Nonlinear elasticity of silica nanofiber

Abstract

Optical nanofibers (ONFs) are excellent nanophotonic platforms for various applications such as optical sensing, quantum and nonlinear optics, due to both the tight optical confinement and their wide evanescent field in the sub-wavelength limit. Other remarkable features of these ultrathin fibers are their surface acoustic properties and their high tensile strength. Here we investigate Brillouin light scattering in silica-glass tapered optical fibers 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 and remarkable 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 remarkably agrees with our experimental data. These new regimes open the way to the development of compact tensile strain optical sensors based on nanofibers.

Large evanescently-induced Brillouin scattering at the surrounding of a nanofibre

“…The resonant Brillouin frequency of the simulation result before applying strain is at 8.2 GHz with an amplitude of 38. As a result of the strain, the resonances due to surface acoustic modes and hybrid acoustic modes both shift to higher frequencies, perfectly matching with our previous analysis 38 .…”

Large evanescently-induced Brillouin scattering at the surrounding of a nanofibre

“…3. As a result of the strain, the resonances due to surface acoustic modes and hybrid acoustic modes both shift to higher frequencies, perfectly matching with our previous analysis [34].…”

Ultra-sensitive Brillouin nanofiber force sensor

“…This expression clearly shows that the sensitivity of the BFS to the force is proportional to the Brillouin strain coefficient 𝐶 𝜖 , linked to the nature of elastic waves [7], and scales inversely with the square of the nanofiber diameter. The tapered optical fibers are produced from commercial optical fibers using well know heat-brush technique.…”