posted on 2021-07-19, 16:27authored byYuta Imade, Vitalyi E. Gusev, Osamu Matsuda, Motonobu Tomoda, Paul H. Otsuka, Oliver B. Wright
High-frequency
surface phonons have a myriad of applications in
telecommunications and sensing, but their generation and detection
have often been limited to transducers occupying micron-scale regions
because of the use of two-dimensional transducer arrays. Here, by
means of transient reflection spectroscopy we experimentally demonstrate
optically coupled nanolocalized gigahertz surface phonon transduction
based on a gold nanowire emitter arranged parallel to linear gold
nanorod receiver arrays, that is, quasi-one-dimensional emitter–receivers.
We investigate the response up to 10 GHz of these individual optoacoustic
and acousto-optic transducers, respectively, by exploiting plasmon-polariton
longitudinal resonances of the nanorods. We also demonstrate how the
surface phonon detection efficiency is highly dependent on the nanorod
orientation with respect to the phonon wave vector, which constrains
the symmetry of the detectable modes, and on the nanorod acoustic
resonance spectrum. Applications include nanosensing.