Transport and Spatial Separation of Valley Coherence via Few Layer WS 2 Exciton-Polaritons

The optical response in two-dimensional transition-metal dichalcogenides (2D TMDCs) is dominated by excitons. The lack of spatial inversion symmetry in the hexagonal lattice within each TMDC layer leads to valley-dependent excitonic emission of photoluminescence. Here, we demonstrate experimentally...

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Published inACS photonics Vol. 11; no. 3; pp. 1078 - 1084
Main Authors De-Eknamkul, Chawina, Huang, Wenzhuo, Zhang, Xingwang, Ren, Yundong, Cubukcu, Ertugrul
Format Journal Article
LanguageEnglish
Published United States 20.03.2024
Subjects
atomically thin waveguide
guided-mode resonance
directional propagation
2D materials
WS2
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Summary:The optical response in two-dimensional transition-metal dichalcogenides (2D TMDCs) is dominated by excitons. The lack of spatial inversion symmetry in the hexagonal lattice within each TMDC layer leads to valley-dependent excitonic emission of photoluminescence. Here, we demonstrate experimentally the spatial separation of valley coherent emission into orthogonal directions through self-resonant exciton polaritons of a free-standing three-layer (3L) WS waveguide. This was achieved by patterning a photonic crystal consisting of a square array of holes allowing for the far field probing of valley coherence of engendered exciton-polaritons. Furthermore, we report detailed experimental modal characterization of this coupled system in good agreement with theory. Momentum space measurements reveal a degree of valley coherence in the range 30-60%. This work provides a platform for manipulation of valley excitons in coherent light-matter states for potential implementations of valley-coherent optoelectronics.
ISSN:2330-4022
2330-4022
DOI:10.1021/acsphotonics.3c01484