A multi-dimensional wedge-shaped mode spot converter and a manufacturing method thereof

Abstract

The present invention relates to the field of optical fiber communication technologies, and more particularly, to a multi-dimensional wedge mode spot converter and a manufacturing method thereof. The mode spot converter includes, in the longitudinal dimension, a substrate layer, a first dielectric layer, a second dielectric layer, and a third dielectric layer sequentially arranged from bottom to top, and the second dielectric layer adopts an inverted conical waveguide structure; the inverted conical waveguide structure is a single-layer structure, and is inverted conical in both the transverse dimension and the longitudinal dimension from the input end to the output end. The mode spot converter can be directly and efficiently coupled with a standard single-mode optical fiber, and has a low manufacturing cost. The manufacturing method uses a combination of ultraviolet lithography technology and wafer pretreatment technology to replace the expensive electron beam exposure technology, and can process the inverted conical waveguide structure in the mode spot converter.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber communication, and specifically, to a multi-dimensional wedge mode spot converter and a manufacturing method thereof. Background Art

[0002] With the development of the new round of scientific and technological industrial revolution, the dependence of various fields on information and communication networks has been continuously increasing, and optical fiber communication technology has become the focus and high point of international high-tech intellectual property competition. Due to the large refractive index contrast between the core layer and the cladding of the optical waveguide at present, 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 10 μm, which is much larger than the mode spot size range of the optical waveguide (from a fraction of a micron to several microns). In an optical fiber communication system, a mode spot converter 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 to the transmission conditions in the optical fiber, thereby improving the performance and stability of the communication system.

[0003] Researchers have adopted two schemes for optical couplers: one is a grating coupler, whose advantages are that the placement position is not restricted and no processes such as end face cutting and polishing are required. However, its coupling efficiency with the optical fiber is not the highest, and it is very sensitive to polarization; the other coupler commonly used for mode adaptation is an edge coupler. Compared with grating coupling, edge coupling has the advantages of high coupling efficiency, high bandwidth, and polarization insensitivity. Currently, the mainstream edge couplers include tapered mode spot converters, stepped mode spot converters, etc.

[0004] Firstly, the mode spot converter cannot achieve efficient coupling with the standard single-mode fiber (SMF) with its one-dimensional structural size change. Secondly, on the one hand, the tapered mode spot converter uses an etching process to linearly widen or narrow the waveguide width in the transverse dimension, thereby changing the size of the mode spot diameter. The width of the tapered region of this type of mode spot converter is about 200 nm, and a higher-precision electron beam lithography (EBL) process is often required in manufacturing, which greatly increases the manufacturing cost of the device and is not conducive to marketization. On the other hand, the stepped mode spot converter uses an etching process to etch in the longitudinal dimension to form a series of stepped waveguides with height differences, thereby achieving fiber-waveguide mode matching. Although such devices have the advantage of low manufacturing cost, the large loss caused by the destruction of the adiabatic mode is still inevitable.

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

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

[0007] First, the present invention proposes a multi-dimensional wedge-shaped mode field converter.

[0008] The multi-dimensional wedge-shaped mode field converter includes, in the longitudinal dimension, a substrate layer, a first dielectric layer, a second dielectric layer, and a third dielectric layer arranged successively from bottom to top. From the input end to the output end, the second dielectric layer is provided with a waveguide input region, a step transition region, and a wedge-shaped output region in sequence. The wedge-shaped output region has a single-layer tapered waveguide structure, and the line widths of the tapered waveguide structure in both the transverse dimension and the longitudinal dimension are linearly narrowed.

[0009] It should be noted that the "tapered" mentioned in the present invention is in a broad sense, generally referring to a structure whose overall size gradually decreases in the transverse dimension and / or the longitudinal dimension from the input end to the output end: If the outer surface of the tapered 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 tapered 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 concept, for the mode field converter provided by the present invention, the line widths of the tapered waveguide structure in both the transverse dimension and the longitudinal dimension change linearly, but the change rates in the transverse dimension and the longitudinal dimension are not necessarily equal.

[0010] In some embodiments, the set value of the height after narrowing in the longitudinal dimension of the wedge-shaped output region is 0 - 200 nm, and at the same time, the set value of the width after narrowing in the transverse dimension of the wedge-shaped output region is 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 flat waveguide, and the ridge of the wedge-shaped ridge waveguide and the wedge-shaped flat waveguide together form a tapered waveguide structure; there is a preset step height difference in the longitudinal dimension between the ridge optical waveguide and the wedge-shaped ridge waveguide, forming a step transition region.

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

[0013] In some embodiments, the line width of the flat part of the wedge-shaped ridge waveguide is linearly narrowed 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 dielectric layer and the refractive index of the third dielectric layer are both lower than the refractive index of the second dielectric layer.

[0016] In some embodiments, the material of the second dielectric layer is silicon, lithium niobate, or indium phosphide;

[0017] The material of the first dielectric layer is silicon dioxide, silicon nitride, or silicon oxynitride;

[0018] The material of the third dielectric layer is silicon dioxide, silicon nitride, or silicon oxynitride.

[0019] In some embodiments, the third dielectric layer completely covers the second dielectric layer;

[0020] Alternatively, the third dielectric layer only covers the waveguide input region and the wedge-shaped output region of the second dielectric layer and does not cover the step transition region.

[0021] Secondly, the present invention proposes a manufacturing method for a multi-dimensional wedge-shaped mode spot converter for manufacturing the above multi-dimensional wedge-shaped mode spot converter.

[0022] In the manufacturing method, the side cone configuration of the second dielectric layer is processed by an ultraviolet lithography process to realize the taper change of the inverted conical waveguide structure in the transverse dimension; and the top cone configuration of the second dielectric layer is processed by a wafer pretreatment process to realize the taper change of the inverted conical waveguide structure in the longitudinal dimension.

[0023] The present invention has the following beneficial effects.

[0024] (1) The multi-dimensional wedge-shaped mode spot converter disclosed by the present invention has an inverted conical waveguide structure that is a single-layer structure and is inverted conical in both the transverse dimension and the longitudinal dimension from the input end to the output end, and can be directly and efficiently coupled with a standard single-mode optical fiber.

[0025] (2) The multi-dimensional wedge-shaped mode spot converter disclosed by the present invention is fabricated at the input / output waveguide of a photonic chip. At the input end, its mode field matches the 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 from the fiber mode field to the micro-nano waveguide mode field and increasing the coupling efficiency.

[0026] (3) The multi-dimensional wedge-shaped mode spot converter disclosed by the present invention has a low line-width single-layer structure for its inverted conical waveguide structure, and the minimum size of the structure can be realized by an ultraviolet lithography process, which is suitable for batch processing of 6-inch or 8-inch wafers and can effectively reduce the process cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic three-dimensional structure diagram of the multi-dimensional wedge-shaped mode spot converter in the present invention.

[0028] Figure 2 This is a three-dimensional structural schematic diagram of the multi-dimensional wedge mode spot converter in the present invention after hiding the third dielectric layer.

[0029] Figure 3 It is Figure 2 The corresponding right view.

[0030] Figure 4 It is Figure 2 The corresponding front view.

[0031] Figure 5 This is the optical transmission simulation effect diagram of the multi-dimensional wedge mode spot converter in the present invention.

[0032] Figure 6 This is the cross-sectional mode field diagram of the multi-dimensional wedge mode spot converter in the present invention.

[0033] Figure 7 This is the manufacturing flow chart of the multi-dimensional wedge mode spot converter in the present invention.

[0034] Icon: 110, substrate layer; 120, first dielectric layer; 130, second dielectric layer; 131, waveguide input region; 132, step transition region; 133, wedge output region; 1331, wedge ridge waveguide; 1332, wedge flat waveguide; 140, third dielectric layer. Detailed implementation manners

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. It should be understood that the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments, and therefore should not be regarded as a limitation of the protection scope. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "arranged", "connected" and "coupled" 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 also be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0037] Embodiment 1:

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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 is sequentially provided with a waveguide input region 131, a stepped transition region 132, and a wedge-shaped output region 133. The wedge-shaped output region 133 has a single-layer inverted conical waveguide structure, and the line widths of the inverted conical waveguide structure in the transverse dimension and the longitudinal dimension are both linearly narrowed.

[0043] First of all, in this embodiment, the waveguide structure of the wedge-shaped output region 133 is inverted conical, and the inverted conical waveguide structure is a narrowed structure in both the transverse dimension and the longitudinal dimension, so that the mode spot changes in both dimensions.

[0044] Secondly, compared with the waveguide structure that uses a stepped structure for mode field transition in the prior art, in this embodiment, the line widths of the inverted conical waveguide structure in the transverse dimension and the longitudinal dimension are both linearly narrowed, ensuring a uniform change of the mode spot and further reducing the coupling loss.

[0045] Furthermore, compared with the multi-layer structure that uses multiple 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.

[0046] In addition, in this embodiment, the second dielectric layer 130 is provided with a stepped transition region 132. After the mode field enters the stepped transition region 132, it starts to be slowly expanded in the wedge-shaped output region 133, and finally realizes mode matching with the transmission optical fiber. The existence 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 wedge length. At the same time, it reserves sufficient grinding distance for the subsequent end face polishing process.

[0047] Based on the specific structure of the above multi-dimensional wedge mode converter, while improving the product performance, it can also effectively reduce the manufacturing difficulty and processing cost.

[0048] As Figure 1 shown, the straight line X represents the transverse dimension, and the straight line Y represents the longitudinal dimension. In this embodiment, in the horizontal direction, the spatial layout of the waveguide input region 131, the stepped transition region 132, and the wedge-shaped output region 133 corresponds to the transverse dimension; while in the vertical direction, the spatial layout from the substrate layer 110, the first dielectric layer 120, the second dielectric layer 130, to the third dielectric layer 140 corresponds to the longitudinal dimension.

[0049] If the top surface of the first dielectric layer 120 is used as the reference plane in the horizontal direction, the direction perpendicular to the reference plane is denoted as the vertical direction; at this time, the spatial dimension of the inverted tapered waveguide structure in the horizontal direction from the input end to the output end is the length, the spatial dimension perpendicular to the length is the width, and the spatial dimension of the inverted tapered waveguide structure in the vertical direction is the height. Thus, "the line widths in both the transverse dimension and the longitudinal dimension of the inverted tapered waveguide structure linearly narrow" is equivalent to the width and height of the inverted tapered waveguide structure becoming smaller on the path of the optical signal transmitting from the input end to the output end. At this time, both the transverse dimension in the horizontal direction and the longitudinal dimension in the vertical direction of the inverted tapered waveguide structure are wedge-shaped. The concepts of the transverse dimension, the longitudinal dimension, the horizontal direction, and the vertical direction are not the improvement points of this embodiment and are common knowledge in the art. This embodiment only describes the inverted tapered waveguide structure through directions, so it will not be elaborated further.

[0050] In a specific embodiment, the inverted tapered waveguide structure has four conical surfaces, where the bottom conical surface is in contact with the first dielectric layer 120, the top conical surface is opposite to the bottom conical surface, and the two side surfaces between the top conical surface and the bottom conical surface are the side conical surfaces. Further, both the top conical surface and the side conical surfaces are flat surfaces.

[0051] Based on the above multi-dimensional wedge-shaped mode converter, the side conical surface configuration of the second dielectric layer 130 is processed through an ultraviolet lithography process to achieve the taper change of the inverted tapered waveguide structure in the transverse dimension; the top conical surface configuration of the second dielectric layer 130 is also processed through a wafer pre-treatment process to achieve the taper change of the inverted tapered waveguide structure in the longitudinal dimension. Among them, the ultraviolet lithography process is implemented using an I-line (i-line) lithography machine.

[0052] The minimum structure size of this embodiment is greater than 500 nm. On the one hand, only the ultraviolet lithography process is required to achieve the taper change 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 pre-treatment processes such as laser direct writing, wet etching, and chemical mechanical polishing. High-efficiency coupling from the optical fiber to the chip is achieved without adding new process steps and mask plates, which is suitable for batch processing of 6-inch or 8-inch wafers.

[0053] Embodiment 2:

[0054] This embodiment is described based on Embodiment 1.

[0055] The set value of the height after narrowing of the wedge-shaped output region 133 in the longitudinal dimension is 0 - 200 nm, and at the same time, the set value of the width after narrowing of the wedge-shaped output region 133 in the transverse dimension is 100 - 600 nm. It can be seen that since the acceptable range of the structural size in the transverse dimension is relatively large, an i-line lithography machine can be considered when making the transverse pattern, which can avoid using expensive EBL equipment.

[0056] In some embodiments, such as Figure 2 、 Figure 4 shown, the wedge-shaped output region 133 includes a wedge-shaped ridge waveguide 1331 and a wedge-shaped planar waveguide 1332. The ridge of the wedge-shaped ridge waveguide 1331 and the wedge-shaped planar waveguide 1332 together form an inverted conical waveguide structure. The inverted conical waveguide structure linearly narrows in line width in both the transverse dimension and the longitudinal dimension from one side of the connection 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. The mode field begins to be slowly expanded in the wedge-shaped output region 133 after entering the step transition region 132, and finally realizes mode matching with the transmission optical fiber. The step transition region 132 can effectively shorten the SSC length, thereby improving the system integration degree.

[0057] In some embodiments, the lengths of the two parts of the wedge-shaped ridge waveguide 1331 and the wedge-shaped planar waveguide 1332 in the transverse dimension are similar or equal. Further, the absolute value of the length difference between the wedge-shaped ridge waveguide 1331 and the wedge-shaped planar waveguide 1332 does not exceed 500 μm.

[0058] 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 reported tip width of the inverted cone waveguide is about 200 nm, and generally expensive electron beam lithography is used. In this embodiment, the waveguide width of the waveguide input region 131 is set to be greater than 0.5 μm, and at this time, the waveguide line width dimension that can be achieved by i-line ultraviolet lithography.

[0059] 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, and the wedge-shaped output region 133 is further subdivided into a wedge-shaped ridge waveguide 1331 and a wedge-shaped planar waveguide 1332. There is a preset step height difference in the longitudinal dimension 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, forming the step transition region 132. Therefore, the step transition region 132 is actually a mutant structure. Since both of the two optical waveguides corresponding to the mutant structure forming the step transition region 132 are ridge optical waveguides, the step transition region 132 can also be understood as a ridge optical waveguide.

[0060] In some embodiments, the line width of the flat part of the wedge-shaped ridge waveguide 1331 linearly narrows in the longitudinal dimension, ensuring uniform change of the mode spot and further reducing the coupling loss.

[0061] Other parts of this embodiment are the same as those of Embodiment 1, so they will not be described again.

[0062] Embodiment 3:

[0063] This embodiment is further described on the basis of Embodiment 1 or Embodiment 2.

[0064] This embodiment provides a multi-dimensional wedge mode spot converter, which includes a substrate layer 110, a first dielectric layer 120, a second dielectric layer 130, and a third dielectric layer 140.

[0065] The first dielectric layer 120 and the third dielectric layer 140 are made of a low refractive index dielectric material, and the second dielectric layer 130 is made of a high refractive index dielectric material. Generally, a low refractive index dielectric material refers to a material with a refractive index below 2, while a high refractive index dielectric material refers to a material with a refractive index of 2 or above.

[0066] These low refractive index materials can completely cover the wedge mode spot converter made of a wedge-shaped high refractive index material, or only cover the waveguide input region 131 and above the wedge-shaped output region 133; the mode spot converter structure formed by the third dielectric layer 140 and the second dielectric layer 130 can also be covered or not covered by another material with a lower refractive index. As Figure 1 shown, the third dielectric layer 140 completely covers the second dielectric layer 130.

[0067] The low refractive index dielectric materials include but are not limited to silicon dioxide, silicon nitride, and silicon oxynitride. The high refractive index dielectric materials include but are not limited to silicon, lithium niobate, and indium phosphide.

[0068] In some embodiments, the substrate layer 110 is made of materials such as silicon, lithium niobate, quartz, and lithium tantalate. 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.

[0069] 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. The thickness of the third dielectric layer 140 is 1 - 10 μm.

[0070] Other parts of this embodiment are the same as those of Embodiment 1 or Embodiment 2, so they will not be elaborated here.

[0071] Embodiment 4:

[0072] This embodiment is further described on the basis of any one of Embodiments 1 - 3.

[0073] 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. Among them, the thickness of the second dielectric layer 130 is 400 nm, and the thickness of the third dielectric layer is 3 μm. At this time, refer to Figure 5The propagation path diagram shows that in integrated optical simulation software such as Rsoft and Lumerical, the coupling efficiency between the TE fundamental mode and the standard single-mode fiber can reach 66%, and the coupling loss can be as low as 1.8 dB, which is much lower than the loss value of direct coupling between a single-mode waveguide and a standard single-mode fiber (>10 dB). The reduction of loss allows the replacement of expensive high numerical aperture fibers with inexpensive standard single-mode fibers, which will greatly save the process cost. The input mode field distribution in the ridge lithium niobate waveguide gradually spreads after passing through the wedge-shaped SSC until it matches the standard single-mode fiber, as Figure 6 shown.

[0074] 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 μm. The presence of the steps can better control the total length of the wedge-shaped output region 133, reduce the large device transmission loss caused by a long length, and at the same time reserve sufficient grinding distance for the subsequent end-face polishing process.

[0075] Other parts of this embodiment are the same as any one of Embodiments 1 - 3, so they will not be elaborated here.

[0076] Embodiment 5:

[0077] This embodiment is further described based on any one of Embodiments 1 - 4.

[0078] This embodiment proposes a manufacturing method for a multi-dimensional wedge-shaped mode spot converter. The side cone configuration of the second dielectric layer is processed through ultraviolet lithography technology to achieve the taper change of the inverted conical waveguide structure in the lateral dimension; the top cone configuration of the second dielectric layer is also processed through wafer pretreatment technology to achieve the taper change of the inverted conical waveguide structure in the longitudinal dimension.

[0079] Specifically, as Figure 7 shown, the manufacturing method includes the following steps.

[0080] Step S1: Prepare the 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 polishing liquid corrosion on the substrate.

[0081] Step S2: Deposit the mask layer, perform photolithography and etching to make the mask pattern. In this step, the pattern is transferred to the mask layer through micro-nano processes such as photolithography and etching, and the photoresist is removed.

[0082] Step S3: Chemical mechanical polishing to produce a longitudinal wedge pattern and remove the mask layer. In this step, the substrate with the mask pattern is adsorbed on a polishing fixture for planar polishing to produce a longitudinal wedge and step pattern. After completion, the mask layer is etched away to obtain a step and wedge structure with a linearly narrowing height in the longitudinal direction. The longitudinal wedge pattern corresponds to the top conical surface. The step pattern corresponds to the steps in the step transition region 132.

[0083] Step S4: Lithography and etching to produce a transverse wedge and waveguide pattern. In this step, when manufacturing a waveguide, ridge waveguide patterns and planar waveguide patterns are fabricated on the substrate surface using processes such as lithography and etching, and at the same time, a wedge structure with a linearly narrowing width in the transverse direction is obtained. The transverse wedge pattern corresponds to the side conical surfaces on both sides. The ridge waveguide pattern corresponds to the ridge optical waveguide in the waveguide input region 131 and the wedge ridge waveguide 1331 in the wedge output region 133; the planar waveguide pattern corresponds to the wedge planar waveguide 1332 in the wedge output region 133.

[0084] Step S5: Deposit the third dielectric layer 140 to complete the fabrication. A layer of low-refractive-index third dielectric layer 140 is deposited on the substrate surface, and then the required end face structure is obtained by means of cleavage or chemical mechanical polishing, etc., to complete the fabrication.

[0085] The hard mask materials required for the chemical mechanical polishing include, but are not limited to, chromium, copper, aluminum, etc.

[0086] Other parts of this embodiment are the same as any one of Embodiments 1 - 4, so they will not be elaborated here.

[0087] As described above, only the specific implementation manners of this application are provided, but the protection scope of this application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in this application, and all should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to 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 lateral dimension and the longitudinal dimension is linearly narrowed; 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 forming an inverted cone waveguide structure; the ridge optical waveguide and the wedge-shaped ridge waveguide (1331) have a preset step height difference in the longitudinal dimension, forming a step transition region (132); The line width of the planar portion of the wedge-shaped ridge waveguide (1331) is linearly narrowed in the longitudinal dimension.

2. A 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 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.

4. 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.

5. 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).

6. The multi-dimensional wedge-shaped pattern converter according to claim 5, 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.

7. 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).

8. 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 7; 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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