Phonon-plasmon interaction in film-coupled metallic nanoparticles mediated by surface acoustic waves

We demonstrate by numerical analysis enhanced optomechanical interaction in a film-coupled gold nanoridges or pillars mediated by surface acoustic waves. The nanoparticles are placed atop a multilayer structure consisting of a thin dielectric spacer covering a gold film layer on a silicon dioxide/or silicon substrate. The design supports both localized surface plasmons (infrared range) confined under the nanoparticles and elastic phonons (sub-GHz) localized in the latters. Phonon-plasmon coupling is evaluated from the shift in the plasmon eigenfrequency