Design of two-dimensional photonic crystal based ultra compact optical RS flip-flop

The presented research deals with designing of a new ultra compact all-optical RS flip-flop on a two-dimensional (2-D) hexagonal photonic crystal platform. The flip-flop is designed by using two NOR gates, photonic crystal waveguides, four silicon ring resonators, four input ports and two output ports. The designed flip-flop structure has hexagonal silicon rods in the air host with a lattice constant a of 630 nm. Si rods have a radius of 0.2a and operating waveleangth of 1550 nm. The novel design provides proper distinction between logic 1 and logic 0 at the output by giving 8.7 dB and 4 dB contrast ratio at Q and Qbar output, respectively. Furthermore, uncomplicated structure resulting in small dimension of 28 μm * 28 μm makes it appropriate for optical integrated circuit in optical networks. FDTD method is used to model the proposed structure and simulated using RSoft FullWAVE simulator tool.