Room-temperature unidirectional routing of valley excitons of monolayer WSe2 via plasmonic near-field interference in symmetric nano-slits
Author:
Wen Xinglin12ORCID, Zhou Yunxi1, Chen Sijie1, Yao Wendian1, Li Dehui12ORCID
Affiliation:
1. School of Optical and Electronic Information , Huazhong University of Science and Technology , Wuhan 430074 , China 2. Wuhan National Laboratory for Optoelectronics, Optical Valley Laboratory , Huazhong University of Science and Technology , Wuhan 430074 , China
Abstract
Abstract
Due to the short valley polarization time, it is hardly to separate opposite valley pseudospin of transition metal dichalcogenides (TMDs) for their practical applications in valleytronics. Coupling TMDs to unidirectional surface plasmon polariton (SPP) can overcome this obstacle. However, it is required to break the symmetry to induce the asymmetric coupling between valley exciton dipole and SPP to route valley exciton in previously proposed strategies. Herein, by utilizing a new mechanism that near-field interference can create directional SPP in symmetric nanostructures, we realize directional routing of valley exciton emission of monolayer WSe2 at room temperature with a symmetric nano-slits array. The near-field interference enabled directional SPP in our device not only render the exciton diffusion length increase from 0.9 to 3.0 μm, but also lead to a valley exciton separation length of 0.7 μm with degree of valley polarization up to 22 %. This valley excitons separation is attributed to the non-flat WSe2 in the nano-slits region, which makes the exciton dipoles present in-plane and out-of-plane simultaneously. Our work provides a convenient and promising strategy towards room temperature on-chip integrated valleytronic devices.
Funder
National Natural Science Foundation of China HUST grant
Publisher
Walter de Gruyter GmbH
Subject
Electrical and Electronic Engineering,Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials,Biotechnology
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