Merging of defect modes in a superlattice of one-dimensional metamaterials photonic crystals

The optical properties are investigated in a new type of one-dimensional photonic crystal, which consists of two-layer unit cells. The first layer consists of a material with a negative refractive index (NIM) and the other is made of AlxGa1-xAs with a positive refractive index (x is content of Al in GaAs slab). Based on the transfer matrix method (TMM) and the Maxwell's equation the dependence of photonic bandgaps (PBGs) and omni-directional photonic bandgaps (OPBGs) on the geometrical structure, characteristic of incident light and the content parameter are studied theoretically, in both TE and TM polarization modes. The bandgap in the transmission spectrum originate from the Bragg's condition in the superlattice, while the existence of the defect layer gives rise to defect modes in the photonic bandgaps. Our results may be useful to better control the position of bandgaps in the optical filters and sensors designing. (c) 2019 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).