Unidirectional absorption properties in a defective semiconductor-dielectric asymmetric triadic Cantor photonic crystal

It is well known that the defective asymmetric bilayer photonic crystal (PC), air/(DB)(N) A(BD)(M) /air, where A and B are dielectrics, D is lossy material, and N, M are stack numbers with N not equal M exhibits unidirectional absorption phenomena. In this work we theoretically study whether the defective asymmetric Cantor PC also exhibit the unidirectional optical property. The considered PC is the defective asymmetric Cantor PC, air/TCSN/A/TCSM/ air, where TCSN is the N stage triadic Cantor structure composed of B and D; the semiconductor, n-InSb, is chosen as D. Our results show that their absorption spectra also exhibit unidirectional properties. Besides, the absorption peaks has defect mode depending on the defect layers just similar to the defect modes in the transmittance spectra of the usual symmetry photonic crystals.