Slow light structure with enhanced delay–bandwidth product

Abstract

In this study, we propose a special type of slow light photonic crystal (PC) waveguide structure to achieve slow light with an improved delay and bandwidth product (DBP). The waveguide is based on a triangular lattice PC with a line defect imposed by changing the radii and locations of the holes lying along the waveguide centerline. By altering the locations of these central holes, group indices ranging approximately from 25 to 40 are obtained over frequency intervals, attaining a nearly constant group index. It is also observed that the group index spectrum has an S-like shape under certain circumstances. The manipulations of structural parameters easily allow attaining higher or lower group indices. For special configurations, normalized DBPs can be enhanced up to a value of 0.554. According to the best of the authors’ knowledge, this value is the highest value achieved with PC waveguide structures, and this value is achieved without using any special optimization methods such as topology optimization. Group velocity dispersion values of various configurations are minimized to enable proper optical pulse propagation.