in loss can replace the expensive high numerical aperture fiber with the cheap standard single-mode fiber, which will greatly save the process cost. The input mode field distribution in the ridge lithium niobate waveguide gradually diffuses to match the standard single-mode fiber after the wedge-shaped SSC, such as Figure 6 shown.

[0067] In some embodiments, the step height in the step transition region 132 is 0-100 nm, and the lateral length of the wedge-shaped output region 133 is 100-500 um; the presence of the step can better control the total length of the wedge-shaped output region 133, and can also reduce the large device transmission loss caused by the long length, while reserving sufficient grinding distance for the subsequent end face polishing process.

[0068] The other parts of this embodiment are the same as any one of Embodiments 1 to 3, and thus will not be described in detail.

[0069] Embodiment 5: This embodiment is further explained based on any one of Embodiments 1 to 4.

[0070] This embodiment proposes a method for manufacturing a multi-dimensional wedge-shaped pattern spot converter, in which the side cone surface configuration of the second dielectric layer is processed by an ultraviolet lithography process to achieve the taper change of the inverted cone waveguide structure in the lateral dimension; the top cone surface configuration of the second dielectric layer is processed by a wafer pretreatment process to achieve the taper change of the inverted cone waveguide structure in the longitudinal dimension.

[0071] Specifically, Figure 7 As shown, the manufacturing method includes the following steps.

[0072] Step S1, preparing a substrate. This step requires preparing a substrate including a first dielectric layer 120 and a second dielectric layer 130, and depositing a mask layer resistant to corrosion by a polishing liquid on the substrate.

[0073] Step S2, depositing a mask layer, and performing photolithography and etching to produce a mask pattern. In this step, the pattern is transferred to the mask layer through micro-nano processes such as photolithography and etching, and the resist is removed.

[0074] Step S3, chemical mechanical polishing, making a longitudinal wedge pattern, and removing the mask layer. In this step, the substrate with the mask pattern is adsorbed on a polishing fixture for plane polishing to make a longitudinal wedge and step pattern. After the completion, the mask layer is etched away to obtain a step and wedge structure with a high linear narrowing in the longitudinal direction. The longitudinal wedge pattern corresponds to the top cone surface. The step pattern corresponds to the step of the step transition area 132.

[0075] Step S4, photolithography and etching to make transverse wedge and waveguide patterns. In this step, when making waveguides, ridge waveguide patterns and slab waveguide patterns are made on the substrate surface by photolithography, etching and other processes, and a wedge-shaped structure with linearly narrowed width in the transverse direction is obtained. The transverse wedge pattern corresponds to the side cones on both sides. The ridge waveguide pattern corresponds to the ridge optical waveguide of the waveguide input area 131 and the wedge-shaped ridge waveguide 1331 of the wedge-shaped output area 133; the slab waveguide pattern corresponds to the wedge-shaped slab waveguide 1332 of the wedge-shaped output area 133.

[0076] Step S5, depositing the third dielectric layer 140, and the manufacturing is completed. A third dielectric layer 140 with a low refractive index is deposited on the surface of the substrate, and then the required end face structure is obtained by cleavage or chemical mechanical polishing, and the manufacturing is completed.

[0077] The hard mask material required for the chemical mechanical polishing includes but is not limited to chromium, copper, and aluminum.

[0078] The other parts of this embodiment are the same as any one of Embodiments 1 to 4, and thus will not be described in detail.

[0079] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A multi-dimensional wedge-shaped pattern spot converter, comprising, in a longitudinal dimension, a substrate layer (110), a first dielectric layer (120), a second dielectric layer (130), and a third dielectric layer (140) arranged in sequence from bottom to top; characterized in that: From the input end to the output end, the second dielectric layer (130) is provided with a waveguide input area (131), a step transition area (132), and a wedge-shaped output area (133) in sequence; the wedge-shaped output area (133) has a single-layer inverted cone waveguide structure, and the line width of the inverted cone waveguide structure in both the transverse dimension and the longitudinal dimension is linearly narrowed.

2. The multi-dimensional wedge-shaped pattern converter according to claim 1, characterized in that: The height setting value of the wedge-shaped output area (133) after being narrowed in the longitudinal dimension is 0-200 nm, and the width setting value of the wedge-shaped output area (133) after being narrowed in the transverse dimension is 100-600 nm.

3. The multi-dimensional wedge-shaped pattern converter according to claim 1, characterized in that: The waveguide input region (131) is a ridge optical waveguide; the wedge-shaped output region (133) comprises a wedge-shaped ridge waveguide (1331) and a wedge-shaped slab waveguide (1332); the ridge of the wedge-shaped ridge waveguide (1331) and the wedge-shaped slab waveguide (1332) together form an inverted cone waveguide structure; the ridge optical waveguide and the wedge-shaped ridge waveguide (1331) have a preset step height difference in a longitudinal dimension, forming a step transition region (132).

4. The multi-dimensional wedge-shaped pattern converter according to claim 3, characterized in that: The absolute value of the length difference between the wedge-shaped ridge waveguide (1331) and the wedge-shaped slab waveguide (1332) in the lateral dimension does not exceed 500 μm.

5. The multi-dimensional wedge-shaped pattern converter according to claim 3, characterized in that: The line width of the planar portion of the wedge-shaped ridge waveguide (1331) is linearly narrowed in the longitudinal dimension.

6. The multi-dimensional wedge-shaped pattern converter according to claim 1, characterized in that: The waveguide width of the waveguide input region (131) is greater than 0.5 μm.

7. The multi-dimensional wedge-shaped pattern converter according to claim 1, characterized in that: The refractive index of the first medium layer (120) and the refractive index of the third medium layer (140) are both lower than the refractive index of the second medium layer (130).

8. The multi-dimensional wedge-shaped pattern converter according to claim 7, characterized in that: The material of the second dielectric layer (130) is silicon, lithium niobate or indium phosphide; the material of the first dielectric layer (120) is silicon dioxide, silicon nitride or silicon oxynitride; and the material of the third dielectric layer (140) is silicon dioxide, silicon nitride or silicon oxynitride.

9. The multi-dimensional wedge-shaped pattern converter according to claim 1, characterized in that: The third dielectric layer (140) completely covers the second dielectric layer (130); or the third dielectric layer (140) only covers the waveguide input region (131) and the wedge-shaped output region (133) of the second dielectric layer (130) but does not cover the step transition region (132).

10. A method for manufacturing a pattern spot converter, characterized in that: The manufacturing method is used to manufacture a multi-dimensional wedge-shaped pattern spot converter as described in any one of claims 1 to 9; wherein the side cone surface configuration of the second dielectric layer (130) is processed by an ultraviolet lithography process to achieve a taper change in the lateral dimension of the inverted cone waveguide structure; and the top cone surface configuration of the second dielectric layer (130) is processed by a wafer pretreatment process to achieve a taper change in the longitudinal dimension of the inverted cone waveguide structure.

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