Synchronizing high-dimensional chaotic optical ring dynamics

We study chaotic ring laser systems as possible elements in a communications system. To be useful it must be possible to synchronize the transmitter and receiver lasers. We show that chaotic ring lasers can be synchronized using direct light injection from one laser into the optical cavity of the second. This synchronization occurs even when both lasers are quite high dimensional and each possesses many positive Lyapunov exponents. When the lasers are synchronized, the transmitted light can be modulated with information bearing signals and the message accurately recovered at the receiver.