Nonlinear elasticity of silica nanofiber

Adrien Godet,Jean-Charles Beugnot,Jacques Chrétien,Vincent Pêcheur,Thibaut Sylvestre,Kien Phan Huy

doi:10.1063/1.5103239

Abstract

Optical nanofibers (ONFs) represent versatile nanophotonic platforms for important photonic applications such as optical sensing and quantum and nonlinear optics. The attractiveness of ONFs arises from the tight optical confinement, their wide evanescent field in the subwavelength limit, their surface acoustic properties, and their high tensile strength. Here we investigate Brillouin light scattering in silica-glass ONFs under high tensile strain and show that the fundamental properties of elastic waves dramatically change due to elastic anisotropy and nonlinear elasticity for strain larger than 2%. This yields to unexpected Brillouin strain coefficients for all Brillouin resonances including surface and hybrid waves, followed by a nonlinear evolution at high tensile strength. We further provide a complete theoretical analysis based on third-order nonlinear elasticity of silica that agrees well with our experimental data. These new regimes open the way to the development of compact tensile strain optical sensors based on nanofibers.

Highlights

Optical micro- and nanofibers (ONFs) are long and uniform ultrathin fibers manufactured by heating and tapering standard optical fibers down to the submicrometer scale.1–5 In addition to providing tight optical confinement, they exhibit a strong evanescent field in the subwavelength limit, which is very attractive for applications such as optical sensing and quantum photonics.3–8 They possess notable mechanical and elastic properties, with large extensibility and high tensile strength.9 From an acoustic viewpoint, it has been recently shown that Optical nanofibers (ONFs) support a new class of acoustic waves compared to standard fibers owing to the strong coupling between shear and longitudinal waves.10,11 These waves include hybrid acoustic waves (HAWs) and surface acoustic waves (SAWs) that move at a lower speed than the longitudinal acoustic velocity
We have reported a detailed investigation of backward Brillouin scattering in tapered optical nanofibers under tensile strain
Our results revealed that the fundamental properties of acoustic waves dramatically change because of elastic anisotropy

Summary

INTRODUCTION

Optical micro- and nanofibers (ONFs) are long and uniform ultrathin fibers manufactured by heating and tapering standard optical fibers down to the submicrometer scale. In addition to providing tight optical confinement, they exhibit a strong evanescent field in the subwavelength limit, which is very attractive for applications such as optical sensing and quantum photonics. They possess notable mechanical and elastic properties, with large extensibility and high tensile strength. From an acoustic viewpoint, it has been recently shown that ONFs support a new class of acoustic waves compared to standard fibers owing to the strong coupling between shear and longitudinal waves. These waves include hybrid acoustic waves (HAWs) and surface acoustic waves (SAWs) that move at a lower speed than the longitudinal acoustic velocity. In addition to providing tight optical confinement, they exhibit a strong evanescent field in the subwavelength limit, which is very attractive for applications such as optical sensing and quantum photonics.3–8 They possess notable mechanical and elastic properties, with large extensibility and high tensile strength.. It has been recently shown that ONFs support a new class of acoustic waves compared to standard fibers owing to the strong coupling between shear and longitudinal waves.. It has been recently shown that ONFs support a new class of acoustic waves compared to standard fibers owing to the strong coupling between shear and longitudinal waves.10,11 These waves include hybrid acoustic waves (HAWs) and surface acoustic waves (SAWs) that move at a lower speed than the longitudinal acoustic velocity. 43 GPa nanofiber and the transition region contributions to the Brillouin spectrum

CONTEXT

EXPERIMENTS

THEORY

Findings

CONCLUSION