Research NewsPhysics

Researchers Build Novel Laser By Putting a Lock on Atoms

Science  03 Nov 1995:
Vol. 270, Issue 5237, pp. 737-738
DOI: 10.1126/science.270.5237.737


A golden rule of laser technology is that a majority of the atoms in the lasing medium must be in the excited, light-emitting state. But two teams of physicists have managed to break this rule: They have obtained light from just a few excited atoms by preventing the others from absorbing photons. The trick was to use a second laser to alter the atomic energy levels, creating two different paths by which the atoms could absorb the light. The paths competed, and absorption was stymied. See sidebar (p. 738).