Coherent vibrations of submicron spherical gold shells in a photonic crystal

TL;DR

This paper reports the observation of coherent radial vibrations in submicron gold shells within a photonic crystal, revealing strong acousto-optical coupling and confirming theoretical predictions of oscillation frequencies.

Contribution

It demonstrates the excitation and detection of coherent vibrations in gold shells using ultrashort pulses and highlights enhanced acousto-optical effects in photonic crystals.

Findings

Oscillations observed within subnanosecond timescale

Reflectivity modulation up to 4% due to acousto-optical coupling

Oscillation frequencies match Lamb theory predictions

Abstract

Coherent acoustic radial oscillations of thin spherical gold shells of submicron diameter excited by an ultrashort optical pulse are observed in the form of pronounced modulations of the transient reflectivity on a subnanosecond time scale. Strong acousto-optical coupling in a photonic crystal enhances the modulation of the transient reflectivity up to 4%. The frequency of these oscillations is demonstrated to be in good agreement with Lamb theory of free gold shells.