On-Chip RF Signal Shaping by Coherent Control of Optically Driven Acoustic Wave Interference

Abstract

Photonic-phononic systems that mix photons and acoustic waves have been actively investigated for the development of next-generation integrated photonics for signal processing. Here, we propose a new method of arbitrary RF signal shaping using active control of optically driven acoustic-wave interference, offering new photonic-phononic-microwave signal processing schemes with MHz linewidths at GHz carrier frequencies. The demonstrated system consists of two suspended optical waveguides and an asymmetric Mach-Zehnder interferometer. The two waveguides generate acoustic waves at a 3.03 GHz carrier frequency with a 3.3 MHz bandwidth, and one of the paths of the asymmetric interferometer experiences phase modulation induced by the acoustic waves. Then, the interferometer converts the phase information to RF signals of complicated shapes using a linear combination of multiple optical envelopes. This RF signal-shaping method will open new applications of optomechanical systems for microwave photonics.