Directional coupling of valley exciton emissions from monolayer MoS2 on periodic plasmonic nanostructures

ORAL

Abstract

The unique coupled spin-valley physics in two-dimensional (2D) transition metal dichalcogenides (TMDs) has triggered abundant research activities in realizing valleytronic applications. Due to the valley contrast optical selection rule, excitons in monolayer TMDs formed at two degenerate but inequivalent K and K’valleys can couple to light with different helicities. Here, we demonstrate the spatial separation of valley-polarized excitons at room temperature by coupling monolayer MoS2 with the surface plasmon polariton (SPP) of a periodic metallic structures. Due to the spin-orbit coupling of light, the SPP waves excited by exciton emissions with opposite helicities interacting with the periodic metallic struuctures can be separated into different directions. When the exciton emissions are on resonance with the SPP modes, we observe the valley-dependent directional coupling of exciton emissions in both real and momentum space by polarization-resolved photoluminescence imaging. Our results demonstrate a route for controlling and detecting the valley polarization of TMDs by optical means.

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Presenters

  • Chien-Ju Lee

    Department of Electrophysics, National Chiao Tung University

Authors

  • Chien-Ju Lee

    Department of Electrophysics, National Chiao Tung University

  • Chih-Lun Wu

    Department of Electrophysics, National Chiao Tung University

  • Li-Shuan Lu

    Electrophysics, National Chiao Tung University, Department of Electrophysics, National Chiao Tung University, Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan, Department of Electrophysics, National Chiao Tung University, Taiwan

  • Wen-Hao Chang

    Electrophysics, National Chiao Tung University, Department of Electrophysics, National Chiao Tung University, Department of Electrophysics, National Chiao Tung University,, Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan, Department of Electrophysics, National Chiao Tung University, Taiwan