NRZ format all-optical clock extraction at 3.2 Gbit/s using two-contact semiconductor devices

Bit-error-ratio (BER) measurements have been demonstrated with all-optical clock recovery from a 3.2 Gbit/s NRZ sequence using two-contact semiconductor devices. A nonlinear optical amplifier generated the missing clock component in the NRZ modulation spectrum which then locked the output of a selfpulsating laser. BER measurements showed that the resulting clock signal was extremely pure and stable giving a 0.2 dB improvement in receiver sensitivity when compared to measurements using a clock from the transmitter. This type of optical clock recovery technique could have a major impact on future gigabit per second telecommunication systems.