Enlarged photonic band gaps in one-dimensional magnetic star wave guide structure

Abstract

Photonic band structure and reflection properties of one-dimensional magnetic star wave-guide (MSWG) structure composed of a backbone (or substrate) waveguide along which a finite side branches grafted periodically have been investigated. The dispersion relation and hence the photonic band gaps (PBGs) of the magnetic SWG structure have been obtained by applying the Interface Response Theory (IRT). Investigation of dispersion characteristics shows that the existence of band gaps in magnetic SWG structures does not require the contrast in the wave impedance of the constituent materials, which is unlike the usual magnetic photonic crystal structure, where there must be the contrast in the wave impedance for the existence of the band gaps. Moreover, magnetic SWG structures have wider reflection bands in comparison to normal magnetic photonic crystal (MPC) structure for the same contrast in the wave impedance. Analysis shows that the width of forbidden bands for MSWG structure changes with the change in permittivity and permeability of the backbone, and side branches materials even the ratio of wave impedance is the same, but it remains the same in case of MPC structure. In addition to this, we have studied the effects of variation of number of grafted branches and substrates, i.e., number of nodes on the reflection bands of magnetic SWG structure.