All-Optical General RS Flip-Flop and Clocked RS Flip-Flop Based on Cascaded PPLN Waveguides

By utilizing the principle of optical logic signal processing of periodically poled lithium niobate (PPLN) waveguide, this paper proposes schemes of all-optical general set-reset (RS) flip-flop and clocked RS flip-flop based on cascaded second-order nonlinearities of sum-frequency generation (SFG) and difference-frequency generation (DFG), and the principle is theoretically investigated. The waveforms, eye diagrams, extinction ratio (ER) and full width at half maximum (FWHM) of the light waves are calculated and simulated numerically. The results of static simulation demonstrate that the logic of general and clocked RS flip-flops are achieved well by these schemes; the timing sequential simulation demonstrate that the logic properties of flip-flops with a feedback loop can also be achieved well for timing sequential optical signals.