Mode Exchange and Phase Jumps at Exceptional Points in Anisotropy-Driven Layered Non-Hermitian Structures

Exceptional points (EPs) are the most intriguing features of non-Hermitian systems associated with symmetry- and topology-driven applications. In this paper, we study the influence of tunable anisotropy on the topological properties of EPs in PT-symmetric layered structures. In particular, the eigenvalues exchange and eigenmodes exchange are predicted at the points of equal light transmission of different polarizations. We also unveil that the EPs tailored by the anisotropy parameters are associated with the π phase jump of reflection coefficients. Indirect evidence for the topological nature of EPs shown here is important for deeper insights into behaviors of anisotropic non-Hermitian systems and can be further used for the development of tunable non-Hermitian sensors and other applications.