Non-collinear counter-propagating beams in epsilon-near-zero films: enhancement and inhibition of nonlinear optical processes

Abstract

Epsilon-near-zero (ENZ) materials are excellent platforms for nonlinear optical interactions. We demonstrate that the linear interference of two non-collinear, counter-propagating beams impinging at oblique angle can either enhance or suppress nonlinear optical processes depending on their initial phase difference. Our results validate the idea that using ENZ materials allows one to circumvent both phase-matching conditions and the use of resonant structures, thus providing a path for efficient and effective control of nonlinear processes.