Scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) and the California Institute of Technology (Pasadena, California, U.S.A.) used a process called stimulated emission to create the first-of-its-kind phonon laser.
Like an optical laser--an acronym for Light Amplification by Stimulated Emission of Radiation--which uses emitted light, the “sound” laser, or phonon laser, is called a “saser"--an acronym for Sound Amplification by Stimulated Emission of Radiation.
The saser, also called an acoustic laser, uses a highly coherent beam of ultrasound.
Phonons are important in solid-state physics because they produce many properties inherent in solids.
For instance, the thermal (heat) and electrical conductivities of solids are provided in large part by phonons. And, sounds heard in solids are also present because of phonons, which is why phonons mean “voice” in Latin.
The summary of their work is published online in the journal Nature Physics (Publication 16. August 09, DOI: 10.1038/ NPHYS1367).
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The Nature Physics paper is entitled “A phonon laser.” Its authors are Kerry Vahala, Maximilian Herrmann, S. KnÃ¼nz, V. Batteiger, G. Saathoff, Theodor W. HÃ¤nsch, and Th. Udem.
For many years, scientists have wanted to find some way to build a phonon laser, one that emits “quanta of vibrational energy—so called phonons—instead of light.”
One important reason that such a phonon laser is needed in science is to dramatically increase the resolution within imaging techniques, such as tomography.
Consequently, the first ever creation of a phonon laser is the first step toward the accomplishment of this goal.
Dr. Theodor W. HÃ¤nsch, at the Max Planck Institute, and Dr. Kerry Vahala, at the California Institute of Technology (now working at MPI), led the team of scientists in this development of the phonon laser.
Page three concludes.
The Max Planck/CalTech team was “… able to demonstrate for the first time the effect of coherent phonon generation with a single magnesium ion cooled to a temperature of around 1 milli-Kelvin in an electromagnetic trap. The pump source to this process is blue-detuned laser radiation.”
"The device in its present form could possibly be used as a sensor for extremely weak forces. The extension of the system to an ion chain or a two-dimensional ion array could perhaps make the breakthrough to possible applications.”
Within the MPI press release, Dr. Maximilian Herrmann, also at the Max Planck Institute and one of the scientists in the development of the phonon laser (saser), states, "An important step in the realization of this kind of phonon laser was the insight that blue-detuned laser light does not merely heat an ion as it is widely believed, but instead, by appropriate choice of frequency and intensity, can stimulate coherent amplification of its motion."
The press release from the Max Planck Institute also states how further development of the saser is possible.
It states, "The device in its present form could possibly be used as a sensor for extremely weak forces. The extension of the system to an ion chain or a two-dimensional ion array could perhaps make the breakthrough to possible applications."
The August 31, 2009 CalTech press release is entitled “Scientists Create Phonon Laser.”