Slow light in an alternative row of ellipse-hole photonic crystal waveguide

High normalized delay-bandwidth product (NDBP) and wideband slow light are achieved in an alternative row of ellipse-hole photonic crystal waveguide. Two different criteria of flat ratio are adopted. Under a constant group index criterion, a high NDBP of 0.446 with a group index of 42 and a bandwidth of 16.4 nm are obtained by plane wave expansion calculations, while under a low dispersion criterion, the NDBP, group index, and bandwidth come to 0.352, 41, 13.1 nm, respectively. Low dispersion slow light propagation is numerically demonstrated by studying the relative temporal pulse-width spreading with the two-dimensional finite-difference time-domain method. As a whole, the presented results give indications about the "ultimate" possible improvement of slow light waveguide metrics by using noncircular holes.