Metasurface optical device
By designing metasurface optical devices with pillar arrays on the substrate, the aberration problems existing in traditional lenses and the lack of flexibility in light wavefront manipulation are solved, enabling flexible manipulation of light waves and miniaturization and quality improvement of optical systems.
Patent Information
- Application Number
- CN202323137008.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Priority Date
- 2022-04-19
- Filing Date
- 2023-04-13
- Publication Date
- 2025-01-21
- Estimated Expiration
- 2033-04-13
AI Technical Summary
Traditional lenses in existing optical systems have aberration problems and are difficult to achieve flexibility and miniaturization of optical wavefront manipulation.
The pillar array on the substrate is used as a metasurface optical device, and the diffraction, interference and polarization manipulation of light waves are achieved through the design of the diameter, spacing and outer coating of the pillars.
It achieves light wavefront manipulation without the thickness of traditional lenses, overcomes the aberration problem of traditional lenses, and can adapt to a wider range of optical needs, achieving system miniaturization and quality improvement.
Smart Images
Figure CN222379907U_ABST
Abstract
Description
[0001] This application is a divisional application of an application with application date of 2023 / 04 / 13, application number 202320823210.5, and name “Metasurface Optical Device”. Technical Field
[0002] The utility model relates to an optical super surface. Background Art
[0003] Optical metasurfaces can manipulate light wavefronts without traditional lenses. They can include structures on or in a substrate, such as pillars, ribs or holes with subwavelength dimensions.
[0004] These structures can vary in size, shape, and spacing on the surface of the substrate. Each structure size, shape, and spacing can provide a unique electromagnetic response. Metasurfaces can provide the desired wavefront manipulation (phase, polarization, and amplitude) of light without the thickness of a traditional lens. Metasurfaces can overcome the aberration problems of traditional lenses.
[0005] Metasurface structures with sizes comparable to the wavelength of light can diffract incident light. These structures can be of nanometer dimensions. Rather than relying on curvature like traditional lenses, optical metasurfaces rely on the size and pattern of the structures to diffract light into a desired pattern. The diffracted light waves can interfere with each other to form a desired, altered wavefront.
[0006] Metasurfaces can focus light, collimate light, diffract light, diffuse light, change the polarization of light, or separate white light into many different colors. Metasurfaces can be used to miniaturize and improve the quality of optical systems. Metasurfaces can reduce the number of optical components in a system. Metasurfaces can accommodate a wider range of needs than traditional lenses. Metasurfaces can be used to detect light intensity, depth sensing, imaging, photosensitive electronics, microspectroscopy, security, and cryptography. Summary of the invention
[0007] The metasurface optical device may include an array of pillars on a substrate, including pillars of different diameters from each other. Each pillar may have a proximal end closest to the substrate and a distal end farthest from the substrate. An outer coating may be located at the distal end of the pillar, or a filling material may be located between the pillars. The outer coating may span the gaps between the pillars. The filling material may fill the gaps between the pillars. The outer coating or the filling material may be transparent and solid.
[0008] The first aspect of the utility model relates to a metasurface optical device, characterized in that the metasurface optical device comprises: an array of pillars on a substrate, comprising pillars with different diameters from each other; each pillar has a proximal end closest to the substrate and a distal end farthest from the substrate; and an outer coating located at the distal end of the pillar, the outer coating spanning the gaps between the pillars, and the outer coating is transparent and solid.
[0009] In one embodiment, the pitch between adjacent pillars is non-uniform throughout the array of pillars.
[0010] In one embodiment, the outer coating extends down the sidewall of the post for a distance of ≤ 90% from the distal end to the proximal end.
[0011] In one embodiment, the outer coating extends down the sidewall of the post for a distance of ≥5% and ≤90% from the distal end to the proximal end.
[0012] In one embodiment, the different pillars having different diameters include at least five different pillars having different diameters from each other.
[0013] In one embodiment, the proximal end of the post lies in a proximal plane, and the distal end of the post lies in a distal plane.
[0014] In one embodiment, the pillars are transparent in the visible spectrum.
[0015] In one embodiment, each pillar has a thickness of ≥100nm and ≤2μm measured perpendicular to the substrate; each pillar has a diameter of ≥25nm and ≤750nm; the pitch between adjacent pillars is ≥75nm and ≤2μm; and the outer coating has a thickness of ≥50nm and ≤750nm measured perpendicular to the substrate.
[0016] In one embodiment, the gap is filled with air.
[0017] In one embodiment, the pillars have a uniform thickness, and the thickness is measured perpendicular to the substrate. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 is a top view of a metasurface optical device 10 having an array of pillars P on a substrate 11. The pillars P may have diameters different from each other. The gaps G between adjacent pillars P may be uniform. The pitch may be different.
[0019] Figure 2 2 is a cross-sectional side view of a metasurface optical device 20, including an outer coating 21 on the metasurface optical device 10. The cross-sectional side view of the metasurface optical device 10 is taken along Figure 1 Intercepted at line 2-2.
[0020] Figure 3 is a top view of a metasurface optical device 30 having an array of pillars P on a substrate 11. The pillars P may have diameters that are different from each other. The pitch between adjacent pillars P may be uniform. The gap sizes may vary.
[0021] Figure 4 4 is a cross-sectional side view of a metasurface optical device 40, including an outer coating 21 on a metasurface optical device 30. The cross-sectional side view of the metasurface optical device 30 is taken along Figure 3 Intercepted at line 4-4.
[0022] Figure 5 is a cross-sectional side view of a metasurface optical device 50, including a filling material 51 filling the gaps G between the pillars P of the metasurface optical device 10. The cross-sectional side view of the metasurface optical device 10 is taken along Figure 1 Intercepted at line 2-2.
[0023] Figure 6 60, including filler material 51 filling most of the gaps G between the posts P of the metasurface optical device 30. The cross-sectional side view of the metasurface optical device 30 is shown along Figure 3 Intercepted at line 4-4.
[0024] Reference numerals in the drawings
[0025] Metasurface Optics 10, 20, 30, 40, 50 and 60
[0026] Substrate 11
[0027] Outer coating 21
[0028] Filling material 51
[0029] The outer coating 21 extends downward along the side wall by a distance D
[0030] Remote DE
[0031] Distal plane DP
[0032] Gap G
[0033] The gap G1 between the smallest diameter column P1 and the closest adjacent column P
[0034] The gap G5 between the largest diameter column P5 and the nearest adjacent column P
[0035] Pillar P
[0036] Pillars P1, P2, P3, P4 and P5 with diameters D1, D2, D3, D4 and D5 respectively
[0037] The pitch between the two smallest pillars P1 is P11
[0038] The pitch P12 between the pillar P1 and the adjacent pillar P2
[0039] The pitch P15 between the pillar P1 and the adjacent pillar P5
[0040] Pitch P55 between the two largest columns P5
[0041] Proximal PE
[0042] Proximal plane PP
[0043] The thickness of the column P is Th
[0044] Thickness T21 of the outer coating layer 21
[0045] As used herein, the phrase "equal spacing" means that the spacing is exactly equal; the spacing is equal within normal manufacturing tolerances; or the spacing is almost exactly equal, so that the effect of any deviation from the exact equality of the spacing is negligible for normal use of the device.
[0046] As used herein, uniform gap means completely uniform; uniform within normal manufacturing tolerances; or nearly completely uniform, such that the effect of any deviation from completely uniform is negligible for normal use of the device.
[0047] As used herein, the terms "on," "on," "located," and "over" mean directly above or located with some other solid material therebetween. The terms "directly on" and "adjacent" mean direct and immediately adjacent contact. DETAILED DESCRIPTION
[0048] like Figure 1-6 As shown, metasurface optical devices 10, 20, 30, 40, 50, and 60 include an array of posts P on a substrate 11. The following two paragraphs summarize the comparative advantages between these various devices, followed by their illustrative details.
[0049] Metasurface optics 10 and 20 are superior to optics 30 and 40 because optics 10 and 20 have a variable pitch to achieve a more uniform gap G between posts P. Thus, the outer coating 21 can extend a consistent distance down the sidewalls of posts P in metasurface optic 20 .
[0050] Metasurface optics 50 is superior to metasurface optics 60 because metasurface optics 50 has a variable pitch to achieve a more uniform gap G between posts P. This allows filler material 51 to more uniformly fill the gaps G between posts P of metasurface optics 50. Note that metasurface optics 60 may have undesirable air pockets between posts P that are spaced closer together.
[0051] Each pillar P may have a proximal end PE closest to the substrate 11 and a distal end DE farthest from the substrate 11. Figure 2 As shown, the pillars P may have a uniform thickness Th in the array, the thickness Th being measured between the proximal end PE and the distal end DE. The proximal end PE of the pillars P may be located in a proximal plane PP, and the distal end DE of the pillars P may be located in a distal plane DP.
[0052] The array of pillars P may include different pillars P with different diameters from each other. Five different pillars P1, P2, P3, P4 and P5 are shown, each having different diameters D1, D2, D3, D4 and D5. The present invention may include any number of different pillars P with different diameters. For example, there may be ≥2, ≥3, ≥4 or ≥5 different pillars P with different diameters from each other. The pillars P with different diameters may interact with incident light to provide unique electromagnetic responses, such as light collimation, imaging, light aberration correction, and focusing each polarization of light separately.
[0053] The different diameters can be very different from each other to achieve the desired optical effect. The following are example relationships between the diameter D5 of the largest diameter pillar P5 and the diameter D1 of the smallest diameter pillar P1 to achieve the above purposes: D5 / D1≥1.5, D5 / D1≥2, D5 / D1≥3, or D5 / D1≥4; and D5 / D1≤6, D5 / D1≤10 or D5 / D1≤25. Each application and wavelength range will have a different pillar P relationship. Both diameters D5 and D1 are measured at the midpoint between the proximal end PE and the distal end DE. If the pillar P is not circular (parallel to the surface of the substrate 11), the diameter is the minimum distance from one edge of the pillar P to the opposite edge of the pillar P.
[0054] like Figure 2 and Figure 4 As shown, the outer coating 21 can be located at the distal end DE of the pillars P. The outer coating 21 can span the gaps G between the pillars P. The outer coating 21 can be transparent in the ultraviolet spectrum, the visible spectrum, the infrared spectrum, or a combination thereof. The outer coating 21 can be solid. The outer coating 21 can protect the pillars P.
[0055] The outer coating layer 21 may be formed by sputtering deposition. Due to the small gap G, only a negligible amount of the outer coating layer 21 or no outer coating layer 21 may reach the substrate 11 between the pillars P.
[0056] The outer coating 21 may extend partially downward along the sidewall of the pillar P. For example, the outer coating 21 may extend downward along the sidewall of the pillar P by a distance D that is ≥5%, ≥10%, ≥25%, ≥50%, or ≥75% of the thickness Th of the pillar P. As another example, the outer coating 21 may extend downward along the sidewall of the pillar P by a distance D that is ≤25%, ≤50%, ≤75%, or ≤90% of the thickness Th of the pillar P. The distance D that the outer coating 21 extends downward along the sidewall of the pillar P of the metasurface optical device 20 is approximately 20% of the thickness Th of the pillar P, with negligible variations.
[0057] A disadvantage of the metasurface optical device 40 is that the distance D that the outer coating 21 extends down the sidewall of the pillar P can vary greatly. This is a result of the uniform pitch and variable size gaps G in the metasurface optical device 30. Such large variations in the distance D of the outer coating 21 on the sidewalls can result in variations in the refractive index in the gaps G across the device. These variations can interfere with the desired optical effect.
[0058] On metasurface optical device 40, the average distance D that overcoat 21 extends down the sidewall of post P is 38% of the thickness Th of post P. The distance D that overcoat 21 extends down the sidewall of post P varies from 3% to 78%.
[0059] In contrast, the distance D that the outer coating 21 extends down the sidewalls of the pillars P of the metasurface optical device 20 varies negligibly. This negligible variation in the outer coating 21 on the sidewalls results in a consistent proportion of the outer coating filling the gaps G on the device. This can better achieve the desired optical effect.
[0060] The negligible variation in distance D is a result of the uniformly sized gaps G and the variable pitch in the metasurface optical device 10. Thus, in the optical devices 10 and 20, the array of posts is uniform with respect to the gaps G between each post P and the closest neighboring post P (i.e., the nearest neighboring post P).
[0061] Thus, by designing the gap G to be uniformly sized, the overcoat 21 can extend a consistent distance down the sidewall of the pillar P. For example, the distance of the overcoat 21 down the sidewall can vary across the device by + / -3%, + / -5%, + / -10%, or + / -15% from the average distance D of the overcoat 21 down the sidewall.
[0062] Therefore, a metasurface optical device 10 having posts P that are equally spaced from one another is preferred. The benefits of minimal variation in the distance D that the overcoat 21 extends down the sidewalls of the posts P can be achieved, however, with some small variation in the posts P spacing.
[0063] The following are example gap G relationships for achieving this minimum change in distance D: G1 / G5≤1.2, G1 / G5≤1.5, G1 / G5≤2, or G1 / G5≤5; and G5 / G1≤1.2, G5 / G1≤1.5, G5 / G1≤2, or G5 / G1≤5. G1 is the gap between the smallest diameter post P1 and the nearest neighboring post P to P1. G5 is the gap between the largest diameter post P5 and the nearest neighboring post P to P5. G1 and G5 are measured as the minimum straight line path from the midpoint between the proximal end PE and the distal end DE to the nearest neighboring post. For metasurface optics 10 and 20, G1 / G5 is approximately equal to 1. For metasurface optics 30 and 40, G1 / G5 is approximately equal to 15.
[0064] A reduction in the distance D that the outer coating 21 covers the sidewalls can be achieved by adjusting the pitch between the pillars P.
[0065] The pitches between posts P in metasurface optics 30 and 40 are approximately equal. For example, the pitch P12 between post P1 and adjacent post P2 is approximately the same as the pitch P15 between post P1 and adjacent post P5. Metasurface optics 40 has the disadvantage of variable distance D of outer coating 21 down the sidewall due to uniform pitch and variable gap G.
[0066] In contrast, in metasurface optical devices 10 and 20, the pitch varies to achieve a consistent distance D of the outer coating 21 down the sidewall. The pitch between adjacent smaller pillars P can be smaller than the pitch between adjacent larger pillars P. For example, P55 / P11=1.9, where P55 is the pitch between the two largest pillars P5, and P11 is the pitch between the two smallest pillars P1. Thus, the pitch P55 between the two largest pillars can be at least 1.2, at least 1.5, or at least 2 times greater than the pitch P11 between the two smallest pillars.
[0067] like Figure 5-6 As shown, the metasurface optical devices 50 and 60 may include a filling material 51 between the pillars P, and the filling material 51 may fill the gaps G between the pillars P. The filling material 51 may be transparent within the wavelength range of the intended use, such as the ultraviolet spectrum, the visible spectrum, the infrared spectrum, or a combination thereof. The filling material 51 may be solid. The filling material 51 may provide better protection for the pillars P than the outer coating 21; however, compared with the outer coating 21, the filling material 51 may impair the performance of the device.
[0068] Metasurface optical device 50 is superior to metasurface optical device 60. Metasurface optical device 50 has equal spacing between posts P. This can result in more uniform filling of the gaps G between posts P. The gaps G can be completely filled with filling material 51. The spacing characteristics of posts P described above for metasurface optical device 20 can be used for metasurface optical device 50.
[0069] The metasurface optics 60 has equal pitches between adjacent posts P, but unequal gaps G. Therefore, there may be air gaps / voids 61 lacking the filling material 51. The reason is that it is difficult to adjust the application of the filling material 51 to fill wide and narrow gaps G.
[0070] This paragraph includes example dimensions for components of the metasurface optics described herein. Each pillar P may have a thickness Th ≥ 100 nm and ≤ 2 μm (see Figure 2 Each pillar P may have a diameter D1, D2, D3, D4 or D5 of ≥25 nm and ≤750 nm (see Figure 1 and Figure 3 ). The pitch P11, P12, P15 or P55 of adjacent pillars P may be ≥75nm and ≤2μm (see Figure 1 and Figure 4 The outer coating layer 21 may have a thickness T21 of ≥50 nm and ≤750 nm (see Figure 2 ). The thickness Th and T21 are measured perpendicular to the substrate 11.
[0071] This section includes example materials for components of the metasurface optics described herein. For transparent metasurface optics, substrate 11 may include glass, silicon, or both. For reflective metasurface optics, substrate 11 may be metallic. For example, substrate 11 may include aluminum. Pillars P may be made of the same material as the substrate, or may be made of a different material. Pillars P are typically transparent over the wavelength range used. Pillars P may include niobium oxide, silicon, glass, silicon nitride, titanium oxide, or a combination thereof. The outer coating 21 is typically transparent over the wavelength range used. The outer coating 21 may include silicon dioxide.
Claims
1. A metasurface optical device, characterized in that: The metasurface optical device comprises: an array of pillars on a substrate, comprising pillars having diameters that are different from one another; Each post has a proximal end closest to the substrate and a distal end farthest from the substrate; and an outer coating at the distal ends of the pillars, the outer coating spanning the gaps between the pillars, the outer coating being transparent and solid, Wherein, the metasurface optical device has a variable pitch to achieve uniform gaps between the pillars.
2. The metasurface optical device according to claim 1, characterized in that: The outer coating extends down the sidewall of the pillar for a distance that is ≤ 90% of the thickness of the pillar.
3. The metasurface optical device according to claim 1, characterized in that: The outer coating extends down the sidewall of the post for a distance of ≥5% and ≤90% from the distal end to the proximal end.
4. The metasurface optical device according to claim 1, characterized in that: The pillars having different diameters from each other include at least five pillars having different diameters from each other.
5. The metasurface optical device according to claim 1, characterized in that: The proximal end of the post lies in a proximal plane, and the distal end of the post lies in a distal plane.
6. The metasurface optical device according to claim 1, characterized in that: In the visible spectrum, the pillars are transparent.
7. The metasurface optical device according to claim 1, characterized in that: Each pillar has a thickness measured perpendicular to the substrate of ≥100 nm and ≤2 μm; Each pillar has a diameter of ≥25 nm and ≤750 nm; The pitch between adjacent pillars is ≥75nm and ≤2μm; and The overcoat layer has a thickness measured perpendicular to the substrate of ≥50 nm and ≤750 nm.
8. The metasurface optical device according to claim 1, characterized in that: The pillars have a uniform thickness, and the thickness is measured perpendicular to the substrate.