Phonon Bloch oscillations in acoustic-cavity structures

TL;DR

This paper proposes a semiconductor multilayer structure capable of exhibiting acoustic phonon Bloch oscillations, with methods to generate, detect, and measure these oscillations using Raman spectra and femtosecond laser pulses.

Contribution

It introduces a novel multilayer structure for phonon Bloch oscillations and demonstrates measurement techniques via Raman spectra and optical reflectivity simulations.

Findings

Raman spectra reveal phononic Wannier-Stark ladder

Femtosecond laser pulses can generate and probe phonon oscillations

Time-dependent reflectivity shows temporal beatings matching energy splitting

Abstract

We describe a semiconductor multilayer structure based in acoustic phonon cavities and achievable with MBE technology, designed to display acoustic phonon Bloch oscillations. We show that forward and backscattering Raman spectra give a direct measure of the created phononic Wannier-Stark ladder. We also discuss the use of femtosecond laser impulsions for the generation and direct probe of the induced phonon Bloch oscillations. We propose a gedanken experiment based in an integrated phonon source-structure-detector device, and we present calculations of pump and probe time dependent optical reflectivity that evidence temporal beatings in agreement with the Wannier-Stark ladder energy splitting.