Brillouin light scattering from surface acoustic waves in a subwavelength-diameter optical fibre

Abstract

Brillouin scattering in optical fibres is a fundamental interaction between light and sound with important implications ranging from optical sensors to slow and fast light. In usual optical fibres, light both excites and feels shear and longitudinal bulk elastic waves, giving rise to forward-guided acoustic wave Brillouin scattering and backward-stimulated Brillouin scattering. In a subwavelength-diameter optical fibre, the situation changes dramatically, as we here report with the first experimental observation of Brillouin light scattering from surface acoustic waves. These Rayleigh-type surface waves travel the wire surface at a specific velocity of 3,400 m s−1 and backscatter the light with a Doppler shift of about 6 GHz. As these acoustic resonances are sensitive to surface defects or features, surface acoustic wave Brillouin scattering opens new opportunities for various sensing applications, but also in other domains such as microwave photonics and nonlinear plasmonics.

Numerical modelling on stimulated Brillouin scattering characterization for Graphene-clad tapered silica fiber

“…Chalcogenide (ChG) fiber which secured acoustic confinement in the fiber core shows a low threshold power at 52 mW [8]. On the contrary, recent finding in SBS across tapered Silica fiber presented a high threshold power (60 W) which is undesired in SBS application [9]. This happens because Surface Acoustic Wave (SAW) at tapered waist region has minimum interaction with optical wave.…”

“…The Brillouin peak gain is achieved under condition where the difference between pump and stoke frequency is equivalent to the Brillouin shift, [35,36]. (9) where is the numerical factor manipulated by fiber length and is approximated to a constant value ≈ 21. eff and ff are the effective area and effective length of fiber, respectively. K is the polarization factor range between 1-2 [37].…”

Evolution of Surface Acoustic Waves in an Optical Microfiber

“…Acoustic wave satisfies the Hooke's Law which relates the stress (tensor) and strain (force) of the waveguiding materials [23][24][25][26][27].…”

Opto-acoustic phenomena in whispering gallery mode resonators

“…Optical fibers with the ability of confining light in a small mode area and a long distance have been successfully used to enhance and study the SBS processes. SBS has thus been demonstrated in traditional fibers, [2][3][4][5][6][7][8][9][10][11][12] photonics crystal fibers [13] and sub-wavelength microfibers [14] . On-chip optical waveguides are also very promising platforms for integrated solutions to harvest the SBS effect [15][16][17] .…”