All-optical flip-flop based on an active Mach–Zehnder interferometer with a feedback loop

A novel architecture for an all-optical flip-flop is validated experimentally. The architecture comprises a single semiconductor optical amplifier–based Mach–Zehnder interferometer with an external feedback loop. The experimental results show optical bistable operation for a latching device with an on–off contrast ratio of $11\mathrm{dB}$ that employs set and reset pulses of less than $250\mathrm{pJ}$, although the energy of these pulses could be greatly reduced by optical integration of the whole device.