Slow light in a 2D semiconductor plasmonic structure

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 WSe₂ 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 10⁵ m/s. Our work paves the way toward on-chip actively switched delay lines and optical buffers that utilize 2D semiconductors as active elements.

Slow light effects are interesting for telecommunications and quantum photonics applications. Here, the authors use coupled exciton-surface plasmon polaritons (SPPs) in a hybrid monolayer WSe₂-metallic waveguide structure to demonstrate a 1300-fold reduction of the SPP group velocity.