For those of us who grew up in the 1960s, the ubiquity of lasers in modern physical science is astonishing. For the year 2000, for example, the physical science database INSPEC catalogued more than 20,000 entries – about 6% of all abstracts – that contained the word “laser”. Furthermore, for the past 30 years this figure has been increasing at a steady linear rate, such that we can confidently foresee that 100% of all scientific research will be laser-based by the year 2900! Yet it was not so long ago that lasers were deemed a solution in search of a problem.
Now Igor Bargatin and Michael Roukes of the California Institute of Technology aim to recapitulate this history. In a recent preprint they propose to replace the familiar resonant cavities of optical lasers with resonant nano-scale cantilevers, and have dubbed the magneto-mechanical device a “cantilaser” (arXiv.org/abs/cond-mat/0304605).
The active medium in a conventional laser is an electromagnetic cavity that resonates at the same frequency as the optical transitions of electrons in the medium. This requires a population inversion of atoms that are in excited states, which is maintained by “pumping” the cavity externally. In contrast, the active medium in the mechanical laser is the intrinsic angular momenta (spin) of electrons and nuclei.
In the July issue of Physics World John A Sidles from the University of Washington in Seattle explains how a magnetic resonance force microscope could form the basis of a mechanical laser.
