Brillouin scattering self-cancellation.

O Florez,P Dainese,Y A V Espinel,P F Jarschel,T P Mayer Alegre,G S Wiederhecker,C M B Cordeiro

doi:10.1038/ncomms11759

O Florez, P Dainese + Show 5 more

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https://doi.org/10.1038/ncomms11759

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Journal: Nature communications	Publication Date: Jun 10, 2016
Citations: 87	License type: CC BY 4.0

Affiliation: Universidade Estadual de 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.

Highlights

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
We refer to this effect as the Brillouin scattering ‘self-cancellation’ (BSC), since the cancellation arises from the same acoustic mode that creates each effect individually
Demonstrating the BSC effect validates our fundamental understanding of the photon–phonon interaction in sub-wavelength confinement regime, opening up the possibility to selectively suppress or further enhance the interaction by exploring both effects simultaneously

Summary

Introduction

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. As the surface-to-volume ratio becomes larger and the index contrast higher, such as in nanooptical waveguides and cavities, the optical field experiences an additional surface effect due to the vibrating boundary[32,33,34,35], referred to as moving-boundary effect (or mb-effect) With these two effects simultaneously perturbing the dielectric constant, precise engineering of the optical and acoustic modes in a certain structure can be used to control their interaction, that is, enhancing or suppressing it. Demonstrating the BSC effect validates our fundamental understanding of the photon–phonon interaction in sub-wavelength confinement regime, opening up the possibility to selectively suppress or further enhance the interaction by exploring both effects simultaneously

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