Dispersion of coupled mode-gap cavities

TL;DR

This paper investigates the asymmetric dispersion in coupled mode-gap cavities, revealing that the dispersive nature of cavity mode profiles causes the asymmetry, which can be accurately modeled without additional parameters.

Contribution

It introduces a mode coupling model that accounts for dispersive mode profiles, explaining asymmetric dispersion in photonic crystal cavities beyond standard tight binding models.

Findings

Dispersive cavity mode profiles cause asymmetric dispersion.

Standard tight binding models cannot explain the observed asymmetry.

The new model accurately describes dispersion without extra parameters.

Abstract

The dispersion of a CROW made of photonic crystal mode-gap cavities is pronouncedly asymmetric. This asymmetry cannot be explained by the standard tight binding model. We show that the fundamental cause of the asymmetric dispersion is the fact that the cavity mode profile itself is dispersive, i.e., the mode wave function depends on the driving frequency, not the eigenfrequency. This occurs because the photonic crystal cavity resonances do not form a complete set. By taking into account the dispersive mode profile, we formulate a mode coupling model that accurately describes the asymmetric dispersion without introducing any new free parameters.