LASING WITHOUT INVERSION WITH A FLUCTUATING PUMP - GAIN DEPENDENCE ONPUMP NOISE AND FREQUENCY

Recently it was reported that replacing an incoherent pumping mechanis m by a spectrally colored (partially coherent) pump can lead to signif icant gain enhancement in lasing without inversion schemes [Phys. Rev. A 48, R4055 (1993)]. We extend that study further by considering the effects of the noise parameters (strength and bandwidth) of the pump o n the gain in two types of three-level atomic energy-level schemes-the ladder and the LAMBDA models. The calculations presented in this pape r show a way to continuously ''tune'' the bandwidth of the pump and ma ke a direct comparison between the gain obtained for coherent, incoher ent, and partially coherent pumping. We find that for a given set of a tom-field parameters, the gain for coherent pumping is larger than for incoherent pumping, and that maximum gain is obtained for a partially coherent pump. Increasing the strength of the noise also leads to an increase in the gain. The frequency of the colored pump plays a critic al role in determining the maximum gain that can be obtained.