Subterahertz monochromatic acoustic wave propagation using semiconductor superlattices as transducers

We demonstrate both semiconductor superlattices and nanocavities as narrow-band acoustic transducers in the subterahertz range. Picosecond ultrasonics with pump and probe incident on opposite sides of the substrate allows full decoupling of the phonon generation and detection processes. Pumping in the nanotransducers, we generate spectrally narrow wave packets which propagate over macroscopic distances. Probing in the nanotransducers, we evidence them as very sensitive and spectrally selective detectors.