Sharif Digital Repository

The optical properties of a four-level atomic system via coherent and incoherent pumping fields are investigated. The giant Kerr nonlinearity with reduced linear and nonlinear absorption, which has a major role in decreasing the threshold of optical bistability (OB), can be obtained with subluminal light propagation via adjusting the intensities of coupling fields. An incoherent pumping field is noticed to be an extra parameter to reduce the threshold of OB and multistability, and it can be used as an effective parameter in producing lasing with or without population inversion. In this model, optical multistability is achieved simply by tuning the intensity of coupling laser fields.... 

We theoretically investigate the optical bistability (OB) in a V-type three-level atomic system confined in a unidirectional ring cavity via incoherent pumping field. It is shown that the threshold of optical bistability can be controlled by the rate of an incoherent pumping field and by interference mechanism arising from the spontaneous emission and incoherent pumping field. We demonstrate that the optical bistability converts to optical multi-stability (OM) by the quantum interference mechanism  

Two atomic models are proposed for an Er 3+-doped YAG crystal with application to lasing with and without population inversion. It is shown how an incoherent pumping field and coherent control coupling field can produce a laser in the presence and absence of population inversion  

We investigate the optical bistability (OB) and optical multi-stability (OM) in a four-level N-type atomic system. The effect of spontaneously generated coherence (SGC) on OB and OM is then discussed. It is found that SGC makes the medium phase dependent, so the optical bistability and multi-stability threshold can be controlled via relative phase between applied fields. We realize that the frequency detuning of probe and coupling fields with the corresponding atomic transition plays an important role in creation OB and OM. Moreover, the effect of laser coupling fields and an incoherent pumping field on reduction of OB and OM threshold is then discussed