5 GHz all-optical binary counter employing SOA-MZIs and an optical NOT gate

We present an all-optical two-bit binary counter using two stages of optical T-flip-flop (T-FF) and an optical NOT Gate. The T-FF comprises a single semiconductor optical amplifier based Mach–Zehnder interferometer (SOA-MZI) and an external feedback loop. The NOT gate is realized by means of the cross gain modulation effect in an SOA. The proposed counter requires the minimum number of active components and just a single control signal as input. Featuring distinctive simplicity for reduced footprint and low power consumption, it is ideal for photonic integration and operation at multi-Gb s⁻¹ speeds. (paper)