Optical selection rule based on valley-exciton locking in monolayer TMDC (Presentation Recording)

Jun Xiao; Ziliang Ye; Ying Wang; Hanyu Zhu; Yuan Wang; Xiang Zhang

doi:10.1117/12.2186685

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5 October 2015 Optical selection rule based on valley-exciton locking in monolayer TMDC (Presentation Recording)

Jun Xiao, Ziliang Ye, Ying Wang, Hanyu Zhu, Yuan Wang, Xiang Zhang

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Proceedings Volume 9552, Carbon Nanotubes, Graphene, and Emerging 2D Materials for Electronic and Photonic Devices VIII; 95520G (2015) https://doi.org/10.1117/12.2186685
Event: SPIE Nanoscience + Engineering, 2015, San Diego, California, United States

Abstract

Layered transition metal dichalcogenide (TMDC) with hexagonal lattice structure has six valleys at corners of the Brillouin zone. The nontrivial Berry curvature distribution renders the adjacent valleys with distinguishable valley angular momentum, which enables itself as an ideal 2D valleytronic platform. Recent studies reported strong excitonic effect in monolayer WS2 and each excitonic state is identified with a well-defined orbital angular momentum, however the anticipated selection rules involve nonlinear optical processes are not clear. Here we show valley angular momentum (VAM) together with exciton angular momentum (EAM) impose different valley-exciton locked selection rules for second harmonic generation (SHG) and two photon luminescence (TPL) in monolayer WS2. Moreover, the two-photon induced valley populations yield net circular polarized photoluminescence after a sub-ps interexciton relaxation. The work demonstrates a new approach to control valley population at different excitonic states for next generation of optical circuits and quantum information computing.

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Jun Xiao, Ziliang Ye, Ying Wang, Hanyu Zhu, Yuan Wang, and Xiang Zhang "Optical selection rule based on valley-exciton locking in monolayer TMDC (Presentation Recording)", Proc. SPIE 9552, Carbon Nanotubes, Graphene, and Emerging 2D Materials for Electronic and Photonic Devices VIII, 95520G (5 October 2015); https://doi.org/10.1117/12.2186685

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