Accordable filters by defect modes in single and double negative star waveguides grafted dedicated to electromagnetic communications applications

Abstract

In the framework of the Green Function approach, we determine the transmission spectrum and the band structure of detective one-dimensional photonic star waveguides. This structure is composed of backbones’ periodicity that is characterized by negative magnetic permeability μ and positive dielectric permittivity ϵ, grafted in each site by resonators of negative permittivity and positive magnetic permeability. In the middle of the structure, we consider geometrical or/and material defect at the backbone level. The presence of such defect in this structure creates inside the photonic band gaps of the perfect structure, very narrow filtered frequencies (defect modes) with a significant quality factor Q and a very high transmission coefficient. The frequencies of the defect modes are strongly sensitive to the variation of the length and the relative permittivity of the defect. These electromagnetic characteristics of the considered structure provide good information for the design of adjustable wide gap filters.

KEYWORDS:

• Star waveguide
• filter
• defect modes
• double-negative (DNG)
• single-negative (SNG)