Exceptional Points in Non-Hermitian Photonic Crystals Incorporated With a Defect

Abstract

We explored exceptional points (EPs) in one dimensional non-Hermitian photonic crystals incorporated with a defect. The defect was asymmetric with respect to the center. Two EPs could be derived by modulating the normalized frequency and the gain-loss coefficient of defect. The reflection coefficient complex phase changed dramatically around EPs, and the change in complex phase was π at EPs. The electric field of EPs was mainly restricted to the defect, which can induce a giant Goos–Hänchen (GH) shift. Moreover, we found a coherent perfect absorption-laser point (CPA-LP) in the structure. A giant GH shift also existed around the CPA-LP. The study may have found applications in highly sensitive sensors.

Two-parameter Optical Sensing Based on Multilayer Parity-time-symmetric Structure

“…To verify the presence of EP, the phase change at some particular τ is extracted [24,25]. The phase angles t φ of transmission coefficients t is calculated by TMM.…”