Gigahertz Optomechanical Photon–Phonon Transduction between Nanostructure Lines

Abstract

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.

Optical Metasurfaces for Energy Conversion

“…Because of the coupling to the substrate, SAWs may be produced there, being detectable at least a few micrometers away from the oscillating source NP . The approach of producing SAWs with single nanoparticles was further exploited to produce plane SAWs by using metallic nanowires, which can be seen as nanorods with very high aspect ratios . On the other hand, the use of oscillating single NPs coupled to a substrate represents the smallest realization of a SAW source, leading to the possibility of designing ultracompact devices with frequencies in the few-GHz range.…”

“…565 The approach of producing SAWs with single nanoparticles was further exploited to produce plane SAWs by using metallic nanowires, which can be seen as nanorods with very high aspect ratios. 566 On the other hand, the use of oscillating single NPs coupled to a substrate represents the smallest realization of a SAW source, leading to the possibility of designing ultracompact devices with frequencies in the few-GHz range. Some decades ago, it was observed using a transient absorption technique that by exciting a colloid with 15 nm Au NPs with ultrafast laser pulses a transient bleaching of the metal plasmon resonance occurred.…”

Excitation and detection of acoustic phonons in nanoscale systems

“…[261][262][263][264][265][266] For example, coherent acoustic phonons generated by light-induced vibrations in gold nanoantennas have been shown to create propagating surface acoustic waves in the substrate, with the oscillation amplitude and frequency set by the nanoantenna geometry. 267,268 In another example, induced coherent acoustic phonons generated via gold nanorods also allow the measurement of the mechanical moduli of polymers at GHz frequencies. 269 These represent a few of the many applications in which pump-probe techniques have been incorporated for phonon generation and detection.…”

Substrate influence on the vibrational response of gold nanoresonators: Towards tunable acoustic nanosources

“…For this reason, pre-structured substrates are usually used to study the vibrations of suspended mNOs [23,33,34,[39][40][41]. On an other hand, it has also been highlighted that nano-objects vibrating could be used as sources to generate acoustic waves in the GHz range [20,35,40,42,43]. Such acoustic sources with suboptical sizes are of great interest to perform acoustic imaging.…”