Optical module and method of forming an optical module

Abstract

An optical module includes a substrate structure and a superlens. The substrate structure includes an optical waveguide. The superlens is located above the substrate structure. The superlens includes a dielectric structure and a plurality of superatoms. The dielectric structure is located above the substrate structure. The plurality of superatoms are located in the dielectric structure and each includes a first portion and a second portion located above the first portion. A region of a footprint of the second portion on the substrate structure at least partially overlaps a region of a footprint of the first portion on the substrate structure. The superatom and superlens structure with high aspect ratio can be formed and effectively improve the coupling efficiency and packaging reliability of the optical module. The superlens is used to receive optical signals from the optical waveguide.

Description

Technical Field

[0001] This invention relates to an optical module and a method for forming an optical module. Background Technology

[0002] With advancements in process technology and increasing demands for data transmission and computing speeds, semiconductor processes face the challenge of integrating more complex circuits into a single area. Silicon photonics technology, with its advantages of high bandwidth, low power consumption, and compatibility with CMOS processes, has become a focal point in the field of optoelectronic integration. However, the size and distribution of the beam transmitted by silicon photonic circuits and optical fibers differ significantly, resulting in extremely high optical losses when directly coupled.

[0003] To improve coupling efficiency, meta-lenses with subwavelength structures are used for beam focusing. Among them, meta-lens designs with high aspect ratios can further expand the phase modulation range and improve optical efficiency. However, the integration of meta-lenses with silicon photonic chips or fiber array units (FAUs) requires sub-micron level alignment precision, and process tolerances and packaging displacements can cause optical axis misalignment, thereby reducing the yield of the optical module. Therefore, how to stably produce meta-lens structures with high aspect ratios and accurately align and couple them to silicon photonic chips or fiber array units has gradually become a key area where the industry is eager to invest research and development resources. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide an optical module and a method for forming an optical module.

[0005] One aspect of the present invention relates to an optical module comprising a substrate structure and a meta-lens. The substrate structure includes an optical waveguide. The meta-lens is located above the substrate structure. The meta-lens includes a dielectric structure and a plurality of meta atoms. The dielectric structure is located above the substrate structure. The plurality of meta atoms are located in the dielectric structure and each includes a first portion and a second portion located above the first portion. The orthographic projection area of ​​the second portion on the substrate structure at least partially overlaps with the orthographic projection area of ​​the first portion on the substrate structure. The meta-lens is used to receive optical signals from the optical waveguide.

[0006] In some embodiments, the dielectric structure includes a first dielectric layer and a second dielectric layer located above the first dielectric layer. The top surface of the first dielectric layer is substantially flush with the top surface of the first portion. The top surface of the second dielectric layer is substantially flush with the top surface of the second portion.

[0007] In some implementations, the first dielectric layer and the second dielectric layer comprise different materials.

[0008] In some embodiments, the refractive index of the first dielectric layer is less than the refractive index of the first portion. The refractive index of the second dielectric layer is less than the refractive index of the second portion.

[0009] In some embodiments, one of the plurality of metaatoms also includes a residue. The residue is located between the first site and the second site. The residue comprises the same material as the first dielectric layer.

[0010] In some implementations, the ratio of the orthographic projection area of ​​the second part to the orthographic projection area of ​​the first part is between 0.3 and 1.

[0011] In some embodiments, the materials comprising the second portion and the first portion have a refractive index between 1.2 and 4.

[0012] In some embodiments, the cross-sectional area of ​​the second portion and the first portion decreases upward along a direction perpendicular to the substrate structure.

[0013] In some embodiments, the substrate structure includes a silicon photonics wafer. The silicon photonics wafer has an optical waveguide for coupling an optical signal to a meta-lens. The core width of the optical waveguide is less than 150 micrometers. The meta-lens also includes a reflective structure. The reflective structure is located above the substrate structure and configured to reflect the optical signal.

[0014] In some embodiments, the substrate structure includes fiber optic array units. Each fiber optic array unit has an optical waveguide for coupling an optical signal to a metalens. The core diameter of the optical waveguide is less than 150 micrometers. The metalens also includes a reflective structure. The reflective structure is located above the substrate structure and configured to reflect the optical signal.

[0015] In some embodiments, the meta-lens further includes a reflective structure. The reflective structure is located between a first and a second portion of one of the plurality of metaatoms.

[0016] In some embodiments, the lateral feature size of at least one of the first and second portions is between 30 nanometers and 450 nanometers.

[0017] In some embodiments, a third portion is further included above the second portion of one of the plurality of metaatoms. The orthographic projection region of the third portion onto the substrate structure at least partially overlaps with the orthographic projection region of the second portion onto the substrate structure.

[0018] Another aspect of the present invention relates to a method of forming an optical module, comprising: depositing a first metamaterial layer over a substrate structure; patterning the first metamaterial layer until the substrate structure is exposed to form a plurality of first portions separated from each other, such that the plurality of first portions form a plurality of subwavelength structures; depositing a dielectric material covering the plurality of first portions and the substrate structure, wherein the refractive index of the dielectric material is less than the refractive index of the first metamaterial layer; performing a planarization process on the dielectric material such that the top surface of the planarized dielectric material is substantially flush with a plurality of top surfaces of the plurality of first portions; depositing a second metamaterial layer over the planarized dielectric material; patterning the second metamaterial layer until the dielectric material is exposed to form a plurality of second portions separated from each other, such that the plurality of second portions form a plurality of subwavelength structures, wherein each of the plurality of second portions at least partially overlaps a corresponding one of the plurality of first portions; and providing an optical waveguide, wherein the plurality of first portions and the plurality of second portions are for receiving optical signals from the optical waveguide.

[0019] In some embodiments, the materials comprising the plurality of second portions and the plurality of first portions have a refractive index between 1.2 and 4.

[0020] In some embodiments, the orthographic projection area of ​​each of the plurality of second portions on the substrate structure overlaps with the orthographic projection area of ​​the corresponding of the plurality of first portions on the substrate structure. The overlap ratio is between 0.3 and 1.

[0021] In some embodiments, the method further includes forming a reflective structure over one of the plurality of second portions.

[0022] Another aspect of the present invention relates to a method for forming an optical module, comprising: depositing a first dielectric material over a substrate structure; patterning the first dielectric material to form a plurality of first trenches exposing the substrate structure; depositing a first metamaterial layer covering the patterned first dielectric material and filling the plurality of first trenches; performing a first planarization process on the first metamaterial layer to form a plurality of first portions separated from each other located in the plurality of first trenches, such that the plurality of first portions form a plurality of subwavelength structures, wherein a plurality of top surfaces of the plurality of first portions are substantially flush with the top surface of the patterned first dielectric material; and depositing a second dielectric material. The material is placed over a patterned first dielectric material and the plurality of first portions; a second dielectric material is patterned to form a plurality of second trenches; a second metamaterial layer is deposited to cover the patterned second dielectric material and fill the plurality of second trenches; a second planarization process is performed on the second metamaterial layer to form a plurality of second portions separated from each other located in the plurality of second trenches, such that the plurality of second portions form a plurality of subwavelength structures, and the plurality of second portions at least partially overlap the plurality of first portions; and an optical waveguide is provided, wherein the plurality of first portions and the plurality of second portions are used to receive optical signals from the optical waveguide.

[0023] In some embodiments, the first dielectric material and the second dielectric material comprise different materials.

[0024] In some embodiments, the method further includes: after forming the plurality of first portions, forming a reflective structure over at least one of the plurality of first portions, wherein a second dielectric material is deposited such that the second dielectric material covers the reflective structure.

[0025] In summary, in the optical modules and methods for forming optical modules according to some embodiments of the present invention, the formation of meta-atoms with high aspect ratios through layered stacking provides a wider phase modulation range and higher optical efficiency. Furthermore, by simultaneously configuring meta-lenses with both reflective and transmissive functions within the meta-lens array, during alignment, the reflective meta-lenses can reflect a portion of the optical signal from the silicon photonic wafer or fiber array unit, and a photodetector can measure the intensity of the returned light to accurately determine the optical axis alignment status. This allows for automated sub-micron level alignment accuracy during packaging without the need for external microscopes or manual adjustments. Simultaneously, the methods used to form the optical module can employ standard thin-film deposition and photolithography processes, possessing high mass production potential and effectively improving the coupling efficiency and packaging reliability of the optical module.

[0026] These and other aspects of the invention will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, but variations and modifications may be made therein without departing from the spirit and scope of the novel concept of the invention. Attached Figure Description

[0027] The accompanying drawings illustrate one or more embodiments of the invention and, together with the written description, serve to explain the principles of the invention. Throughout the drawings, the same reference numerals are used wherever possible to refer to similar or identical elements of the embodiments, wherein: Figures 1 to 5 These are cross-sectional schematic diagrams of various stages of a method for forming an optical module according to some embodiments of the present invention.

[0028] Figure 6A For optical modules according to some embodiments of the present invention along Figure 5 A cross-sectional diagram showing line segment A-A' in the diagram.

[0029] Figure 6B For optical modules according to some embodiments of the present invention along Figure 5 A cross-sectional diagram showing line segment B-B' in the diagram.

[0030] Figures 7 to 11 These are cross-sectional schematic diagrams of various stages of a method for forming an optical module according to other embodiments of the present invention.

[0031] Figure 12 and Figure 13 These are cross-sectional schematic diagrams of optical modules according to other embodiments of the present invention.

[0032] Figure 14 This is a three-dimensional schematic diagram of an optical module according to other embodiments of the present invention.

[0033] Figure 15 For optical modules according to other embodiments of the present invention along Figure 14 A cross-sectional diagram showing line segment C-C' in the diagram.

[0034] Figure 16 This is a three-dimensional schematic diagram of an optical module according to other embodiments of the present invention.

[0035] Figure 17 For optical modules according to other embodiments of the present invention along Figure 16 A cross-sectional diagram showing line segment D-D' in the diagram.

[0036] Figure 18 and Figure 19 This is a cross-sectional schematic diagram of an optical module according to other embodiments of the present invention. Detailed Implementation

[0037] The following disclosure will be described more fully with reference to the accompanying drawings and references, some of which illustrate exemplary embodiments. The invention may be embodied in different forms and should not be limited to the embodiments mentioned below. However, these embodiments are provided to aid in a more complete understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0038] In the accompanying drawings, the thicknesses of layers, films, panels, regions, etc., are enlarged for clarity. Throughout the specification, the same reference numerals refer to similar elements. It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected" to another element, it may be directly on or connected to the other element, or intermediate elements may also be present. Conversely, when an element is referred to as being "directly on" or "directly connected" to another element, no intermediate elements are present. As used herein, "connection" can refer to a physical and / or electrical connection. Furthermore, "electrical connection" or "coupling" may mean that other elements exist between the two elements.

[0039] It should be understood that although the terms "first," "second," "third," etc., can be used in this invention to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or portion from another element, component, region, layer, or portion. Therefore, the terms "first element," "component," "region," "layer," or "part" discussed below can be referred to as a second element, component, region, layer, or portion without departing from the teachings of this invention.

[0040] The terminology used herein is for the purpose of describing particular embodiments only and is not restrictive. As used herein, unless the content clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to include the plural forms, including “at least one.” “Or” means “and / or.” As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. It should also be understood that, when used in this specification, the terms “comprising” and / or “comprising” specify the presence of the stated features, areas, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, areas, integrals, steps, operations, elements, components, and / or combinations thereof.

[0041] The terms “about,” “approximately,” or “substantially” used in this invention can be selected based on the optical properties, etching properties, or other properties to choose a more acceptable range of deviations or standard deviations, rather than applying a single standard deviation to all properties.

[0042] Please refer to Figures 1 to 6B . Figures 1 to 5 These are cross-sectional schematic diagrams of various stages of a method for forming an optical module 10 according to some embodiments of the present invention. Figure 6A and Figure 6B Optical module 10 along Figure 5 The diagram shows the cross-sections of line segments A-A' and B-B'.

[0043] like Figure 1 As shown, a first metamaterial layer 114A is first deposited over the substrate structure 100. The substrate structure 100 may include a substrate 102. In some embodiments, the substrate 102 may include silicon, glass, optical resin, optical plastic, or a combination thereof.

[0044] In some embodiments, the substrate structure 100 may further include an antireflective layer 104 above the substrate 102 to reduce interface reflection loss and improve transmission efficiency. The antireflective layer 104 may include silicon oxide (SiO), silicon nitride (SiN), titanium oxide (TiO), hafnium oxide (HfO), tantalum oxide (TaO), or combinations thereof.

[0045] In some embodiments, the first metamaterial layer 114A may include a material suitable for forming meta-atoms, such as amorphous silicon, polycrystalline silicon, gallium nitride (GaN), titanium oxide (TiO), hafnium oxide (HfO), silicon nitride (SiN), silicon oxide (SiO), or combinations thereof. In some embodiments, the refractive index of the first metamaterial layer 114A is between 1.2 and 4. It is worth noting that the term "metamaterial layer" as used herein refers to a material layer that will subsequently be formed into a subwavelength geometry through various processes to achieve a specific electromagnetic response, thereby realizing specific refractive, phase modulation, or polarization control capabilities.

[0046] Next, a mask layer 300 is formed over the first metamaterial layer 114A. The mask layer 300 is patterned to have a first pattern. In some embodiments, the mask layer 300 can be a photoresist or a hard mask. The patterning of the mask layer 300 can be performed using lithography or electron beam lithography. This can be achieved using beamlithography, nanoimprint lithography, or other patterning techniques suitable for defining subwavelength characteristics. When a hard mask is used as the mask layer 300, the mask layer 300 may include silicon oxide (SiO), silicon nitride (SiN), or a metal thin film.

[0047] like Figure 2 As shown, the first metamaterial layer 114A is patterned using a process such as etching through the masking layer 300 until the top surface of the substrate structure 100 is exposed. In this way, the first pattern of the masking layer 300 is transferred onto the first metamaterial layer 114A, thereby forming a plurality of first portions 114 separated from each other. These first portions 114 form a plurality of subwavelength structures whose feature size and period are smaller than the operating wavelength of the target incident light. Figure 2 As shown, the dimensions of these first portions 114 can vary depending on the defined first pattern. For example, located in Figure 2 The width of the first first part 114 on the left and the width of the first first part 114 on the right can be greater than the width of the four first parts 114 in the middle.

[0048] like Figure 3 As shown, the mask layer 300 is removed from the first portion 114 to expose the top surface of the first portion 114. In some embodiments, depending on the composition of the mask layer 300, the mask layer 300 can be removed by methods such as ashing, wet etching, or solvent stripping.

[0049] Next, a first dielectric material 116A is deposited to cover the top surface of the first portion 114 and the substrate structure 100. The refractive index of the first dielectric material 116A is less than that of the first portion 114. The first dielectric material 116A may include silicon oxide (SiO), silicon nitride (SiN), titanium oxide (TiO), hafnium oxide (HfO), tantalum oxide (TaO), solgel-derived material, or combinations thereof. In some embodiments, the refractive index of the first dielectric material 116A is between 1.2 and 3.

[0050] like Figure 4As shown, a planarization process, such as chemical mechanical polishing (CMP), is performed on the first dielectric material 116A to expose the top surface of the first portion 114, thereby forming a first dielectric layer 116. The first dielectric layer 116 laterally surrounds the first portion 114. In some embodiments, the planarization process is performed such that the top surface of the first dielectric layer 116 is substantially flush with the top surface of the first portion 114.

[0051] Next, a second portion 118 is formed over the first portion 114. The formation of the second portion 118 can employ a similar process to that used for the first portion 114. For example, a second metamaterial layer is deposited over the first portion 114 and the first dielectric layer 116, and the second metamaterial layer is patterned using a masking layer until the first dielectric layer 116 is exposed, thereby forming a plurality of separate second portions 118. Similarly, these second portions 118 form a plurality of subwavelength structures.

[0052] like Figure 4 As shown, each second part 118 corresponds to a first part 114 and is located vertically above the corresponding first part 114.

[0053] In some embodiments, the orthographic projection area of ​​the second portion 118 at least partially overlaps the orthographic projection area of ​​the first portion 114. More specifically, the overlap ratio between the first portion 114 and the second portion 118 is between 0.3 and 1. It is worth noting that the term "orthographic projection area" of an element herein refers to the area covered by the vertical projection of the element onto the substrate structure 100. Furthermore, the "overlap ratio" between two elements is defined as the ratio of the overlapping area of ​​the orthographic projection areas of the two elements to the area of ​​the orthographic projection area of ​​the lower of the two elements.

[0054] For example, such as Figure 4 As shown, the orthographic projection area of ​​the second portion 118 substantially overlaps with the orthographic projection area of ​​the first portion 114. In some embodiments, when the first portion 114 and the second portion 118 have the same cross-sectional profile, the overlap ratio between the first portion 114 and the second portion 118 is 1. More specifically, the second portion 118 and the first portion 114 are aligned in the vertical direction. In some embodiments, the second portion 118 may at least partially contact the top surface of the corresponding first portion 114.

[0055] The second portion 118 may include the same or different material as the first portion 114. In some embodiments, the second portion 118 may include amorphous silicon, polycrystalline silicon, gallium nitride (GaN), titanium oxide (TiO), hafnium oxide (HfO), silicon nitride (SiN), silicon oxide (SiO), or combinations thereof. In some embodiments, the refractive index of the material included in the second portion 118 is between 1.2 and 4. In some embodiments, the aforementioned planarization process may produce residues located between the first portion 114 and the second portion 118. These residues have the same material as the first dielectric layer 116.

[0056] like Figure 5 As shown, a second dielectric layer 120 is formed above the first portion 114 and the first dielectric layer 116, and laterally surrounds the second portion 118. The top surface of the second dielectric layer 120 is substantially flush with the top surface of the second portion 118. The refractive index of the second dielectric layer 120 is less than that of the second portion 118. The second dielectric layer 120 may comprise the same or different material as the first dielectric layer 116. In some embodiments, the second dielectric layer 120 may comprise silicon oxide (SiO), silicon nitride (SiN), titanium oxide (TiO), hafnium oxide (HfO), tantalum oxide (TaO), sol-gel derived material, or combinations thereof. In some embodiments, the refractive index of the material comprising the second dielectric layer 120 is between 1.2 and 3.

[0057] Subsequently, a third portion 122, a third dielectric layer 124 laterally surrounding the third portion 122, a fourth portion 126, and a fourth dielectric layer 128 laterally surrounding the fourth portion 126 are formed in a similar manner. As shown, the third portion 122 and the fourth portion 126 are sequentially and vertically stacked above the second portion 118. The materials of the third portion 122 and the fourth portion 126 may be exactly the same as, partially different from, or completely different from the materials of the first portion 114 and the second portion 118, respectively. For example, the third portion 122 may comprise a material different from the first portion 114 and the second portion 118, while the fourth portion 126 may comprise a material the same as the first portion 114. In some embodiments, the refractive index of the materials comprised in the third portion 122 and the fourth portion 126 is between 1.2 and 4. Residues may exist between the second portion 118 and the third portion 122, which may comprise the same material as the second dielectric layer 120. Residues may also exist between the third portion 122 and the fourth portion 126, which may comprise the same material as the third dielectric layer 124.

[0058] A third dielectric layer 124 and a fourth dielectric layer 128 are sequentially stacked on top of a second dielectric layer 120. The top surface of the third dielectric layer 124 is substantially flush with the top surface of the third portion 122. The refractive index of the third dielectric layer 124 is less than that of the third portion 122. The top surface of the fourth dielectric layer 128 is substantially flush with the top surface of the fourth portion 126. The refractive index of the fourth dielectric layer 128 is less than that of the fourth portion 126. The materials of the third dielectric layer 124 and the fourth dielectric layer 128 may be exactly the same as, partially different from, or completely different from the first dielectric layer 116 and the second dielectric layer 120, respectively. For example, the third dielectric layer 124 comprises a material different from the first dielectric layer 116 and the second dielectric layer 120, while the fourth dielectric layer 128 comprises a material the same as the first dielectric layer 116. In some embodiments, the refractive indices of the materials comprised in the third dielectric layer 124 and the fourth dielectric layer 128 are between 1.2 and 3.

[0059] In some embodiments, the lateral feature dimensions (FDs, such as width, diameter, or equivalent diameter) of the first portion 114, the second portion 118, the third portion 122, and the fourth portion 126 are between 30 nanometers and 450 nanometers. In some embodiments, the heights of the first portion 114, the second portion 118, the third portion 122, and the fourth portion 126 are between 200 nanometers and 1000 nanometers. In some embodiments, the ratio between the height and width of each of the first portion 114, the second portion 118, the third portion 122, and the fourth portion 126 is between 1 and 8.

[0060] Each first portion 114, together with a second portion 118, a third portion 122, and a fourth portion 126 stacked vertically above it, constitutes a meta-atom 110, configured to modulate the phase, amplitude, and / or polarization of electromagnetic waves through a subwavelength geometry. In some embodiments, the ratio between the height and width of each meta-atom 110 may be greater than 10. A first dielectric layer 116, a second dielectric layer 120, a third dielectric layer 124, and a fourth dielectric layer 128 together constitute a dielectric structure 112 above the substrate structure 100. In this way, a plurality of meta-atoms 110 are arranged in the dielectric structure 112, for example, in an array, to form a meta-lens ML.

[0061] Depending on the desired electromagnetic behavior, the geometry of each layer of the meta-atom 110 can be adjusted. Each layer of the meta-atom 110 can have the same or different cross-sectional profiles, such as circular, square, or cross-shaped. For example, in other embodiments, such as... Figure 6A and Figure 6BAs shown, the cross-sectional profile of the first portion 114 is square, while the cross-sectional profile of the second portion 118 is circular. In these embodiments, the orthographic projection area of ​​each second portion 118 on the substrate structure 100 completely overlaps with the orthographic projection area of ​​the first portion 114 on the substrate structure 100. Therefore, according to the definition of "overlap ratio" herein, the overlap ratio of the orthographic projection area of ​​the second portion 118 to the orthographic projection area of ​​the first portion 114 is [value missing]. / 4. In some embodiments, the ratio of the overlap between the orthographic projection regions of two adjacent portions of the metaatom 110 is between 0.3 and 1.

[0062] Please refer to Figures 7 to 11 These are schematic cross-sectional views of various stages of a method for forming an optical module 10A according to other embodiments of the present invention. It is worth noting that, due to... Figures 7 to 11 The middle part of the structure and process steps Figures 1 to 5 The contents shown are the same or similar. The following will only explain the differences, and the repeated contents will not be repeated.

[0063] like Figure 7 As shown, a first dielectric material 116A is first deposited over the substrate structure 100. Next, a mask layer 302 is formed on the first dielectric material 116A. The mask layer 302 is patterned to have a second pattern. The second pattern is consistent with... Figure 1 The first pattern is complementary.

[0064] like Figure 8 As shown, a patterning process, such as etching, is performed on the first dielectric material 116A through a mask layer 302 until the top surface of the substrate structure 100 is exposed. In this way, the second pattern of the mask layer 302 is transferred onto the first dielectric material 116A. The patterned first dielectric material 116A forms a first dielectric layer 116 having a plurality of first trenches. The top surface of the substrate structure 100 is exposed through these first trenches. Figure 2 As shown, the dimensions of these grooves can vary depending on the defined second pattern. For example, the width of the first groove on the left and the width of the first groove on the right can be greater than the width of the four first grooves in the middle.

[0065] like Figure 9 As shown, a masking layer 302 is removed from the first dielectric layer 116 to expose the top surface of the first dielectric layer 116. Next, a first metamaterial layer 114A is deposited to cover the first dielectric layer 116 and fill each first trench.

[0066] like Figure 10As shown, a planarization process, such as chemical mechanical polishing (CMP), is performed on the first metamaterial layer 114A to expose the top surface of the first dielectric layer 116, thereby forming a plurality of first portions 114 separated from each other in the first trenches of the first dielectric layer 116. These first portions 114 form a plurality of subwavelength structures. In some embodiments, the planarization process is performed such that the top surface of the first dielectric layer 116 is substantially flush with the top surface of the first portions 114. Next, a second dielectric layer 120 is formed over the first dielectric layer 116 and the first portions 114. The formation of the second dielectric layer 120 can employ a process similar to that of the first dielectric layer 116. For example, a second dielectric material is deposited over the first portions 114 and the first dielectric layer 116, and the second dielectric material is patterned using a masking layer to form a plurality of second trenches. The patterned second dielectric material forms a second dielectric layer 120 having a plurality of second trenches. Each second trench at least partially exposes the top surface of one first portion 114. It is worth noting that the second dielectric layer 120 may have the same pattern as the first dielectric layer 116 but offset to the right. For example, as Figure 10 As shown, the pattern of the second dielectric layer 120 is offset to the right by a distance d relative to the pattern of the first dielectric layer 116. In other words, the second dielectric layer 120 exposes a portion of the top surface of the first portion 114 and a portion of the top surface of the first dielectric layer 116. In these embodiments, the second dielectric layer 120 overlaps each first portion 114. In some embodiments, the second dielectric layer 120 may contact each first portion 114.

[0067] like Figure 11 As shown, a second metamaterial layer is deposited over the second dielectric layer 120 and fills the second trench. Next, a planarization process is performed on the second metamaterial layer to expose the top surface of the second dielectric layer 120, thereby forming a plurality of separated second portions 118 in the second trench of the second dielectric layer 120. These second portions 118 form a plurality of subwavelength structures. Each second portion 118 corresponds to a first portion 114 and is offset to the right by a distance d relative to its corresponding first portion 114. In these embodiments, the orthographic projection area of ​​each second portion 118 on the substrate structure 100 at least partially overlaps with the orthographic projection area of ​​its corresponding first portion 114 on the substrate structure 100. Similarly, the ratio of the overlap between the orthographic projection areas of the second portions 118 and the first portions 114 on the substrate structure 100 is between 0.3 and 1. For example, in Figure 11 In the corresponding implementation, the ratio of the overlap between the orthographic projection areas of the second part 118 and the first part 114 is between 0.5 and 0.8.

[0068] Subsequently, a third portion 122, a third dielectric layer 124 laterally surrounding the third portion 122, a fourth portion 126, and a fourth dielectric layer 128 laterally surrounding the fourth portion 126 are formed in a similar manner. As shown in the figure, each third portion 122 corresponds to a second portion 118 and is offset to the right relative to the corresponding second portion 118. The orthographic projection area of ​​each third portion 122 on the substrate structure 100 at least partially overlaps with the orthographic projection area of ​​the corresponding second portion 118 on the substrate structure 100. In some embodiments, the overlap ratio between the third portion 122 and the corresponding second portion 118 is between 0.3 and 1. Each fourth portion 126 corresponds to a third portion 122 and is offset to the right relative to the corresponding third portion 122. The orthographic projection area of ​​each fourth portion 126 on the substrate structure 100 at least partially overlaps with the orthographic projection area of ​​the corresponding third portion 122 on the substrate structure 100. In some implementations, the overlap ratio between the fourth portion 126 and the corresponding third portion 122 is between 0.3 and 1.

[0069] Please refer to Figure 12 This is a cross-sectional schematic diagram of an optical module 10B according to some embodiments of the present invention. One difference between optical module 10B and optical module 10 is that the second portion 118 of optical module 10B is offset to the right relative to the first portion 114, while the third portion 122 is not offset relative to the first portion 114. Furthermore, the width of the fourth portion 126 is smaller than the width of the third portion 122, and each fourth portion 126 is located directly above its corresponding third portion 122. In these embodiments, the overlap ratio between the orthographic projection area of ​​the fourth portion 126 and the orthographic projection area of ​​its corresponding third portion 122 is between 0.3 and 0.5, but the present invention is not limited thereto. On the other hand, when the third portion 122 and the first portion 114 have the same cross-sectional profile, the orthographic projection area of ​​the third portion 122 on the substrate structure 100 completely overlaps with the orthographic projection area of ​​the first portion 114 on the substrate structure 100. In other words, the overlap ratio between the third portion 122 and the first portion 114 is 1.

[0070] Please refer to Figure 13 This is a cross-sectional schematic diagram of an optical module 10C according to other embodiments of the present invention. One difference between optical module 10C and optical module 10 is that the cross-sectional profiles of the first portion 114, the second portion 118, the third portion 122, and the fourth portion 126 of optical module 10C are trapezoidal, such that their cross-sectional areas decrease upward along the direction perpendicular to the substrate structure 100, thereby increasing the overlap area and / or contact area between two adjacent portions, thereby reducing interface discontinuities caused by process variations, and thus maintaining the optical uniformity and stability of the structure.

[0071] In addition, such as Figure 13 As shown, the number of third portions 122 is less than the number of second portions 118, and the number of fourth portions 126 is less than the number of third portions 122 and the number of second portions 118. In other words, in the optical module 10C, some metaatoms include only the first portions 114 and the second portions 118, some metaatoms include only the first portions 114, the second portions 118 and the third portion 122, and other metaatoms include the first portions 114, the second portions 118, the third portions 122 and the fourth portion 126. Similarly, in a metaatom, the orthographic projection regions of two adjacent portions overlap at least partially, and the overlap ratio is between 0.3 and 1. In this way, multiple metaatoms in a metalens ML can have different heights to increase the degree of freedom in vertical design.

[0072] Please refer to Figure 14 and Figure 15 . Figure 14 This is a perspective view of an optical module 20 according to some other embodiments of the present invention. Figure 15 For optical module 20 along Figure 14 The diagram shows a cross-sectional view drawn with line segment C-C'. It is worth noting that since the structure of optical module 20 is the same as or similar to some of the structures of the aforementioned optical module, the following only describes the differences, and repeated content will not be repeated.

[0073] The optical module 20 includes a substrate structure 100 and a meta-lens array structure located above the substrate structure 100. For example, the meta-lens array structure includes meta-lens ML1, meta-lens ML2, meta-lens ML3, and meta-lens ML4.

[0074] The substrate structure 100 includes a silicon photonic chip (SiPh). The silicon photonic chip 130 includes an optical waveguide, such as a waveguide 140, coupled to an optical fiber (OF). The waveguide 140 is used to couple optical signals from the optical fiber OF to a meta-lens array structure. In some embodiments, the core width (CW) of the core of the waveguide 140 can be less than 150 micrometers. More specifically, the core width (CW) can be between 100 nanometers and 2 micrometers.

[0075] The meta-lens array structure includes a dielectric structure 112 and a plurality of meta-atoms 110. The dielectric structure 112 is located above the substrate structure 100. The plurality of meta-atoms 110 are located within the dielectric structure 112. The meta-atoms 110 and dielectric structure 112 of the optical module 20 are similar to those of the optical module 10, and therefore will not be described in detail here.

[0076] like Figure 15 As shown, in some embodiments, the substrate structure 100 further includes a substrate 102 above the silicon photonic wafer 130. In some embodiments, the substrate 102 may include silicon, glass, optical resin, optical plastic, or a combination thereof. In some embodiments, the substrate structure 100 further includes an anti-reflection layer 104 located above the substrate 102 to reduce interface reflection loss and improve transmission efficiency.

[0077] Accordingly, to couple the optical waveguide and meta-lens array structure included in the silicon photonic wafer 130, the method for forming the optical module 20 further includes setting the optical waveguide to couple with the meta-lens array structure, wherein the meta-lens array structure is used to receive optical signals from the optical waveguide. There are at least two implementations for setting the optical waveguide. In an embodiment where the substrate structure 100 includes a substrate 102, the method may include: forming a dielectric structure 112 and meta-atoms 110 above the substrate 102, and then transferring and bonding the substrate 102 above the silicon photonic wafer 130, such that the meta-atoms 110 are coupled to the optical waveguide of the silicon photonic wafer 130. In an embodiment where the substrate structure 100 does not include a substrate 102, the method may include: directly forming the dielectric structure 112 and meta-atoms 110 above the silicon photonic wafer 130, such that the meta-atoms 110 are directly coupled to the optical waveguide of the silicon photonic wafer 130.

[0078] In some embodiments, the meta-lens array structure further includes an anti-reflection layer 132 covering the meta-atoms 110 and the dielectric structure 112 to reduce interface reflection loss and improve transmission efficiency. In some embodiments, the anti-reflection layer 132 includes silicon oxide (SiO), silicon nitride (SiN), titanium oxide (TiO), hafnium oxide (HfO), tantalum oxide (TaO), or a combination thereof.

[0079] In some embodiments, the meta-lens array structure further includes a reflective structure 134 partially covering the anti-reflective layer 132. In some embodiments, the reflective structure 134 is a deposited metal thin film. The material of the reflective structure 134 may include aluminum (Al), copper (Cu), gold (Au), silver (Ag), or combinations thereof. The metal thin film has broadband reflectivity, achieving a reflectivity of 80% to 90% in the visible to near-infrared band.

[0080] Accordingly, the method of forming the optical module 20 further includes forming an antireflective layer 132 covering the meta-atoms 110 and the dielectric structure 112 after forming the meta-atoms 110 and the dielectric structure 112. Next, a reflective structure 134 is formed over the antireflective layer 132 and covers a portion of the top surface of the antireflective layer 132. In embodiments where each meta-atom 110 includes at least a first portion and a second portion, the reflective structure 134 is formed over the second portion of at least one meta-atom 110.

[0081] The above structure forms metalenses ML1, ML2, ML3, and ML4 as shown in the figure. Metalenses ML1 and ML4 include a reflective structure 134, while metalenses ML2 and ML3 do not. This creates a dual-mode metalens array structure capable of both transmission and reflection, allowing for simultaneous normal optical operation and alignment correction.

[0082] Furthermore, meta-lenses without reflective structures, such as meta-lenses ML2 and ML3, are used for normal optical operation. Conversely, meta-lenses ML1 and ML4, which have reflective capabilities, can be used to assist in the optical alignment between the meta-lens array structure and the silicon photonics wafer 130. For example, an optical signal from the fiber optic OF is transmitted via an optical waveguide, such as waveguide 140, of the silicon photonics wafer 130 to meta-lenses ML1 and ML4. After passing through meta-atoms 110, the optical signal reaches the reflective structure 134 and is reflected back to the fiber optic OF. A photodetector or power meter can be installed at the end of the fiber optic OF to receive and measure the intensity of the returned light, thereby determining whether the optical axes of meta-lenses ML1 and ML4 are aligned with the silicon photonics wafer 130. Higher light intensity indicates more precise alignment. A decrease in light intensity indicates a misalignment. In other embodiments, the silicon photonic chip 130 can further integrate an optical splitter and photodetectors, allowing the reflected light signal to be distributed to different photodetectors within the chip for multi-point alignment or directional offset analysis, thereby improving alignment accuracy. This alignment method can achieve automatic correction and channel-level feedback using reflected light signals, without relying on imaging systems or mechanical scanning and manual adjustments. Furthermore, the meta-lens array structure including a metal reflective layer formed using the aforementioned method can be fabricated using common thin-film deposition and photolithography processes, can be integrated into standard CMOS processes, and possesses high mass production potential.

[0083] Please refer to Figure 16 and Figure 17 . Figure 16 This is a perspective view of an optical module 30 according to some other embodiments of the present invention. Figure 17 For optical module 30 along Figure 16 A cross-sectional diagram showing line segment D-D' in the diagram.

[0084] The optical module 30 includes a substrate structure 200 and a meta-lens array structure located above the substrate structure 200. For example, the meta-lens array structure includes meta-lens ML5, meta-lens ML6, meta-lens ML7, and meta-lens ML8.

[0085] The substrate structure 200 includes a fiber array unit 230 (FAU). The FAU includes multiple optical waveguides, such as optical fibers (OFs), arranged at a fixed spacing to form a fiber array. The OFs are used to couple optical signals to the meta-lens array structure. In some embodiments, the core diameter CD of the core 250 of the OF can be less than 150 micrometers. More specifically, the core diameter CD can be between 5 micrometers and 70 micrometers.

[0086] The meta-lens array structure includes a dielectric structure 212 and a plurality of meta-atoms 210. The dielectric structure 212 is located above the substrate structure 200. The plurality of meta-atoms 210 are located within the dielectric structure 212. The meta-atoms 210 and dielectric structure 212 of the optical module 30 are similar to the meta-atoms 110 and dielectric structure 112 of the optical module 10, and therefore will not be described in detail here.

[0087] like Figure 17 As shown, in some embodiments, the substrate structure 200 further includes a substrate 202 above the fiber array unit 230. In some embodiments, the substrate structure 200 further includes an anti-reflection layer 204 located above the substrate 202 to reduce interface reflection loss and improve transmission efficiency. The substrate 202 and the anti-reflection layer 204 are similar to the substrate 102 and the anti-reflection layer 104 of the optical module 20, and therefore will not be described in detail here.

[0088] Accordingly, to couple the optical waveguide included in the fiber array unit 230 with the meta-lens array structure, the method for forming the optical module 30 further includes setting the optical waveguide to couple with the meta-lens array structure, wherein the meta-lens array structure is used to receive optical signals from the optical waveguide. There are at least two implementations for setting the optical waveguide. In an embodiment where the substrate structure 200 includes a substrate 202, the method may include: forming a dielectric structure 212 and meta-atoms 210 above the substrate 202; then transferring and bonding the substrate 202 above the fiber array unit 230, such that the meta-atoms 210 are coupled to the optical waveguide of the fiber array unit 230. In an embodiment where the substrate structure 200 does not include a substrate 202, the method may include: directly forming the dielectric structure 212 and meta-atoms 210 above the fiber array unit 230, such that the meta-atoms 210 are directly coupled to the optical waveguide of the fiber array unit 230.

[0089] In some embodiments, the meta-lens array structure further includes an anti-reflection layer 232 covering the meta-atoms 210 and the dielectric structure 212. The anti-reflection layer 232 is similar to the anti-reflection layer 132 of the optical module 20, and therefore will not be described in detail here.

[0090] In some embodiments, the superlens array structure further includes a reflective structure 236 partially covering the antireflective layer 232. In some embodiments, the reflective structure 236 includes vertically stacked dielectric layers 238, 240, 242, 244, and 246. Adjacent dielectric layers use different materials, thicknesses, and refractive indices to form a Bragg-type reflective stack, enabling the reflective structure 236 to achieve a high reflectivity of 99.9% within a specific narrow frequency band. The reflective structure 236 can also be applied to the optical module 20.

[0091] Accordingly, the method of forming the optical module 30 further includes forming an anti-reflective layer 232 covering the meta-atoms 210 and the dielectric structure 212 after forming the meta-atoms 210 and the dielectric structure 212. Next, a reflective structure 236 is formed over the anti-reflective layer 232 and covers a portion of the top surface of the anti-reflective layer 232. In embodiments where each meta-atom 210 includes at least a first portion and a second portion, the reflective structure 236 is formed over the second portion of at least one meta-atom 210.

[0092] The above structure forms metalenses ML5, ML6, ML7, and ML8 as shown in the figure. Similarly, metalenses ML5 and ML8 include a reflective structure 236, while metalenses ML6 and ML7 do not have a reflective structure. This forms a dual-mode metalens array structure that can simultaneously achieve transmission and reflection functions. The metalenses without reflective structures, such as ML6 and ML7, are used for normal optical operation, while the reflective metalenses ML5 and ML8 assist in the optical alignment between the metalens array structure and the fiber optic array unit 230.

[0093] Specifically, the fiber optic OF can output a portion of the optical signal, which is transmitted to meta-lens ML5 and ML8. After passing through the meta-atoms 210, the optical signal reaches the reflective structure 236 and is reflected back to the fiber optic OF. A photodetector can be installed at the end of the fiber optic OF to receive and measure the intensity, distribution, or temporal changes of the returned light, thereby determining whether the relative position between the meta-lens array structure and the fiber array unit 230 is offset. When their optical axes are aligned, the light intensity is higher. If there is lateral displacement, angular offset, or height error, the light intensity will decrease. In this way, by measuring the changes in the returned light, a quantifiable alignment index can be established to guide the position adjustment during the packaging process.

[0094] In other embodiments, the fiber array unit 230 can output multiple sets of optical signals and use reflective meta-lenses (such as meta-lens ML5 and meta-lens ML8) at different positions to perform multi-point back-return detection, so as to simultaneously determine the offset in different coordinate axis directions and further improve the alignment accuracy.

[0095] Please refer to Figure 18 This is a cross-sectional schematic diagram of an optical module 20A according to other embodiments of the present invention. One difference between optical module 20A and optical module 20 is that the metalens ML1 and metalens ML4 of optical module 20A include a reflective structure 148. The reflective structure 148 is a reflective grating structure used to generate high reflectivity in a specific wavelength band, such as guided film resonance. Mode resonance (GMR) gratings or subwavelength diffraction gratings. Among them, a guided-film resonant grating can induce strong resonant reflection of incident light within a specific narrow frequency band, achieving a near-total internal reflection effect. A subwavelength diffraction grating, on the other hand, can change the phase and effective refractive index of light, enabling high-efficiency reflection within a specific wavelength range. The reflective structure 148 can also be applied to the optical module 30.

[0096] Please refer to Figure 19 This is a cross-sectional schematic diagram of an optical module 20B according to some embodiments of the present invention. One difference between optical module 20B and optical module 20 is that the reflective structure 154 of optical module 20B is located between the upper and lower layers of meta-atom 110. For example, the meta-atom 110 of the meta-lens of optical module 20B includes a first portion 149 and a second portion 151 located above the first portion 149. The dielectric structure 112 of optical module 20B includes a first dielectric layer 150 and a second dielectric layer 152 located above the first dielectric layer 150. The reflective structure 154 is located above the first dielectric layer 150 and a portion of the first portion 149. The second dielectric layer 152 covers the reflective structure 154. A portion of the second portion 151 is located above the reflective structure 154 and aligned with its corresponding first portion 149. The reflective structure 154 is a metasurface reflector with partial reflection (i.e., partial reflection and partial transmission) function. Besides providing reflection, it can also integrate other special optical effects, such as polarization control, wavefront shaping, and beam deflection. By embedding the reflective structure 154 in the intermediate layer of multiple meta-atoms 110 (such as between the first portion 149 and the second portion 151), multifunctional optical control can be achieved while maintaining an ultra-thin structure, further enhancing the design flexibility and application versatility of the optical module 20B. In some embodiments, the aforementioned reflective structure can also be combined with a single metalens to achieve a preset reflection band and reflectivity.

[0097] Accordingly, the method for forming the optical module 20B includes forming a reflective structure 154 over the first dielectric layer 150 and a portion of the first portion 149 after forming the first portion 149 and the first dielectric layer 150. Next, a second dielectric layer 152 and a second portion 151 are formed. For example, the steps of forming the second dielectric layer 152 and the second portion 151 include depositing a second dielectric material over the reflective structure 154, the first portion 149, and the first dielectric layer 150. Next, a pattern is formed in the second dielectric material to form a second trench, a portion of which exposes the reflective structure 154, and another portion of which exposes the first portion 149. Next, a second portion 151 is formed in the second trench such that a portion of the second portion 151 is located over the reflective structure 154, and another portion of the second portion 151 is located over the first portion 149.

[0098] From the detailed description of the specific embodiments of the present invention above, it is evident that in the optical modules and methods for forming optical modules according to some embodiments of the present invention, the formation of meta-atoms with high aspect ratios through layered stacking can provide a larger phase modulation range and higher optical efficiency. Furthermore, by simultaneously configuring meta-lenses with both reflective and transmissive functions in the meta-lens array, during the alignment process, the reflective meta-lenses can reflect a portion of the optical signal from the silicon photonic wafer or fiber array unit, and a photodetector can measure the intensity of the returned light to accurately determine the optical axis alignment status. In this way, automated sub-micron level alignment accuracy can be achieved during the packaging process without the need for external microscopes or manual adjustments. Simultaneously, the method used to form the optical module can employ standard thin-film deposition and photolithography processes, possessing high mass production potential and effectively improving the coupling efficiency and packaging reliability of the optical module.

[0099] The foregoing description is only intended to illustrate and describe exemplary embodiments of the present invention and is not intended to exhaustively describe or limit the precise forms of the invention disclosed herein. The above teachings may be modified or varied.

[0100] The selected and illustrated embodiments are intended to explain the content of the invention and its practical application, thereby inspiring others skilled in the art to utilize the invention and its various embodiments, and to make various modifications to suit specific intended uses. Alternative embodiments will be apparent to those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the appended claims, and not by the foregoing description and the exemplary embodiments described therein.

[0101] [Symbol Explanation] 10, 10A, 10B, 10C, 20, 20A, 20B, 30: Optical modules 100, 200: Substrate structure 102, 202: Substrate 104, 132, 204, 232: Anti-reflective layer 110, 210: Super-intrinsic atoms 112, 212: Dielectric structure 114, 149: First part 114A: First Metamaterial Layer 116, 150: First dielectric layer 116A: First dielectric material 118, 151: Second part 120, 152: Second dielectric layer 122: Third part 124: Third dielectric layer 126: Fourth Part 128: Fourth dielectric layer 130: Silicon photonic wafer 134, 148, 154, 236: Reflective structures 140: Waveguide 230: Fiber optic array unit 238, 240, 242, 244, 246: Dielectric layers 250: Core 300, 302: Masking layer A-A', B-B', C-C', D-D': line segments CD: Core Diameter CW: Core Width d: distance FD: Lateral Feature Dimension ML, ML1, ML2, ML3, ML4, ML5, ML6, ML7, ML8: Super Lenses OF: Optical fiber.

Claims

1. An optical module, characterized in that, Include: The substrate structure includes an optical waveguide; and A super-lens, located above the substrate structure, comprises: Dielectric structure, located above the substrate structure; and Multiple superatoms are located in the dielectric structure and each includes a first portion and a second portion located above the first portion, wherein the orthographic projection region of the second portion on the substrate structure at least partially overlaps with the orthographic projection region of the first portion on the substrate structure. The superconducting lens is used to receive optical signals from the optical waveguide.

2. The optical module according to claim 1, characterized in that, The dielectric structure includes a first dielectric layer and a second dielectric layer located above the first dielectric layer, wherein the top surface of the first dielectric layer is substantially flush with the top surface of the first portion, and the top surface of the second dielectric layer is substantially flush with the top surface of the second portion.

3. The optical module according to claim 2, characterized in that, The first dielectric layer and the second dielectric layer contain different materials.

4. The optical module according to claim 2, characterized in that, The refractive index of the first dielectric layer is less than that of the first portion, and the refractive index of the second dielectric layer is less than that of the second portion.

5. The optical module according to claim 2, characterized in that, One of the plurality of superatoms further comprises a residue located between the first and second portions, and the residue comprises the same material as the first dielectric layer.

6. The optical module according to claim 1, characterized in that, The ratio of the orthographic projection area of ​​the second part to the orthographic projection area of ​​the first part is between 0.3 and 1.

7. The optical module according to claim 1, characterized in that, The second portion and the material contained in the first portion have a refractive index between 1.2 and 4.

8. The optical module according to claim 1, characterized in that, The cross-sectional area of ​​the second part and the first part decreases upward along a direction perpendicular to the substrate structure.

9. The optical module according to claim 1, characterized in that, The substrate structure includes a silicon photonic wafer having an optical waveguide for coupling the optical signal to the meta-lens. The core width of the optical waveguide is less than 150 micrometers, and the meta-lens further includes a reflective structure located above the substrate structure and configured to reflect the optical signal.

10. The optical module according to claim 1, characterized in that, The substrate structure includes an optical fiber array unit having an optical waveguide for coupling the optical signal to the meta-lens. The core diameter of the optical waveguide is less than 150 micrometers, and the meta-lens further includes a reflective structure located above the substrate structure and configured to reflect the optical signal.

11. The optical module according to claim 1, characterized in that, The meta-lens further includes a reflective structure located between the first and second portions of one of the plurality of meta atoms.

12. The optical module according to claim 1, characterized in that, The lateral feature size of at least one of the first and second portions is between 30 nanometers and 450 nanometers.

13. The optical module according to claim 1, characterized in that, The second portion of one of the plurality of superatoms further includes a third portion, wherein the orthographic projection region of the third portion on the substrate structure at least partially overlaps the orthographic projection region of the second portion on the substrate structure.

14. A method for forming an optical module, characterized in that, Include: Deposit the first metamaterial layer on top of the substrate structure; The first metamaterial layer is patterned until the substrate structure is exposed to form a plurality of first portions that are separated from each other, and the plurality of first portions form a plurality of subwavelength structures; A dielectric material is deposited to cover the plurality of first sites and the substrate structure, wherein the refractive index of the dielectric material is less than the refractive index of the first metamaterial layer; A planarization process is performed on the dielectric material so that the top surface of the planarized dielectric material is substantially flush with the top surfaces of the plurality of first portions; A second metamaterial layer is deposited over the planarized dielectric material; The second metamaterial layer is patterned until the dielectric material is exposed to form a plurality of second portions that are separated from each other, and such that the plurality of second portions form a plurality of subwavelength structures, wherein each of the plurality of second portions at least partially overlaps with a corresponding one of the plurality of first portions; as well as An optical waveguide is provided, wherein the plurality of first portions and the plurality of second portions are used to receive optical signals from the optical waveguide.

15. The method according to claim 14, characterized in that, The materials contained in the plurality of second portions and the plurality of first portions have a refractive index between 1.2 and 4.

16. The method according to claim 14, characterized in that, The orthographic projection area of ​​each of the plurality of second portions on the substrate structure overlaps with the orthographic projection area of ​​the corresponding of the plurality of first portions on the substrate structure, and the overlap ratio is between 0.3 and 1.

17. The method according to claim 14, characterized in that, It also includes forming a reflective structure above one of the plurality of second portions.

18. A method for forming an optical module, characterized in that, Include: Deposit the first dielectric material on top of the substrate structure; The first dielectric material is patterned to form a plurality of first trenches exposing the substrate structure; A first metamaterial layer is deposited to cover the patterned first dielectric material and fill the plurality of first trenches; A first planarization process is performed on the first metamaterial layer to form a plurality of first portions separated from each other located in the plurality of first trenches, and to form a plurality of subwavelength structures in the plurality of first portions, wherein the plurality of top surfaces of the plurality of first portions are substantially flush with the top surface of the patterned first dielectric material. A second dielectric material is deposited over the patterned first dielectric material and the plurality of first portions; The second dielectric material is patterned to form a plurality of second trenches; A second metamaterial layer is deposited to cover the patterned second dielectric material and fill the plurality of second trenches; A second planarization process is performed on the second metamaterial layer to form a plurality of second portions separated from each other located in the plurality of second trenches, such that the plurality of second portions form a plurality of subwavelength structures, and the plurality of second portions at least partially overlap the plurality of first portions; as well as An optical waveguide is provided, wherein the plurality of first portions and the plurality of second portions are used to receive optical signals from the optical waveguide.

19. The method according to claim 18, characterized in that, The first dielectric material and the second dielectric material contain different materials.

20. The method according to claim 18, characterized in that, Also includes: After the plurality of first portions are formed, a reflective structure is formed above at least one of the plurality of first portions. The second dielectric material is deposited such that it covers the reflective structure.

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