Phase knob for switching steady-state behaviors from bistability to multistability via spontaneously generated coherence

We conducted a theoretical investigation of the optical steady-state behavior in N four-level Y-type atoms driven coherently by a probe laser and a single elliptically polarized field (EPF) by means of a unidirectional ring cavity. It was found that the optical bistability can be observed for a wide regime of frequency detuning of the probe field, intensity of the EPF, and the atomic cooperation parameter. Interestingly, in principle the optical steady-state behavior can be switched from optical bistability to multistability or vice versa by adjusting the phase difference between two components of the polarized electric field of the EPF if the perfect spontaneously generated coherence of atoms is included. Our results illustrate the potential to utilize EPF for all-optical switching in atomic systems through the phase control, as well as provide guidance in the design for possible experimental implementations. (C) 2014 Optical Society of America