Sasers, the sonic equivalent of lasers, are today the center of fascinating investigations which, besides their promising technological applications, may help to unveil fundamental issues on coherence and spontaneous order.
SASER is the acronym for Sound Amplification by Stimulated Emission of Radiation. The main function of a saser or phonon laser is to produce a highly coherent beam of ultrasound. As we emphasize below, sasers are of much current fundamental and technological interest.
My contribution to this field was done within the context of a long time collaboration between the groups of Sergio Makler (Rio de Janeiro, Brazil) and Horacio Pastawski (Cordoba, Argentina) [1,2], we proposed [3,4] an alternative scheme for the generation of terahertz phonons in a double barrier resonant tunneling device. The essential idea is to transform the kinetic energy that the electrons acquire from an applied electric field into lattice vibrations (phonons).
"...And not only do they survive; they proliferate. With every rebound through the tube, they give birth to more and more perfect copies of themselves, reinforcing their light and creating a magnificient beam of perfectly synchronized [phonons]..."
Steven Strogatz, SYNC: How Order Emerges From Chaos In the Universe, Nature, and Daily Life.
Some Links on SASERs or phonon lasers
Nowadays, the quest for the construction of SASERs (phonon lasers), continues to attract much current interest, see for example:
- "Phonon lasers gain a sound foundation", Physics 3, 16 (2010).
- "A sonic boom in the world of laser", June 17th, 2009.
- “A little big noise - The birth of a new technology? ”, The Economist, June 8th 2006. [pdf]
- “Pump up the volume”, New Scientist, March 27th, 1999. [pdf]
- "Picosecond ultrasonics", H. Maris, Scientific American p.86, January 1998.
Braz. J. Phys. 24, 330 (1994). [pdf]
 S. S. Makler, M. I. Vasilevskiy, E. V. Anda, D. E. Tuyarot, J. Weberszpil, and H. M. Pastawski, J. Phys.: Condens. Matter 10, 5905 (1998); see also I. Camps and S. S. Makler, Solid State Commun. 116, 191 (2000).
 L. E. F. Foa Torres, H. M. Pastawski, S. S. Makler, Physical Review B 64, 193304 (2001) [pdf]; Solid State Communications 124, 363-371 (2002)
 See also: I. Camps, S.S. Makler, H.M. Pastawski and L.E.F. Foa Torres, Physical Review B 64, 125311 (2001) [pdf].