Gold nanoparticles Mechanical oscillations Metamaterial antennas Nanoantennas Plasmonics Plasmons Probes Pump-probe experiments Vibrations (mechanical) Acoustic surface wave devices Acoustic waves Aspect ratio Circuit oscillations Coherent acoustic phonon Coherent acoustic phonons Electronic relaxation Excitation light Frequency contents Gold Hypersound Lattice vibrations Light absorption Mechanical constraints Metal nanoparticles Nanoparticles Nanorods Numerical methods Optical properties Optical response Orders of magnitude