Dielectric metasurface optical elements
A dielectric gradient metasurface optical device provides optical wavefront shaping using an ultrathin (less than 100 nm thick) layer of nanoscale geometric Pancharatnam-Berry phase optical elements deposited on a substrate layer. The optical elements are nanobeams composed of high refractive index dielectric material. The nanobeams have uniform size and shape and are arranged with less than 200 nm separations and spatially varying orientations in the plane of the device such that the optical device has a spatially varying optical phase response capable of optical wavefront shaping. The high refractive index dielectric material may be materials compatible with semiconductor electronic fabrication, including silicon, polysilicon, germanium, gallium arsenide, titanium dioxide, or iron oxide.
1. A dielectric gradient metasurface optical device comprising a less than 100 nm thick layer of nanoscale geometric Pancharatnam-Berry phase optical elements deposited on a substrate layer, wherein the optical elements are nanobeams composed of high refractive index dielectric material, wherein the nanobeams have uniform size and shape and are arranged with less than 200 nm separations and spatially varying orientations in the plane of the device such that the optical device has a spatially varying optical phase response capable of optical wavefront shaping.
2. The optical device of claim 1 wherein the high refractive index dielectric material is silicon.
3. The optical device of claim 2 wherein the high refractive index dielectric material is polysilicon, germanium, gallium arsenide, titanium dioxide, or iron oxide.
4. The optical device of claim 1 wherein the substrate is quartz or glass, or other low refractive index material.
5. The optical device of claim 1 wherein the spatially varying optical phase response of the optical device functions as an optical blazed grating, lens, or axicon.