General conditions for intrinsic optical bistability at the atomic and molecular scale: An effective spin-Hamiltonian approach

Abstract

A model for intrinsic optical bistability is presented in the case of systems that can be described as two weakly interacting subsystems embedded in a matrix M. This model is based on an effective spin-Hamiltonian and a semiclassical density-matrix approach. It is shown that optical bistability should occur when the interaction between the two subsystems fluctuates more rapidly than the characteristic time of the interaction. The validity of the model is demonstrated in the case of bistable electron magnetic resonance, involving real spins. It is also shown that this model provides a semiquantitative explanation of intrinsic optical bistability for ${\mathrm{Yb}}^{3+}$ pairs in ${\mathrm{CsCdBr}}_{3}$ matrix.