Brillouin scattering self-cancellation

Agradecimentos: This work was supported by the São Paulo Research Foundation (FAPESP) under grants 2013/20180-3, 2012/17765-7, 2012/17610-3 and 08/57857-2, and by the National Council for Scientific and Technological Development (CNPq), grant 574017/2008-9. O.F. and Y.A.V.E. wish to thank the Coordination for the Improvement of Higher Education Personnel (CAPES) for financial support. Scanning electron microscopy was performed at the Center for Semiconductor Components (University of Campinas) 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. Here, we experimentally demonstrate the perfect cancellation of Brillouin scattering arising from Rayleigh acoustic waves 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 FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Aberto