All-optical binary counter based on semiconductor optical amplifiers

A cascadable all-optical binary counter is demonstrated by using optical flip flops and logic gates based on semiconductor optical amplifiers. Two-bit counting operation as well as optical-frequency division at two different frequencies is presented. The proposed scheme is tunable in the entire C-band and can work at different counting rates without any reconfiguration. Performance evaluations in terms of Q factor confirm the effectiveness of the scheme in cascadable configurations. Counting-speed limitation is investigated, and photonic integration is identified as a feasible solution to increase the functioning rate beyond gigahertz.