Nonlocal and nonlinear plasmonics in atomically thin heterostructures

TL;DR

This paper demonstrates how nonlocal effects in atomically thin heterostructures enable strong, tunable nonlinear plasmonic interactions, paving the way for advanced nonlinear nanophotonics applications.

Contribution

It reveals the role of nonlocal effects and symmetry in shaping nonlinear responses in 2D heterostructures through atomistic simulations.

Findings

Nonlocal effects mediate strong nonlinear plasmonic responses.

Symmetry and inter-ribbon coupling influence harmonic generation.

Tunable geometry and carrier density enable control of nonlinear processes.

Abstract

Plasmons in atomically thin materials offer a compelling route to trigger nonlinear light-matter interactions through extreme optical confinement in the two-dimensional (2D) limit. However, optical nonlocality in plasmons is typically associated with losses in the linear response regime. Here, we show that nonlocal effects mediate strong plasmon-assisted optical nonlinearity in electrically reconfigurable 2D heterostructures. Using atomistic simulations that capture quantum finite-size and nonlocal effects in the nonlinear plasmonic response of graphene and phosphorene nanoribbon dimers, we reveal how symmetry and inter-ribbon coupling shape harmonic generation processes in perturbative and high-harmonic regimes. Independent tuning of geometry and carrier density in nanoribbon heterostructures is shown to induce inter-ribbon plasmon hybridization, impacting inversion symmetry governing even-ordered nonlinear processes like second-harmonic generation. These results reveal design principles for active and passive tuning of nonlinear plasmonic effects and enable selective enhancement of specific harmonic processes, establishing 2D heterostructures as a versatile platform for nonlinear nanophotonics.