Photonic Crystal Slabs with Hexagonal Optical Atoms and Their Application in Waveguides

Abstract

The standard plane wave expansion (PWE) method with the supercell method was used to calculate the band diagrams of photonic crystal slabs (PCSs) with hexagonal optical atoms. A hole-type PCS with hexagonal optical atoms has almost the same width of first band gap for the TE-like mode as its two-dimensional (2D) counterpart. However, the first band gap of a pillar-type PCS with hexagonal optical atoms shrinks considerably compared with that of its 2D counterpart. The hole-type PCS with normal hexagonal optical atoms has a slightly wider first band gap for TE-like modes than does that with orthogonal hexagonal optical atoms. PCSs with normal and orthogonal hexagonal optical atoms have band gaps that can be compared to those of PCSs with circular optical atoms. Hence they are appropriate structures for fabricating PC devices. The dispersion curves of line-defect PC waveguides were also calculated by the PWE method with the supercell method and several potential methods for modulating their dispersion curves were also discussed. Modulating the width of the line defect and the size of the optical atoms along the line defect were proved to be effective ways for obtaining a single-mode line-defect PC waveguide with a large bandwidth.