Meta-optical devices, optical systems, and methods for aberration correction

Abstract

To provide an optical device comprising metasurfaces.SOLUTION: A meta optical device is provided, comprising an array of meta structures. Each of the meta structures comprises a plurality of stacked layers including at least a first layer having a first refractive index and a second layer having a second refractive index, the first refractive index being different from the second refractive index.SELECTED DRAWING: Figure 2A

Description

[Technical field]

[0001] The present invention relates to optical devices, and in particular to optical devices that include metasurfaces. [Background technology]

[0002] In recent years, metasurfaces have attracted much attention in the field of optics. For example, they can be used in combination with image sensors, such as CMOS image sensors (CIS). CIS products can be used in digital cameras, camera phones, web cameras, notebook security devices, automobiles, and medical equipment. Metasurfaces can manipulate the properties of electromagnetic waves (e.g., incident waves). For example, metasurfaces can be used as lenses, polarizers, beam shapers, and tunable phase modulators. Metasurfaces can also be designed to correct aberrations, including spherical aberration, chromatic aberration, and so on. Thus, image quality can be improved. Summary of the Invention [Problem to be solved by the invention]

[0003] An optical device is provided that includes a metasurface. [Means for solving the problem]

[0004] According to some embodiments, a meta-optical device is provided. The meta-optical device includes an array of meta-structures. Each of the meta-structures includes a stack of multiple layers including at least a first layer having a first refractive index and a second layer having a second refractive index. The first and second refractive indices are different.

[0005] In some embodiments, the difference between the first and second refractive indices is between 0.1 and 2.5. Also, the difference between the first and second refractive indices is between 0.3 and 2.0. Also, the difference between the first and second refractive indices is between 0.5 and 1.8. In some embodiments, the metastructure comprises a dielectric material. In some embodiments, the stack further comprises a third layer having a third refractive index, the third refractive index being different from the second refractive index, and the second layer is located between the first layer and the third layer. In some embodiments, the second refractive index is greater than the first refractive index and the third refractive index. In some embodiments, the first refractive index is equal to the third refractive index.

[0006] In some embodiments, the first thickness of the first layer is different from the second thickness of the second layer. In some embodiments, the first thickness and the third thickness of the third layer are greater than the second thickness. In some embodiments, the first thickness is equal to the third thickness. In some embodiments, each of the metastructures has an aspect ratio of 10 or less. In some embodiments, each of the metastructures has a shape, in a top view, that is circular, elliptical, polygonal, or hollow polygonal. In some embodiments, the metastructures are arranged in a rectangular or hexagonal array. In some embodiments, the metastructures include different geometric shapes, sizes, or orientations. In some embodiments, the stack further includes a plurality of odd layers having a first refractive index and a plurality of even layers having a second refractive index.

[0007] According to some embodiments, an optical system is provided. The optical system includes an image sensor and a meta-optical device. The image sensor includes a plurality of microlenses and a plurality of color filters disposed below the microlenses. The meta-optical device is disposed above the color filters. The meta-optical device includes an array of meta-structures, each of the meta-structures including a stack of multiple layers including a first layer having a first refractive index and a second layer having a second refractive index. The first refractive index and the second refractive index are different.

[0008] In some embodiments, the meta-optical device is disposed above the microlens and the color filter, or between the microlens and the color filter, In some embodiments, the distance between the bottom surface of the meta-optical device and the top surface of the image sensor is 10 μm or less, between 10 μm and 1 mm, or between 1 mm and 3 mm.

[0009] According to some embodiments, a method of aberration correction is provided. The method includes calculating the amount of aberration correction required. The method includes determining a desired position of a meta-optical device (e.g., meta-optical device 100) located near an image sensor (but relatively far from the near-field region), where the distance between the meta-optical device and the image sensor is between 10 μm and 3 mm. In some other embodiments, the distance between the meta-optical device and the image sensor is 10 μm or less. In some other embodiments, the meta-optical device may be located within the image sensor. The meta-optical device includes an array of meta-structures, each of the meta-structures including a stack of multiple layers including at least a first layer having a first refractive index and a second layer having a second refractive index, where the first refractive index and the second refractive index are different. The method includes determining and / or adjusting a geometry, size, or orientation of the meta-structures. The method further includes placing the meta-optical device according to the amount and the desired position. [Brief description of the drawings]

[0010] According to some embodiments, the present disclosure can be more fully understood from the following detailed description and examples taken in conjunction with the accompanying drawings. [Figure 1A] FIG. 1A shows a schematic diagram of the positional relationship between a meta-optical device and an image sensor. [Figure 1B] FIG. 1B shows a schematic diagram of the positional relationship between the meta-optical device and an image sensor. [Figure 1C] FIG. 1C shows a schematic diagram of the positional relationship between the meta-optical device and an image sensor. [Figure 2A] FIG. 2A shows a schematic representation of a different meta-optical device. [Figure 2B] FIG. 2B shows a schematic representation of a different meta-optical device. [Figure 2C] FIG. 2C shows a schematic representation of a different meta-optical device. [Figure 2D] FIG. 2D shows a schematic representation of a different meta-optical device. [Figure 2E] FIG. 2E shows a schematic representation of a different meta-optical device. [Figure 2F] FIG. 2F shows a schematic representation of a different meta-optical device. [Figure 2G] FIG. 2G shows a schematic representation of a different meta-optical device. [Figure 2H] FIG. 2H shows a schematic representation of a different meta-optical device. [Figure 2I] FIG. 2I shows a schematic representation of a different meta-optical device. [Figure 2J] FIG. 2J illustrates a schematic of a different meta-optical device. [Figure 2K] FIG. 2K shows a schematic of a different meta-optical device. [Figure 2L] FIG. 2L shows a schematic of a different meta-optical device. [Figure 3A] FIG. 3A shows a schematic diagram of the relationship between the efficiency of several different metastructures and the wavelength of the incident wave. [Figure 3B] FIG. 3B shows a schematic diagram of the relationship between the efficiency of several different metastructures and the wavelength of the incident wave. [Figure 3C] FIG. 3C shows a schematic diagram of the relationship between the efficiency of several different metastructures and the wavelength of the incident wave. [Figure 3D] FIG. 3D shows a schematic diagram of the relationship between the efficiency of several different metastructures and the wavelength of the incident wave. [Figure 3E] FIG. 3E shows a schematic diagram of the relationship between the efficiency of several different metastructures and the wavelength of the incident wave. [Figure 4A]FIG. 4A shows a schematic representation of the geometrical evolution of the metastructure. [Figure 4B] FIG. 4B shows a schematic representation of the size evolution of the metastructure. [Figure 4C] FIG. 4C shows a schematic representation of the orientation change of the metastructure. [Figure 4D] FIG. 4D shows a schematic diagram of the phase change of incident light having an incident angle of about 15 degrees. [Figure 5A] FIG. 5A shows a schematic diagram of a simulation for performing aberration correction. [Figure 5B] FIG. 5B shows a schematic diagram of a simulation for performing aberration correction. [Figure 5C] FIG. 5C shows a schematic diagram of a simulation for performing aberration correction. [Figure 5D] FIG. 5D shows a schematic representation of the result of aberration correction of the incident wave. [Figure 5E] FIG. 5E shows a schematic representation of the result of aberration correction of the incident wave. [Figure 6] FIG. 6 is a flow chart of a method for correcting aberrations. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In the following disclosure, many different embodiments or examples are provided for implementing different features of the provided subject matter. In order to briefly explain the present disclosure, specific embodiments of elements and arrangements are described below. These are, of course, merely for illustration and are not intended to be limiting. For example, in the following disclosure, a first feature formed "on" or "above" a second feature can include embodiments in which the first and second features are formed in direct contact, and can also include embodiments in which an additional feature is formed between the first and second features such that the first and second features are not in direct contact. The ordinal numbers such as "first", "second" and the like used in the present specification and claims do not themselves imply a priority, order, or sequence of an element relative to another element, but rather are merely used as a label to distinguish one element from other elements having the same name. Also, symbols and alphabets may be repeated in different examples of the present disclosure.

[0012] Additionally, spatially relative terms, such as "above" and the like, are used for simplicity of description to describe the relationship of one element or feature to another element(s) and feature(s) in the figures. The spatially relative terms are intended to encompass different orientations of the device for use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees, or at other orientations) and the spatially relative descriptions used herein may be interpreted accordingly.

[0013] According to some embodiments, an optical system 1 is provided. The optical system 1 includes an image sensor 20 and a meta-optical device 100. The image sensor 20 corresponds to a camera 10. As shown in FIG. 1A to FIG. 1C, FIG. 1A to FIG. 1C show schematic positional relationships between the image sensor 20 and the meta-optical device 100. An incident wave W passing through the camera 10 can be converted into an image on the image sensor 20. In some embodiments, the image sensor 20 can be a CIS. The image sensor 20 can include one or more microlenses 21, one or more color filters 22, one or more optical sensor layers 23, one or more isolated metal layers 24, and one or more silicon transistors 25.

[0014] As shown in Fig. 1A, meta-optical device 100 may be disposed within image sensor 20. Specifically, in Fig. 1A, meta-optical device 100 is disposed between microlens 21 and color filter 22. In other words, meta-optical device 100 is disposed below microlens 21 and above color filter 22, optical sensor layer 23, insulating metal layer 24, and silicon transistor 25.

[0015] As shown in Figures 1B and 1C, meta-optical device 100 may be disposed above image sensor 20. Specifically, in Figures 1B and 1C, meta-optical device 100 is disposed above microlens 21, color filter 22, optical sensor layer 23, insulating metal layer 24, and silicon transistor 25. The difference between Figures 1B and 1C is that meta-optical device 100 is farther away from image sensor 20 in Figure 1C. Also, in Figure 1B, filter 50 may be disposed between meta-optical device 100 and image sensor 20.

[0016] Meta-optical device 100 can provide two optical functions: phase correction and aberration correction. When meta-optical device 100 is used as a phase corrector, the phase of the incident wave W can be modulated. When meta-optical device 100 is used as an aberration corrector, the performance and / or image quality of image sensor 20 can be improved. The function of meta-optical device 100 can be determined by its position relative to image sensor 20.

[0017] In some embodiments, when meta-optical device 100 is disposed within image sensor 20 or above image sensor 20 within a distance of 10 μm or less, meta-optical device 100 can also be referred to as a phase corrector. For example, as shown in Figures 1A and 1B, the dashed lines represent the wavefront of an incident wave W. After incident wave W passes through meta-optical device 100, the tilted wavefront is changed to be horizontal and substantially parallel to the top surface of color filter 22. That is, the phase of incident wave W is modulated.

[0018] In some embodiments, when meta-optical device 100 is disposed above image sensor 20 and the distance between meta-optical device 100 and image sensor 20 is between 1 mm and 3 mm, meta-optical device 100 can also be referred to as an aberration corrector. As shown in FIG. 1C, the quality of the image formed on image sensor 20 can be improved by meta-optical device 100. When the distance between meta-optical device 100 and image sensor 20 is between 10 μm and 1 mm, meta-optical device 100 can also be referred to as a combination of a phase corrector and an aberration corrector.

[0019] Based on practical requirements, the positional relationship between the image sensor 20 and the meta-optical device 100 may be adjusted. In Figures 1A to 1C, the optical system 1 includes only one meta-optical device 100. In some other embodiments, the optical system 1 can include multiple meta-optical devices 100, where some meta-optical devices 100 are used as phase correctors and other meta-optical devices 100 are used as aberration correctors.

[0020] In the following, identical or similar elements are indicated by identical or similar symbols. As shown in FIG. 2A to FIG. 2L, FIG. 2A to FIG. 2L show schematic diagrams of optical devices 100A to 100L. The meta-optical devices 100A to 100L include an array of meta-structures 110A to 110L. The meta-structures 110A to 110L may include a dielectric material, a metal material, and the like. For example, the meta-structures 110A to 110L may include carbon nanotubes (CNTs), two-dimensional transition metal dichalcogenides (2D TMDs), SiC, ZrO2, ZrO 2-x , TiO x , SiN x , ITO, Si, a-Si, p-Si, III-V semiconductor compounds, or combinations thereof. The metastructures 110A-110L can be arranged in a rectangular or hexagonal array.

[0021] In the present disclosure, each of the metastructures 110A-110L includes a stack having different refractive indices. For example, each of the metastructures 110A-110L can include at least two layers having the highest and second highest refractive indices, respectively. In FIG. 2A-FIG. 2L, the different refractive indices are shown in different patterns. In some embodiments, the difference between the highest and second highest refractive indices can be between 0.1-2.5. In some embodiments, the difference between the highest and second highest refractive indices is between 0.3-2.0. In some embodiments, the difference between the highest and second highest refractive indices is between 0.5-1.8. It should be noted that this difference can be applied in other cases as well. For example, in some embodiments, the highest and lowest refractive indices of all the refractive indices of the stack can also be between 0.1-2.5, 0.3-2.0, or 0.5-1.8.

[0022] The different refractive indices of the metastructures 110A-110L allow for both refraction and absorption of the incident wave W, thus improving image quality as well as efficiency. Details regarding the evaluation of efficiency are provided in FIG. 3A to FIG. 3E. Also, the thickness of the multi-layer metastructures 110A-110L can be reduced. In some embodiments, the aspect ratio of the multi-layer metastructures 110A-110L is less than or equal to 10, making the fabrication more feasible due to the relatively small aspect ratio. For the single-layer metastructure, if the refractive index of the single-layer metastructure is high, absorption may become significant and the efficiency may be poor. If the refractive index of the single-layer metastructure is low, the thickness of the single-layer metastructure may be large and the image quality may be poor.

[0023] In FIG. 2A, the shape of each of the meta structures 110A is circular in top view. In some other embodiments, the shape of each of the meta structures 110A may be elliptical in top view. Each of the meta structures 110A includes a first layer 111A, a second layer 112A, and a third layer 113A. The second layer 112A is disposed between the first layer 112A and the third layer 113A. The first layer 111A has a first refractive index. The second layer 112A has a second refractive index. The first and second refractive indices are different. The third layer 113A has a third refractive index. In some embodiments, the second refractive index of the second layer 112A is greater than the first refractive index of the first layer 111A. In some embodiments, the first refractive index of the first layer 111A is equal to the third refractive index of the third layer 113A.

[0024] In some embodiments, the difference between the first refractive index of the first layer 111A and the second refractive index of the second layer 112A can be between 0.1 and 2.5, for example, 2.0. In some embodiments, the difference between the first refractive index of the first layer 111A and the second refractive index of the second layer 112A can be between 0.3 and 2.0, for example, 1.7. In some embodiments, the difference between the first refractive index of the first layer 111A and the second refractive index of the second layer 112A can be between 0.5 and 1.8, for example, 0.5.

[0025] The first layer 111A has a first thickness T1. The second layer 112A has a second thickness T2. The third layer has a third thickness T3. In some embodiments, the first thickness T1 is different from the second thickness T2. In some embodiments, the first thickness T1 is greater than the second thickness T2. In some embodiments, the first thickness T1 is equal to the third thickness T3. The sum of the first thickness T1, the second thickness T2, and the third thickness T3 can be 1 μm or less, e.g., 700 nm. The diameter D of each metastructure can be equal to or less than the wavelength range of interest, e.g., 120 nm. As described above, the aspect ratio can be defined as (T1+T2+T3) / D, and the aspect ratio can be 10 or less.

[0026] In Figures 2B to 2D, similar to Figure 2A, each of the metastructures 110B-110D includes three layers, and each of the metastructures 110B-110D has a different shape. In Figure 2B, each of the metastructures 110B has a rectangular shape in top view. In Figure 2C, each of the metastructures 110C has a pentagonal shape in top view. In Figure 2D, each of the metastructures 110D has a hexagonal shape in top view.

[0027] In FIG. 2E to FIG. 2H, each of the meta structures 110E to 110H is a hollow structure. In FIG. 2E, each of the meta structures 110E is a cylinder having a cylindrical bore (hole) therein, and therefore, the shape of each of the meta structures 110E is a circle having a circular hole therein when viewed from above. In FIG. 2F, each of the meta structures 110F is a rectangular parallelepiped having a rectangular parallelepiped bore therein, and therefore, the shape of each of the meta structures 110G is a rectangle having a rectangular hole therein when viewed from above. In FIG. 2G, each of the meta structures 110G is a cylinder having a rectangular parallelepiped bore therein, and therefore, the shape of each of the meta structures 110G is a circle having a rectangular hole therein when viewed from above. In FIG. 2H, each of the meta structures 110H is a rectangular parallelepiped having a cylindrical bore therein, and therefore, the shape of each of the meta structures 110H is a rectangle having a circular hole therein when viewed from above.

[0028] Also, the metastructure may include more than two layers, such as metastructures 110I-110L, as shown in Figures 2I-2L. The more layers, the thinner the overall thickness of the metastructure. In Figure 2I, each of the metastructures 110I includes four layers 111I-114I. In Figure 2J, each of the metastructures 110J includes five layers 111J-115J. In Figures 2I and 2J, the odd layers (i.e., layers 111I and 113I, or layers 111J, 113J, and 115J) have the same refractive index, and the even layers (i.e., layers 112I and 114I, or layers 112J and 114J) have the same refractive index that is different from the refractive index of the odd layers. That is, each of the metastructures 110I and 110J has two different refractive indexes in an alternating arrangement.

[0029] In FIG. 2K and FIG. 2L, each of the metastructures 110K and 110L includes five layers 111K-115K having two or more different refractive indices. For example, in FIG. 2K, the layer having the highest refractive index is the second highest layer 112K, and the layers adjacent to the second highest layer 112K (i.e., the highest layer 111K and the third highest layer 113K) have different refractive indices. That is, each of the metastructures 110K has two or more different refractive indices in a random arrangement. In FIG. 2L, the layer having the highest refractive index is the third highest layer 113L, and the layers adjacent to the third highest layer 113L (i.e., the second highest layer 112L and the fourth highest layer 114L) have the same refractive index. Furthermore, the thickness of the layer 112K is different from the thickness of the layers adjacent to the layer 112K (i.e., the layers 111K and 113K).

[0030] In summary, the shape of each of the metastructures (e.g., metastructures 110A-110L) can be adjusted by the thickness of each layer of each of the metastructures, the number of layers of each of the metastructures, the difference between the refractive indices, the number of refractive indices, and the arrangement of layers with different refractive indices of the metastructures. In some embodiments, the shape of each of the metastructures can be circular, elliptical, polygonal, or hollow polygonal in top view. In some embodiments, the thickness of each of the stacks can be controlled. In some embodiments, the thickness of the layer with the lower refractive index can be greater than the thickness of the layer with the higher refractive index. In some embodiments, there can be two or more layers. In some embodiments, if the number of layers is increased, the total thickness of the metastructure is decreased. In some embodiments, the difference between the refractive indices can be between 0.1 and 2.5. In some embodiments, each of the metastructures includes two or more refractive indices. In some embodiments, the layers with the same refractive index are alternately arranged or irregularly arranged.

[0031] Next, as shown in FIG. 3A to FIG. 3E, FIG. 3A to FIG. 3E show the relationship between the efficiency and wavelength of the incident wave of several different metastructures. In order to select a suitable metastructure, the criteria can be arbitrarily set. For example, the efficiency criteria can be set to a certain value or more to find the applicability and / or specific value of the wavelength range of interest for various applications. For example, the specific value of the efficiency criteria can be set to, but is not limited to, 0.6, 0.8, 0.9 or more. The specific value of the efficiency criteria can be set according to the actual requirements, such as the performance requirements of the meta-optical device. In some embodiments, when the range of wavelengths of the incident wave is considered as the applicable range, the efficiency is definitely higher than, but is not limited to, 0.6. In some embodiments, the specific value of the wavelength can be determined according to the highest efficiency.

[0032] 3A-3C can be used to evaluate the effect of the difference between the refractive indices. In particular, FIG. 3A-3C can be obtained from metastructures having all the same parameters except for the difference between the highest and second highest refractive indices. For example, the difference between the highest and second highest refractive indices can be maximum in FIG. 3A and minimum in FIG. 3C. For example, the difference between the highest and second highest refractive indices can be, but is not limited to, about 0.5 in FIG. 3A, about 1.7 in FIG. 3B, and about 2.0 in FIG. 3C, respectively.

[0033] In some embodiments, Figure 3A has the widest applicable range of the wavelength of the incident wave among Figures 3A to 3C. For example, when the criterion is set to 0.6 or more, the applicable range of the wavelength of the incident wave can be between about 450 nm and 620 nm in Figure 3A, about 550 nm and 700 nm in Figure 3B, and about 530 nm and 580 nm in Figure 3C, respectively. On the other hand, when the incident wave has only a single incident wavelength, the specific value of the wavelength of the incident wave can be about 580 nm in Figure 3A, about 620 nm in Figure 3B, and about 690 nm in Figure 3C, respectively.

[0034] 3D and 3E can be used to evaluate the effect of the arrangement of the stack of metastructures. In particular, FIG. 3D and FIG. 3E can be obtained from metastructures having all the same parameters except for the position of the layer with the highest refractive index. For example, the layer with the highest refractive index can be the second highest layer in FIG. 3D and the third highest layer in FIG. 3E, such as, but not limited to, metastructures 110K and 110L shown in FIG. 2K and FIG. 2L. As shown in FIG. 3D and FIG. 3E, the applicable range and the specific value of the wavelength of the incident wave are different. For example, if the criterion is set to 0.6 or more, the applicable range of the wavelength of the incident wave can be between about 410 nm to 470 nm in FIG. 3D and 500 nm to 600 nm in FIG. 3E, respectively. On the other hand, if the incident wave has only a single incident wavelength, the specific value of the wavelength of the incident wave can be about 450 nm in FIG. 3D and about 540 nm in FIG. 3E, respectively.

[0035] In summary, appropriate metastructures can be selected based on the actual requirements, such as the wavelength ranges targeted in different applications (e.g., visible light covers the wavelength range of about 400 nm to 750 nm), the required efficiency, etc.

[0036] Furthermore, in some embodiments, the geometry, size, and orientation of the metastructures may vary. As shown in FIG. 4A-FIG. 4C, for ease of illustration, but not limited to, the metastructures 110X-110Z of the meta-optical devices 100X-100Z of FIG. 4A-FIG. 4C are three-layer structures. FIG. 4A shows a schematic representation of the geometrical variation of the metastructures 110X. As shown in FIG. 4A, each of the metastructures 110X has two sides with different included angles 115X. FIG. 4B shows a schematic representation of the size variation of the metastructures 110Y. As shown in FIG. 4B, the metastructures 110Y gradually expand such that the largest metastructures 110Y are located in the peripheral regions of the array of metastructures 110Y. In some other embodiments, the largest metastructures 110Y are located in the central region, rather than the peripheral regions, of the array of metastructures 110Y. FIG. 4C shows a schematic representation of the orientation variation of the metastructures 110Z. As shown in FIG. 4C, each of the metastructures 110Z can have the same shape and size, but have different spatial orientations. In some embodiments, each metastructure 110Z is rotated the same amount (also Δθ degrees) from its previous, adjacent metastructure 110Z on the line. In some embodiments, Δθ can be a factor of 360 degrees. For example, Δθ can be 15 degrees, 30 degrees, 45 degrees, etc.

[0037] By adjusting the geometry, size, and orientation of the metastructures (e.g., metastructures 110A-110L and metastructures 110X-110Z), the bending of the incident wave can be controlled in any manner. As shown in FIG. 4D, the bending of the incident wave is controlled at an incident angle θ of about 15 degrees. in 4D, the meta-optical device 100 of the present disclosure modulates the wavefront of the incident wave W. The incident angle θ of the incident wave W is in It should be understood that is only one example. Phase correction of an incident wave W having almost any angle of incidence can be achieved. In such a situation, meta-optical device 100 is used as a phase corrector. Compared to the central region of optical system 1, the angle of incidence θ incan be relatively large in the peripheral regions of the optical system 1. Therefore, at larger angles of incidence θ in To correct for this, the number of optical devices 100 arranged in the peripheral region of the optical system 1 may be greater than the number of optical devices 100 arranged in the central region of the optical system 1 .

[0038] Next, it will be understood how the meta-optical device 100 is used as an aberration corrector, as shown in Figures 5A to 5E. In particular, the meta-structure of the meta-optical device can correct the aberration, for example, the dispersion of the meta-structure can correct the aberration. Figures 5A to 5C show a schematic simulation for reducing the aberration. Figures 5D and 5E show a schematic result of the aberration correction of the incident wave W. Below and in Figures 5A to 5E, as a basis for the simulation, the original incident angle θ1 of the incident wave W is set to 35 degrees, and the corrected angle θ2 of the wave exiting the metal optical device 100 is set to 20 degrees, but only as an example. Phase changes of the incident wave W with almost any incident angle and any correction angle can be achieved. It should be noted that the camera 10 may also include one or more module lenses designed to correct the aberration. Based on the present disclosure, the module lenses in the camera 10 may not need to be designed to correct all types of aberrations. In some embodiments, meta-optical device 100 can correct aberrations individually. In some embodiments, both meta-optical device 100 and a module lens in camera 10 can correct aberrations. For example, some aberrations (e.g., higher order aberrations (HOA)) are corrected via meta-optical device 100, and the remaining aberrations are corrected via a module lens of camera 10. Thus, manufacturing flexibility can be improved. Additionally or alternatively, manufacturing costs can be reduced, and the dimensions of the module lens and / or the entire camera 10 can also be reduced, thereby achieving compactness.

[0039] As shown in FIG. 5A, the X-axis (x-position) represents the distance between the position and the midpoint, and the Y-axis (phase) represents the amount of aberration correction required. That is, for any position, the amount of aberration correction required can be calculated and determined. Since the position can also be determined, it can be called the desired position. In some embodiments, the distance between the desired position of the meta-optical device and the image sensor is between 10 μm and 3 mm, for example, between 1 mm and 3 mm.

[0040] 5B and 5C are enlarged views of FIG. 5A, which shows the amount of aberration correction required at positions A and B. The positions in FIG. 5A are shown in millimeters, while the positions in FIGS. 5B and 5C are shown in micrometers. The geometry, size, or orientation of the metastructures may also be adjusted to help achieve the aberration correction. As shown in FIGS. 5D and 5E, after the amount of aberration correction required at the desired positions (e.g., positions A and B in FIG. 5A) is determined, the meta-optical device 100 may be positioned at the desired positions to achieve the required aberration correction.

[0041] FIG. 6 is a flow chart of a method 600 of aberration correction. The method 600 includes four steps 601-604. In step 601, the method 600 includes calculating a required amount of aberration correction. In step 602, the method 600 includes determining a desired position of a meta-optical device (e.g., meta-optical device 100) located near an image sensor (e.g., image sensor 20), the distance between the meta-optical device and the image sensor being between 10 μm and 3 mm. The meta-optical device includes an array of meta-structures, each of the meta-structures including a stack of multiple layers including at least a first layer having a first refractive index and a second layer having a second refractive index. The first refractive index and the second refractive index are different. In step 603, the method 600 includes determining and / or adjusting a geometry, size, or orientation of the meta-structures. In step 604, the method 600 further includes placing the meta-optical device according to the required amount and the desired position.

[0042] As described above, a meta-optical device is provided. The meta-optical device includes an array of meta-structures, each of which includes a stack of multiple layers with different refractive indices. The different refractive indices allow for both refraction and absorption of the incident wave, thus improving image quality as well as efficiency. Also, the thickness of the multi-layer meta-structure can be reduced, which makes the manufacturing more feasible due to the relatively small aspect ratio. Also, the shape of each meta-structure, the thickness of each layer of each meta-structure, the number of layers of each meta-structure, the difference between the refractive indices, the number of refractive indices, and the arrangement of the layers with different refractive indices of the meta-structure can be adjusted.

[0043] Furthermore, the meta-optical device can provide two optical functions, phase correction and aberration correction. When the meta-optical device is used as a phase corrector, the phase of the incident wave can be modulated. When the meta-optical device is used as an aberration corrector, the performance and / or image quality of the image sensor can be improved. The function of the meta-optical device can be determined by its position relative to the image sensor. The distance between the meta-optical device and the image sensor can be 3 mm or less.

[0044] The foregoing outlines the features of some embodiments so that those skilled in the art can better understand the aspects of the present disclosure. Those skilled in the art can easily understand that the present disclosure can be used as a basis for designing or modifying other processes and structures to carry out the same purpose and / or achieve the same advantages of the embodiments introduced herein. Those skilled in the art should also understand that such equivalent structures do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the present disclosure. Moreover, the scope of the present disclosure is not limited to the specific embodiments described herein, and each claim constitutes a separate embodiment, and combinations of the various claims and embodiments are within the scope of the present disclosure. [Explanation of symbols]

[0045] 1 Optical system 10. Camera 20 Image Sensor 21 Microlens 22 Color Filter 23 Optical Sensor Layer 24 Insulating metal layer 25 Silicon Transistor 50 Filters 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H, 100I, 100J, 100K, 100L, 100X, 100Y, 100Z Meta-Optical Devices 110, 110A, 110B, 110C, 110D, 110E, 110F, 110G, 110H, 110I, 110J, 110K, 110L, 110X, 110Y, 110Z Metastructure 111A First Layer 112A Second Layer 113A Third Layer 111I, 112I, 113I, 114I, 111J, 112J, 113J, 114J, 115J, 111K, 112K, 113K, 114K, 115K, 111L, 112L, 113L, 114L, 115L layer 115X included angle 600 ways Steps 601, 602, 603, 604 D diameter T1 First thickness T2 Second thickness T3 Third thickness W incident wave θ1 Origin angle of incidence θ2 corrected angle θ in angle of incidence Δθ Angle change

Claims

1. A meta-optical device disposed inside or on top of an image sensor and used for phase correction and aberration correction of a wave incident on the image sensor, comprising: an array of metastructures, each of said metastructures comprising a stack of a plurality of layers including at least a first layer having a first refractive index and a second layer having a second refractive index, each layer of said stack having the same shape and size in a top view, said first refractive index and said second refractive index being different, a difference between said first refractive index and said second refractive index being between 0.5 and 1.8; A meta-optical device, wherein depending on the position of the meta-optical device relative to the image sensor, the meta-optical device provides a phase correction function and / or an aberration correction function.

2. A meta-optical device disposed inside or on top of an image sensor and used for phase correction and aberration correction of a wave incident on the image sensor, comprising: the array of metastructures, each of the metastructures comprising a stack of multiple layers including at least a first layer having a first refractive index and a second layer having a second refractive index, the first refractive index and the second refractive index being different, the metastructures comprising a dielectric material, each of the metastructures being circular in a top view, each layer of the stack having the same size in a top view, and having an aspect ratio of 10 or less; A meta-optical device, wherein depending on the position of the meta-optical device relative to the image sensor, the meta-optical device provides a phase correction function and / or an aberration correction function.

3. 2. The meta-optical device of claim 1 , wherein the stack further comprises a third layer having a third refractive index, the third refractive index being different from the second refractive index, the second layer being located between the first layer and the third layer, the second refractive index being greater than the first refractive index and the third refractive index, and the first refractive index being equal to the third refractive index.

4. 2. The meta-optical device of claim 1 , wherein the stack further comprises a third layer having a third refractive index, the third refractive index being different from the second refractive index, the second layer being located between the first layer and the third layer, a first thickness of the first layer being different from a second thickness of the second layer, the first thickness and a third thickness of the third layer being greater than the second thickness, and the first thickness being equal to the third thickness.

5. The meta-optical device of claim 1 , wherein each of the metastructures has a shape that, in a top view, is circular, elliptical, polygonal, or hollow polygonal, the metastructures are arranged in a rectangular or hexagonal array, and the metastructures include different geometric shapes, sizes, or orientations.

6. 10. The meta-optical device of claim 1, wherein said stack further comprises a plurality of odd layers having said first refractive index and a plurality of even layers having said second refractive index.

7. A plurality of microlenses; a plurality of color filters disposed under the microlenses; and A meta-optical device is disposed between the microlens and the color filter or above the microlens, and is used for phase correction and aberration correction of a wave incident on the image sensor; The meta-optical device comprises: an array of metastructures, each of said metastructures comprising a stack of a plurality of layers including a first layer having a first refractive index and a second layer having a second refractive index, each layer of said stack having the same shape and size in a top view, said first refractive index and said second refractive index being different, and a difference between said first refractive index and said second refractive index being between 0.5 and 1.8; An optical system, wherein the meta-optical device provides phase correction and / or aberration correction functionality depending on the position of the meta-optical device relative to the image sensor.

8. The optical system described in claim 7, wherein the meta-optical device is used as a phase corrector when the meta-optical device is positioned between the microlens and the color filter, or when the meta-optical device is positioned on top of the microlens and the distance between the bottom surface of the meta-optical device and the top surface of the image sensor is 10 μm or less.

9. The optical system described in claim 7, wherein the meta-optical device is used as a combination phase corrector and aberration corrector, when the meta-optical device is positioned on top of a microlens and the distance between the bottom surface of the meta-optical device and the top surface of the image sensor is between 10 μm and 1 mm.

10. The optical system described in claim 7, wherein the meta-optical device is used as an aberration corrector when the meta-optical device is positioned on top of the microlens and the distance between the bottom surface of the meta-optical device and the top surface of the image sensor is between 1 mm and 3 mm.

11. A step of calculating an amount required for aberration correction of a wave incident on an image sensor; determining a desired position for a meta-optical device to be placed near the image sensor, a distance between the meta-optical device and the image sensor being between 10 μm and 3 mm, the meta-optical device comprising an array of meta-structures, each of the meta-structures comprising a stack of multiple layers including at least a first layer having a first refractive index and a second layer having a second refractive index, each layer of the stack having the same top view shape and size, the first refractive index and the second refractive index are different, and a difference between the first refractive index and the second refractive index is between 0.5 and 1.8; adjusting the geometry, size, or orientation of the metastructure; and A method of aberration correction comprising positioning said meta-optical device in accordance with said required amount and said desired position.

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