High-efficient harmonic generation via Plasmonic Tamm states

Plasmonic Tamm states in nanoscaled plasmonic waveguides can increase the electric and magnetic field intensity separately by three orders of magnitude via the spatial confinement and phase-matching. Theoretical or numerical models about plasmonic Tamm states have been proposed in metal-insulator-metal plasmonic waveguides and graphene plasmonic crystals. In this work, we experimentally realized plasmonic Tamm states by combining a nanoantenna with a plasmonic Tamm structure. The field enhancement was characterized by our home-made multi-photon microscope, in which highly efficient second and third harmonic generations were both observed. Our work demonstrates a promising potential for electromagnetic nanofocusing and nanosensing.