Abstract

Stimulated Brillouin Scattering (SBS) is an acousto-optic, resonant nonlinear process with various potential applications ranging from novel light sources [1] to high frequency signal processing in the context of microwave photonics [2]. Such applications greatly benefit from a miniaturization of the SBS-active optical waveguide and its integration on an optical chip [3]. Recently, completely or nearly suspended silicon nanowires were proposed [4] and experimentally investigated [5] as on-chip waveguides that exhibit extraordinarily high SBS-gain constants due to a strong radiation pressure on the material boundaries. Ref. [5] also mentions that the acoustic properties become somewhat sensitive to geometric fabrication imperfections, leading to an inhomogeneous broadening of the forwards SBS resonance line. In this work, we focus on a second mechanism for geometry-related resonance broadening that arises from the optical wave equation. It is irrelevant in forward SBS situations, but can easily become the dominant effect in backward SBS.

© 2015 IEEE