Negative Refraction at Visible Frequencies

TLDR

Nanofabricated photonic materials offer opportunities for crafting the propagation and dispersion of light in matter. We demonstrate an experimental realization of a two-dimensional negative‑index material in the blue‑green region of the visible spectrum, substantiated by direct geometric visualization of negative refraction. Negative indices were achieved with an ultrathin Au‑Si₃N₄‑Ag waveguide sustaining a surface plasmon polariton mode with antiparallel group and phase velocities. All‑angle negative refraction was observed at the interface between the bimetal waveguide and a conventional Ag‑Si₃N₄‑Ag slot waveguide, indicating potential for practical negative‑index optical designs in the visible regime.

Abstract

Nanofabricated photonic materials offer opportunities for crafting the propagation and dispersion of light in matter. We demonstrate an experimental realization of a two-dimensional negative-index material in the blue-green region of the visible spectrum, substantiated by direct geometric visualization of negative refraction. Negative indices were achieved with the use of an ultrathin Au-Si 3 N 4 -Ag waveguide sustaining a surface plasmon polariton mode with antiparallel group and phase velocities. All-angle negative refraction was observed at the interface between this bimetal waveguide and a conventional Ag-Si 3 N 4 -Ag slot waveguide. The results may enable the development of practical negative-index optical designs in the visible regime.