All-optical flip-flop memory by using two coupled polarization switches

An all-optical flip-flop memory with separate set and reset inputs is presented. The flipflop is formed from two coupled polarization switches that are operated by utilizing the nonlinear polarization rotation in semiconductor optical amplifiers. The concept of the system is explained and experimental results are presented, demonstrating that a contrast ratio of over 20 dB between output states and a switching power of less than -3 dBm can be obtained. The all-optical flip-flop can be utilized in all-optical packet switches.