Phonon Laser: Light from Phonons

Celebrating 50 years of LASER

A phonon laser has been demonstrated by optical pumping of a trapped ion. The optomechanical interaction associated with the scattering force gives rise to a Van der Pol dynamical system in which amplification is provided by stimulated emission of centre-of-mass phonons. Steady-state operation occurs by saturation of the mechanical amplification, and excellent agreement is obtained between theory and observed mechanical motion versus pumping. The ability to locate microscopic sources of vibrational coherence that are optically driven and cooled (and addressable using wavelength) might provide a new tool in the field of trapped-ion physics. The fact that phonon laser action is sustained by very low power levels suggests that the ion might be used as an ultra-sensitive force probe. Moreover, amplification of the centre-of-mass motion36 is potentially useful in its own right. The single ion, as a class of phonon laser, represents a kind of zerodimensional limit in which there is no vibronic output coupling. In a Fabry Perot laser analogy, the mirrors would be 100% reflecting and threshold would be determined by internal cavity losses. At the same time, however, this does not preclude other types of useful coupling to the ion's vibrational motion (such as electromagnetic). For example, successful injection locking of the ion phonon laser, in analogy to slaving of a laser oscillator by an external master oscillator, has been achieved recently and will be reported elsewhere.

Picture: A Continuous Wave argon ion laser (514.5 nm) in use.

More details at:
http://www.nature.com/nphys/journal/v5/n9/full/nphys1367.html