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Optical bistability (OB) of an electromagnetically induced transparency (EIT) medium placed in a conventional unidirectional ring cavity is investigated numerically. The medium is excited by a coupling and probe laser lights via a five-level cascade scheme. It is shown that optical bistabe states with controllable switching threshold intensities and width are established simultaneously in three spectral regions corresponding to EIT windows. The current numerical result is compared to a previous analytical result showing influence of coherence terms neglected in the analytical model.

This paper presents the measurement of the dispersion spectrum of the gaseous Rubidium 85 at room temperature in the presence of electromagnetically induced transparency (EIT). We consider the system of the V-type configuration in which D2 line transition is simultaneously targeted by two counter-propagating laser fields - a strong coupling laser field and a weak probing laser field. Under the EIT effect, the anomalous dispersion in the resonant region is split into six “normal-anomalous” dispersion giving rise to six EIT-windows. Our experimental result suggested that the positions, as well as the slope of the curve at the dispersion domains, are controllable through both frequency and intensity of the coupling laser field. This insight is important for applications in high-resolution dispersion management

We investigate the propagation dynamics of a pair of probe and coupling laser pulses in a three-level type-V atomic medium under the condition of electromagnetically induced transparency (EIT) by numerical solving the Maxwell-Bloch equations for atoms and fields. Influences of the intensity and pulse area of the coupling laser on the EIT formation of probe laser pulse are studied in a wide region from micro- to pico-second of pulse duration. It is found that a nearly solition pulse can be established at the smallest pulse area in the pico-second region and with the largest pulse area in the micro-second region. These results can be important for applications in all-optical switching, and quantum information processing and transmission.

Under weak probe field, rotating wave and electric dipole approximations, we have derived analytic expressions for absorption and dispersion coefficients, group index and group velocity in a four-level cascade atomic medium interacting with the probe and pump laser fields. The model is applied to 85Rb atomic system to study the control of the fast and slow light propagation of the probe beam according to the intensity and frequency of the pump laser beam. With this excitation model, we find two transparent domains and thus the light group velocity is also controlled at these two frequency domains. In particular, the amplitude and the sign of the group index are easily changed by adjusting the intensity or frequency of the pump laser. That is, the probe beam propagation can be changed between fast and slow light modes by adjusting the intensity or frequency of the pump laser. Our analytical results can be useful for related experimental studies.