Propagation of electromagnetic waves in one dimensional symmetric and asymmetric Comb-like photonic structure containing defects

In this paper, we study theoretically the transmission spectrum and the dispersion relation of a periodic photonic comb-like waveguide consisting of periodic segments of length d(1) along which two different symmetric or asymmetric resonators of lengths d(2) and d(3) are grafted in each site. We study the presence of geometrical defects on the transmission spectrum. The creation of defects at the resonators levels of lengths d(02) and d(03) inside the perfect structure; enable to deduce the localized states (defects modes) inside the band gaps. In this research, we demonstrate the existence of two frequencies filtering with the presence of a single defect at the resonator level. In the same time, we investigate three frequencies filters in the existence of two defect resonators of lengths d(02) and d(03). (C) 2020 The Authors. Published by Elsevier Ltd.