Defect modes properties in periodic lossy multilayer containing negative index materials with symmetric and asymmetric geometric structures

TL;DR

This study investigates how defect modes in one-dimensional lossy photonic crystals with negative and positive index materials are affected by geometry, polarization, and incidence angle, revealing insights for designing narrow optical filters.

Contribution

It introduces a comprehensive analysis of defect modes in symmetric and asymmetric structures with negative index materials, highlighting the effects of geometry and incidence angle.

Findings

Number of defect modes depends on structure symmetry.

Defect mode frequency increases with incidence angle.

Negative index defect layers influence transmission properties.

Abstract

In this paper the characteristic matrix method is used to study the propagation of electromagnetic waves through one-dimensional lossy photonic crystals composed of negative and positive refractive index material layers with symmetric and asymmetric geometric structures with a defect layer at the center of the structure. First, the positive index material defect layer is considered, and the effects of the polarization and the angle of incidence on the defect mode in the transmission spectra of the both structures are investigated. The results show that the number of the defect modes in the transmission spectra depends on the geometry (symmetric or asymmetric) of the structure. In addition, it is shown that the defect mode frequency increases as the angle of incidence increases. This property is independent of the geometry of the structure. Then, for normal incidence, the negative index material defect layer is considered, and the properties of defect modes for both structures are investigated. The results can lead to designing new types of transmission narrow filters.