ALL-OPTICAL CLOCK RECOVERY FROM 5 GB/S RZ DATA USING A SELF-PULSATING 1.56 MU-M LASER DIODE

All-optical clock extraction from 5 Gb/s RZ data is demonstrated using a two-contact InGaAsP semiconductor self-pulsating laser diode (SP-LD). The saturable absorber region of the device was doped with zinc ions to reduce the carrier lifetime in this region such that strong self pulsations at frequencies up to 5.2 GHz were obtained. Injection of a 10-mu-W optical data signal at a wavelength close to one of the Fabry-Perot wavelengths was sufficient to synchronize the self pulsations to the incoming data stream. The resultant optical clock signal was used to perform bit-error-ratio measurements on the PRBS data. A system penalty of 0.5 dB was observed compared to the transmitter clock measurements. Such all-optical clock extraction techniques may find application in all-optical as well as optoelectronic regenerators and for switch synchronization in future multi-Gb/s optical networks.