Switching through symmetry breaking in coupled nonlinear micro-cavities.

We describe stable symmetry-breaking states in systems with two coupled nonlinear cavities, using coupled-mode theory and rigorous simulations. Above a threshold input level the symmetric state of the passive Kerr system becomes unstable, and we show how this phenomenon can be employed for switching and flip-flop purposes, using positive pulses only. A device with compact photonic crystal microcavities is proposed by which we numerically demonstrate the principle.