Protected Long-Distance Guiding of Hypersound Underneath a Nano-Corrugated Surface

TL;DR

This paper demonstrates a method for guiding hypersound waves at the nanoscale beneath a nano-corrugated surface, enabling long-distance, coherent data transmission for advanced on-chip communication systems.

Contribution

It introduces a novel approach to deliver subsurface hypersound waves at ~20 GHz using pulsed optical excitation in a multilayer semiconductor with nanograting, surpassing Rayleigh wave propagation lengths.

Findings

Hypersound modes propagate coherently over 50 μm beneath nanograting.

The method retains surface imprinted information during propagation.

Potential applications include interfacing quantum emitters and optical communication encoding.

Abstract

Within a new paradigm for communications on the nanoscale, high-frequency surface acoustic waves are becoming effective data carrier and encoder. On-chip communications require acoustic wave propagation along nano-corrugated surfaces which strongly scatter traditional Rayleigh waves. Here we propose the delivery of information using subsurface acoustic waves with hypersound frequencies ~20 GHz, which is a nanoscale analogue of subsurface sound waves in the ocean. A bunch of subsurface hypersound modes is generated by pulsed optical excitation in a multilayer semiconductor structure with a metallic nanograting on top. The guided hypersound modes propagate coherently beneath the nanograting, retaining the surface imprinted information, on a distance of more than 50 {\mu}m which essentially exceeds the propagation length of Rayleigh waves. The concept is suitable for interfacing single photon emitters, such as buried quantum dots, carrying coherent spin excitations in magnonic devices, and encoding the signals for optical communications at the nanoscale.