Properties of defect modes in cylindrical photonic crystals

In this research, we study the properties of the defect modes that arise in the photonic band gap of a cylindrical photonic crystal (CPC) by using the transfer matrix method in the cylindrical coordinates. We consider two defective CPCs stacked in symmetric and asymmetric geometries. We examine the number of modes and their properties in the two CPCs structures. The dependencies of the modes on the azimuthal number and the inner radius of the CPC are also discussed. Numerical results show that the defect mode in the asymmetric CPCs has higher Q factor than those in the symmetric CPCs. Beside many potential optical communications and filtering applications, the structure may be a candidate for refractive index sensing with average sensitivity of 200 nm/RIU in the refractive index range from 1 to 1.6.