The influence of spontaneously generated coherence and phase of laser fields on optical bistability in a three-level atomic medium: an analytical approach

The influence of spontaneously generated coherence and relative phase of laser fields on optical bistability in a three-level atomic medium under electromagnetically induced transparency was studied by using a density matrix theory. An input-output intensity relation of a probe laser field is derived as an analytical function of parameters of a controlling light field, the relative phase, and the spontaneously generated coherence. This function can be fitted with experimental values to be a semi-empirical model which is helpful for finding related applications. It is shown that thresholds and width of the optical bistability hysteresis loop can be manipulated with the controllable parameters. On the other hand, the influence of population relaxation between two ground hyperfine levels on the optical bistability behavior is significant for small coupling field intensity.