Group-Delay Properties of Coupled-Defect Structures in Photonic Crystals

Abstract

Changes in group-delay properties of coupled-defect structures formed in one-dimensional photonic crystals were systematically studied. It was found that the edge region of the photonic crystal plays an essential role in forming a smoothed wavelength-dependence of the group delay, which is important for avoiding degradation of the light-pulse transmission. Utilizing this knowledge, the authors designed an optimized structure that is composed of SiO 2 /Ta 2 O 5 layers and produces the transmittance of nearly 100% and the smoothed group-delay curve. A fabricated sample structure confirmed the designed characteristics and, thus, shows the potential applications of the coupled-defect structure to optical devices such as dispersion compensators.