Coupled-resonator-induced reflection in photonic-crystal waveguide structures

TL;DR

This paper introduces a novel coupled-resonator-induced reflection (CRIR) effect in photonic crystal waveguides with high tunability, distinct from the known CRIT phenomenon, with potential applications in slow-light control and optical switching.

Contribution

It reports the discovery and analysis of CRIR, a new resonant reflection effect with high quality factor, in coupled-resonator photonic structures, expanding the understanding of Fano-Feshbach resonances.

Findings

CRIR exhibits a high and tunable quality factor.

CRIR differs from CRIT in physical origin and behavior.

Potential for controlling slow-light and optical switching applications.

Abstract

We study the resonant transmission of light in a coupled-resonator optical waveguide interacting with two nearly identical side cavities. We reveal and describe a novel effect of the coupled-resonator-induced reflection (CRIR) characterized by a very high and easily tunable quality factor of the reflection line, for the case of the inter-site coupling between the cavities and the waveguide. This effect differs sharply from the coupled-resonator-induced transparency (CRIT) -- an all-optical analogue of the electromagnetically-induced transparency -- which has recently been studied theoretically and observed experimentally for the structures based on micro-ring resonators and photonic crystal cavities. Both CRIR and CRIT effects have the same physical origin which can be attributed to the Fano-Feshbach resonances in the systems exhibiting more than one resonance. We discuss the applicability of the novel CRIR effect to the control of the slow-light propagation and low-threshold all-optical switching.