2-MODE LAMBDA-LASER WITH ATOMS INJECTED IN A SUPERPOSITION OF THEIR STATES

The master equation for the field in the two-mode Lambda laser with at oms injected in a superposition of their states is presented, and lasi ng without population inversion is studied from this vantage. An expli cit expression for the steady-state photon distribution is derived und er the conditions of detailed balance and no injected coherence. We st udy the photon statistics, as well as the decay of off-diagonal densit y-matrix elements and the linewidths of the two laser modes. The effec t of an injected atomic coherence on the amplification of light is exa mined. It is shown that the interference terms in the master equation cancel the absorption terms if the field in each mode is in a coherent state and the conditions for atomic trapping are fulfilled. Numerical calculations demonstrate the buildup of lasing without inversion from the vacuum state of the field.