Multi-channel unidirectional and bidirectional wavelength filters in two dimensional photonic crystals

The unidirectional and bidirectional filtering properties of the two-dimensional square-lattice photonic crystal devices are thoroughly studied. Through carefully designing the coupling regions between the single defect and the neighboring waveguides, the multi-channel unidirectional and bidirectional wavelength filtering can be synchronously realized in the same structure. Moreover, the designed photonic devices can effectively function as beam splitters except for wavelength filters, which may be potentially applied in the complex optical integrated circuits.