Modulation of atomic exit and injection rates on the phase-dependent gain without inversion in a Doppler broadened open four-level system

摘要

It is shown that in a Doppler broadened open N-type four-level atomic system with spontaneously generated coherence (SGC),the gain without inversion (GWI) is very sensitive to the variation of the relative phase between the probe field and the driving field; the atomic exit rate (R0) and the ratio (S) of the atomic injection rates have a considerable modulation effect on the phase-dependent GWI.GWI first increases and then decreases with R0 increasing;in a certain value range of S,GWI increases monotonically with S increasing; by adjusting the values of R0 and S,in an open system a much larger GWI can be obtained than in the corresponding closed system [2011 Phys.Rev.A 83 043805].The modulation effects of R0 and S on the phase-dependent GWI in the case with the counter-propagating probe and driving fields are stronger than those in the co-propagating case,GWI in the co-propagating case is much larger than that in the counter-propagating case.