Refractive Fabry-Perot bistability with linear absorption: Theory of operation and cavity optimization

We present a theory of optical bistability for a Fabry-Perot cavity containing a medium with nonlinear refraction but linear absorption with only plane-wave and slowly varying envelope approximations. An analytic expression for the critical intensity Icfor the onset of bistability is derived and used to compare cavity designs. It is shown that 1) the important material parameter for minimum Icis the ration₂/ 2) the limit to Icis set by limitations on finesse due to inhomogeneities rather than the absorption itself, and 3) the cavity design which gives lowest Icfor a given finesse is that for which the mirror transmissivity equals the absorption per pass; at high finesse this design leads to a total peak cavity transmission of 1/4 when mirror reflectivities are equal.