The optical propagation of a pulse through one dimensional finite gratings and photonic crystals is discussed. In the case of shallow gratings the light transport properties are derived within the frame of the Coupled Mode Theory, while the Transfer Matrix Method is used for investigating photonic crystal (PC) structures. The so-called superluminal tunneling of wave-packets through the band-gap region is investigated, and the dwell time is computed. Because of the analyticity of the wave equation, the Einstein causality principle is not violated, although the group velocity can exceed the speed of the light in vacuum. We show that the dwell time is a propagation phenomenon and not a quasi-static process in which the incident pulse envelope modulates the amplitude of an exponentially decaying standing wave. Nevertheless, the group velocity cannot be always used to compute the transmission group delay, because the latter does not represent the time spent by the energy to propagate through the band-gap.

Date Published: 20 December 2004
PDF: 11 pages
Proc. SPIE 5577, Photonics North 2004: Optical Components and Devices, (20 December 2004); doi: 10.1117/12.567367

Published in SPIE Proceedings Vol. 5577:
Photonics North 2004: Optical Components and Devices
John C. Armitage; Simon Fafard; Roger A. Lessard; George A. Lampropoulos, Editor(s)