Phonon avalanches in an acoustic cavity
L. G. Tilstra, A. F. M. Arts, and H. W. de Wijn
Faculty of Physics and Astronomy, and Debye Research Institute, Utrecht
University, P.O. Box 80.000, 3508 TA Utrecht, The Netherlands
We have observed stimulated emission of resonant acoustic phonons by
Zeeman-split E(2E) doublets in dilute ruby
following local population inversion by selective optical pumping. The
phonons generated reverberate in the crystal acting as an acoustic cavity,
the phonon beam being amplified upon each passage through the active zone.
The frequency spread of the avalanche is found to be 55 MHz.