Metasurfaces with asymmetric gratings for redirecting light and methods for fabricating
First Claim
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1. An optical system comprising:
- an optically transmissive substrate comprising a multi-level metasurface comprising a lower level and an upper level, the lower-level comprising, as seen in a top-down cross-sectional view;
a plurality of unit cells, each unit cell comprising;
a laterally-elongated first nanobeam having a first width; and
a laterally-elongated second nanobeam spaced apart from the first nanobeam, the second nanobeam having a second width larger than the first width,wherein heights of the first and the second nanobeams are in a range between 10 nm to 450 nm, andwherein the upper-level comprises a layer of material on a top of each of the first and the second nanobeams, wherein material forming the layer of material is different from material forming either of the first or the second nanobeams.
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Abstract
An optical system comprises an optically transmissive substrate comprising a metasurface which comprises a grating comprising a plurality of unit cells. Each unit cell comprises a laterally-elongated first nanobeam having a first width; and a laterally-elongated second nanobeam spaced apart from the first nanobeam by a gap, the second nanobeam having a second width larger than the first width. A pitch of the unit cells is 10 nm to 1 μm. The heights of the first and the second nanobeams are: 10 nm to 450 nm where a refractive index of the substrate is more than 3.3; and 10 nm to 1 μm where the refractive index is 3.3 or less.
84 Citations
51 Claims
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1. An optical system comprising:
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an optically transmissive substrate comprising a multi-level metasurface comprising a lower level and an upper level, the lower-level comprising, as seen in a top-down cross-sectional view; a plurality of unit cells, each unit cell comprising; a laterally-elongated first nanobeam having a first width; and a laterally-elongated second nanobeam spaced apart from the first nanobeam, the second nanobeam having a second width larger than the first width, wherein heights of the first and the second nanobeams are in a range between 10 nm to 450 nm, and wherein the upper-level comprises a layer of material on a top of each of the first and the second nanobeams, wherein material forming the layer of material is different from material forming either of the first or the second nanobeams. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for forming a multi-level metasurface, the method comprising:
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providing an optically transmissive substrate; providing an optically transmissive layer over the substrate; and patterning the optically transmissive layer to define a plurality of unit cells on a lower level of the metasurface, each unit cell comprising, as seen in a top-down view; a laterally-elongated first nanobeam having a first width; and a laterally-elongated second nanobeam spaced apart from the first nanobeam, the second nanobeam having a second width larger than the first width, wherein heights of the first and the second nanobeams are in a range between 10 nm to 450 nm, and forming an upper level of the metasurface by depositing a layer of material on a top of each of the first and the second nanobeams, wherein the material of the layer of material defines a gap between the first and the second nanobeams, wherein material forming the layer of material is different from material forming either of the first or the second nanobeams. - View Dependent Claims (22, 23, 24, 25, 26)
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27. An optical system comprising:
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an optically transmissive substrate comprising a multi-level metasurface comprising a lower level and an upper level, the lower-level comprising; a plurality of unit cells, each unit cell comprising, as seen in a top-down cross-sectional view; a laterally-elongated first nanobeam having a first width; and a laterally-elongated second nanobeam spaced apart from the first nanobeam, the second nanobeam having a second width larger than the first width, wherein a pitch of the unit cells is 10 nm to 1 μ
m,wherein the upper-level comprises a layer of material on a top of each of the first and the second nanobeams, wherein material forming the layer of material is different from material forming either of the first or the second nanobeams. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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48. A method for forming a multi-level metasurface, the method comprising:
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providing an optically transmissive substrate; providing an optically transmissive layer over the substrate; patterning the optically transmissive layer to define a grating comprising a plurality of unit cells on a lower level of the metasurface, each unit cell comprising, as seen in a top-down view; a laterally-elongated first nanobeam having a first width; and a laterally-elongated second nanobeam spaced apart from the first nanobeam, the second nanobeam having a second width larger than the first width, wherein a pitch of the unit cells is 10 nm to 1 μ
m, andforming an upper level of the metasurface by depositing a layer of material on a top of each of the first and the second nanobeams, wherein the material of the layer of material defines a gap between the first and the second nanobeams, wherein material forming the layer of material is different from material forming either of the first or the second nanobeams. - View Dependent Claims (49, 50, 51)
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Specification