Abstract

Laser-induced atomic coherence has been a subject of much current interest.^1-3 Here we present an analysis of inversionless gain and lasing in a three-level V- type atomic system⁴ and point out the subtle differences among different light amplification mechanisms. Explicitly, we show that the V system exhibits lasing without population inversion in any state basis only if the frequency detuning of the strong coupling laser is small. When the coupling laser detuning is increased to a value comparable to the Rabi frequency of the coupling laser, a population inversion for the stimulated Raman scattering is created. Further increases of the coupling laser detuning will lead to a population inversion in the dressed states. Therefore the interpretation of the experiments on lasing without inversion in atomic vapor cells will necessarily have to take the frequency detuning of the coupling laser-atom transition manifested by the Doppler shifts into account, and the population distribution in different state basis can become quite complicated.

© 1996 Optical Society of America