Phase-controlled two-wave mixing in a moving grating

Abstract

Two-wave mixing is fundamental to applications in optical signal processing, holographic information, and imaging science. Conventionally, it takes place in a nonlinear medium where self-induced optical grating can effectively couple two optical waves. However, it demands high input power to trigger nonlinearities and is complicated by the phase shift of the optical grating for the given medium. Here, we separate these physical processes by studying near-degenerated two-wave mixing in a moving grating induced independently by an external acoustic optical modulator. Two-wave mixing is observed under Bragg's phase matching condition, which is greatly affected by phase shifting. Moreover, we show that two-wave mixing here is unidirectional due to the propagation of acoustic waves, which may offer new avenues for applications in optical information processing.