Long-Lived Coherent Acoustic Phonons in Epitaxially Grown III-V Adiabatic Cavities

Abstract

We provide evidence of strongly confined coherent acoustic phonons inside high quality factor phononic cavities that exhibit tailoredphonon potentials. Using GaAs/AlAs quasiperiodic superlattices, these functional phonon potentials are realized by adiabatically changing the layer thicknesses along the growth direction. Room temperature ultrafast vibrational spectroscopy reveals discrete phonon levels in the range of $\approx 96-101$ GHz. Additionally, we confirm that phononic cavities significantly retard the energy loss rate of the photoexcited carriers as evidenced by time-resolved photoluminescence measurements. These results highlight the potential of opto-phononic devices that can bridge the divide between phononics and optoelectronics by concurrently engineering electronic and phononic properties.

In this version, we have incorporated a new section addressing the temporal dynamics of cavity phonons. Additionally, the analysis and discussion of time-resolved photoluminescence (TRPL) results have been enhanced

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