Lasing without inversion in an open Λ-type system: self-pulse and continuous wave

Using the numerical calculation results, the transient evolution processes and steady outputs of the continuous wave lasing without inversion (LWI) originating from Pitchfork bifurcation instability and self-pulsing LWI originating from Hopf bifurcation instability in a resonant open Λ-type three level atomic system are studied. We found that the two kinds of LWI have some obvious differences not only from the steady outputs but also from the transient evolution processes. The effects of the unsaturated gain coefficient, cavity loss coefficient, ratio of the atomic injection rates and atomic exit rate on the transient evolution processes and steady outputs are discussed.