Effect of exit and injection rates on phase-dependent transient evolution of gain without inversion

It is shown that in an open Λ-type system with spontaneously generated coherence, the transient evolution rule of the gain of lasing without inversion (LWI) is very sensitive to variation of the relative phase φ between the probe and driving fields; the variety of the atomic exit rateγ_0 and the ratio C of the atomic injection rates also have a considerable effect on the phase-dependent transient evolution rule of LWI gain. We find that whenφ=0, the transient and stationary LWI gain increases with C increasing but decreases with γ_0 increasing; whenφ≠0 , the effect of C andγ_0 on LWI gain is just opposite to that when φ=0 ; in order to get the largest transient and stationary LWI gain, we need selecting suitable values of φ,γ_0 and C.

It is shown that in an open A-type system with spontaneously generated coherence, the transient evolution rule of the gain of lasing without inversion （LWI） is very sensitive to variation of the relative phase φbetween the probe and driving fields; the variety of the atomic exit rate γo and the ratio C of the atomic injection rates also have a considerable effect on the phase-dependent transient evolution rule of LWI gain. We find that when φ =0, the transient and stationary LWI gain increases with C increasing but decreases with γ0 increasing; when φ≠0, the effect of C and γ0 on LWI gain is just opposite to that when φb=0 ; in order to get the largest transient and stationary LWI gain, we need selecting suitable values of φ, γ0andC.