Related Experiment Video
Updated: Jun 12, 2026

Using Microwave and Macroscopic Samples of Dielectric Solids to Study the Photonic Properties of Disordered Photonic Bandgap Materials
Published on: September 26, 2014
Defect state characteristics of one-dimensional PT-symmetric photonic crystals
Abstract:
In this work, we investigate the defect-state characteristics of a one-dimensional defective photonic crystal (DPhC) operating at terahertz frequencies using the transfer-matrix and scattering-matrix methods. The structure comprises central defect layers sandwiched between periodic gain-passive-loss layers on both sides. For a lossless DPhC, the resonant peak exhibits unitary transmission and zero reflection in both the forward and backward directions. This results in a conventional energy-conservation relation, and the eigenvalues of the scattering matrix have a single crossing point. On the contrary, in a DPhC based on a PT-symmetric structure, where gain and loss are delicately introduced into the SiO2 layer, the transmission remains the same in the forward and backward directions. However, the zero reflection differs in the forward and backward directions. This results in a pseudo-unitary conservation relation. Further, the eigenvalues of the scattering matrix's crossings are split into a pair. These two points are known as exceptional points where the transmission is unitary. In addition, we examine how the eigenvectors coalesce and the Petermann factor diverges at the EPs and their behaviour in the unbroken and broken PT phases. Finally, we investigate the influence of structural parameters and oblique angles of incidence on PBG and EP bandwidths.
Related Concept Videos
Imperfections in Crystal Structure: Point, Line and Plane Defects
Imperfections in Crystal Structure: Stoichiometric Point Defects
Imperfections in Crystal Structure: Non-Stoichiometric Defects
The Seven Crystal Systems: Overview
Lattice Centering and Coordination Number
Types of Unit Cells
Imagine taking a large number of identical...
Crystallographic Point Groups

