Coupled mode approach to square gradient Bragg reflection resonances in corrugated dielectric waveguides

TL;DR

This paper reveals unexpected reflection resonances caused by boundary curvature in corrugated dielectric waveguides, significantly affecting transmission and important for waveguide design, validated through coupled mode theory and simulations.

Contribution

It introduces a coupled mode approach to identify and analyze curvature-induced Bragg reflection resonances in dielectric waveguides, a novel insight for waveguide design.

Findings

Curvature causes strong reflection resonances comparable to standard Bragg resonances.

Reflection reduces waveguide transmission by approximately 20%.

Analytical predictions match numerical simulations.

Abstract

We demonstrate the appearance of unexpected reflection resonances in corrugated dielectric waveguides. These are due to the curvature of the boundary. The effect is as strong as the ordinary Bragg resonances, and reduces the transmission through our waveguide by 20%. It is thus of high relevance for the design of optimized waveguiding structures. We validate our analytical predictions based on coupled mode theory by a comparison to numerical simulations.