Systematic design of wideband slow light in ellipse-hole photonic crystal waveguides

Abstract

This study presents a systematic optimization procedure to generate slow light with large group index, wideband, and low dispersion in an ellipse-hole photonic crystal waveguide. The group index, bandwidth, and dispersion can be tuned efficiently by changing the orientation of the ellipse holes in the first row and a longitudinal hole position shift of the third row. Under a constant group index criterion of ±10% variation, the corresponding bandwidths of the flat band reach are 13.5, 9.4, 7.8, and 6.1 nm around 1550 nm when the group indices are approximately the constants 46, 63, 78, and 100, respectively. A nearly constant group index–bandwidth product of 0.39 was achieved for all cases. Low-dispersion slow-light propagation was confirmed by studying the relative temporal pulsewidth spreading with the two-dimensional finite difference time-domain method.