Slow light in a 2D semiconductor plasmonic structure.

Klein, Matthew; Binder, Rolf; Koehler, Michael R; Mandrus, David G; Taniguchi, Takashi; Watanabe, Kenji; Schaibley, John R · Nat Commun · 2022

basic_science · Level V

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Abstract

Spectrally narrow optical resonances can be used to generate slow light, i.e., a large reduction in the group velocity. In a previous work, we developed hybrid 2D semiconductor plasmonic structures, which consist of propagating optical frequency surface-plasmon polaritons interacting with excitons in a semiconductor monolayer. Here, we use coupled exciton-surface plasmon polaritons (E-SPPs) in monolayer WSe<sub>2</sub> to demonstrate slow light with a 1300 fold decrease of the SPP group velocity. Specifically, we use a high resolution two-color laser technique where the nonlinear E-SPP response gives rise to ultra-narrow coherent population oscillation (CPO) resonances, resulting in a group velocity on order of 10<sup>5</sup> m/s. Our work paves the way toward on-chip actively switched delay lines and optical buffers that utilize 2D semiconductors as active elements.