Bifunctional sensing based on an exceptional point with bilayer metasurfaces
Yicheng Li, Zhengwei Deng, Chunhua Qin, Shicheng Wan, Bo Lv, Chunying Guan, Jun Yang, Shuang Zhang, Jinhui Shi
Abstract
Exceptional points (EPs), the critical phase transition points of non-Hermitian parity-time ( PT ) systems, exhibit many novel physical properties and associated applications, such as ultra-sensitive detection of perturbations. Here, a bilayer metasurface with two orthogonally oriented split-ring resonators (SRRs) is proposed and a phase transition of the eigenpolarization states is introduced via changing the conductivity of vanadium dioxide (VO 2 ) patch integrated into the gap of one SRR. The metasurface possesses a passive PT symmetry and an EP in polarization space is observed at a certain conductivity of the VO 2 . Two sensing schemes with the metasurface are proposed to achieve high-sensitivity sensing of temperature and refractive index in the terahertz (THz) range. The metasurface is promising for applications in THz biosensing and polarization manipulation.