Wideband and Low Dispersion Slow Light in Lattice-Shifted Photonic Crystal Waveguides

We propose a new type of photonic crystal waveguide structure to achieve wideband slow light with large group index and low dispersion. The waveguide is based on triangular lattice photonic crystal imposed by simply a selective altering the locations of the holes adjacent to the line defect. Keeping the group index at 31, 44, 61, 71, 94, and 132, respectively, while restricting its variation within a +/- 10% range, we accordingly attain an available bandwidth of 19.1, 13.0, 9.0, 7.5, 5.5, and 3.6 nm around 1550 nm. The normalized delay-bandwidth product keeps around 0.35 for all cases. Low dispersion slow light propagation is confirmed by studying the relative temporal pulsewidth spreading with the 2-D finite-difference time-domain method.