Abstract
Sound amplification in an electrically biased superlattice (SL) is studied in optical experiments with 100 fs time resolution. Coherent SL phonons with frequencies of 40, 375, and 410 GHz give rise to oscillatory reflectivity changes. With currents from 0.5 to 1.3 A, the Fourier amplitude of the 410 GHz phonon increases by more than a factor of 2 over a 200 ps period. This amplification is due to stimulated Čerenkov phonon emission by electrons undergoing intraminiband transport. The gain coefficient of is reproduced by theoretical calculations and holds potential for novel sub-THz phonon emitters.
- Received 13 November 2015
DOI:https://doi.org/10.1103/PhysRevLett.116.075504
© 2016 American Physical Society
Physics Subject Headings (PhySH)
Synopsis
Pumping up the Sound
Published 18 February 2016
An optical amplification scheme for sound can double the intensity of phonons traveling through a solid.
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