53‐4: Dielectric Metasurfaces: Design for Manufacturability

Abstract

Metasurface systems are enabling new classes of optical elements through spatial-phase engineering. Prior works focused on the role of refractive index of the material used to build the metasurface on efficiency and numerical aperture of metasurface lenses. In this work we focus on the issue of manufacturing tolerances of metasurfaces for infrared and visible optical waves, and specifically on the role the dielectric refractive index plays. A simple model system represented by simple analytical equations is used to extract proxy parameters that have an impact on the tolerance to manufacturing errors. These proxy parameters include rate of change of phase with particle size. It is found that although higher refractive index materials (e.g. Si) can provide better performance than lower refractive index materials (e.g. Si3N4), the relative tolerance to manufacturing errors is better for smaller index materials. This poses a challenge to the manufacturability of metasurfaces using relatively high refractive index, and brings attention to materials with medium refractive index (e.g. TiO2) to strike a balance between high performance and manufacturability of metasurface devices.