Design of a channel drop filter by using a donor-type cavity with high-quality factor in a two-dimensional photonic crystal slab

We report a design of the surface-emitting-type channel drop filters based on point defect cavities and line defect waveguides in two-dimensional photonic crystal slabs, which aim to improve the filtering resolution and light emission characteristics. Since the filters are passive, the mode volume size of the defects needs not be minimized, but the interaction between the defect cavity and the line defect waveguide must be considered. By adopting a donor-type point defect with three missing holes of linear shape, the quality factor of the filter theoretically increases to values as high as 2900 while it reached only 500 in the previously utilized acceptor-type defect. The results suggest that this donor-type defect is very useful for the development of ultrasmall channel add/drop devices. (C) 2003 American Institute of Physics.