Optical devices including metastructures and methods for fabricating the optical devices
Methods of manufacturing an optical device can include, in some implementations, providing a substrate having a first polymeric layer on a surface of the substrate and a second polymeric layer on the first polymeric layer, forming first openings in the second polymeric layer to define an etch mask composed of material of the second polymeric layer, and etching to form second openings in the first polymeric layer, wherein locations of the second openings are defined by the etch mask. A material is deposited in the second openings to form meta-atoms of a first metastructure, wherein adjacent ones of the meta-atoms are separated from one another by polymeric material of the first polymeric layer. Optical devices including metastructures can be formed, where meta-atoms of the metastructure have a relatively high aspect ratio.
1 . A method of manufacturing an optical device comprising:
providing a substrate having a first polymeric layer over a surface of the substrate and a second polymeric layer on the first polymeric layer;
forming first openings in the second polymeric layer to define an etch mask composed of material of the second polymeric layer;
etching to form second openings in the first polymeric layer, wherein locations of the second openings are defined by the etch mask, wherein etching to form the second openings comprises leaving a residual thin film of the first polymeric layer in the second openings; and
depositing a material in the second openings to fill the second openings with meta-atoms of a first metastructure, wherein adjacent ones of the meta-atoms are separated from one another by polymeric material of the first polymeric layer, wherein the meta-atoms of the first metastructure are an oxide, a nitride or a metal.
2 . The method of claim 1 wherein the etching is performed using an etchant that preferentially etches the first polymeric material at a higher etch rate than the etchant etches the second polymeric layer.
3 . The method of claim 1 wherein the meta-atoms have an aspect ratio of at least 1.6.
4 . The method of claim 1 wherein the first polymeric is composed of poly(methyl methacrylate).
5 . The method of claim 4 wherein the second polymeric layer is composed of photoresist.
6 . The method of claim 1 wherein the first openings in the second polymeric layer are formed using a photolithographic technique.
7 . The method of claim 1 wherein the first openings in the second polymeric layer are formed by imprinting.
8 . The method of claim 1 wherein the material deposited in the second openings to form the meta-atoms includes TiO 2 .
9 . The method of claim 1 wherein the etching continues until the mask composed of the second polymeric layer is removed.
10 . The method of claim 1 wherein the material is deposited in the second openings of the first polymeric layer by atomic layer deposition.
11 . The method of claim 1 further including:
providing a third polymeric layer over the first metastructure; and
forming a second metastructure in the third polymeric layer.
12 . The method of claim 11 wherein forming the second metastructure includes:
providing a fourth polymeric layer on the third polymeric layer;
forming third openings in the fourth polymeric layer to define a second etch mask composed of material of the fourth polymeric layer;
etching to form fourth openings in the third polymeric layer, wherein locations of the fourth openings are defined by the second etch mask; and
depositing a material in the fourth openings to form meta-atoms of the second metastructure, wherein adjacent ones of the meta-atoms of the second metastructure are separated from one another by polymeric material of the third polymeric layer.
13 . The method of claim 11 wherein an arrangement of the meta-atoms of the second metastructure differs from an arrangement of the meta-atoms of the first metastructure.
14 . The method of claim 11 wherein at least one of materials, dimensions or optical characteristics of the second metastructure differ from materials, dimensions or optical characteristics of the first metastructure.