Meta-optical element and electronic device including the same

Abstract

To provide a meta optical element and an electronic apparatus including the same.SOLUTION: A meta optical element includes a first layer including a plurality of first nanostructures and a first peripheral substance disposed adjacent to the first nanostructures, and a second layer disposed on the first layer and including a plurality of second nanostructures and a second peripheral substance disposed adjacent to the second nanostructures. The first layer and the second layer include regions where the symbols of the effective refractive index change rate in a predetermined first direction are opposite, and are configured to exhibit a predetermined target phase delay profile with respect to incident light with a predetermined wavelength band. The meta optical element can implement the phase delay profile hardly having discontinuity by adjusting the refractive index change and the distribution change of each layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a metasurface optical element and an electronic device including the same.

Background Art

[0002] Flat diffractive elements utilizing a meta-structure can exhibit various optical effects that cannot be achieved by existing refractive elements, can realize a thin optical system, and are attracting increasing attention in many fields.

[0003] The meta-structure has a nanostructure to which a numerical value smaller than the wavelength of incident light is applied in terms of shape, period, etc. In order to realize desired optical performance, for light in a desired wavelength band, the nanostructure is designed so that a phase delay profile set for each position is satisfied. When discontinuity is shown in such a phase delay profile, light diffraction occurs in an unintended direction, resulting in low optical efficiency.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a metasurface optical element that acts over a wide band and exhibits high efficiency.

[0005] The problem to be solved by the present invention is also to provide an electronic device utilizing the metasurface optical element.

Means for Solving the Problems

[0006] According to one type, a first layer including a plurality of first nanostructures and a first peripheral material arranged adjacent to them; and a second layer arranged on the first layer, including a plurality of second nanostructures and a second peripheral material arranged adjacent to them; are included. The first layer and the second layer include a region where the signs of the effective refractive index change rates in a predetermined first direction are opposite to each other, and a meta-optical element configured to exhibit a predetermined target phase delay profile for incident light in a predetermined wavelength band is provided.

[0007] The first layer and the second layer may also have different ratios of the dispersion change rate to the effective refractive index change rate in the first direction.

[0008] The target phase delay profile also has a dispersion of 0 with respect to the wavelength in the predetermined wavelength band.

[0009] The phase delay profile shown by the first layer and the target phase delay profile also have the same sign of the change rate in the first direction.

[0010] The ratio of the dispersion change rate to the effective refractive index change rate in the first direction of the second layer is larger than the ratio of the dispersion change rate to the effective refractive index change rate in the first direction of the first layer.

[0011] The material included in the second layer has a larger dispersion than the material included in the first layer.

[0012] The phase delay profiles shown by the first layer and the second layer also have opposite signs of the change rates corresponding to the position change in the first direction.

[0013] The target phase delay profile is also a continuous function for a predetermined position of the meta-optical element in the predetermined wavelength band.

[0014] The first nanostructures and the second nanostructures can have a columnar shape.

[0015] The ratio of the height to the width of the first nanostructure and the second nanostructure is greater than 2.

[0016] The height of the first nanostructure and the second nanostructure is greater than the central wavelength of the predetermined wavelength band.

[0017] The first nanostructure can have a refractive index higher than that of the first surrounding material, and the second nanostructure can have a refractive index higher than that of the second surrounding material.

[0018] The tendency of the change in width of the first nanostructure and the second nanostructure along one direction away from the center of the meta-optical element is also opposite to each other.

[0019] The first nanostructure can have a refractive index lower than that of the first surrounding material, and the second nanostructure can have a refractive index higher than that of the second surrounding material.

[0020] The tendency of the change in width of the first nanostructure and the second nanostructure along one direction away from the center of the meta-optical element is also the same as each other.

[0021] The first nanostructure can have a shape including an inner pillar and a shell pillar surrounding the inner pillar.

[0022] The refractive index of the inner pillar is lower than that of the shell pillar.

[0023] The refractive index of the shell pillar is higher than that of the first surrounding material.

[0024] The second nanostructure also has a refractive index higher than that of the second surrounding material.

[0025] The tendency of the change in width of the first nanostructure and the second nanostructure along one direction away from the center of the meta-optical element is also opposite to each other.

[0026] The second nanostructure also has a refractive index lower than that of the second surrounding material.

[0027] The first nanostructure and the second nanostructure also have the same tendency of width change along one direction away from the center of the meta-optical element.

[0028] The first nanostructure can have a hole shape encapsulated by the first surrounding material.

[0029] The second nanostructure also has a refractive index higher than that of the second surrounding material.

[0030] The hole of the first nanostructure and the second nanostructure also have the same tendency of width change along one direction away from the center of the meta-optical element.

[0031] The second nanostructure also has a refractive index lower than that of the second surrounding material.

[0032] The hole of the first nanostructure and the second nanostructure also have opposite tendencies of width change along one direction away from the center of the meta-optical element.

[0033] The meta-optical element further includes a substrate that supports the first layer and the second layer.

[0034] The meta-optical element may further include a spacer layer provided between the first layer and the second layer.

[0035] For light of a predetermined wavelength in the predetermined wavelength band, the target phase delay profile has a dispersion smaller than 0.

[0036] For light of a predetermined wavelength in the predetermined wavelength band, the target phase delay profile has a dispersion larger than 0.

[0037] The meta-optical element is also a lens.

[0038] The meta-optical element is also a beam deflector.

[0039] The meta-optical element is also a beam shaper.

[0040] The predetermined wavelength band also ranges from a wavelength of 400 nm to 700 m.

[0041] The ratio of the length of the region in the first direction to the overall length of the meta-optical element in the first direction is also 80% or more.

[0042] The diffraction efficiency related to the light in the predetermined wavelength band is also 0.8 or more.

[0043] According to one type, an imaging lens assembly including one or more refractive lenses and any one of the aforementioned meta-optical elements; and an image sensor that converts an optical image formed by the imaging lens assembly into an electrical signal; are provided.

[0044] According to one type, an electronic device including a light source; any one of the aforementioned meta-optical elements that modulates light from the light source and transmits it to an object; and a light detection unit that senses light from the object; is provided.

[0045] According to one type, in a meta-optical element, a first layer including a plurality of first nanostructures and a first peripheral material arranged adjacent to them; and a second layer arranged on the first layer and including a plurality of second nanostructures and a second peripheral material arranged adjacent to them; are included, and the first layer and the second layer include a region where the signs of the effective refractive index change rates in a predetermined first direction are opposite to each other, and the tendency of the change in the width of the plurality of first nanostructures and the tendency of the change in the width of the plurality of second nanostructures are the same as each other or opposite to each other along the direction away from the center of the meta-optical element, and a meta-optical element is provided.

Advantages of the Invention

[0046] The meta-optical element of the present invention utilizes nanostructures arranged in a multi-layer structure, adjusts the refractive index change and dispersion change of each layer, and can realize a phase delay profile with almost no discontinuity.

[0047] The meta-optical element of the present invention can exhibit high diffraction efficiency for light in a wide wavelength band.

[0048] The meta-optical element of the present invention is also utilized in lenses, beam deflectors, beam shapers, etc., and is also adopted in various electronic devices that utilize them.

Brief Description of the Drawings

[0049]

Figure 1

Figure 2

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Figure 7A

Figure 7B

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Figure 9

Figure 10A

Figure 10B

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Figure 16

Figure 17

Figure 18

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Figure 23

Best Mode for Carrying Out the Invention

[0050] Hereinafter, with reference to the accompanying drawings, this embodiment will be described in detail. The described embodiments are merely exemplary, and various modifications are possible from such embodiments. In the following drawings, the same reference numerals indicate the same components, and on the drawings, the sizes of the respective components are exaggerated for clarity and convenience of explanation.

[0051] Hereinafter, where it is described as "upper part" or "above", it may include not only what is in direct contact and directly above, but also what is above without contact.

[0052] Terms such as first and second can be used to describe various components, but are used only for the purpose of distinguishing one component from another. Such terms do not limit that the substances or structures of the components are different.

[0053] Singular expressions include plural expressions unless the context clearly indicates otherwise. Also, when a part "includes" a certain component, it means that, unless there is a special contrary description, it does not exclude other components and may further include other components.

[0054] Also, terms such as "… part" and "module" described in the specification mean a unit that processes at least one function or operation, and it can be implemented by hardware or software, or also by a combination of hardware and software.

[0055] The use of the term "the foregoing" and similar directive terms applies to both singular and plural.

[0056] The steps constituting the method may be performed in any suitable order unless expressly stated to be performed in the order described. In addition, the use of all exemplary terms (such as, for example, etc.) is merely for the purpose of explaining the technical idea in detail, and such terms are not intended to limit the scope of the claims, except as otherwise limited by the claims.

[0057] Fig. 1 is a conceptual diagram showing the schematic configuration and function of a meta-optical element according to an embodiment, and Fig. 2 is a plan view showing the schematic configuration of multiple layers constituting the meta-optical element according to an embodiment.

[0058] The meta-optic element 100 is a diffractive element utilizing nanostructures having sub-wavelength geometries and is detailed to exhibit a predetermined target phase retardation profile for incident light of a predetermined wavelength band, where the sub-wavelength is the central wavelength λ of the predetermined wavelength band. 0 It means a smaller number.

[0059] After passing through the meta-optical element 100, the incident light L is modulated in phase for each position of the meta-optical element 100. m When light enters the meta-optical element 100 and passes through it, the light encounters a refractive index distribution due to the arrangement of multiple nanostructures NS1 and NS2, which have a refractive index different from that of the surrounding materials. The shape of a wavefront connecting points with the same phase in the path of light is different before and after passing through the refractive index distribution due to the arrangement of nanostructures NS1 and NS2, which is expressed as phase delay. The degree of the phase delay differs depending on each position, which is a variable of the refractive index distribution. The degree of the phase delay differs depending on the x and y coordinates on a plane perpendicular to the traveling direction of the light (Z direction) at a position immediately after the incident light L, which is incident in the Z direction, passes through the meta-optical element 100. In this way, the phase of the light after passing through the meta-optical element 100 is different from the phase at the time of incidence. Modulated light L m The target phase delay profile φ is given by tindicates the relative phase with respect to the phase of the incident light L. The target phase delay profile φ t indicates the phase delay corresponding to each position after passing through the metasurface optical element 100. Such a phase delay also depends on the wavelength λ of the incident light. The target phase delay profile φ t is thus a function φ t of position and wavelength, expressed as φ(r,λ).

[0060] The target phase delay profile φ t defines the optical performance of the metasurface optical element 100, for example, its function as a lens, mirror, beam deflector, or beam shaper, etc.

[0061] The metasurface optical element 100 includes a first layer 120 and a second layer 160. The first layer 120 has a structure based on the first nanostructure NS1 and serves as a phase delay layer. The second layer 160 has a structure based on the second nanostructure NS2 and serves as a dispersion control layer.

[0062] The first layer 120 serving as the phase delay layer and the second layer 160 serving as the dispersion control layer also have opposite signs of the effective refractive index change rate depending on their positions. For example, when the material and shape of the first nanostructure NS1 are set such that the effective refractive index gradually increases along a predetermined first direction in the first layer 120, the material and shape of the second nanostructure NS2 in the second layer NS2 can be set such that the effective refractive index gradually decreases along the first direction.

[0063] Such a multi-layer structure realizes the target phase delay profile φ t desired by the metasurface optical element 100, but it is for minimizing the phase discontinuity due to the position of the target phase delay profile φ t and enhancing the optical efficiency.

[0064] In general optical materials, in the visible light wavelength band, the dispersion has a negative value, and as the refractive index increases, the size of the dispersion also tends to increase. Therefore, in a structure that patterns one type of substance, it is difficult to implement a phase delay profile without discontinuity. For example, the phase delay profile by the first layer 120 and the phase delay profile by the second layer 160 may have discontinuities. The phase discontinuity may be mainly shown at the boundaries of the plurality of regions (2π zone) R 1 ,…,R k ,…,R N illustrated in FIG. 2. However, the meta-optical element 100 according to one embodiment subdivides the functions of the first layer 120 and the second layer 160 from the viewpoints of adjusting the refractive index change and the dispersion change, and for the unit components UE combined with various materials and shapes, derives an optimized structure for each position. In the configuration where the first layer 120 and the second layer 160 are combined, a phase delay profile with almost no discontinuity can be shown.

[0065] The meta-optical element 100 according to one embodiment includes a layer showing a phase delay profile having the same tendency as the target phase delay profile φ t and a layer showing a phase delay profile opposite thereto. In other words, the first layer 120 and the second layer 160 can show different phase delay profiles from each other. The first layer 120 that plays the role of the phase delay layer can have the shape and arrangement of the first nanostructure NS1 set so as to show a phase delay profile having a tendency like the target phase delay profile φ t . The second layer 160 that plays the role of the dispersion adjustment layer shows a phase delay profile having a tendency different from the target phase delay profile φ t , but the shape and arrangement of the second nanostructure NS2 can be set so that the main function is to adjust the refractive index dispersion according to the wavelength.

[0066] Here, the phase delay profile of the first layer 120 means the relative phase distribution with respect to the phase when light is incident on the first nanostructure NS1 at the position immediately after passing through the nanostructure NS1 of the first layer 120. And the phase delay profile of the second layer 160 means the relative phase distribution with respect to the phase when light is incident on the second nanostructure NS2 at the position immediately after passing through the nanostructure NS2 of the second layer 160.

[0067] The positions of the first layer 120 and the second layer 160 may change with respect to each other. In FIG. 1, it is illustrated as an arrangement in which the incident light L is incident on the second layer 160 after passing through the first layer 120, but this is exemplary and not limited thereto. In relation to the incident light L, the order of the first layer 120 and the second layer 160 may be interchanged. This is the same in all the following embodiments. Also, for convenience of explanation, it is described that the first layer 120 functions as a phase delay layer and the second layer 160 functions as a dispersion control layer, but the various embodiments described later are exemplary structures having such two layers, and the functions are not limited by the names.

[0068] The shapes of the first nanostructures NS1 and the second nanostructures NS2 provided in each layer are also determined by a function of the positions of the plurality of first nanostructures NS1 and second nanostructures NS2 respectively. For example, the first nanostructure NS1 provided in the first layer 120 is also determined by a function of the coordinates (x, y) on the surface S1 where the first nanostructure NS1 is placed. Such coordinates (x, y) are also determined by a function of the distance from the point where the surface S1 meets the central axis C of the meta-optical element 100 and the angle θ between the radius vector at that position and the x-axis. The second nanostructure NS2 provided in the second layer 160 is also determined by a function of the coordinates (x, y) on the surface S2 where the second nanostructure NS2 is placed. Such coordinates (x, y) are also determined by a function of the line from the point where the surface S2 meets the central axis C of the meta-optical element 100 and the angle θ between the radius vector at that position and the x-axis. The first nanostructure NS1 provided in the first layer 120 and the second nanostructure NS2 provided in the second layer 160 are also determined by a polar symmetric function that depends only on the distance from their respective centers.

[0069] In one embodiment, the shapes and distributions of the first nanostructures NS1 and the second nanostructures NS2 are also set such that the aforementioned effective refractive index change and phase delay profile are realized along the radial direction away from the center defined on the surfaces S1 and S2 on which they are respectively placed.

[0070] The shapes of the first nanostructures NS1 and the second nanostructures NS2 follow a predetermined rule, and the first layer 120 and the second layer 160 forming the meta-optical element 100 are also divided by this predetermined rule. The regions of the first layer 120 and the second layer 160 are divided into a central circular shape and a plurality of annular regions R 1 ,…,R k ,…,R N , as exemplified in FIG. 2. In each layer, the nanostructures NS1 and NS2 within the same region are also arranged according to the same rule.

[0071] Said regions R 1 ,…,R k ,…,RN is a region showing a phase delay within a predetermined range, and the phase modulation range of the second region R 2 to the Nth region R N may be the same. The phase modulation range may be 2π radians. The phase modulation range of the first region R 1 may be 2π radians, or may be smaller than that. However, the first region R1 to the Nth region R N are generally all also called 2π zones.

[0072] The function of each region, the number N or width W of the regions 1 ,…,W k ,…,W N also become major variables in the performance of the meta-optical element 100.

[0073] In order for the meta-optical element 100 to function as a lens, the rules within the region are set such that the width of each region is not constant and the direction in which the incident light is diffracted in each region is slightly different. The number N of the regions is related to the magnitude (absolute value) of the refractive power, and the sign of the refractive power can be determined according to the rules within each region. For example, in each region, a positive refractive power can be realized by a regular arrangement in which the sizes of the nanostructures NS1, NS2 decrease along the radial direction, and a negative refractive power can be realized by a regular arrangement in which the sizes of the nanostructures NS1, NS2 increase along the radial direction.

[0074] In order for the meta-optical element 100 to function as a beam deflector, the widths W 1 ,…,R k ,…,R N of each region R 1 ,…,W k ,…,W N are constant, and the rules within the region can be set such that the incident light L is diffracted in a predetermined fixed direction in each region.

[0075] In addition to lenses and beam deflectors, the meta-optical element 100 can also function as a beam shaper having an arbitrary position-dependent distribution. In order for the above-described functions to be efficiently exhibited within a desired wavelength band through the meta-optical element 100, discontinuities due to position should not be shown as much as possible in the target phase delay profile related to the above-described functions. When the target phase delay profile has phase discontinuity, a part of the light passing through the meta-optical element 100 diffracts in other directions instead of the desired diffraction direction, thereby reducing the diffraction efficiency. The diffraction efficiency is also expressed by the ratio of the energy of the light diffracted in the intended direction among the light transmitted through the meta-optical element 100. The meta-optical element 100 of one embodiment has a diffraction efficiency of 0.8 or more in a desired wavelength band, for example, in a broadband of 400 nm to 700 nm, and the shapes, arrangements, and materials of the first nanostructures NS1 and the second nanostructures NS2 of the first layer 120 and the second layer 160 can be set so that the diffraction efficiency becomes 0.8 or more.

[0076] The first nanostructures NS1 and the second nanostructures NS2 may include a material having a refractive index difference from the surrounding material. For example, it can have a high refractive index with a difference of 0.5 or more from the refractive index of the surrounding material, or a low refractive index with a difference of 0.5 or less from the refractive index of the surrounding material. One of the first nanostructures NS1 and the second nanostructures NS2 can have a refractive index higher than that of the surrounding material, and the other can have a refractive index lower than that of the surrounding material.

[0077] When the first nanostructures NS1 or the second nanostructures NS2 contain a material with a higher refractive index than the surrounding material, the first nanostructures NS1 or the second nanostructures NS2 may include at least one of c-Si, p-Si, a-Si III-V compound semiconductors (such as GaAs, GaP, GaN, GaAs, etc.), SiC, TiO 2 , SiN, or a combination thereof, and the low refractive index surrounding material may include a polymer material such as SU-8·PMMA, SiO 2 , or SOG.

[0078] When the first nanostructure NS1 or the second nanostructure NS2 contains a material with a refractive index lower than that of the surrounding material, the first nanostructure NS1 or the second nanostructure NS2 may contain SiO 2 or air, and the high refractive index surrounding material may contain at least one of c-Si, p-Si, a-Si III-V compound semiconductors (such as GaAs, GaP, GaN, GaAs, etc.), SiC, TiO 2 , SiN, or a combination thereof.

[0079] Figure 3 is a graph exemplarily showing the wavelength-dependent and position-dependent effective refractive index and dispersion of the phase delay layer provided in the meta-optical element of Figure 1, and Figure 4 is a graph exemplarily showing the wavelength-dependent and position-dependent effective refractive index and dispersion of the dispersion control layer provided in the meta-optical element of Figure 1.

[0080] The effective refractive index is a concept assuming that the unit component of the meta-optical element 100 can be regarded as a homogeneous medium. When the unit component contains media having different refractive indices from each other, the concept of the effective refractive index may include the distribution of media having different refractive indices from each other.

[0081] The refractive index dispersion means the degree (∂n / ∂λ) shown such that the refractive index varies with wavelength, and in a structure containing media having different refractive indices from each other, it means the dispersion of the effective refractive index. Hereinafter, it is also simply referred to as dispersion.

[0082] Referring to both Figure 3 and Figure 4, the phase delay layer and the dispersion control layer have opposite tendencies in the change of the effective refractive index in a predetermined first direction. In the graph, the tendency of the change of the effective refractive index is shown along the radial direction r. The phase delay layer may show an effective refractive index change with the same tendency as the target phase delay profile depending on the position.

[0083] Due to such a tendency of the change in the effective refractive index, the sign of the rate of change of the phase delay profile exhibited by the phase delay layer is the same as that of the target phase delay profile depending on the position, and the sign of the rate of change of the phase delay profile exhibited by the dispersion adjustment layer is opposite to that of the target phase delay profile depending on the position. In other words, the sign of the rate of change of the phase delay profile exhibited by the phase delay layer and the sign of the rate of change of the phase delay profile exhibited by the dispersion adjustment layer may be opposite to each other depending on the position.

[0084] The phase delay layer and the dispersion adjustment layer also differ from each other in the ratio of the rate of change of dispersion ∂ / ∂r, ∂n / ∂λ with respect to the change in the effective refractive index ∂n / ∂r depending on the position.

[0085] In the case of the phase delay layer, as shown in the graph of FIG. 3, the width of the change in the effective refractive index depending on the position is larger than the width of the change in the effective refractive index depending on the position of the dispersion adjustment layer as shown in FIG. 4. Conversely, the degree to which the dispersion, that is, the effective refractive indices differ from each other depending on the wavelength is smaller in the phase delay layer than in the dispersion adjustment layer. Thereby, the ratio of the rate of change of dispersion to the change in the effective refractive index depending on the position has a larger value in the case of the dispersion adjustment layer than in the case of the phase delay layer. For this reason, the material contained in the dispersion adjustment layer has a larger dispersion than the material contained in the phase delay layer. As materials having a large dispersion, for example, Si and TiO 2 etc. are used, and as materials having a small dispersion, for example, SiO 2 and Si 3 N 4 etc. can be used. However, that is exemplary and not limited thereto. The ratio of the rate of change of dispersion to the change in the effective refractive index depending on the position has a close relationship with the dispersion, refractive index, shape distribution, etc. of the medium. For example, when the refractive index of the material constituting the nanostructure is smaller than the refractive index of the material surrounding it, the rate of change of dispersion depending on the position is even smaller than when the refractive index of the nanostructure material is larger than the refractive index of the material surrounding it. Therefore, the ratio of the rate of change of dispersion to the change in the effective refractive index depending on the position can be adjusted by a combination of materials and shapes different from the above-mentioned examples.

[0086] The specific details of the graphs in FIGS. 3 and 4 are an example shown such that the tendency of the change in the effective refractive index depending on the position and the ratio of the change rate of dispersion with respect to the change in the effective refractive index are different from each other in the two layers, but are not limited thereto. Also, in each region R 1 , R 2 , …, R k is illustrated such that the above-described constant tendency is shown at all positions, which means the general tendency shown in most regions. For example, at some positions, the tendency of the change in the effective refractive index of the first layer and the second layer is also the same. Such some positions may occur due to errors in the nanostructure process, where the determined height and width are not realized at the determined positions. Or, in a boundary region accompanied by a sharp change in the effective refractive index, that is, a region R 1 , R 2 , …, R k adjacent to the boundary regions where the 2π zone is present, a tendency of change in the effective refractive index different from the intended tendency may also be shown. In one embodiment, the region where the tendency of the change in the effective refractive index of the two layers is opposite is at least 50% or more, or 80% or more of the entire region. Here, the above-described ratio is based on the length in a predetermined first direction (for example, the radial direction) showing the change in the effective refractive index. That is, it means the ratio of the length in the first direction where the tendency of the change in the effective refractive index of the two layers is shown to be opposite to the total length in the first direction showing the change in the effective refractive index.

[0087] FIG. 5 is a graph exemplarily showing the wavelength-dependent phase delay profile by the meta-optical element of FIG. 1.

[0088] A meta-optical element 100 in which two layers showing properties such as the graphs in FIGS. 3 and 4 are combined can show a phase delay profile without discontinuity depending on the position.

[0089] On the one hand, in the graph of FIG. 5, for three wavelengths, the phase delay profile has the same form but is shifted by a constant value, which corresponds to the case where the dispersion is 0. However, this is illustrative, and a phase delay profile with a dispersion greater than 0 or less than 0 can be realized depending on the detailed dispersion distribution in the phase delay layer and the dispersion adjustment layer.

[0090] Hereinafter, for the sake of realizing a phase delay profile with less phase discontinuity depending on the position regardless of the wavelength, the theory from which the above structure is derived will be described.

[0091] For light in a predetermined wavelength band, in order to realize a phase delay profile with less discontinuity, unit components with different magnitudes of phase delay and amounts of dispersion can be used for the meta-optical element 100.

[0092] The phase delay of the light passing through the unit component of the meta-optical element 100 can be linearly approximated and expressed as follows.

[0093]

Equation

[0094] Here, ω is 2π / λ, ω 0 is 2π / λ 0 and λ is the wavelength, λ 0 is the central wavelength of the predetermined wavelength band, A is the magnitude of the phase delay dispersion ∂φ / ∂λ, B is the magnitude of the phase delay φ|λ=λ 0 at the central wavelength, and φ ref is the reference phase profile.

[0095] In order to make the phase delay profile continuous depending on the position of the meta-optical element 100, a set of unit components having A values and B values within the following ranges is required. The unit component means an optical structure having a sub-wavelength, that is, a shape dimension smaller than the central wavelength.

[0096] [Number]

[0097] [Number]

[0098] The claim range of A varies depending on the chromatic aberration of the meta-optical element 100. When the meta-optical element 100 is a lens, the larger the lens diameter and the numerical aperture, the wider it becomes. In the operating wavelength range, when the phase delay profile due to position is the same, it corresponds to A = 0. B1 - B0, which is the claim range of B, must be greater than 2π.

[0099] Assuming that the unit component of the meta-optical element 100 is a homogeneous medium that can be expressed by the effective refractive index, the phase delay of the light passing through the unit component can be expressed as follows.

[0100] [Number]

[0101] Here, n is the effective refractive index, and h is the height of the unit component.

[0102] Substitute Equation 4 into Equation 1.

[0103] [Number]

[0104] To simplify, if the reference phase profile is defined to increase linearly with frequency, the effective refractive index of the unit component required for the phase delay profile with less discontinuity can be expressed as follows.

[0105] [Number]

[0106] or

[0107]

Math

[0108] As can be known through Equation 5 and Equation 6, in order to realize a phase delay profile with less discontinuity, it can be seen that an effective refractive index having various sizes and dispersions must be realized through unit components.

[0109] For example, under the condition of A = 0 which is the simplest case, as the phase delay at the center wavelength increases, a unit component with a positive value of the change in effective refractive index dispersion is required. If this condition is expressed by an equation at the center wavelength, it is as follows.

[0110]

Math

[0111]

Math

[0112] Here, n is the effective refractive index at the center wavelength λ 0 and is the effective refractive index at.

[0113] That is, as the effective refractive index at the center wavelength increases, the change in the dispersion size of the effective refractive index must have a positive value.

[0114] However, most of the optical materials existing in nature have a negative value for dispersion at the optical frequency and tend to have a larger dispersion size as the refractive index increases. Therefore, it is difficult to satisfy Equation 7a and Equation 7b only with the existing methods of patterning a single substance.

[0115] That is, generally, since the effective refractive index of the non-resonant unit element generally has the following characteristics, it is difficult to satisfy Equations 7a and 7b.

[0116]

Number

[0117] For example, when changing the phase delay at the center wavelength by the width of the nanopillar, which is a generally used method, if the width of the nanopillar is increased, the effective refractive index increases. However, due to the electric field focusing of the guided mode, the refractive index dispersion size, which is a negative number, also increases. That is, a dispersion change opposite to Equations 7a and 7b will be obtained.

[0118] In the foregoing description, the case of the simplest condition of the A = 0 condition was exemplified. When A is not 0, since a unit component having a more diverse combination of refractive index dispersion and refractive index size is required, it is difficult to implement a high-efficiency meta-optical element in the existing technology over a wide wavelength range.

[0119] The meta-optical element 100 according to an embodiment is proposed to have a structure that can finely adjust the dispersion by using unit components that are distinguished into a plurality of layers with different characteristics depending on the position of the effective refractive index and the wavelength.

[0120] Similar to Equation 6, the relational expression between the effective refractive index of the unit component distinguished into a plurality of layers and the condition for the continuous phase profile is also expressed as follows.

[0121]

Number

[0122] Here, n i is the effective refractive index of the i-th layer, and h iis the height of the unit component in the i-th layer.

[0123] When similar to Equation 7a and Equation 7b, and in the case of A = 0 which is the simplest condition, the condition for having a phase delay profile without discontinuity can be expressed at the central wavelength as follows.

[0124]

Number

[0125]

Number

[0126] Assuming that the effective refractive index of each layer constituting the meta-optical element 100 satisfies Equation 8, in order to satisfy Equation 10a and Equation 10b, at least one layer must, as follows, have a negative change in the effective refractive index due to the change in the magnitude B of the phase delay at the central wavelength.

[0127]

Number

[0128] Here, n j is the effective refractive index at the central wavelength of the j-th layer. Generally, considering the property of natural substances where the higher the refractive index, the greater the dispersion, the change in the phase delay of the effective refractive index dispersion of the j-th layer with respect to the magnitude B will have a positive value.

[0129] Due to the change in the phase delay of the dispersion of the j-th layer having a positive value that is not a negative value, it becomes possible to satisfy Equation 10a and Equation 10b under specific conditions.

[0130] For example, when the meta-optical element 100 includes two layers, the heights h1 and h2 of each layer are as follows.

[0131]

Number

[0132]

Number

[0133] Here, in order for the heights h1 and h2 to have positive values, the following conditions must be satisfied.

[0134]

Number

[0135]

Number

[0136]

Number

[0137] Assuming that each layer satisfies Equation 8, Equations 13b and 13c can be used as follows.

[0138]

Number

[0139] That is, the change rate ∂n i / ∂B of the effective refractive index of the i-th layer due to the change in the magnitude B of the phase delay at the required central wavelength is positive, and the change rate ∂nj / ∂B of the effective refractive index of the j-th layer due to the change in the magnitude B of the phase delay is negative (Equation 14). If the magnitude of the dispersion change rate ∂ / ∂B(∂nj / ∂λ) compared to the change rate ∂nj / ∂B of the effective refractive index of the j-th layer due to the change in the magnitude B is larger than that in the case of the i-th layer (Equation 13a), Equation 7 is satisfied, and in the operating wavelength region, it is possible to realize a phase delay profile with less discontinuity.

[0140] The above conditions can be satisfied by, for example, using substances with different refractive indices and dispersions for the unit constituent elements that make up each layer and using different design parameter spaces for each layer.

[0141] In the above description, n, φ, A, B, etc. were described as wavelength functions with their positions fixed based on the unit constituent elements, but they are all concepts expressed by position functions.

[0142] Therefore, within each layer of the meta-optical element 100, the change in the effective refractive index ∂n / ∂r due to position and the change in dispersion ∂ / ∂r(∂n / ∂λ) due to position can be adjusted to satisfy the above conditions.

[0143] FIG. 6 is a cross-sectional view showing a schematic structure of a meta-optical element according to an embodiment, and FIGS. 7A and 7B are perspective views showing exemplary shapes of nanostructures that can be employed in the meta-optical element of FIG. 6.

[0144] The meta-optical element 101 includes a first layer 121 and a second layer 161, and may further include a substrate SU for supporting the first layer 121 and the second layer 161.

[0145] The first layer 121 includes a plurality of first nanostructures NS1 and a first peripheral substance EN11 that encapsulates them. The first nanostructure NS1 can have a width d1 and a height h1 defined by position. As shown in the figure, the heights h1 of the first nanostructures NS1 are all the same, but are not limited thereto.

[0146] The second layer 161 includes a plurality of second nanostructures NS2 and a second peripheral substance EN21 that encapsulates them. The second nanostructure NS2 can have a width d2 and a height h2 defined by position. As shown in the figure, the heights h2 of the second nanostructures NS2 are all the same, but are not limited thereto.

[0147] The substrate SU has the property of being transparent to light in the operating wavelength band of the meta-optical element 101 and can be made of any one of materials such as glass (fused silica, BK7, etc.), polymer (PMMA, SU-8, etc.), and other transparent plastics.

[0148] The first nanostructure NS1 and the second nanostructure NS2 can have an aspect ratio greater than 1 in order to avoid optical resonance inside the structure. That is, h1 / d1 and h2 / d2 are greater than 1, for example, greater than 2.

[0149] The first nanostructure NS1 and the second nanostructure NS2 at positions facing each other can form a repeated unit component UE. The detailed shapes included in the unit component UE, that is, the width d1 and height h1 of the first nanostructure NS1, the width d2 and height h2 of the second nanostructure NS2, and the arrangement period p of the unit component UE are set to be suitable for the phase delay value required at each position.

[0150] d1, d2, and p are also sub-wavelength dimensions. That is, d1, d2, and p are smaller than the central wavelength λ of the operating wavelength band of the meta-optical element 101. 0 h1 and h2 are larger than λ. 0 h1 and h2 are larger than λ. 0 h1 and h2 are larger than λ and smaller than 10λ. 0

[0151] A spacer layer 140 can be interposed between the first layer 121 and the second layer 161. The spacer layer 140 can have a refractive index lower than that of the first nanostructure NS1 and the second nanostructure NS2. The spacer layer 140 is the same substance as the first surrounding substance EN11 or the same substance as the second surrounding substance EN21. The thickness s of the spacer layer 140 is also 400 nm or less. The spacer layer 140 can be omitted. In other words, the thickness s of the spacer layer 140 is 0.

[0152] The first nanostructure NS1 and the second nanostructure NS2 are also columnar structures. For example, they can have a hexahedral shape as shown in FIG. 7A or a cylindrical shape as shown in FIG. 7B. The indicated width D corresponds to d1 or d2, and the height H corresponds to h1 or h2. In addition to these, various columns with cross-sectional shapes such as rectangular, cross-shaped, polygonal, or elliptical are also applicable to the first nanostructure NS1 and the second nanostructure NS2.

[0153] In this embodiment, the first nanostructure NS1 can have a refractive index higher than that of the first surrounding substance EN11, and the second nanostructure NS2 can have a refractive index higher than that of the second surrounding substance EN21. With such a refractive index arrangement, the tendency for the widths d1 and d2 to change along one direction away from the center of the meta-optical element 101 is set to be opposite between the first nanostructure NS1 and the second nanostructure NS2. Thereby, the signs of the effective refractive index change rates of the first layer 121 and the second layer 161 with respect to position are opposite to each other. Also, the materials, shape dimensions, etc. included in the unit component UE are set according to position so that the ratios of the dispersion change rates with respect to the effective refractive index change of the first layer 121 and the second layer 161 are different from each other.

[0154] Either one of the first layer 121 and the second layer 161 is also a phase delay layer that exhibits a phase profile having the same tendency as the target phase profile realized by the meta-optical element 101, that is, having an effective refractive index change rate depending on position with the same tendency as the target phase profile, and the remaining one layer is also a dispersion adjustment layer that exhibits an effective refractive index change rate with a tendency opposite to that of the target phase profile.

[0155] The layer that is the dispersion adjustment layer can be set with the tendency of change in material and width such that the ratio of the dispersion change rate with respect to the effective refractive index change is even larger than that of the other layers.

[0156] This embodiment is also modified when the first nanostructure NS1 has a refractive index smaller than that of the first surrounding substance EN11 and the second nanostructure NS2 has a refractive index smaller than that of the second surrounding substance EN21.

[0157] Hereinafter, meta-optical elements according to various embodiments will be described. In the following description of the embodiments, the differences from the meta-optical element 101 in FIG. 6 will be mainly described, and for the components not described, the foregoing description may be applicable.

[0158] FIG. 8 is a cross-sectional view showing a schematic structure of a meta-optical element according to another embodiment.

[0159] The meta-optical element 102 includes a first layer 122, a second layer 162, and a substrate SU that supports the first layer 122 and the second layer 162. The first layer 122 includes a plurality of first nanostructures NS1 and a first surrounding material EN12 that encapsulates them. The second layer 162 includes a plurality of second nanostructures NS2 and a second surrounding material EN22 that encapsulates them.

[0160] In this embodiment, unlike the meta-optical element 101 in FIG. 6, the first nanostructure NS1 can have a refractive index lower than that of the first surrounding material EN12. The second nanostructure NS2 can have a refractive index higher than that of the second surrounding material EN22.

[0161] In such a refractive index arrangement, the first nanostructure NS1 and the second nanostructure NS2 are arranged along a direction away from the center of the meta-optical element 102, and the widths d1 and d2 in the one direction tend to change in the same manner as each other. Thereby, the signs of the effective refractive index change rates of the first layer 122 and the second layer 162 are opposite to each other. Also, the materials and widths included in each layer can be set such that the ratios of the dispersion change rates related to the effective refractive index changes of the first layer 122 and the second layer 162 are different from each other.

[0162] This embodiment can also be modified such that the first nanostructure NS1 has a refractive index higher than that of the first surrounding material EN12, and the second nanostructure NS2 has a refractive index lower than that of the second surrounding material EN22.

[0163] FIG. 9 is a cross-sectional view showing a schematic structure of a meta-optical element according to still another embodiment. FIGS. 10A and 10B are plan views showing exemplary shapes of the first nanostructures that can be employed in the first layer of the meta-optical element of FIG. 9.

[0164] The meta-optical element 103 includes a first layer 123, a second layer 163, and a substrate SU that supports the first layer 123 and the second layer 163.

[0165] The first layer 123 includes a plurality of first nanostructures NS1 and a first peripheral material EN13 that encapsulates them. The second layer 163 includes a plurality of second nanostructures NS2 and a second peripheral material EN23 that encapsulates them.

[0166] The first nanostructure NS1 can have a shape including an internal pillar 10 having a width of dc1 and a shell pillar 20 that surrounds the internal pillar 10. The refractive index of the internal pillar 10 is lower than the refractive index of the shell pillar 20, and the refractive index of the shell pillar 20 is higher than the refractive index of the first peripheral material EN13.

[0167] The second nanostructure NS2 can have a refractive index higher than that of the second peripheral material EN23.

[0168] In such a refractive index arrangement, the first nanostructure NS1 and the second nanostructure NS2 are set such that along one direction away from the center of the meta-optical element 103, the tendency for the width in the one direction to change is opposite to each other. Thereby, the first layer 123 and the second layer 163 have signs of the effective refractive index change rate depending on the position that are opposite to each other. Also, the details of the unit component UE can be set such that the ratio of the dispersion change rate to the effective refractive index change is different between the first layer 123 and the second layer 163.

[0169] Either one of the first layer 123 and the second layer 163 is also a phase retardation layer showing a phase profile having the same tendency as the target phase profile realized by the meta-optical element 103, and the remaining one layer is also a dispersion adjustment layer.

[0170] On the one hand, when the first nanostructure NS1 provided in the first layer 123 is in a form where the inside of the high refractive index shell pillar 20 is filled with a low refractive index inner pillar 10, as the width d1 of the first nanostructure NS1 increases, the phenomenon that the effective refractive index rapidly increases is alleviated, which is advantageous for minimizing the dispersion change due to position. In such a point, it is advantageous that the first layer 123 is utilized as a phase retardation layer showing a phase profile having the same tendency as the target phase profile realized by the meta-optical element 103. The second layer 163 is a dispersion adjustment layer, and the change tendency of the material and the width is also set in detail so that the ratio of the dispersion change rate related to the effective refractive index change rate is larger than that of the first layer 123.

[0171] FIG. 11 is a graph showing the relationship between the detailed dimensions of the unit component of the meta-optical element in FIG. 9 and the phase retardation.

[0172] This graph relates to the case where the first nanostructure NS1 is set to the shape as shown in FIG. 10A and the second nanostructure NS2 is set to the shape as shown in FIG. 7A. In this graph, the heights of the first nanostructure NS1 and the second nanostructure NS2, h1 and h2, are fixed at constant values. The width d1 of the first nanostructure NS1, the width d2 of the second nanostructure NS2, the width dc1 of the inner pillar 10 included in the second nanostructure NS2, and the array period p of the unit component UE are changed, and the phase retardation of the light transmitted through such a unit component UE is shown.

[0173] The detailed dimensions of the unit component UE suitable for the required phase retardation value can be set from such a graph. Also, such a graph can be obtained for different values of h1 and h2, and the detailed dimensions of the unit component UE by position suitable for the target phase profile to be realized therefrom can be set.

[0174] FIGS. 12 and 13 are graphs showing the diffraction efficiency of the meta-optical element in FIG. 9.

[0175] Figures 12 and 13 show the diffraction efficiency in the wavelength band of 400 nm to 700 nm with the incident angles of 0°, 30°, and 60° for TE-mode and TM-mode light, respectively.

[0176] The diffraction efficiency indicates the ratio of the energy of the light diffracted in the intended diffraction direction among the light transmitted through the meta-optical element 103. As shown in the graph, the diffraction efficiency in the desired wavelength band is 0.8 or more, and mostly shows a high value of 0.9 or more. Such a high diffraction efficiency is considered to be due to the fact that the meta-optical element 103 is designed to embody a target phase delay profile with almost no phase discontinuity in the wavelength band.

[0177] Figure 14 is a cross-sectional view showing a schematic structure of a meta-optical element according to still another embodiment.

[0178] The first layer 124 of the meta-optical element 104 includes a plurality of first nanostructures NS1 and a first surrounding material EN14 that encapsulates them. The second layer 164 of the meta-optical element 104 includes a plurality of second nanostructures NS2 and a second surrounding material EN24 that encapsulates them.

[0179] The first nanostructure NS1 can have a shape including an internal pillar 10 having a width of dc1 and a shell pillar 20 surrounding the internal pillar 10. The refractive index of the internal pillar 10 is lower than that of the shell pillar 20, and the refractive index of the shell pillar 20 is higher than that of the first surrounding material EN14.

[0180] Unlike the meta-optical element 103 of FIG. 9, the meta-optical element 104 of the present embodiment can have a refractive index lower than that of the second surrounding material EN24 for the second nanostructure NS2.

[0181] In such a refractive index arrangement, the first nanostructure NS1 and the second nanostructure NS2 are set such that, along one direction away from the center of the meta-optical element 103, the tendency for the width in the one direction to change is the same for both. Thereby, the first layer 124 and the second layer 164 have signs of the effective refractive index change rate depending on the position that are opposite to each other. Also, the materials and the degree of the tendency for the width to change included in the two layers can be set such that the ratio of the dispersion change rate with respect to the effective refractive index change is different between the first layer 124 and the second layer 164.

[0182] The first layer 124 is also a phase retardation layer showing a phase profile having the same tendency as the target phase profile realized by the meta-optical element 104, the second layer 164 is a dispersion adjustment layer, and the details of the unit component UE can be set for each position such that the ratio of the dispersion change rate related to the effective refractive index change is larger than that of the first layer 124.

[0183] FIG. 15 is a cross-sectional view showing a schematic structure of a meta-optical element according to still another embodiment.

[0184] The first layer 125 of the meta-optical element 105 includes a plurality of first nanostructures NS1 and a first peripheral substance EN15 that encloses them. The second layer 165 of the meta-optical element 105 includes a plurality of second nanostructures NS2 and a second peripheral substance EN25 that encloses them.

[0185] The first nanostructure NS1 has a hole shape surrounded by the first peripheral substance EN15, and the inside of the hole is empty, that is, has a structure of air. The refractive index of the first nanostructure NS1 is 1 and has a refractive index lower than that of the first peripheral substance EN15.

[0186] The second nanostructure NS2 has a refractive index higher than that of the second peripheral substance EN25.

[0187] The hole of the first nanostructure NS1 and the second nanostructure NS2 are arranged along a direction away from the center of the meta-optical element 105, and the detailed numerical values of the unit component UE are set for each position such that the tendencies of the widths in the one direction to change are the same for each other. Thereby, the signs of the effective refractive index change rates with respect to the position of the first layer 125 and the second layer 165 are opposite to each other. Also, for the first layer 125 and the second layer 165, details such as the materials included in the two layers and the degree of tendency for the widths to change can be set such that the ratios of the dispersion change rates with respect to the effective refractive index change are different from each other.

[0188] The first layer 125 is also a phase retardation layer that exhibits a phase profile having the same tendency as the target phase profile realized by the meta-optical element 105. The second layer 165 is a dispersion adjustment layer, and the details of the unit component UE can be set for each position such that the ratio of the dispersion change rate with respect to the effective refractive index change is larger than that of the first layer 125.

[0189] FIG. 16 is a graph showing the phase retardation according to the detailed dimensions of the first nanostructure forming the first layer of the meta-optical element of FIG. 15.

[0190] In the graph, the hole of the first nanostructure NS1 has a square cross-section, and the second nanostructure NS2 is related to the case where it is set to the shape as shown in FIG. 7A. In the graph, the height of the first nanostructure NS1 and the height of the second nanostructure NS2 are fixed, and the width d1 of the first nanostructure NS1, the width d2 of the second nanostructure NS2, and the arrangement period p of the unit component UE are changed, and the resulting phase retardation is shown.

[0191] The detailed dimensions of the unit component UE suitable for the required phase retardation value can be set from such a graph. Also, such a graph can be obtained for different values of h1 and h2, and the detailed dimensions of the unit component UE for each position suitable for the target phase profile to be realized from them can be set.

[0192] FIG. 17 is a graph showing the diffraction efficiency of the meta-optical element of FIG. 15.

[0193] The graph relates to incident light with an incident angle of 0°, shows high values of 0.9 or more in the wavelength range of 400 nm to 700 nm, and shows a diffraction efficiency close to 1 in most wavelength bands.

[0194] Such a result is analyzed to show a higher diffraction efficiency than in the case of the meta-optical element 103 according to the embodiment of FIG. 9, in which the shape of the first nanostructure NS1 is that of the low-refractive-index internal pillar 10 and the high-refractive-index shell pillar 20 surrounding it. It is considered to be the result of using a hollow structure with an empty interior, which makes it even easier to adjust the desired dispersion.

[0195] FIG. 18 is a cross-sectional view showing the schematic structure of a meta-optical element according to still another embodiment.

[0196] The first layer 126 of the meta-optical element 106 includes a plurality of first nanostructures NS1 and a first peripheral material EN16 that encapsulates them. The second layer 166 of the meta-optical element 106 includes a plurality of second nanostructures NS2 and a second peripheral material EN26 that encapsulates them.

[0197] The first nanostructure NS1 has a hole shape encapsulated by the first peripheral material EN16, and the interior of the hole has a structure that is empty, i.e., air. The refractive index of the first nanostructure NS1 is 1, which is lower than that of the first peripheral material EN16.

[0198] Unlike the meta-optical element 105 in FIG. 15, in the meta-optical element 106 of this embodiment, the second nanostructure NS2 has a refractive index lower than that of the second peripheral material EN26.

[0199] The hole of the first nanostructure NS1 and the second nanostructure NS2 are arranged such that the unit component UE by position has a tendency that the widths in one direction along which they move away from the center of the meta-optical element 105 change in opposite directions. As a result, the signs of the effective refractive index change rates of the first layer 126 and the second layer 166 are opposite to each other depending on the position. Also, the materials and the degree of the tendency of the widths to change included in the two layers can be set such that the ratios of the dispersion change rates with respect to the effective refractive index change of the first layer 126 and the second layer 166 are different from each other.

[0200] The first layer 126 is also a phase delay layer that exhibits a phase profile having the same tendency as the target phase profile realized by the meta-optical element 106. The second layer 166 is a dispersion control layer, and the details of the unit component UE by position can be set such that the ratio of the dispersion change rate related to the effective refractive index change is larger than that of the first layer 126.

[0201] In the descriptions of the meta-optical elements 103, 104, 105, and 106 in FIGS. 9, 14, 15, and 18, it was described that the first layers 123, 124, 125, and 126 function as layers (phase delay layers) that exhibit an effective refractive index change (and phase delay profile) having the same tendency as the target phase delay profile, and the second layers 164, 164, 165, and 166 function as layers (dispersion control layers) that exhibit an effective refractive index change (and phase delay profile) having the opposite tendency to the target phase delay profile, but it is not limited thereto. In other words, the described examples describe that nanostructures having a hole shape or a shape including an internal pillar and a shell pillar have advantages in being applied as a phase delay layer, and due to the refractive index distribution, the above-described structure can also be applied as a nanostructure of a dispersion control layer.

[0202] The above-mentioned meta-optical element can exhibit various optical functions such as a lens, a beam deflector, and a beam shaper, and can be combined with general optical elements to exhibit various optical functions. For example, when the meta-optical element with a phase delay dispersion (A = ∂φ / ∂λ) of 0 is embodied as a lens, it can exhibit a predetermined chromatic aberration. Such chromatic aberration is a negative chromatic aberration in which the wavelength and the focal length are inversely proportional, which is opposite to the positive chromatic aberration in which the focal length is proportional to the wavelength exhibited by a general refractive lens. Such a property is also expressed by a negative Abbe number. The meta-optical element can, therefore, be combined with a general refractive lens to exhibit a predetermined refractive power and can play a role in correcting the chromatic aberration of the refractive lens.

[0203] Many parts of the above description were derived on the premise of the phase delay profile illustrated in FIG. 5, that is, the case where the phase delay dispersion (A = ∂φ / ∂λ) with respect to the wavelength is 0. However, by using the same principle, that is, by adopting a layer having a refractive index change with the same tendency as the target phase delay profile and a layer having a refractive index change with the opposite tendency, and adjusting the ratio of the refractive index change rate related to the effective refractive index change rate depending on the position in each layer, it is also possible to embody a meta-optical element that has a phase delay dispersion that is not 0, that is, A > 0 or A < 0, and exhibits a phase delay profile with almost no phase discontinuity.

[0204] FIG. 19 is a graph exemplarily showing the wavelength-dependent phase delay profile of an optical meta-optical element according to still another embodiment. Here, R, G, and B each become a relatively long wavelength, a medium wavelength, and a short wavelength, respectively. For example, R becomes 700 nm, G becomes 550 nm, and B becomes 400 nm.

[0205] The illustrated phase delay profile is such that there are regions where the wavelength-dependent phase delay dispersion ∂φ / ∂λ is less than 0, regions where it is 0, and regions where it is greater than 0. When the position where the phase delay dispersion ∂φ / ∂λ becomes 0 is r0 (the position where the slope of the reference phase profile and the phase delay dispersion are the same), the phase delay dispersion ∂φ / ∂λ in the region where the position r is less than r0 is less than 0, and the phase delay dispersion ∂φ / ∂λ in the region where the position r is greater than r0 is greater than 0.

[0206] When configuring the target phase delay profile such that the dispersion related to the wavelength has such a form, it is possible to exhibit an optical performance having a chromatic aberration greater than the chromatic aberration exhibited by a general optical element. Such a chromatic aberration is a negative chromatic aberration showing a focal length inversely proportional to the wavelength, and becomes larger than that shown by a metasurface where the wavelength-dependent phase delay dispersion ∂φ / ∂λ is 0, and much larger than that shown by a general refractive lens. Such a property is a phase delay profile that further increases the chromatic aberration, and is also utilized for the function of separating incident light by wavelength. For example, when implementing a beam deflector with the illustrated target phase delay profile, the incident light can be deflected in different directions depending on the wavelength. Also, the illustrated target phase delay profile is utilized for a micro-spectrometer that branches incident light by wavelength. Also, when implementing a beam shaper with the illustrated target phase delay profile, it is possible to form different beam distributions depending on the wavelength of the incident light.

[0207] FIG. 20 is a graph exemplarily showing the wavelength-dependent phase delay profile by an optical meta-optical element according to still another embodiment. Here, R, G, and B respectively become relatively long wavelengths, medium wavelengths, and short wavelengths. For example, R becomes 700 nm, G becomes 550 nm, and B becomes 400 nm.

[0208] The illustrated phase delay profile is a case where there are regions where the phase delay dispersion ∂φ / ∂λ with respect to wavelength is less than 0, regions where it is 0, and regions where it is greater than 0. When the position where the phase delay dispersion ∂φ / ∂λ becomes 0 is r0 (the position where the slope of the reference phase profile and the phase delay dispersion are the same), the phase delay dispersion ∂φ / ∂λ in the region where the position r is less than r0 is greater than 0, and the phase delay dispersion ∂φ / ∂λ in the region where the position r is greater than r0 is less than 0.

[0209] When configuring the target phase delay profile so that the dispersion with respect to wavelength has such a form, the meta-optical element can exhibit achromatic optical performance. For example, when such a meta-optical element is a lens, the incident light is focused without deviation due to wavelength. For example, when such a meta-optical element is a beam deflector, the incident light exhibits a constant deflection angle without deviation due to wavelength. For example, when such a meta-optical element is a beam shaper, the incident light will have a beam distribution in a predetermined design pattern without deviation due to wavelength.

[0210] The above-mentioned meta-optical element can set the target phase profile to match the optical performance in the desired wavelength band and exhibit various optical functions. Also, since the phase discontinuity can be minimized, the light efficiency showing the above-mentioned optical functions can be increased. Also, since the sign of the phase delay dispersion ∂φ / ∂λ with respect to wavelength can be adjusted to be 0, greater than 0, or less than 0, various performance realizations are possible.

[0211] The aforementioned meta-optical element is also applicable to various electronic devices. For example, it can be mounted on electronic devices such as smartphones, wearable devices, Internet of Things (IoT) devices, household appliances, tablet personal computers (PCs), personal digital assistants (PDAs), portable multimedia players (PMPs), navigation devices, drones, robots, driverless cars, self-driving cars, and advanced driver assistance systems (ADASs).

[0212] FIG. 21 is a block diagram showing a schematic configuration of an electronic device according to an embodiment.

[0213] Referring to FIG. 21, in a network environment 2200, an electronic device 2201 can communicate with another electronic device 2202 via a first network 2298 (such as a short-range wireless communication network) or communicate with still other electronic devices 2204 and / or a server 2208 via a second network 2299 (such as a long-range wireless communication network). The electronic device 2201 can communicate with the electronic device 2204 via the server 2208. The electronic device 2201 may include a processor 2220, a memory 2230, an input device 2250, an acoustic output device 2255, a display device 2260, an audio module 2270, a sensor module 2210, an interface 2277, a haptic module 2279, a camera module 2280, a power management module 2288, a battery 2289, a communication module 2290, a subscriber identification module 2296, and / or an antenna module 2297. Some of these components (such as the display device 2260) may be omitted from the electronic device 2201, or other components may be added. Some of these components may also be implemented by one integrated circuit. For example, a fingerprint sensor 2211, an iris sensor, an illuminance sensor, etc. of the sensor module 2210 may be implemented by being embedded in the display device 2260 (such as a display).

[0214] The processor 2220 can execute software (such as program 2240), control one or more other components (hardware components, software components, etc.) of the electronic device 2201 connected to the processor 2220, and perform various data processing or operations. As part of the data processing or operation, the processor 2220 can load instructions and / or data received from other components (such as the sensor module 2210 and the communication module 2290) into the volatile memory 2232, process the instructions and / or data stored in the volatile memory 2232, and store the result data in the non-volatile memory 2234. The processor 2220 may include a main processor 2221 (such as a central processing unit or an application processor), and an auxiliary processor 2223 (such as a graphics processing unit, an image signal processor, a sensor hub processor, a communication processor, etc.) that can operate independently or together with the main processor 2221. The auxiliary processor 2223 can use less power than the main processor 2221 and perform specialized functions.

[0215] The auxiliary processor 2223 can replace the main processor 2221 while the main processor 2221 is in an inactive state (sleep state), or can control the functions and / or states related to some of the components (such as the display device 2260, the sensor module 2210, the communication module 2290, etc.) of the electronic device 2201 together with the main processor 2221 while the main processor 2221 is in an active state (application execution state). The auxiliary processor 2223 (such as an image signal processor or a communication processor) is also embodied as part of other functionally related components (such as the camera module 2280 and the communication module 2290).

[0216] The memory 2230 can store various data required by components of the electronic device 2201 (such as the processor 2220, the sensor module 2210, etc.). The data may include, for example, software (such as the program 2240), and input data and / or output data related to the instructions associated therewith. The memory 2230 may include a volatile memory 2232 and / or a non-volatile memory 2234.

[0217] The program 2240 is also stored as software in the memory 2230 and may include an operating system 2242, middleware 2244, and / or an application 2246.

[0218] The input device 2250 can receive instructions and / or data used by components of the electronic device 2201 (such as the processor 2220, etc.) from outside the electronic device 2201 (such as a user). The input device 2250 may include a microphone, a mouse, a keyboard, and / or a digital pen (such as a stylus pen).

[0219] The acoustic output device 2255 can output an acoustic signal to the outside of the electronic device 2201. The acoustic output device 2255 may include a speaker and / or a receiver. The speaker is also used for general purposes such as multimedia playback or recording playback, and the receiver is also used for receiving incoming calls. The receiver may be coupled to a part of the speaker or implemented as a separate independent device.

[0220] The display device 2260 can visually provide information to the outside of the electronic device 2201. The display device 2260 may include a display, a hologram device or a projector, and a control circuit for controlling the device. The display device 2260 may also include a touch circuitry set to sense touch, and / or a sensor circuit (such as a pressure sensor) set to measure the intensity of the force generated by the touch.

[0221] The audio module 2270 can convert sound into an electrical signal or vice versa. The audio module 2270 can acquire sound via the input device 2250, or output sound via the acoustic output device 2255 and / or the speakers and / or headphones of the electronic device 2201 and / or other electronic devices (such as the electronic device 2102) directly or wirelessly connected to the electronic device 2201.

[0222] The sensor module 2210 can sense the operating state (such as power, temperature, etc.) of the electronic device 2201 or the external environmental state (such as the user state, etc.), and generate an electrical signal and / or data value corresponding to the sensed state. The sensor module 2210 may include a fingerprint sensor 2211, an acceleration sensor 2212, a position sensor 2213, a 3D sensor 2214, etc. In addition, it may also include an iris sensor, a gyro sensor, a barometric pressure sensor, a magnetic sensor, a grip sensor, a proximity sensor, a color sensor, an IR (infrared) sensor, a biological sensor, a temperature sensor, a humidity sensor, and / or an illuminance sensor.

[0223] The 3D sensor 2214 can irradiate a predetermined light on an object, analyze the light reflected from the object, and sense the shape, movement, etc. of the object, so as to be equipped with any one of the meta-optical elements 100, 101, 102, 103, 104, 105, 106 according to the foregoing embodiments.

[0224] The interface 2277 can support one or more specified protocols used for the electronic device 2201 to be directly or wirelessly connected to other electronic devices (such as the electronic device (2102), etc.). The interface 2277 may include an HDMI (registered trademark) (high definition multimedia interface), a USB (registered trademark) (universal serial bus) interface, an SD card interface, and / or an audio interface.

[0225] The connection terminal 2278 may include a connector through which the electronic device 2201 can be physically connected to another electronic device (such as the electronic device 2102). The connection terminal 2278 may include an HDMI connector, a USB connector, an SD card connector, and / or an audio connector (such as a headphone connector).

[0226] The haptic module 2279 can convert an electrical signal into a mechanical stimulus (such as vibration or movement) or an electrical stimulus that can be perceived by the user through the sense of touch or kinesthesia. The haptic module 2279 may include a motor, a piezoelectric element, and / or an electrical stimulation device.

[0227] The camera module 2280 can capture still images and videos. The camera module 2280 may include a lens assembly including one or more lenses, an image sensor, an image signal processor, and / or a flash. The lens assembly included in the camera module 2280 can collect light emitted from a subject that is the object of image capture, and such a lens assembly may include any one of the meta-optical elements 100, 101, 102, 103, 104, 105, 106 according to the foregoing embodiments.

[0228] The power management module 2288 can manage the power supplied to the electronic device 2201. The power management module 2238 is also implemented as part of a PMIC (power management integrated circuit).

[0229] The battery 2289 can supply power to the components of the electronic device 2201. The battery 2289 may include a non-rechargeable primary battery, a rechargeable secondary battery, and / or a fuel cell.

[0230] The communication module 2290 can assist in establishing a direct (wired) communication channel and / or a wireless communication channel between the electronic device 2201 and other electronic devices (such as the electronic device 2102, the electronic device 2104, the server 2108, etc.), and in performing communication via the established communication channel. The communication module 2290 operates independently of the processor 2220 (such as an application processor) and may include one or more communication processors that support direct communication and / or wireless communication. The communication module 2290 may include a wireless communication module 2292 (such as a cellular communication module, a short-range wireless communication module, a GNSS (global navigation satellite system) communication module, etc.) and / or a wired communication module 2294 (such as a LAN (local area network) communication module, a power line communication module, etc.). Among these communication modules, the corresponding communication module can communicate with other electronic devices via the first network 2298 (a short-range communication network such as Bluetooth (registered trademark), WiFi (registered trademark) direct or IrDA (infrared Data Association)) or the second network 2299 (a long-range communication network such as a cellular network, the Internet or a computer network (LAN, WAN, etc.)). Such various types of communication modules may be integrated into one component (such as a single chip) or implemented by a plurality of separate components (multiple chips) from each other. The wireless communication module 2292 can utilize the subscriber information (such as the international mobile subscriber identifier (IMSI)) stored in the subscriber identification module 2296 to identify and authenticate the electronic device 2201 within a communication network such as the first network 2298 and / or the second network 2299.

[0231] The antenna module 2297 can transmit signals and / or power to the outside (such as other electronic devices) and receive them from the outside. The antenna may include a reflector composed of a conductive pattern formed on a substrate (such as a PCB). The antenna module 2297 may include one or more antennas. When a plurality of antennas are included, the communication module 2290 can select an antenna suitable for the communication method used in a communication network such as the first network 2298 and / or the second network 2299 from among the plurality of antennas. Signals and / or power are transmitted and received between the communication module 2290 and other electronic devices via the selected antenna. In addition to the antenna, other components (such as RFICs) are also included as part of the antenna module 2297.

[0232] Some of these components are connected to each other via a communication method with peripheral devices (such as a bus, GPIO (general purpose input and output), SPI (serial peripheral interface), MIPI (mobile industry processor interface)), and can exchange signals (such as commands and data).

[0233] The command or the data can be transmitted or received between the electronic device 2201 and the external electronic device 2204 via the server 2108 connected to the second network 2299. The other electronic devices 2202 and 2204 can be the same as the electronic device 2201 or different types of devices. All or part of the operations executed by the electronic device 2201 can also be executed in one or more of the other electronic devices 2202, 2204, and 2208. For example, when the electronic device 2201 has to perform a certain function or service, instead of autonomously executing the function or the service, it can request one or more other electronic devices to perform part or all of the function or the service. One or more other electronic devices that receive the request can execute the additional function or service related to the request and transmit the execution result to the electronic device 2201. For this purpose, technologies of cloud computing, distributed computing, and / or client-server computing can be utilized.

[0234] FIG. 22 is a block diagram exemplarily showing a schematic configuration of a camera module provided in the electronic device of FIG. 21.

[0235] Referring to FIG. 22, the camera module 2280 may include a lens assembly 2310, a flash 2320, an image sensor 2330, an image stabilizer 2340, a memory 2350 (such as a buffer memory), and / or an image signal processor 2360. The lens assembly 2310 can collect light emitted from a subject that is an object of image shooting, and may include any one of the aforementioned meta-optical elements 100, 101, 102, 103, 104, 105, and 106. The lens assembly 2310 may include one or more refractive lenses and a meta-optical element. The meta-optical element provided therein is also designed by a lens having a target phase delay profile indicating a dispersion suitable for a predetermined aberration correction and a predetermined refractive index. The lens assembly 2310 including such a meta-optical element can embody desired optical performance and have a short overall optical length.

[0236] In addition, the camera module 2280 can further include an actuator. The actuator can drive the position of the lens elements that make up the lens assembly 2310 and adjust the separation distance between the lens elements, for example, for zooming and / or autofocus (AF).

[0237] The camera module 2280 may include a plurality of lens assemblies 2310. In such a case, the camera module 2280 can also be a dual camera, a 360° camera, or a spherical camera. Some of the plurality of lens assemblies 2310 can have the same lens attributes (such as angle of view, focal length, autofocus, F number, optical zoom, etc.) or different lens attributes. The lens assembly 2310 may include a wide-angle lens or a telephoto lens.

[0238] The flash 2320 can emit light used to enhance the light emitted or reflected from the subject. The flash 2320 may include one or more light-emitting diodes (such as RGB (red·green·blue) LEDs, white LEDs, infrared LEDs, ultraviolet LEDs, etc.) and / or a xenon lamp. The image sensor 2330 is also the image sensor 1200 described in FIGS. 1, 5, and 7, and can obtain an image corresponding to the subject by converting the light emitted or reflected from the subject and transmitted through the lens assembly 2310 into an electrical signal. The image sensor 2330 may include one or more sensors selected from image sensors with different attributes, such as an RGB sensor, a BW (black and white) sensor, an IR sensor, or a UV sensor. Each sensor included in the image sensor 2330 is also embodied as a CCD (charge coupled device) sensor and / or a CMOS (complementary metal oxide semiconductor) sensor.

[0239] The image stabilizer 2340 can respond to the movement of the camera module 2280 or the electronic device 2201 including the same, and move one or more lenses or the image sensor 2330 included in the lens assembly 2310 in a specific direction, or control the operating characteristics of the image sensor 2330 (such as adjusting the read-out timing), so that the negative impact caused by the movement can be compensated. The image stabilizer 2340 can utilize a gyro sensor (not shown) or an acceleration sensor (not shown) disposed inside or outside the camera module 2280 to sense the movement of the camera module 2280 or the electronic device 2201. The image stabilizer 2340 is also implemented optically.

[0240] The memory 2350 can store some or all of the image data acquired via the image sensor 2330 for the next image processing operation. For example, when a plurality of images are acquired at high speed, the acquired original data (such as Bayer pattern data, high-resolution data) is stored in the memory 2350, and only the low-resolution images are displayed, and then the original data of the selected (such as user selection) image is transmitted to the image signal processor 2360. The memory 2350 is integrated with the memory 2230 of the electronic device 2201 or configured as a separate memory that operates independently.

[0241] The image signal processor 2360 can perform one or more image processes on an image acquired via the image sensor 2330 or image data stored in the memory 2350. The one or more image processes may include depth map generation, three-dimensional modeling, panorama generation, feature point extraction, image synthesis, and / or image compensation (such as noise reduction, resolution adjustment, brightness adjustment, blurring, sharpening, softening, etc.). The image signal processor 2360 can perform control (such as exposure time control or readout timing control) on components (such as the image sensor 2330) included in the camera module 2280. The image processed by the image signal processor 2360 is further stored in the memory 2350 for additional processing or can also be provided to external components of the camera module 2280 (such as the memory 2230, the display device 2260, the electronic device 2202, the electronic device 2204, the server 2208, etc.). The image signal processor 2360 can be integrated into the processor 2220 or configured as a separate processor operating independently of the processor 2220. When the image signal processor 2360 is configured as a separate processor from the processor 2220, the image processed by the image signal processor 2360 is also displayed via the display device 2260 after undergoing additional image processing by the processor 2220.

[0242] The electronic device 2201 may include a plurality of camera modules 2280 having different attributes or functions. In such a case, one of the plurality of camera modules 2280 is a wide-angle camera, and another one is a telephoto camera. Similarly, one of the plurality of camera modules 2280 is a front camera, and another one is a rear camera.

[0243] FIG. 23 is a block diagram showing a schematic configuration of the 3D sensor provided in the electronic device of FIG. 21.

[0244] The 3D sensor 2214 irradiates a target object with predetermined light, receives and analyzes the light reflected from the target object, and senses the shape, movement, etc. of the target object. The 3D sensor 2214 includes a light source 2420, a meta-optical element 2410, a light detection unit 2430, a signal processing unit 2440, and a memory 2450. As the meta-optical element 2410, any one of the meta-optical elements 100, 101, 102, 103, 104, 105, 106 according to the foregoing embodiments is adopted, and a target phase delay profile can be set so as to function as a beam deflector or a beam shaper.

[0245] The light source 2420 irradiates light used for analyzing the shape and position of the target object. The light source 2420 may include a light source that generates and irradiates light of a specific wavelength. The light source 2420 may include light sources such as an LD (laser diode), an LED (light emitting diode), and an SLD (super luminescent diode) that generate and irradiate light in a wavelength band suitable for analyzing the position and shape of the target object, for example, light in the infrared band wavelength. The light source 2420 is also a wavelength-variable laser diode. The light source 2420 can also generate and irradiate light in a plurality of mutually different wavelength bands. The light source 2420 can generate and irradiate pulsed light or continuous light.

[0246] The meta-optical element 2410 modulates the light irradiated from the light source 2420 and transmits it to the target object. When the meta-optical element 2410 is a beam deflector, the meta-optical element 2410 deflects the incident light in a predetermined direction so as to direct it toward the target object. When the meta-optical element 2410 is a beam shaper, the meta-optical element 2410 modulates the incident light so that the incident light has a distribution having a predetermined pattern. The meta-optical element 2410 can also form structured light suitable for three-dimensional shape analysis.

[0247] As described above, the meta-optical element 2410 can set the phase delay dispersion (∂φ / ∂λ) to 0, a positive number, or a negative number, and can embody a continuous phase delay profile. Therefore, achromatic light modulation without wavelength deviation can be performed. Or conversely, the deviation due to wavelength can be enhanced so that the deflection direction is different for each wavelength, or different beam patterns can be formed for each wavelength and the object can be irradiated.

[0248] The light detection unit 2430 receives the reflected light of the light irradiated to the object via the meta-optical element 2410. The light detection unit 2430 may include an array of a plurality of sensors that sense light, or may consist of only one sensor.

[0249] The signal processing unit 2440 can process the signal sensed by the light detection unit 2430 and analyze the shape of the object, etc. The signal processing unit 2440 can analyze the three-dimensional shape including the depth position of the object.

[0250] For this three-dimensional shape analysis, calculations for time of flight measurement of light can be performed. For this light ratio poem interval measurement, various algorithms can be used. For example, the direct time measurement method projects pulsed light onto the object and measures the time it takes for the light reflected from the subject to return with a timer to obtain the distance. The correlation method projects pulsed light onto the object and measures the distance from the brightness of the reflected light reflected from the object and returning. The phase delay measurement method is a method of projecting continuous wave light such as a sine wave onto the object, sensing the phase difference of the reflected light reflected and returning, and converting it into a distance.

[0251] When the object is irradiated with structured light, the depth position of the object can be calculated from the pattern change of the structured light reflected from the object, that is, the result compared with the incident structured light pattern. By tracking the pattern change of the structured light reflected from the object for each coordinate, the depth information of the object can be extracted, and from this, three-dimensional information related to the shape and movement of the object can be extracted.

[0252] The program and other data necessary for the operation of the signal processing unit 2440 can be stored in the memory 2450.

[0253] The operation results in the signal processing unit 2440, that is, the information related to the shape and position of the object, are also transmitted to other units within the electronic device 2200 or other electronic devices. For example, in the application 2246 stored in the memory 2230, such information can be used. Other electronic devices to which the results are transmitted may also include a display device or a printer that outputs the results. In addition to these, they may also include autonomous driving devices such as driverless cars, self-driving cars, robots, drones, smartphones, smart watches, mobile phones, PDAs, laptops, PCs, various wearable devices, and other mobile or non-mobile computing devices, as well as Internet of Things devices, but are not limited thereto.

[0254] The aforementioned meta-optical element and the electronic device including the same have been described with reference to the embodiments illustrated in the drawings, but they are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the disclosed embodiments should be considered from an explanatory rather than a limiting perspective. The scope of this specification is shown not in the foregoing description but in the claims, and it should be construed that all differences within the equivalent scope thereof are included.

Description of Reference Numerals

[0255] 100, 101, 102, 103, 104, 105, 106, 2410 Meta-optical element 120, 121, 122, 123, 124, 125, 126 First layer 160, 161, 162, 163, 164, 165, 166 Second layer EN11, EN12, EN13, EN14, EN15, EN16 First peripheral material EN21, EN22, EN23, EN24, EN25, EN26 Second Peripheral Material NS1, NS2 Nanostructures 2200 Electronic Device 2214 3D Sensor 2280 Camera Module

Claims

1. A first layer including a plurality of first nanostructures and a first peripheral material disposed adjacent thereto, A second layer disposed on the first layer and including a plurality of second nanostructures and a second peripheral material disposed adjacent thereto, The first layer and the second layer include a region where the signs of the effective refractive index change rates in a predetermined first direction are opposite to each other, It is configured to exhibit a predetermined target phase delay profile with respect to incident light in a predetermined wavelength band, The phase delay profile exhibited by the first layer and the target phase delay profile have the same sign of the effective refractive index change rate in the first direction, The phase delay profile exhibited by the second layer and the target phase delay profile have opposite signs of the effective refractive index change rate in the first direction, The ratio of the dispersion change rate to the effective refractive index change rate of the second layer in the first direction is, A meta-optical element greater than the ratio of the dispersion change rate to the effective refractive index change rate of the first layer in the first direction.

2. The meta-optical element according to claim 1, wherein the phase delay profile exhibited by the first layer and the phase delay profile exhibited by the second layer have opposite signs of the effective refractive index change rate corresponding to the position change in the first direction.

3. The meta-optical element according to claim 1 or 2, wherein the first nanostructures and the second nanostructures are columnar structures.

4. The first nanostructure has a refractive index higher than that of the first peripheral material, The second nanostructure has a refractive index higher than that of the second peripheral material, The first nanostructure and the second nanostructure are, The meta-optical element according to claim 3, wherein the tendencies of the width changes along one direction away from the center of the meta-optical element are opposite to each other.

5. The first nanostructure has a refractive index lower than that of the first peripheral material, The second nanostructure has a refractive index higher than that of the second peripheral material, The first nanostructure and the second nanostructure are, The meta-optical element according to claim 3, wherein the tendencies of the width changes along one direction away from the center of the meta-optical element are the same as each other.

6. The first nanostructure has a shape including an inner pillar and a shell pillar surrounding the inner pillar, The refractive index of the inner pillar is lower than that of the shell pillar, and the refractive index of the shell pillar is higher than that of the first peripheral material. The meta-optical element according to claim 3.

7. The second nanostructure has a refractive index higher than that of the second surrounding material, and the first nanostructure and the second nanostructure The meta-optical element according to claim 6, wherein the tendencies of the width changes along one direction away from the center of the meta-optical element are opposite to each other.

8. The second nanostructure has a refractive index lower than that of the second surrounding material, The first nanostructure and the second nanostructure The meta-optical element according to claim 6, wherein the tendencies of the width changes along one direction away from the center of the meta-optical element are the same as each other.

9. The meta-optical element according to claim 3, wherein the first nanostructure has a hole shape encapsulated by the first surrounding material.

10. The second nanostructure has a refractive index higher than that of the second surrounding material, The hole of the first nanostructure and the second nanostructure The meta-optical element according to claim 9, wherein the tendencies of the width changes along one direction away from the center of the meta-optical element are the same as each other.

11. The second nanostructure has a refractive index lower than that of the second surrounding material, The hole of the first nanostructure and the second nanostructure The meta-optical element according to claim 9, wherein the tendencies of the width changes along one direction away from the center of the meta-optical element are opposite to each other.

12. An imaging lens assembly including one or more refractive lenses and the meta-optical element according to any one of claims 1 to 11, An electronic device including an image sensor that converts an optical image formed by the imaging lens assembly into an electrical signal.

13. A light source, The meta-optical element according to any one of claims 1 to 11 that modulates light from the light source and transmits it to an object, An electronic device including a light detection unit that senses light from the object.

Images