Manifestation of P T Symmetry Breaking in Polarization Space with Terahertz Metasurfaces

作者：Mark Lawrence, Ningning Xu, Xueqian Zhang, Longqing Cong, Jiaguang Han, Weili Zhang, Shuang Zhang · 发表于：Physical Review Letters · 年份：2014 · DOI：10.1103/physrevlett.113.093901 · 被引用次数：287 · 研究领域：Metamaterials and Metasurfaces Applications、Quantum Mechanics and Non-Hermitian Physics、Orbital Angular Momentum in Optics

By utilizing the vector nature of light as well as the inherent anisotropy of artificial meta-atoms, we investigate parity time symmetry breaking in polarization space using a metasurface with anisotropic absorption, whose building blocks consist of two orthogonally orientated meta-atoms with the same resonant frequency but different loss coefficients. By varying their coupling strength, we directly observe a phase transition in the eigenpolarization states of the system, across which the long axis of the eigenpolarization ellipses experience a sudden rotation of 45°. Despite the lack of rotational symmetry of the metasurface, precisely at the phase transition, known as the exceptional point, the eigenmodes coalesce into a single circularly polarized state. The PT symmetric metasurfaces are experimentally implemented at terahertz frequencies.