Spontaneously Generated Coherence Effect Research Articles

Phase control of gain and dispersion in an open lambda-type inversionless lasing system

The control role of the relative phase between the probe and driving fields on the gain and dispersion in an open Λ-type inversionless lasing system with spontaneously generated coherence (SGC) is investigated. It is shown that the inversionless gain and dispersion are quite sensitive to variation in the relative phase; by adjusting the value of the relative phase, electromagnetically induced transparency (EIT), a high refractive index with zero absorption and a larger inversionless gain can be realized. It is also shown that, in the contributions to the inversionless gain (absorption) and dispersion, the contribution from SGC is always much larger than that from the dynamically induced coherence for any value of the relative phase. Our analysis shows that variation in the SGC effect will cause the spectrum regions and values of the inversionless gain and dispersion to vary evidently. We also found that, under the same conditions, the values of the inversionless gain and dispersion in the open system are evidently larger than those in the corresponding closed system; EIT occurs in the open system but cannot occur in the closed system.

Resonantly enhanced continuous-wave four-wave mixing with spontaneously generated coherence in a five-state cold atomic medium

Using Schrodinger–Maxwell formalism, we propose and analyse a continuous-wave four-wave mixing (FWM) scheme for the generation of coherent light in a five-state double-Λ atomic system with or without spontaneously generated coherence (SGC) based on electromagnetically induced transparency (EIT). We derive the corresponding explicit analytical expressions for the generated FWM field under the steady-state condition. The influence of hyperfine sublevel and SGC effect on the amplitude of the generated FWM field is predicted in detail via the derived analytical expressions. We also give a brief discussion on the experimental realization of the proposed scheme.

Optical bistability and multistability via the effect of spontaneously generated coherence in a three-level ladder-type atomic system

We investigate the optical bistability (OB) behavior of a nearly equispaced ladder-type three-level atomic system contained in a unidirectional ring cavity. We consider the three-level atoms under conditions that the atomic dipole moments are nonorthogonal so that the effect of spontaneously generated coherence (SGC) is important. We find that the SGC effect significantly affects the OB behavior of such system. Within certain parameter range, OB can be realized due to the SGC effect. The bistable hysteresis cycle becomes wider with the enhancement of SGC effect. Furthermore, such system is much sensitive to the relative phase between the coupling and probe fields. This property makes it possible to switch between bistability and multistability via adjusting the relative phase.