LASING WITHOUT INVERSION IN CAVITIES VIA VACUUM-FIELD CONTROL OF COHERENCE AND DECAY

We demonstrate the possibility of simply and effectively controlling t he inversionless gain between two excited states in a ladder configura tion, by injecting atoms (molecules) into a cavity. The control is eff ected by the cavity-mode decay rate and vacuum Rabi frequency, chosen according to the decay and dephasing rates of the upper and lower stat es. The analogy with the control of inversionless gain by a classical strong field is discussed. This scheme is expected to be robust under conditions of thermal equilibrium or non-selective pumping of excited states. (C) 1998 Elsevier Science B.V. All rights reserved.