Localized modes in defective multilayer structures

TL;DR

This paper investigates localized surface modes in defective multilayer structures, revealing how defect position and thickness influence mode localization, dispersion, and energy flow, with implications for photonic device design.

Contribution

It introduces a detailed analysis of how defect layers affect localized modes and their dispersion in multilayer photonic structures, expanding understanding of defect-induced mode behavior.

Findings

Defect layers support two types of localized modes: surface and defect localized.

The defect shifts the dispersion curve of surface modes within the photonic bandgap.

Defect presence influences the energy flow velocity of surface modes.

Abstract

In this paper, the localized surface modes in a defective multilayer structure has been investigated. It is shown that the defective multilayer structures can support two different kind of localized modes depending on the position and the thickness of the defect layer. One of these modes is localized at the interface between the multilayer structure and a homogeneous medium (the so-called surface mode) and the other one is localized at the defect layer (defect localized mode). We reveal that the presence of defect layer pushes the dispersion curve of surface modes to the lower or the upper edge of the photonic bandgap depending on the homogeneous medium is a left-handed or right-handed medium (e.g. vacuum), respectively. So, the existence region of the surface modes restricted. Moreover, the effect of defect on the energy flow velocity of the surface modes is discussed.