Naming nanolasers

My Photonic Frontiers article coming up in the September issue of Laser Focus World describes recent progress on nanoscale lasers, having volumes smaller than a cubic wavelength. Such emerging technologies are fascinating, but also raise a peculiar problem for those of us who write about them: what do we call the things?

Some groups call their nanoscale lasers "spasers," an acronym for Surface Plasmon Amplification by the Stimulated Emission of Radiation. Surface plasmons are involved in the process, and the catchy term has gained its own Wikipedia entry, some 266,000 hits in a web search, and a fair amount of press coverage even before a paper in the July 27 issue of Science. Score a few points for savvy PR.

But other researchers prefer more general terms like "nanolasers." One reason is that the acronym for spaser defines a specific process--surface plasmon amplification by stimulated emission of radiation. Yet it's not clear that all nanoscale lasers demonstrated so far rely in that process, and some researchers wonder how stimulated emission in a tiny piece of semiconductor can amplify a surface plasmon, which is a group of oscillating electrons on a conductive surface.

A second reason is more philosophical, that "laser" has become a generic term. As Shaya Fainman of the University of California at San Diego (La Jolla, CA) told me, "any time I see light amplification by stimulated emission, I call it a laser." By that logic, if a nanoscale device is amplifying light by stimulated emission, it's a laser.

There are points to be made for both sides, but there also is another dimension to the discussion--defining a new term can be part of claiming credit for a discovery. The International Commission on Zoological Nomenclature has elaborate rules on the proper naming of living or extinct animal species. No such rules exist in physics, so terms compete on their own merits. Interestingly, Gordon Gould's term "laser" won the popularity contest over Charles Townes' original suggestion of "optical maser," but the Nobel Prize went to Townes.

Who eventually will be credited with inventing nanoscale lasers remains to be determined. For now, I'm using "nanolaser" as a generic term for nanoscale laser, as I did in an earlier article. But I'm also watching for future developments in the fast-moving field.