Optical bistability and multistability in a three-level Δ-type atomic system under the nonresonant condition

Under a nonresonant condition, we theoretically investigate hybridabsorptive-dispersive optical bistability and multistabilitybehaviours in a three-level Δ-type system by using a microwavefield to drive a hyperfine transition between two upper excitedstates inside a unidirectional ring cavity. We find that the opticalbistability and multistability behaviours can be controlled byadjusting the intensity of the microwave field or the intensity ofthe coherent coupling field. Furthermore, our studies show aninteresting phenomenon of the transition from the opticalbistability to the optical multistability only by changing thenegative detuning of the coupling field into the positive detuningof the coupling field.