Tunable Strong Plasmon-Exciton Coupling in a Low-Loss Nanocuboid Dimer with Monolayer WS2

TL;DR

Researchers designed a low-loss nanocuboid dimer with WS2 to achieve tunable strong plasmon-exciton coupling for nanoscale light-matter interactions.

Contribution

A tunable low-loss plasmonic platform with WS2 for strong plasmon-exciton coupling is proposed and demonstrated.

Findings

A subradiant bonding plasmonic mode with a linewidth of 60 meV was achieved.

Rabi splitting of ~60 meV and anticrossing behavior were observed in simulations.

Loss engineering and layer modulation enabled tuning between coupling regimes.

Abstract

Strong coupling between plasmons and excitons in two-dimensional materials offers a powerful route for manipulating light–matter interactions at the nanoscale, with potential applications in quantum optics, nanophotonics, and polaritonic devices. Here, we design and numerically investigate a low-loss coupling platform composed of a silver nanocuboid dimer and monolayer of WS2 using finite-difference time-domain (FDTD) simulations. The dimer supports a subradiant bonding plasmonic mode with a linewidth as narrow as 60 meV. This ultralow-loss feature enables strong coupling with monolayer WS2 at relatively low coupling strengths. FDTD simulations combined with the coupled oscillator model reveal a Rabi splitting of ~60 meV and characteristic anticrossing behavior in the dispersion relations. Importantly, we propose and demonstrate two independent tuning mechanisms—loss engineering through nanocuboid tilt and coupling-strength modulation through the number of WS2 layers—that enable transitions between weak and strong coupling regimes. This work provides a low-loss and tunable plasmonic platform for studying and controlling strong light–matter interactions in plasmon-two-dimensional material systems, with potential for room-temperature quantum and optoelectronic devices.

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