Coupling of orthogonal polarization states in a nonlinear birefringent cavity

We discuss the coupling of orthogonally polarized beams in a nonlinear cavity and show experimentally how this can be used to implement gates or latches in which one polarization state is switched by another. These devices must be reset by interrupting a light beam and thus must dissipate energy to switch down. The possibility of up and down switching with positive pulses only is also discussed.