Picosecond all-optical gate using a saturable absorber in mode-locked laser diodes

A novel application of mode-locked laser diodes (MLLD's) for all-optical gate is described, A saturable absorber (SA) shows 8-ps-absorption recovery and has a small switching energy of 0.9 pJ. For this SA used as an all-optical gate in combination with the all-optical clock recovery function of MLLD's, all-optical signal processing (demultiplexer and repeater) may be possible with a compact and robust configuration. To confirm the all-optical gate operation in MLLD's, 40 to 10 Gb/s all-optical DEMUX is successfully demonstrated.