Controllable optical bistability of an asymmetric cavity containing a single two-level atom

Optical bistability of a single-mode cavity containing a two-level atom in the Purcell regime has been analyzed. Compared with the case of a symmetric cavity, we find that the bistable regime of input power in an asymmetric cavity can be controlled by adjusting the cavity-loss rates of the asymmetric walls. Such results provide an optimal window of input power to realize giant optical nonreciprocity, which has promising application as the smallest all-optical diode unit with low operation power and high transmitted contrast.