Dispersion Engineering of Wide Slot Photonic Crystal Waveguides by Bragg-Like Corrugation of the Slot

A comb slot photonic crystal waveguide geometry allowing flexible dispersion engineering of wide slot photonic crystal waveguides is proposed. Additionally, a figure of merit combining confinement within the slot and high group index is introduced to quantify the electromagnetic density within slow wave slot waveguides, and is applied to the proposed waveguide geometries. Group indices exceeding 130 and 90 over bandwidths of 1.5 and 2 nm are achieved for slots wider than 300 nm. The figure of merit exhibits sevenfold and fortyfold enhancements in comparison with classical slot waveguides with slot widths around 50 and 100 nm, respectively.