Acoustic Far-Field Hypersonic Surface Wave Detection with Single Plasmonic Nanoantennas

RODRIGO BERTE; FABRICIO DELLA PICCA; MARTÍN POBLET; YI LI; EMILIANO CORTÉS; RICHARD V. CRASTER; STEFAN A. MAIER; A. V. BRAGAS

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Año: 2018

0031-9007

The optical properties of small metallic particles allow us to bridge the gap between the myriad ofsubdiffraction local phenomena and macroscopic optical elements. The optomechanical coupling betweenmechanical vibrations of Au nanoparticles and their optical response due to collective electronic oscillationsleads to the emission and the detection of surface acoustic waves (SAWs) by single metallic nanoantennas.We take two Au nanoparticles, one acting as a source and the other as a receptor of SAWs and, even thoughthese antennas are separated by distances orders of magnitude larger than the characteristic subnanometricdisplacements of vibrations, we probe the frequency content, wave speed, and amplitude decay of SAWsoriginating from the damping of coherent mechanical modes of the source. Two-color pump-probeexperiments and numerical methods reveal the characteristic Rayleigh wave behavior of emitted SAWs,and show that the SAW-induced optical modulation of the receptor antenna allows us to accurately probe thefrequency of the source, even when the eigenmodes of source and receptor are detuned.