Characterizing the nanoacoustic superlattice in a phonon cavity using a piezoelectric single quantum well

Abstract

We have experimentally and theoretically investigated, both in the time domain and in the frequency domain, the characteristics of a nanoacoustic mirror, which is a 17-period 8nm∕8nm Al0.7Ga0.3N∕Al0.2Ga0.8N superlattice and its first phononic band gap frequency is centered at ∼280GHz. By using a femtosecond optical pulse to excite and detect the nanoacoustic strain pulses with an In0.2Ga0.8N single quantum well, we directly measured the transient dynamics of the acoustic nanowaves inside a phonon cavity composed of the studied nanoacoustic mirror. The phase-resolved reflection transfer function of the phononic band gap superlattice and the properties of the nanophononic cavity have been experimentally obtained and investigated.