Wavelength division multiplexing splitter with directional photonic crystal waveguide couplers

In this paper, we have investigated photonic crystal based optical waveguides implemented into wavelength division multiplexing systems. The wavelength division multiplexing splitters based on a photonic crystal waveguide coupler with square lattice and triangle lattice are proposed. The wavelength multiplexing properties are numerically investigated by using the finite-difference time-domain method. The coupling length can be reduced by using triangle lattice in the photonic crystal waveguide coupler.The symmetrical splitter has two identical photonic crystal waveguide couplers and three output channels that splitsa light wave equally and transfers power to the opposite guide. Theasymmetrical splitter has two different photonic crystalwave guide couplers and three output channels that output different wavelengths to the three output channels. Compared with traditional optical coupler, the sizes of PC coupler are expected to be drastically reduced from a few hundreds of micrometers to a few tens of micrometers.The PC couplers and splitters should enable novel utilizations for designing compact devices in photonic circuits.