Brillouin Scattering Self-Cancellation

TL;DR

This paper demonstrates the experimental cancellation of Brillouin scattering in a silica nanowire by engineering opposing photo-elastic and boundary effects, enabling precise control of photon-phonon interactions.

Contribution

It provides the first experimental evidence of complete Brillouin scattering cancellation through material and structural engineering.

Findings

Achieved perfect cancellation of Brillouin scattering

Controlled photon-phonon interaction via engineering effects

Demonstrated interplay of volume and surface effects

Abstract

The interaction between light and acoustic phonons is strongly modified in sub-wavelength confinement, and has led to the demonstration and control of Brillouin scattering in photonic structures such as nano-scale optical waveguides and cavities. Besides the small optical mode volume, two physical mechanisms come into play simultaneously: a volume effect caused by the strain induced refractive index perturbation (known as photo-elasticity), and a surface effect caused by the shift of the optical boundaries due to mechanical vibrations. As a result proper material and structure engineering allows one to control each contribution individually. In this paper, we experimentally demonstrate the perfect cancellation of Brillouin scattering by engineering a silica nanowire with exactly opposing photo-elastic and moving-boundary effects. This demonstration provides clear experimental evidence that the interplay between the two mechanisms is a promising tool to precisely control the photon-phonon interaction, enhancing or suppressing it.