Experiment on parity-time-symmetry phase transition in non-Hermitian metasurfaces
Jingwei Xu, Shoujian Ouyang, Laibin Luo, Yun Shen, Liner Zou, Zhiyong Tan, Xiaohua Deng
Abstract
Metasurfaces consisting of two orthogonally oriented split-ring resonators with the same resonant frequency but different loss coefficients are proposed to devise a parity-time (PT)-symmetry system. Bovine serum albumin (BSA) solutions with different concentrations are dropped onto the metasurfaces to the realize PT-symmetry phase transitions. Theoretical and experimental results show that eigenstates of the PT system will change from circularly polarized states at the exceptional point to corotating ellipses along <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mspace width="thickmathspace"/> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>±</mml:mo> <mml:mn>45</mml:mn> </mml:mrow> </mml:mrow> <mml:mo>∘</mml:mo> </mml:msup> </mml:math> when the samples are from the bare metasurfaces to these with BSA, indicating phase transitions. Additionally, potential application of the system in a biosensor is illustrated as the transmission and ellipticity angle <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>θ</mml:mi> </mml:math> are sensitive to the concentrations of the BSA solution.