Unidirectional Invisibility Induced by Complex Anti-Parity–Time Symmetric Periodic Lattices

Abstract

Complex anti-parity-time symmetric periodic lattices, in a wide frequency band, can act as unidirectional invisible media. The reflection from one end is suppressed while it is enhanced from the other. Furthermore, unidirectional laser points (ULPs) which correspond to the poles of reflection from one end, arise in the parameter space composed of the permittivity and angular frequency. The phase of the reflection coefficient changes sharply near the ULPs. Subsequently, large lateral shift which is proportional to the slope of phase could be induced for the reflected beam. The study may find great applications in unidirectional invisibility, unidirectional lasers and highly sensitive sensors.

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

“…The PT-symmetry will spontaneously break if the gain and loss surpass some critical value, which is defined as the exceptional point (EP) [8,13]. 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].…”

Low Threshold Optical Bistability in Aperiodic PT-Symmetric Lattices Composited with Fibonacci Sequence Dielectrics and Graphene

“…PT-symmetric systems could induce many unique optical properties, including unidirectional invisibility [49], optical transparency [43,50], power oscillations [51], and the lateral shift of reflected light beam [52]. Otherwise, anti-PT-symmetric systems that satisfy n(r) = −n × (−r) can induce coherent perfect absorption laser points and unidirectional invisibility [53,54].…”