Tailorable Stimulated Brillouin Scattering in Nanoscale Silicon Waveguides

TL;DR

This paper demonstrates the first observation of tailorable stimulated Brillouin scattering in nanoscale silicon waveguides, achieving significantly stronger responses through hybrid photonic-phononic structures and structural engineering.

Contribution

The work introduces a new class of hybrid waveguides enabling tailorable forward stimulated Brillouin scattering in silicon nanophotonics for the first time.

Findings

Achieved 3000 times stronger forward SBS responses than previous systems.

Demonstrated Brillouin resonances from 1 to 18 GHz.

Enhanced photon-phonon coupling via electrostrictive forces and radiation pressure.

Abstract

While nanoscale modal confinement radically enhances a variety of nonlinear light-matter interactions within silicon waveguides, traveling-wave stimulated Brillouin scattering nonlinearities have never been observed in silicon nanophotonics. Through a new class of hybrid photonic-phononic waveguides, we demonstrate tailorable traveling-wave forward stimulated Brillouin scattering in nanophotonic silicon waveguides for the first time, yielding 3000 times stronger forward SBS responses than any previous waveguide system. Simulations reveal that a coherent combination of electrostrictive forces and radiation pressures are responsible for greatly enhanced photon-phonon coupling at nano-scales. Highly tailorable Brillouin nonlinearities are produced by engineering the structure of a membrane-suspended waveguide to yield Brillouin resonances from 1 to 18 GHz through high quality-factor (>1000) phonon modes. Such wideband and tailorable stimulated Brillouin scattering in silicon photonics could enable practical realization of on-chip slow-light devices, RF-photonic filtering and sensing, and ultra-narrow-band laser sources by using standard semiconductor fabrication and CMOS technologies.