Excitability of excitons and biexcitons in a ring cavity

We discuss the excitable behavior of excitons and biexcitons in a nonlinear optical ring cavity. The nonlinearity is due to the process of the creation of biexcitons by photon-assisted conversion of excitons. In the bifurcation analysis a region where a saddle point is close to an equilibrium has been found. In this region the system shows excitability. It is shown that the mechanism of the excitable behavior of excitons and biexcitons in a ring cavity is different from that of two-level atoms in the same system. The possible applications of an excitable ring cavity are discussed.