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.
Highlights
Non-Hermite, which stems from quantum mechanics [1], has promptly expanded to optics [2,3,4,5], acoustics [6], and electronics [7]
We have showed that the light field penetrated more deeply into the photonic crystals (PCs) as the parameters became closer to EP1 and coherent perfect absorption-laser point (CPA-LP), so the dispersion of plane waves was more serious
We have theoretically studied exceptional points (EPs) in one-dimensional non-Hermitian PCs incorporated with a defect
Summary
Non-Hermite, which stems from quantum mechanics [1], has promptly expanded to optics [2,3,4,5], acoustics [6], and electronics [7]. Systems including gain or loss are non-Hermitian [8,9,10,11,12]. The eigenvalues and eigenvectors of Hamiltonian degenerate in non-Hermitian systems at the EPs, around which many fascinating optical properties may be induced, consist of sharp changes in the complex phase [18], unidirectional invisibility [19,20], and topological boundary states [21]. EPs and coherent perfect absorption-laser points (CPA-LPs) exist in PT-symmetric PCs [46]; it is more difficult to make complex dielectrics obey PT symmetry experimentally. We explored the complex phase changes of reflection and transmission coefficients around EPs and CPA-LPs. we investigated the degeneration of the eigenvalues of Hamiltonian at EPs and gave the distribution of the electric field. We simulated the Goos–Hänchen (GH) shift of reflected and transmitted beams around EPs and CPA-LPs
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