Slow Light with High Normalized Delay Bandwidth Product in Photonic Crystal Line Defect Waveguide

Abstract

In this paper, to generate slow light with large group index, wideband, and low dispersion in suggested line defect photonic crystal waveguide, a systematic optimization procedure is performed. Two structural parameters in the adjacent rows of the waveguide are carefully adjusted. Dispersion engineering in the proposed structure is done by using plane wave expansion method. By tuning the structural parameters, normalized delay-bandwidth product (NDBP) with nearly constant group index is significantly improved. In the optimum case, a high NDBP of 0.373 with a group index of 38.6 and a bandwidth of 14.97 nm is obtained, while restricting the group-index variation within a 10% range. Also,a negligible group velocity dispersion over a broad wavelength range is obtained that can cause a small expansion of the pulse through the waveguide.