COMPENSATION OF DOPPLER BROADENING BY VELOCITY-DEPENDENT LIGHT-SHIFTS.

Abstract

The authors propose a new scheme for compensating the Doppler broadening by velocity dependent light-shifts. They have obtained experimental results giving good confidence in the theoretical analysis of such a scheme. Up to now, use has been made of moderate laser intensities (150 mW) and moderate focalizations (w equals 400 mu ). Commercial ring lasers can now give powers higher by a factor of 10, even still higher if one works inside the laser cavity. Also, the laser beam could be focused to smaller waists if one uses a second laser beam for probing the c-a transition rather than a spontaneous emission signal. Consequently, it is possible to obtain, even with c. w. lasers, values of omega //1 of the order of, or larger than, DELTA . In such a case, one could achieve a nearly complete compensation of Doppler broadening, leading to forward-backward asymmetries as large as 10 or 100. This would open the way to various interesting applications such as reduction of threshold in laser media, ring lasers, directed Doppler free superradiance, Doppler free coherent transients, non-reciprocal devices, etc.