A 4*5 Gb/s transmission system with all-optical clock recovery

The authors demonstrate successful 5 Gb/s operation of an all-optical clock extraction circuit in a 20 Gb/s optical time division multiplexing OTDM system. An optical clock signal was obtained by synchronizing a self-pulsating 1.56 mu m laser diode to a 5 GB/s RZ data signal, demultiplexed from a 4*5 Gb/s OTDM transmission system. Synchronization was achieved for pseudo-random-bit sequences from 2/sup 7/-1 to 2/sup 31/-1. At 2/sup 7/-1 full system bit-error-ratio (BER) measurement on one of the 5 GB/s channels using the extracted optical clock for synchronization were made with no observed penalty over transmitter clock measurements. Such clock extraction techniques may be of great importance in a wide variety of telecommunications applications. >