Optical element

Abstract

An optical element according to the present invention comprises: a substrate having a first surface and a second surface opposite to each other; and a metasurface layer laminated on the first face of the substrate and having a metasurface region including a plurality of pillars, in which the metasurface region includes: a central region including a plurality of pillars that are highly uniform; and a plurality of annular regions disposed around the central region and each including a plurality of posts. In each of the plurality of annular regions, a height of the plurality of columns is constant, and the plurality of columns in the plurality of annular regions are arranged to change a height one by one of the annular regions in accordance with a predetermined rule in a direction from the central region toward an outer side.

Description

Technical Field

[0001] The present invention relates to an optical element. Background Art

[0002] There are already technologies that use a metasurface on which microstructures called pillars are two-dimensionally arranged as a lens element. Lens elements using metasurfaces are also called metalens. There are also technologies that use a lens assembly or stacked lens that combines a normal lens (bulk lens) and a metalens (see Patent Document 1). List of citations Patent Literature

[0003] Patent Document 1: International Publication No. WO 2021 / 005870 Summary of the Invention

[0004] When metalenses are manufactured by randomly arranging pillars of varying heights or diameters without regularity, ensuring manufacturing accuracy is difficult, and the reproducibility of optical performance in simulations is low. Furthermore, when metalenses are manufactured using resin materials, increasing their diameter is often difficult due to refractive index limitations and difficulties in microfabrication.

[0005] Therefore, it is desirable to provide an optical element that enables ensuring manufacturing accuracy and has a large diameter and high optical performance.

[0006] An optical element according to an embodiment of the present invention includes a substrate and a metasurface layer. The substrate has a first surface and a second surface opposite to each other. The metasurface layer is stacked on the first surface of the substrate. The metasurface layer includes a metasurface region having a plurality of columns. The metasurface region includes: a central region, the central region including a plurality of columns of constant height; and a plurality of annular regions, the plurality of annular regions being arranged around the central region, and each of the annular regions including a plurality of columns. The height of the plurality of columns in each of the plurality of annular regions is constant, and the plurality of columns in the plurality of annular regions are arranged to change height in units of the annular regions according to a predetermined rule as they move from the central region toward the outside.

[0007] In the optical element according to the embodiment of the present invention, the plurality of pillars in the plurality of annular regions change heights in units of the annular regions from the central region toward the outside according to a predetermined rule. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a cross-sectional view schematically showing a configuration example of an optical element according to an embodiment of the present invention. Figure 2is a plan view showing a structural example of the supersurface layer of the optical element according to the embodiment. Figure 3 is a plan view showing a structural example of the supersurface layer of the optical element according to the embodiment. Figure 4 is an explanatory diagram showing an example of a predetermined step mathematical function serving as a predetermined rule expressing the heights of a plurality of pillars. Figure 5 1 and 2 are explanatory diagrams illustrating the optical effects of the optical element according to the embodiment. Figure 6 is a cross-sectional view showing a configuration example of an optical element according to a first modification example of the embodiment. Figure 7 1 is an explanatory diagram showing a second modification example of the optical element 1 according to the embodiment. Figure 8 is a cross-sectional view showing a configuration example of an optical element according to a third modification example of the present embodiment. Figure 9 is a plan view showing a modification of the arrangement of the plurality of pillars of the optical element according to the embodiment as a fourth modification. Figure 10 is a plan view showing a modification of the arrangement of the plurality of pillars of the optical element according to the embodiment as a fourth modification. Figure 11 1 is an explanatory diagram showing a modification example of the arrangement of the plurality of pillars of the optical element according to the embodiment as a fifth modification example. Figure 12 1 is an explanatory diagram showing a modification example of the arrangement of the plurality of pillars of the optical element according to the embodiment as a sixth modification example. Figure 13 1 is an explanatory diagram showing a modification example of the arrangement of a plurality of pillars of the optical element according to the embodiment as a seventh modification example. Figure 14 1 is an explanatory diagram showing a modification example of the arrangement of a plurality of pillars of the optical element according to the embodiment as an eighth modification example. Figure 15 is a cross-sectional view showing a configuration example of an optical element according to a ninth modification of the present embodiment. Figure 16 is a cross-sectional view showing a configuration example of an optical element according to a tenth modification of the present embodiment. Figure 17 is a cross-sectional view showing a configuration example of an optical element according to an eleventh modification of the present embodiment. Figure 18 is a cross-sectional view showing a configuration example of an optical element according to a twelfth modification of the present embodiment. Figure 19 is a cross-sectional view showing, in an enlarged manner, a main portion of an optical element according to a thirteenth modification of the present embodiment. Figure 20 is a cross-sectional view showing, in an enlarged manner, a main portion of an optical element according to a fourteenth modification of the present embodiment. Figure 21 is a cross-sectional view showing, in an enlarged manner, a main portion of an optical element according to a fifteenth modification of the present embodiment. Figure 22 is a cross-sectional view showing an optical element serving as another configuration example of an optical element according to a fifteenth modification. Figure 23 is a cross-sectional view showing, in an enlarged manner, a main portion of an optical element according to a sixteenth modification of the embodiment. DETAILED DESCRIPTION

[0009] Hereinafter, embodiments for implementing the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the description will be given in the following order. 0. Comparative Example 1. Implementation Plan 1.1 Construction Example ( Figures 1 to 5 ) 1.2 Modification Figures 6 to 23 ) 1.3 Effect 2. Other implementation plans <0. Comparative Example> (Overview and Problems of Optical Components Based on Comparative Examples)

[0010] The material forming the metasurface is typically an inorganic material, and its central level of refractive index is between 2.5 and 3.5 (inclusive). Incidentally, resin materials can also be used to manufacture metasurfaces. However, the refractive index of resin materials is limited to approximately 1.5. Although efforts have been made to develop large-diameter lenses using resin-made metasurfaces, due to the limitations of the refractive index and the difficulty of resin micromachining, it is generally difficult to achieve the goal. In resin-made metasurfaces, the efficiency reduction in the peripheral part is particularly significant.

[0011] Furthermore, when multiple pillars of varying heights or diameters are randomly arranged without regularity to form a metasurface, the reproducibility of optical performance in simulations is low. For example, when adjacent pillars differ significantly in size, the reproducibility of optical performance is low. Furthermore, when multiple pillars of varying heights are randomly arranged, structural non-uniformity occurs from a manufacturing perspective, making it difficult to ensure manufacturing accuracy. <1. Implementation Plan> [1.1 Construction Example]

[0012] Figure 1 is a cross-sectional view schematically showing a configuration example of an optical element 1 according to an embodiment of the present invention. Figure 2 and Figure 3 Each of them is a plan view showing a structural example of the supersurface layer 10 of the optical element 1 according to the embodiment. Figure 1 Corresponding to along Figure 2 The cross section is taken along the line AA'.

[0013] The optical element 1 according to the present embodiment includes a supersurface layer 10 and a substrate 30 .

[0014] The substrate 30 holds the supersurface layer 10. The substrate 30 has a first surface S1 and a second surface S2 opposite to each other.

[0015] The metasurface layer 10 is formed on the first surface S1 of the substrate 30. The metasurface layer 10 includes a metasurface region having a plurality of columns 11. The metasurface region serves as a superlens. In the metasurface region of the metasurface layer 10, a plurality of columns 11 as microstructures are arranged two-dimensionally according to a certain rule to form a metasurface with a lens effect. The metasurface causes a phase delay (for example, 0 to 2π) of the incident light by two-dimensionally arranging a plurality of columns 11 (the columns 11 are microstructures smaller than the wavelength of light in the medium), thereby causing light deflection. It is desired that each of the plurality of columns 11 is formed to have a high aspect ratio with a height greater than a width. The metasurface region is formed as a convex shape as a whole on the first surface S1 of the substrate 30. As Figure 2 and Figure 3 As shown, the plurality of pillars 11 may be arranged in a ring shape.

[0016] In the metasurface layer 10, the metasurface region has a circular region 110 serving as a central region and a plurality of annular regions 111 serving as a plurality of annular regions. The circular region 110 contains a plurality of pillars 11 of constant height. The plurality of annular regions 111 are arranged around the circular region 110, and each annular region 111 contains a plurality of pillars 11.

[0017] Note that the circular area 110 may not be formed as a perfect circle, but may be a substantially circular area that is substantially formed as a circle. Furthermore, the annular areas 111 may not each be formed as a perfect ring, but may each be a substantially annular area that is substantially formed as a ring. Furthermore, the central area and the plurality of annular areas may each be formed as a polygon, for example.

[0018] The pillars 11 in each of the annular regions 111 have a constant height. The pillars 11 in the annular regions 111 are arranged to change height from the circular region 110 toward the outside according to a predetermined rule X.

[0019] In each of the circular area 110 and the plurality of annular areas 111, two or more pillars 11 having different diameters from each other may be provided as the plurality of pillars 11. Providing two or more pillars 11 having different diameters from each other as the plurality of pillars 11 in each of the circular area 110 and the plurality of annular areas 111 enables advantageous control of the phase delay amount (e.g., 0 to 2π).

[0020] Note that among the plurality of pillars 11, there may be pillars 11 that are not accommodated in the circular area 110 and the plurality of annular areas 111. Figure 3 As shown, for example, one or more pillars 11 may exist at one or more positions spanning a boundary 120 between a circular area 110 and an annular area 111 or / and a boundary 121 between any two adjacent annular areas 111 .

[0021] Figure 4 : is an explanatory diagram showing an example of a predetermined step mathematical function used as a predetermined rule X representing the heights of the plurality of pillars 11. Figure 4 , the vertical axis represents the height of each pillar 11, and the horizontal axis represents the outer diameter of the super surface area.

[0022] The predetermined rule X for expressing the heights of the plurality of pillars 11 may be given by Figure 4 The predetermined step mathematical function shown is represented. The height and arrangement of the plurality of pillars 11 can be determined based on the phase mathematical function that enables the metasurface region to act as a convex lens. Figure 4 As shown, the height h of each column in the plurality of columns 11 is k It can be composed of h1, h2, h3, ..., h N Indicates. Note here that the height h k It can be h1 > h2 > h3 >…, > h N In this case, for example, the height of the plurality of pillars 11 within the circular region 110 is represented by h1, and the height of the plurality of pillars 11 within one of the annular regions 111 adjacent to the circular region 110 is represented by h2. Therefore, the metasurface region can function as a focusing lens (convex lens).

[0023] Figure 5 The optical effects of the optical element 1 according to the embodiment are shown.

[0024] The optical element 1 is used as an optical lens. Figure 5 As shown in FIG. 1 , the incident light L1 incident on the optical element 1 is collected by the metasurface formed on the first surface S1. Therefore, the optical element 1 can be used as a focusing lens. Figure 5As shown, when the optical element 1 is used as a condenser lens for condensing incident light L1, optical performance with sufficient aberration correction can be achieved. In addition, a condenser lens with reduced height, cost, and weight can be realized.

[0025] Arranging multiple pillars 11 having heights varying in at least two levels in the metasurface region of the optical element 1 according to the embodiment enables a wider range of phase retardation, even when the metasurface is formed using a material having a low refractive index. Furthermore, arranging multiple pillars 11 having heights varying in multiple levels, for example, according to a predetermined rule X, enables improved reproducibility of optical performance in simulations and ensures manufacturing accuracy.

[0026] In the optical element 1 according to this embodiment, the arrangement of multiple pillars 11 with varying heights in multiple stages according to a predetermined rule X enables the establishment of design rules for the manufacturing side, thereby enabling repeated optimization routines on the design side to ensure design robustness. Furthermore, in the optical element 1 according to this embodiment, the reproducibility of optical performance in simulations can be ensured. The regular arrangement of multiple pillars 11 enables improved reproducibility of optical performance through simulations before and after the arrangement of the multiple pillars 11. Therefore, for example, library methods can be employed, achieving convergence in simulations of a metalens.

[0027] Furthermore, in the optical element 1 according to the embodiment, the regular arrangement of the plurality of pillars 11 ensures manufacturing accuracy. Even when using a material with a low refractive index, the aspect ratio of each pillar 11 can be suppressed, enabling the design of a structure that can be manufactured. Furthermore, since uniformity and regularity are achieved in the structure of the plurality of pillars 11, the processing trends of the metalens can be understood, enabling the establishment of design rules. [1.2 Modifications] (First Modification)

[0028] Figure 6 is a cross-sectional view showing a configuration example of an optical element 1A according to a first modification example of the embodiment.

[0029] The metasurface layer 10 and the substrate 30 may be made of the same material and may be formed integrally. Since the optical element 1A according to the first modification includes an integral structure in which the components serving as the optical lens are made of the same material, it is possible to reduce reflection and scattering that may occur at the interface between components made of different materials. Therefore, it is possible to improve transmittance as an optical performance.

[0030] Other configurations and other effects may be substantially similar to those of the optical element 1 according to the embodiment described above. (Second Modification)

[0031] Figure 7 1 is an explanatory diagram showing a second modification example of the optical element 1 according to the embodiment.

[0032] The planar shape of each of the plurality of pillars 11 may be a rotationally symmetrical shape. Figure 7 An example of a planar shape of each of the plurality of pillars 11 is shown. In the optical element 1 according to the embodiment, the planar shape of each of the plurality of pillars 11 may be a four-axis symmetrical shape or a two-axis symmetrical shape. Figure 7 As shown, the four-axis symmetrical shape can be a circle or a polygon such as a square. Figure 7 As shown, the biaxially symmetrical shape may be an ellipse or a polygon such as a rectangle. The planar shape of each of the plurality of pillars 11 may also be any freely selected rotationally symmetrical shape.

[0033] In the second modified example of the optical element 1 according to the embodiment, when the planar shape of each of the plurality of pillars 11 is a four-axis symmetrical shape, as an optical performance, the same phase delay can be provided to a plurality of incident light beams L1 having different polarization directions, regardless of the polarization direction. Furthermore, when the planar shape is a two-axis symmetrical shape, different phase delays can be provided depending on the polarization direction of the light.

[0034] Other configurations and other effects may be substantially similar to those of the optical element 1 according to the embodiment described above. (Third Modification)

[0035] Figure 8 is a cross-sectional view showing a configuration example of an optical element 1B according to a third modification example of the embodiment.

[0036] The super surface region of the super surface layer 10 may be formed as a whole in a concave shape on the first surface S1 of the substrate 30. Therefore, the plurality of pillars 11 may be formed in a concave shape relative to the outermost surface of the substrate 30. For example, Figure 8 As shown, when the supersurface layer 10 and the substrate 30 are integrally formed using the same material, a plurality of pillars 11 can be formed inside the substrate 30. When the supersurface layer 10 and the substrate 30 are formed using respective materials different from each other, the first surface S1 of the substrate 30 can be formed as a whole into a concave shape, and a plurality of pillars 11 can be formed on the first surface S1 having the concave shape.

[0037] As to whether the super surface region is formed as a convex shape or a concave shape on the first surface S1 of the substrate 30 as a whole, a shape that is easy to process can be selected according to the design or manufacturing method.

[0038] Other configurations and other effects may be substantially similar to those of the optical element 1 according to the embodiment described above. (Fourth Modification)

[0039] Figure 9 and Figure 10 They are plan views showing a modified example of the arrangement of the plurality of pillars 11 of the optical element 1 according to the embodiment as a fourth modified example.

[0040] like Figure 9 As shown in the example shown, the plurality of columns 11 may be arranged in a square lattice shape. Figure 10 As shown in the example shown, the plurality of pillars 11 may be arranged in a hexagonal lattice shape. Alternatively, the plurality of pillars 11 may be arranged in a polar coordinate arrangement (radial arrangement).

[0041] Other configurations and other effects may be substantially similar to those of the optical element 1 according to the embodiment described above. (Fifth Modification)

[0042] Figure 11 : is an explanatory diagram showing a modification of the arrangement of the plurality of pillars 11 of the optical element 1 according to the embodiment as a fifth modification. Figure 11 , the vertical axis represents the height of each pillar 11, and the horizontal axis represents the outer diameter of the super surface area.

[0043] The height and arrangement of the plurality of pillars 11 can be determined based on a phase mathematical function that enables the metasurface region to function as a convex lens. In the optical element 1 according to the embodiment, a plurality of pillar groups can be periodically arranged in the radial direction of the metasurface region, each pillar group including a plurality of pillars 11 having heights that vary according to a predetermined rule X. The plurality of pillar groups can be arranged in at least n periods (n ≥ 2).

[0044] The predetermined rule X may be a number used to represent the height h of each of the plurality of pillars 11. k (k = 1, 2, 3, ..., N) is represented by a predetermined step mathematical function. The number of the plurality of pillar groups including the plurality of pillars 11 represented by the predetermined step mathematical function may correspond to M periods (M ≥ 1). In each period, the height h of each of the plurality of pillars 11 is k It can be composed of h1, h2, h3, ..., h N Indicates. Note here that the height h k It can be h1 > h2 > h3 >…, > h N Therefore, the optical element 1 can be used as a condenser lens (convex lens).

[0045] Note that the arrangement of the plurality of pillars 11 may be started from any point in the predetermined step mathematical function. Furthermore, the arrangement of the plurality of pillars 11 may be ended from any point in the predetermined step mathematical function.

[0046] According to the fifth modification, the diameter of the superlens can be increased.

[0047] Other configurations and other effects may be substantially similar to those of the optical element 1 according to the embodiment described above. (Sixth Modification)

[0048] Figure 12 : is an explanatory diagram showing a modification of the arrangement of the plurality of pillars 11 of the optical element 1 according to the embodiment as a sixth modification. Figure 12 , the vertical axis represents the height of each pillar 11, and the horizontal axis represents the outer diameter of the super surface area.

[0049] With the arrangement of the plurality of pillars 11 according to the fifth modification described above, the period length may be gradually reduced from the first period to the Mth period. Therefore, the optical element 1 can be made to function as a condenser lens (convex lens).

[0050] For example, it is assumed that a plurality of pillar groups each including a plurality of pillars 11 whose heights vary according to a predetermined rule X are arranged for at least n periods (n ≥ 2). When the period length is gradually reduced from the first period to the Mth period and m < n is satisfied, the pillars in the mth period group each have a height h k The number of columns 11 (k = 1, 2, 3, ..., N) is equal to or greater than the number of columns 11 in the nth period, each having a height h k The number of columns is 11.

[0051] According to the sixth modification, the diameter of the superlens can be further increased.

[0052] Other configurations and other functions may be substantially similar to those of the fifth modification described above. (Seventh Modification)

[0053] Figure 13 : is an explanatory diagram showing a modification of the arrangement of the plurality of pillars 11 of the optical element 1 according to the present embodiment as a seventh modification. Figure 13 , the vertical axis represents the height of each pillar 11, and the horizontal axis represents the outer diameter of the super surface area.

[0054] The height and arrangement of the plurality of pillars 11 can be determined based on a phase mathematical function that causes the metasurface region to function as a concave lens. In the optical element 1 according to the embodiment, a plurality of pillar groups can be periodically arranged in the radial direction of the metasurface region, each pillar group including a plurality of pillars 11 whose heights vary according to a predetermined rule X. The plurality of pillar groups can be arranged in at least n periods (n ≥ 2).

[0055] The predetermined rule X may be a number used to represent the height h of each of the plurality of pillars 11. k(k = 1, 2, 3, ..., N) is represented by a predetermined step mathematical function. The number of the plurality of pillar groups including the plurality of pillars 11 represented by the predetermined step mathematical function may correspond to M periods (M ≥ 1). In each period, contrary to the cases in the fifth and sixth modified examples, the height h of each of the plurality of pillars 11 is k can be represented by h N ,…,h3,h2,h1. Note that the height h k It can be h1 > h2 > h3 > ..., > h N Therefore, the optical element 1 can be used as a diffusion lens (concave lens).

[0056] Note that the arrangement of the plurality of pillars 11 may be started from any point of the predetermined step mathematical function. Also, the arrangement of the plurality of pillars 11 may be ended from any point of the predetermined step mathematical function.

[0057] According to the seventh modification, the diameter of the superlens can be increased.

[0058] Other configurations and other effects may be substantially similar to those of the optical element 1 according to the embodiment described above. (Eighth Modification)

[0059] Figure 14 : is an explanatory diagram showing a modification example of the arrangement of the plurality of pillars 11 of the optical element 1 according to the present embodiment as an eighth modification example. Figure 14 In FIG, the vertical axis represents the height of each column 11, and the horizontal axis represents the outer diameter of the super surface area.

[0060] With the arrangement of the plurality of pillars 11 according to the seventh modification described above, the period length may be gradually reduced from the first period to the Mth period. Therefore, the optical element 1 can be made to function as a diffusion lens (concave lens).

[0061] For example, it is assumed that a column group including a plurality of columns 11 each having a height varying according to a predetermined rule X is arranged for at least n periods (n ≥ 2). When the period length is gradually reduced from the first period to the Mth period and m < n is satisfied, the columns in the mth period group each have a height h k The number of columns 11 (k = 1, 2, 3, ..., n) is equal to or greater than the number of columns in the nth period, each having a height h k The number of columns is 11.

[0062] According to the eighth modification, the diameter of the superlens can be further increased.

[0063] Other structures and other functions may be roughly similar to those of the seventh modification example described above. (Ninth Modification)

[0064] Figure 15 is a cross-sectional view showing a configuration example of an optical element 1C according to a ninth modification of the embodiment.

[0065] An anti-reflection film 22 may be formed on the second surface S2 of the substrate 30. In the optical element 1C according to the ninth modification, the anti-reflection film 22 suppresses reflection of light on the second surface S2, thereby improving transmittance as an optical performance. (Tenth Modification)

[0066] Figure 16 is a cross-sectional view showing a configuration example of an optical element 1D according to a tenth modification of the embodiment.

[0067] like Figure 16 As shown, a low refractive index layer 40 may be stacked on the metasurface layer 10. The low refractive index layer 40 comprises a material having a refractive index lower than that of the material of the plurality of pillars 11 and the material of the substrate 30. The low refractive index layer 40 may be stacked on the first surface S1 side of the substrate 30 such that the low refractive index layer 40 fills between the plurality of pillars 11 and the entire metasurface layer 10 becomes flat.

[0068] The optical element 1D according to the tenth modification can improve the mechanical strength of the supersurface layer 10. Furthermore, as shown in the eleventh and twelfth modifications to be described later, other optical function layers can be further stacked on the low refractive index layer 40.

[0069] Other configurations and other effects may be substantially similar to those of the optical element 1 according to the embodiment described above. (Eleventh Modification)

[0070] Figure 17 is a cross-sectional view showing a configuration example of an optical element 1E according to an eleventh modification of the embodiment.

[0071] In the optical element 1E according to the eleventh modification, relative to Figure 16 In the illustrated configuration example, another supersurface layer 10A is further stacked as another optical function layer on the low refractive index layer 40. Therefore, in the optical element 1E according to the eleventh modification, it is possible to further provide an optical function by the other supersurface layer 10A.

[0072] Other structures and other functions may be roughly similar to those of the tenth modification described above. (Twelfth Modification)

[0073] Figure 18 is a cross-sectional view showing a configuration example of an optical element 1F according to a twelfth modification of the embodiment.

[0074] In the optical element 1F according to the twelfth modification, with respect to Figure 16 In the illustrated configuration example, the lens layer 60 is further stacked as another optical function layer on the low refractive index layer 40. Therefore, in the optical element 1F according to the twelfth modification, it is possible to further provide an optical function by the lens layer 60.

[0075] Other structures and other functions may be roughly similar to those of the tenth modification described above. (Thirteenth Modification)

[0076] Figure 19 is a cross-sectional view showing, in an enlarged manner, a main portion of an optical element 1G according to a thirteenth modification of the embodiment.

[0077] like Figure 19 As shown, in the supersurface layer 10, the diameter (width) of each of the plurality of pillars 11 may vary depending on the position in the height direction of the pillar 11. For example, a shape may be employed in which the diameter (width) d1 on the lower side of the pillar 11 is smaller than the diameter (width) d2 on the upper side (a shape in which the pillar becomes thicker toward the upper side).

[0078] Other configurations and other effects may be substantially similar to those of the optical element 1 according to the embodiment described above. (Fourteenth Modification)

[0079] Figure 20 is a cross-sectional view showing, in an enlarged manner, a main portion of an optical element 1H according to a fourteenth modification of the embodiment.

[0080] Among the plurality of columns 11, the columns 11 are arranged across the boundary 120 between the circular region 110 and the annular region 111 or the boundary 121 between two adjacent annular regions 111 (see Figure 3 ) may have a stepped cross-sectional shape. Therefore, it is possible to suppress a sharp change in the refractive index at the boundary 120 or 121 in each region.

[0081] Other configurations and other effects may be substantially similar to those of the optical element 1 according to the embodiment described above. (Fifteenth Modification)

[0082] Figure 21 is a cross-sectional view showing, in an enlarged manner, a main portion of an optical element 1I according to a fifteenth modification of the embodiment. Figure 22 : is a cross-sectional view showing an optical element 1J serving as another configuration example of the optical element 1I according to the fifteenth modification.

[0083] The upper surface of each of the plurality of pillars 11 on the supersurface layer 10 may be convex or concave. Figure 21 In the optical element 1I shown, the upper surface of each of the plurality of pillars 11 is convex. Figure 22 In the optical element 1J shown, the upper surface of each of the plurality of pillars 11 is concave. Therefore, since the refractive index gradually changes near the upper surface of each of the plurality of pillars 11, reflection is reduced, thereby improving transmittance.

[0084] Other configurations and other effects may be substantially similar to those of the optical element 1 according to the embodiment described above. (Sixteenth Modification)

[0085] Figure 23 is a cross-sectional view showing, in an enlarged manner, a main portion of an optical element 1K according to a sixteenth modification of the embodiment.

[0086] At least one of the surface of the metasurface layer 10 or the surface (first surface S1) of the substrate 30 may have roughness (microscopic irregularities). Note that the surface of the metasurface layer 10 includes, for example, the side surfaces of each of the plurality of pillars 11. Therefore, in the optical element 1K according to the sixteenth modification, it is possible to suppress reflection of light on the surface of the metasurface layer 10 or the surface of the substrate 30.

[0087] Other configurations and other effects may be substantially similar to those of the optical element 1 according to the embodiment described above. [1.3 Effect]

[0088] With the optical element 1 according to the embodiment, as described above, the heights of the plurality of pillars within the plurality of annular regions (annular regions 111) change from the central region (circular region 110) toward the outside, in accordance with a predetermined rule X, for each annular region. Therefore, it is possible to provide an optical element having a large diameter and high optical performance.

[0089] When a plurality of pillars 11 having heights or diameters different from each other are randomly arranged without a regular pattern, it is difficult to ensure manufacturing accuracy, and the reproducibility of the optical performance through simulation is low. In contrast, with the optical element 1 according to the embodiment, for example, the pillars 11 having multi-level variations in height are arranged according to a predetermined rule X, so that the reproducibility of the optical performance through simulation can be improved and manufacturing accuracy can be ensured. With the optical element 1 according to the embodiment, it is possible to achieve reproducibility of the optical performance through simulation (which is difficult to achieve by an appropriate simple combination of a plurality of pillars 11 having various types of heights and a library method), thereby enabling the design space to fall within an achievable size. With the optical element 1 according to the embodiment, the ensured reproducibility of the optical performance through simulation, manufacturing accuracy, and design robustness enable the design of a metalens that can be actually manufactured.

[0090] Furthermore, even when a material having a low refractive index is used in the optical element 1 according to the embodiment, the aspect ratio of each pillar 11 can be suppressed, thereby enabling the design of a structure that can be manufactured. Furthermore, since uniformity and regularity are achieved in the structure of the plurality of pillars 11, the processing trend of the metalens can be understood, enabling the establishment of design rules.

[0091] Furthermore, when the optical element 1 according to the present embodiment is used as a module lens having multiple optical functions, it is possible to achieve lower height, lighter weight, and lower costs.

[0092] Note that the effects described in this specification are merely examples. The effects of this technology are not limited to those described in this specification and may be any other effects. The same applies to the effects of other embodiments described below. <2. Other Implementation Options>

[0093] The technology according to the present invention is not limited to the above-mentioned embodiments, and can be modified and implemented in various ways.

[0094] For example, the present technology can have the following configurations. According to the present technology having the following configuration, the heights of the plurality of pillars in the plurality of annular regions change from the central region toward the outside according to a predetermined rule in units of annular regions. (1) An optical element, comprising: a substrate having a first side and a second side opposite to each other; and A supersurface layer is stacked on the first surface of the substrate, wherein the supersurface layer includes a supersurface region having a plurality of pillars, The metasurface region comprises: a central region comprising multiple columns of constant height, and a plurality of annular regions disposed around the central region, each of the annular regions comprising a plurality of pillars, and The heights of the plurality of pillars are constant in each of the plurality of annular areas, and the plurality of pillars in the plurality of annular areas are arranged to change in height in units of the annular areas according to a predetermined rule from the central area toward the outside. (2) The optical element according to the above (1), wherein a plurality of pillar groups are periodically arranged in the radial direction of the metasurface region, and each of the plurality of pillar groups includes the plurality of pillars whose heights vary according to the predetermined rule. (3) The optical element according to (2) above, wherein the plurality of column groups are arranged in at least n periods (n ≥ 2), and when m < n is satisfied, the number of columns having heights hk (k = 1, 2, 3,..., N) respectively in the column group of the m-th period is equal to or greater than the number of columns having the height hk respectively in the column group of the n-th period. (4) The optical element according to any one of (1) to (3) above, wherein the predetermined rule is represented by a predetermined stepped mathematical function. (5) The optical element according to any one of (1) to (4) above, wherein the heights and arrangements of the plurality of columns are determined based on a phase mathematical function such that the metasurface region functions as a convex lens or a concave lens. (6) The optical element according to any one of (1) to (5) above, wherein the central region is a substantially circular region, and each of the annular regions is a substantially annular region. (7) The optical element according to any one of (1) to (6) above, wherein each of the central region and the plurality of annular regions includes two or more columns having different diameters as the plurality of columns. (8) The optical element according to any one of (1) to (7) above, wherein the metasurface layer and the substrate are made of the same material. (9) The optical element according to any one of (1) to (8) above, wherein in each of the central region and the plurality of annular regions, the plurality of columns are arranged in a circular ring shape, a square lattice shape, or a hexagonal lattice shape. (10) The optical element according to any one of (1) to (9) above, wherein the planar shape of each of the plurality of columns is a rotationally symmetric shape. (11) The optical element according to any one of (1) to (10) above, wherein the metasurface region is integrally formed as a convex shape or integrally formed as a concave shape on the first surface of the substrate. (12) The optical element according to any one of (1) to (11) above, wherein an antireflection film is provided on the second surface of the substrate. (13) The optical element according to any one of (1) to (12) above further includes a low-refractive-index layer stacked on the metasurface layer, wherein the low-refractive-index layer includes a material having a lower refractive index than both the material of the plurality of pillars and the material of the substrate. (14) The optical element according to the above (13) further includes another supersurface layer different from the supersurface layer, wherein the other supersurface layer is stacked on the low refractive index layer. (15) The optical element according to the above (13) further includes a lens layer stacked on the low refractive index layer. (16) The optical element according to any one of (1) to (15) above, wherein the diameter of each of the plurality of pillars varies depending on the position in the height direction. (17) The optical element according to any one of (1) to (16) above, wherein the cross-sectional shape of at least one of the plurality of columns arranged at a position straddling the boundary between the central area and the annular area or the boundary between two adjacent annular areas is a step shape. (18) The optical element according to any one of (1) to (17) above, wherein the upper surface of each of the plurality of pillars has a convex shape or a concave shape. (19) The optical element according to any one of (1) to (18) above, wherein at least one of the surface of the supersurface layer and the first surface of the substrate has roughness. (20) The optical element according to any one of (1) to (19) above, which functions as a condenser lens or a diffuser lens for incident light.

[0095] This application claims priority to U.S. patent application No. 63 / 449,188, filed in the U.S. Patent and Trademark Office on March 1, 2023, the entire contents of which are incorporated herein by reference.

[0096] It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made according to design requirements and other factors as long as they are within the scope of the appended claims or the equivalents thereof.

Claims

1. An optical element comprising: a substrate having a first side and a second side opposite to each other; and A supersurface layer is stacked on the first surface of the substrate, wherein the supersurface layer includes a supersurface region having a plurality of pillars, The metasurface region comprises: a central region comprising multiple columns of constant height, and a plurality of annular regions disposed around the central region, each of the annular regions comprising a plurality of pillars, and The heights of the plurality of pillars are constant in each of the plurality of annular areas, and the plurality of pillars in the plurality of annular areas are arranged to change in height in units of the annular areas according to a predetermined rule from the central area toward the outside.

2. The optical element according to claim 1, wherein a plurality of pillar groups are periodically arranged in a radial direction of the metasurface region, and the plurality of pillar groups respectively include the plurality of pillars whose heights vary according to the predetermined rule.

3. The optical element according to claim 2, wherein The plurality of column groups are arranged with at least n periods (n ≥ 2), and When m < n, the number of columns in the column group of the m-th cycle having heights h k (k = 1, 2, 3,..., N) is equal to or greater than the number of columns in the column group of the n-th cycle having the height h k respectively. The optical element according to claim 1 , wherein the predetermined rule is represented by a predetermined step mathematical function.

5. The optical element according to claim 1, wherein The height and arrangement of the plurality of pillars are determined based on a phase mathematical function that causes the metasurface region to function as a convex lens or a concave lens. The optical element according to claim 1 , wherein the central region is a substantially circular region, and each of the annular regions is a substantially toroidal region.

7. The optical element according to claim 1, wherein The central region and each of the plurality of annular regions include two or more pillars having diameters different from each other as the plurality of pillars.

8. The optical element according to claim 1, wherein the metasurface layer and the substrate are composed of the same material as each other.

9. The optical element according to claim 1, wherein In each of the central region and the plurality of annular regions, the plurality of pillars are arranged in a circular ring shape, a square lattice shape, or a hexagonal lattice shape. 10 . The optical element according to claim 1 , wherein a planar shape of each of the plurality of pillars is a rotationally symmetric shape. 11 . The optical element according to claim 1 , wherein the metasurface region is formed in a convex shape as a whole or in a concave shape as a whole on the first face of the substrate. 12 . The optical element according to claim 1 , wherein an anti-reflection film is provided on the second surface of the substrate.

13. The optical element according to claim 1, further comprising a low-refractive-index layer stacked on the metasurface layer, the low-refractive-index layer comprising a material having a refractive index lower than both a material of the plurality of pillars and a material of the substrate. 14 . The optical element according to claim 13 , further comprising another metasurface layer different from the metasurface layer, the another metasurface layer being stacked on the low refractive index layer. 15 . The optical element according to claim 13 , further comprising a lens layer stacked on the low refractive index layer.

16. The optical element according to claim 1, wherein The diameter of each of the plurality of pillars varies depending on the position in the height direction.

17. The optical element according to claim 1, wherein A cross-sectional shape of at least one pillar among the plurality of pillars provided at a position straddling a boundary between the central region and the annular region or a boundary between two adjacent annular regions is a step shape.

18. The optical element according to claim 1, wherein An upper surface of each of the plurality of pillars has a convex shape or a concave shape.

19. The optical element according to claim 1, wherein at least one of a surface of the metasurface layer and the first surface of the substrate has roughness. 20 . The optical element according to claim 1 , used as a condenser lens or a diffuser lens for incident light.

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