Net on-chip Brillouin gain based on suspended silicon nanowires

Abstract

The century-old study of photon-phonon coupling has seen a remarkable revival in the past decade. Driven by early observations of dynamical back-action, the field progressed to ground-state cooling and the counting of individual phonons. Arecent branch investigates the potential of traveling-wave, optically broadband photon-phonon interaction in silicon circuits. Here, we report continuous-wave Brillouin gain exceeding the optical losses in a series of suspended silicon beams, a step towards selective on-chip amplifiers.We obtain efficiencies up to 104 W-1m-1, the highest to date in the phononic gigahertz range.Wealso find indications that geometric disorder poses a significant challenge towards nanoscale phonon-based technologies.