High-efficiency sum frequency generation from inverse designed metasurfaces

Abstract

Sum frequency generation is the process in which two incoming photons are converted into an outgoing photon of higher energy. This process is highly inefficient, and therefore requires either large interaction distances in bulky crystals, or large field concentrations in the non-linear materials. Metasurfaces are one such platform to generate extreme field enhancements with resonant processes. In this work, we use topology optimisation to design metasurfaces that exhibit increase high efficiency sum frequency generation, as well as the ability to tailor the generated polarisation.