Optical flip-flop based on parallel-connected AlGaAs/GaAs pnpn structures

An optical flip-flop using parallel-connected pnpn (thyristor) structures is demonstrated for the first time to our knowledge. We utilize the differential optical switching technique for inverting the state of the flip-flop and the slow dissipation of carriers stored in the gate layers of pnpn structures for retaining the state. The flip-flop operation with 7.2 pJ of optical input energy was attained by using an AlGaAs/GaAs device. The expansibility to monolithic two-dimensional arrays, the high on-off contrast, and the high optical gain of the flip-flop are useful in the design and fabrication of optical parallel processing systems.