Abstract-Resonance of terahertz phonons in an acoustic nanocavity

S. Sandeep, S. L. Heywood, R. P. Campion, A. J. Kent, and R. N. Kini

https://journals.aps.org/prb/abstract/10.1103/PhysRevB.98.235303

We show the resonant behavior of ∼0.5-THz longitudinal acoustic (LA) phonons in an acoustic nanocavity of thickness ∼28 nm sandwiched between two GaAs/AlAs superlattices (SLs). One of the SLs, upon excitation with an ultrafast optical pulse, acts as a source of coherent LA phonons. These phonons, generated outside the cavity, resonantly drive the cavity mode. The phonon dynamics can be modeled using a driven-damped harmonic oscillator. The confinement and enhancement of phonons in the acoustic nanocavity opens up possibilities in the field of nanophononics.

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Abstract-Phonon spectroscopy with chirped shear and compressive acoustic pulses

C. L. Poyser, W. B. York, D. Srikanthreddy, B. A. Glavin, T. L. Linnik, R. P. Campion, A. V. Akimov, and A. J. Kent


https://journals.aps.org/prl/accepted/0207dYadSf71666e44a71350956c6f0a0ce2b8d9d

Picosecond duration compressive and shear phonon wavepackets injected into (311) GaAs slabs transform after propagation through \sim1 mm into chirped acoustic pulses with a frequency increasing in time due to phonon dispersion. By probing the temporal optical response to coherent phonons in a near surface layer of the GaAs slab, we show that phonon chirping opens a transformational route for high-sensitivity terahertz and sub-terahertz phonon spectroscopy. Temporal gating of the chirped phonon pulse allows the selection of a narrow band phonon spectrum with a central frequency up to \SI{0.4}{\tera \hertz} for longitudinal and \SI{0.2}{\tera \hertz} for transverse phonons.