Intrinsic optical bistability at atomic and molecular scale

Abstract
A general model for intrinsic optical bistability is presented for atomic or molecular systems which can be decomposed into two weakly interacting subsystems. It is shown that optical bistability should occur when the interaction between the two subsystems fluctuates faster than the characteristic time of the interaction. The validity of the model is demonstrated in the case of magnetic bistability of conduction electrons. It is extended in the infrared or visible range with pairs of rare earth ions and rare earth-transition metal ions systems.