Electromagnetic filtering and guiding of three frequencies by the presence of defects in one-dimensional photonic star waveguides structure

Abstract

In this work, the propagation of electromagnetic waves in a one-dimensional star waveguides photonic structure is shown to present a novel physical phenomenon. This system contains a periodicity of cells; each cell is composed of finite segment of length d1 with two asymmetric resonators of lengths d2 and d3 are grafted in its extremity. This perfect structure consists of photonic pass bands separated by large photonic band gaps where the propagation of electromagnetic waves cannot propagate inside these forbidden regions. Due to the presence of these large gaps, the electromagnetic waves can be controlled and manipulated by a wide range of applications. On the other hand, the presence of defects, either at the segment level, or the asymmetric resonators located in one site, or the two components of the cell (segment–asymmetric resonators) inside this structure, leads to the appearance of two or three localized states (defect’s modes) inside these gaps with a very high transmission rate and a high-quality factor which reach Q=565850. We show that these localized states depend strongly on the defect lengths. The band structure and the transmission spectra are calculated by using the continuous medium interface response theory, which makes possible to calculate the Green function of any composite material. The structure and results provide a good support for the applications of filtering and guiding the defects modes inside the band gaps.