Synchronization of a network element for optical packet switching using optical correlators and wavelength shifting

The authors demonstrate packet and bit synchronization of an optical switching node to an incoming packet stream. Their module synchronizes to packets with only four preamble bits and employs fiber Bragg gratings as continuous optical correlators and cross-gain modulation of an semiconductor optical amplifier as a wavelength shifter to determine the start of a packet. They use this optical technique to recognize the arrival of 2.5-Gb/s data packets and to route them to one of two outputs of an optical switch in a reconfigurable network. Penalty-free switching with a 1.6-ns guard time is achieved.