Investigation of a channel-add/drop-filtering device using acceptor-type point defects in a two-dimensional photonic-crystal slab

A channel-drop-filtering device using point and line defects in a two-dimensional photonic-crystal slab is investigated. The efficiency to drop light from a line-defect waveguide to the free space via a point-defect cavity is found to be more than 45%, which is very close to the theoretical maximum of the device. The reverse function of the device (channel-add-filtering) is also demonstrated, where photons incident on a point defect from free space are resonantly trapped and transferred to a line-defect waveguide nearby. The spectrum and polarization characteristic of the add-filtering completely agree with those of the drop-filtering. The results indicate that two-dimensional photonic slabs are very promising for realizing ultrasmall optical functional devices. (C) 2003 American Institute of Physics.