Fault-tolerant automatic routing method with two photorefractive double phase conjugate mirrors

We propose a fault-tolerant automatic routing method with two photorefractive double phase conjugate mirrors for a free space optical communication. This method offers automatic routing of a signal beam from the main line to the backup line for the cutoff of the main line by obstacles. The link between the transmitter and the receiver is kept efficiently without any complex optical configuration and electronic devices even if the optical path shifts or tilts. We analyze the temporal response of the signal beam intensity on the main line and the backup line to confirm the automatic routing function, and conduct a basic experiment with a BaTiO₃ crystal and Ar⁺ laser.