Negative Group Velocity and Effective Index of Refraction in One Dimensional Metallic-Dielectric Photonic Band Gap Materials

Abstract

We study the negative group velocity, effective indices of refractions (neff(p) and neff(g)) and absorption in one dimensional metallic-dielectric photonic band gap materials in visible and near ultra-violet regions. The group velocity and effective index of refractions have been computed incorporating the effect of absorption in the metallic layer employing well-known Drude model for the dielectric function. The complex Bloch vector gives complex group velocity, phase velocity and complex effective indices of refraction for all frequencies. The group velocity is negative and larger than the speed of light in free space at the forbidden band gap edge when γ =0.01 ωp. The effective phase index of refraction backbends for γ =0.01 ωp, due to absorbent as compared to γ =0. We found ultra high effective group index of refraction near the band edge for γ =0 and abnormal negative for γ =0.01ωp. Besides this, we have also studied the reflectance, transmission and absorption in visible and near ultraviolet region of electromagnetic spectra. © 2006 ISRAMT. All Rights Reserved.