Stimulated intermodal Brillouin scattering in a hybrid photonic-phononic silicon waveguide

Abstract

On-chip stimulated Brillouin scattering (SBS) has attracted extensive attention by introducing acousto-optic coupling interactions in all-optical signal processing systems. In this article, we demonstrate stimulated intermodal Brillouin scattering (SIMBS) through a hybrid photonic-phononic silicon waveguide on the silicon-on-insulator (SOI) platform. The designed photonic-phononic waveguide can independently control the optical and acoustic fields by introducing the ridge waveguide as a line defect into the honeycomb lattice phononic crystal slab. Small-signal Stokes gain of 0.7 dB is achieved in a 1-cm long straight waveguide device with an on-chip pump power of 42.5 mW. Positive net Brillouin amplification is also expected by effectively reducing the linear loss. Our proposed device offers a potential approach to implementing Brillouin amplifiers, nonreciprocal devices, and signal processing in planar photonic integrated circuits.