A Novel Design of 2-D Photonic Crystal Directional Coupler With High Extinction Ratio and Short Coupling Length

In this paper, a novel structure of a 2 times 2 directional coupler with high extinction ratio, small coupling length, and decoupling input/output channels is proposed, based on a 2-D photonic crystal with a hexagonal lattice of air holes. A total length of the coupling component of 24a and an extinction ratio of -35.07 dB are achieved in simulation using the finite difference time-domain method. Potential applications of this novel structure in wavelength demultiplexing and 4 times 4 directional coupling switches are addressed.