All-optical photonic crystal memory cells based on cavities with a dual-argument hysteresis feature

In this paper, the idea of an all-optical photonic crystal memory cell based on a cavity with a hysteresis feature as a function of two independent variables is introduced. A two-dimensional square lattice of Si rods in a SiO2 background is used for this purpose. Plane wave expansion and finite difference time domain methods are used to simulate the structures. A novel cavity topology with Kerr-type nonlinearity is used for designing the memory cells. The cavity which supports two degenerate orthogonal modes is designed at the intersection of two W1 waveguides and exhibits a fairly wide hysteresis loop. It is shown that such topologies can be used to design fast all-optical memory cells. Two different topologies for the realization of all-optical memories are thereby proposed. Based on the simulation results, for the final structure proposed in this paper, a 2ps-wide Gaussian-shaped trigger pulse can be used to change the state stored in the memory cell. It takes nearly 5ps for the memory to change its state.