Protective structures for manufacture of metasurfaces
The present disclosure describes techniques that, in some instances, can help reduce stress and potential damage during the manufacture of optical elements such as those that include a metastructure formed by imprinting. In one aspect, a method of manufacturing an optical element includes imprinting a stamp into a polymeric material on a substrate, wherein the stamp includes first projections corresponding to an active area of the stamp for formation of meta-atoms in the polymeric material. The stamp further includes a protective structure laterally surrounding the first projections. The protective structure includes at least one additional projection extending in parallel to the first projections. The method includes removing the stamp from the polymeric material, thereby forming openings in the polymeric material in positions corresponding to the first projections and in one or more positions corresponding to the at least one additional projection.
1 . An apparatus comprising:
an optical element comprising:
a metasurface including meta-atoms; and
a protective structure outside of an optically active area of the metasurface,
wherein the protective structure laterally surrounds the optically active area and is composed of a same material as the meta-atoms,
wherein the protective structure includes a plurality of substructures,
wherein the substructures are separated from one another and, collectively, laterally surround the optically active area, and
wherein the substructures are semi-annular shaped.
2 . The apparatus of claim 1 wherein the substructures include a plurality of groups of substructures, wherein adjacent substructures within each particular one of the groups are separated from another by a first distance, and wherein adjacent groups are separated from one another by a second distance that differs from the first distance.
3 . The apparatus of claim 2 wherein the second distance is greater than the first distance.
4 . The apparatus of claim 1 , wherein the substructures have a shape that differs from a shape of the meta-atoms.
5 . The apparatus of claim 1 , wherein the substructures have a height that differs from a height of the meta-atoms.
6 . The apparatus of claim 1 wherein the protective structure and the meta-atoms are composed of nanoparticles embedded in a curable polymer.
7 . A method of manufacturing an optical element, the method comprising:
imprinting a stamp into a polymeric material on a substrate, wherein the stamp includes first projections corresponding to an active area of the stamp for formation of meta-atoms in the polymeric material, the stamp further including a protective structure laterally surrounding the first projections, the protective structure including at least one additional projection extending in parallel to the first projections; and
removing the stamp from the polymeric material, thereby forming openings in the polymeric material in positions corresponding to the first projections and in one or more positions corresponding to the at least one additional projection,
wherein the protective structure of the stamp includes a plurality of second projections,
wherein the second projections are separated from one another and, collectively, laterally surround the active area of the stamp, and
wherein the second projections are semi-annular shaped.
8 . The method of claim 7 further including:
depositing a material in the openings in the polymeric material to form the meta-atoms of the optical element in the positions corresponding to the first projections and to form a protective structure of the optical element that laterally surrounds the meta-atoms.
9 . The apparatus of claim 5 , wherein the plurality of substructures have a height that is greater than a height of the meta-atoms.
10 . The apparatus of claim 5 , wherein the plurality of substructures have a height that is less than a height of the meta-atoms.
11 . The apparatus of claim 1 , wherein the plurality of substructures have a height that is substantially the same as a height of the meta-atoms.
12 . The apparatus of claim 1 , wherein the plurality of substructures have a pyramid shaped cross-section.
13 . The apparatus of claim 12 , wherein the meta-atoms have a rectangular shaped cross-section.
14 . The apparatus of claim 1 , wherein the plurality of substructures have a width that differs from a width of the meta-atoms.
15 . The apparatus of claim 14 , wherein the width of the plurality of substructures is greater than the width of the meta-atoms.
16 . The method of claim 7 , wherein the second projections have a shape that differs from a shape of the meta-atoms.
17 . The method of claim 16 , wherein the second projections have a pyramid shaped cross-section and the meta-atoms have a rectangular shaped cross-section.
18 . The method of claim 7 , wherein the second projections have a height greater than a height of the meta-atoms.
19 . The method of claim 7 , wherein the second projections have a height that is less than a height of the meta-atoms.
20 . The method of claim 7 , wherein the second projections have a height that is substantially the same as a height of the meta-atoms.
21 . The method of claim 7 , wherein the second projections have a width that differs from a width of the meta-atoms.
22 . The method of claim 21 , wherein the width of the second projections is greater than the width of the meta-atoms.
23 . An apparatus comprising:
an optical element comprising:
a metasurface including meta-atoms; and
a protective structure outside of an optically active area of the metasurface,
wherein the protective structure laterally surrounds the optically active area and is composed of a same material as the meta-atoms,
wherein the protective structure includes a plurality of substructures,
wherein the substructures are separated from one another and, collectively, laterally surround the optically active area,
wherein the substructures include a first group of substructures having a first diameter and a second group of substructures having a second diameter greater than the first diameter, and
wherein the substructures are arranged in a circular pattern that alternates between a respective one of the substructures in the first group and a respective one of the substructures in the second group.
24 . The apparatus of claim 23 , wherein the protective structure and the meta-atoms are composed of nanoparticles embedded in a curable polymer.
25 . The apparatus of claim 23 , wherein the substructures have a shape that differs from a shape of the meta-atoms.
26 . The apparatus of claim 23 , wherein the substructures have a height that differs from a height of the meta-atoms.
27 . A method of manufacturing an optical element, the method comprising:
imprinting a stamp into a polymeric material on a substrate, wherein the stamp includes first projections corresponding to an active area of the stamp for formation of meta-atoms in the polymeric material, the stamp further including a protective structure laterally surrounding the first projections, the protective structure including at least one additional projection extending in parallel to the first projections; and
removing the stamp from the polymeric material, thereby forming openings in the polymeric material in positions corresponding to the first projections and in one or more positions corresponding to the at least one additional projection,
wherein the protective structure of the stamp includes a plurality of second projections,
wherein the second projections are separated from one another and, collectively, laterally surround the active area of the stamp, and
wherein the second projections include a first group of second projections having a first diameter and a second group of second projections having a second diameter greater than the first diameter, and
wherein the second projections are arranged in a circular pattern that alternates between a respective one of the second projections in the first group and a respective one of the second projections in the second group.
28 . The method of claim 27 , wherein the second projections have a shape that differs from a shape of the meta-atoms.
29 . The method of claim 27 , wherein the second projections have a height that differs from a height of the meta-atoms.