Exceptional points and enhanced nanoscale sensing with a plasmon-exciton hybrid system
Hong Jiang, Weidong Zhang, Guowei Lü, Lulu Ye, Hai Lin, Jinglin Tang, Zhaohang Xue, Zheng Li, Haitan Xu, Qihuang Gong
Abstract
Singularities in the spectra of open systems, known as exceptional points (EPs), have been shown to exhibit nontrivial topological properties and enhanced sensitivities. Here, we propose a novel approach to realize the EPs in a plasmon-exciton hybrid system and explore their applications in enhanced nanoscale sensing technology. We consider a plasmon-exciton system composed of a gold nanorod and a monolayer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m1"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>WSe</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> . By controlling the geometric parameters of the nano-hybrid system, we obtain simultaneous coalescence of the resonance frequencies and loss rates of the hybrid system, which is a unique feature of EPs. Numerical simulations show its application in enhanced nanoscale sensing for environmental refractive indices. Our work opens the way to a new class of sensors based on EP-enhanced sensing, with intrinsic nanoscale sensitivity due to the sub-diffraction-limit size of the plasmon-exciton nano-hybrid system.