We propose and evaluate a 2-D photonic crystal waveguide with a single line defect that uses rectangular holes adjacent to waveguide, arranged in a hexagonal geometry. With an aspect ratio of 2:1 in rectangular holes, we obtained transmission efficiency of 94% which is larger than previously reported for its circular and elliptical counterpart. By controlling the single parameter of rectangular air hole, the slow light performance of the improved efficiency structure is analyzed. In the irregular waveguide, slow light is achieved with low group velocity and very low group velocity dispersion over large signal bandwidth of 23 GHz. The normalized delay bandwidth product (NDBP) for the proposed design is also measured and compared with NDBP of waveguide when instead of rectangular holes, elliptical holes is used adjacent to waveguide with same aspect ratio 2:1. Improvement in normalized delay bandwidth product is obtained for our proposed design when elliptical air holes of aspect ratio 2:1 adjacent to waveguide are replaced by rectangular holes of same aspect ratio.
We propose a new design for slow-light photonic crystal W1 waveguide, which uses a combination of circular and elliptical air holes arranged in a hexagonal lattice with background material of refractive index n = 2.84. Large value of normalized delay bandwidth product (NDBP = 0.3708) is obtained. We have also analyzed dispersion property for the structure and achieved nearly "zero-dispersion" for a very large bandwidth. Our proposed photonic crystal waveguide has slow light applications such as reduction in length and power consumption of all-optical and electro-optic switches at optical frequency.