Comprehensive study of singular points in a PT-symmetric Thue-Morse multilayer

Abstract

Parity-time symmetric optical systems have a non-Hermitian Hamiltonian with a purely real spectrum. These systems have been extensively explored owing to their ability to generate exotic photon transport phenomena. In this work, we report the spectral singularity of the one-dimensional aperiodic odd-generation Thue-Morse photonic lattice with parity time symmetry. We showed that this multilayer in addition to obvious unidirectional and bidirectional transparencies, displays interesting and singular properties including absorption, lasing and coherent perfect absorption-lasing singularities. Based on the transfer matrix and scattering matrix (S matrix) methods, the behavior of these singular points and reflectionless and invisibility properties of the structure is analyzed with respect to the thickness of the passive film sandwiched between active layers due to phase shift changes, frequency and incident angle of light. The available values of the structural parameters are investigated to obtain extraordinary transmission and reflection phenomena. These optical systems may possess the potential in the design of novel lasing and coherent perfect absorption optical devices with adjustable applications.