Range of existence of optical multistability in a resonator with an optically active medium

Optical bistability in resonators containing a nonlinear gyrotropic isotropic medium is analyzed by studying the dependence of the bifurcation intensity of the incident radiation on its ellipticity. It is found that if the gyrotropy is weak, this dependence may have symmetry-induced singular points or turning points. The stable radiation states in the resonator formed near a singular or turning point differ in respect of the polarization and are due to the evolution of the polarization instability. Bifurcation curves are plotted for a ring resonator containing a medium with a cubic nonlinearity. The form of these curves changes appreciably as the gyrotropy is increased. The change in the resonator transmission accompanying changes in the gyrotropy is studied.