Hybrid Plasmons in Graphene Nano-slits

Introduction: Plasmon coupling and hybridization in complex nanostructures constitutes a fertile playground for controlling light at the nanoscale. Here, we present a semi-analytical model to describe the emergence of hybrid... [ view full abstract ]

Introduction: Plasmon coupling and hybridization in complex nanostructures constitutes a fertile playground for controlling light at the nanoscale. Here, we present a semi-analytical model to describe the emergence of hybrid plasmon modes guided along 2D nano-slits. In particular, we find two coupled plasmonic resonances arising from symmetric and antisymmetric hybridizations of the edge plasmons of the constituent half-sheets.

Methods: We develop a semi-analytical model based on the Green's  functions and an orthogonal polynomials expansion in order to fully determine the plasmon spectrum and corresponding field distribution of the plasmon modes. We then benchmark our results against full-wave numerical simulations having obtained a very good agreement.

Results: We find an 2D slit antibonding and a bonding mode, lying above and below the energy of the bare edge plasmon. We further compare the plasmons of the nano-slit with those of a nanoribbon (the slit's complementary structure), and compare them with 3D MIM/IMI waveguides.

Discussion: Our treatment is notably generic, being able to account for slits of arbitrary width, and remains valid irrespective of the 2D conductive material (e.g., doped graphene, 2D transition metal dichalcogenides, or black phosphorus).