1.
Phys Rev Lett
; 119(25): 255502, 2017 Dec 22.
Article
in English
| MEDLINE
| ID: mdl-29303330
ABSTRACT
Picosecond duration compressive and shear phonon wave packets injected into (311) GaAs slabs transform after propagation through â¼1 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 subterahertz phonon spectroscopy. Temporal gating of the chirped phonon pulse allows the selection of a narrow band phonon spectrum with a central frequency up to 0.4 THz for longitudinal and 0.2 THz for transverse phonons.