Analysis of Unidirectional Absorption in a Defective Superconducting Photonic Crystal

Terahertz unidirectional resonant absorption in a finite one-dimensional defective superconducting photonic crystal is theoretically investigated. We consider an asymmetric photonic crystal (AB)^ND(BA) ^M, where A is a dielectric, B is a superconductor, D is the dielectric defect, and N, M are the stack numbers, respectively. At N ≠ M, it is found that the resonant absorption for the structure exhibits the unidirectional property. The unidirectional resonant absorption points increase as the difference between N and M increases. We also investigate the unidirectional property as a function of angle of incidence. The results show that the unidirectional absorption is nearly independent of the polarization at a given angle of incidence. The proposed structure can be used to design a polarization-independent optical device which may be technically used in superconducting photonics.