Giant enhancement of nanoscale thermal radiation based on hyperbolic graphene plasmons

Excitation of surface plasmons enables super-Planckian thermal radiation far beyond the blackbody limit. By patterning a single layer of graphene sheet into ribbons, the closed circular dispersion of graphene plasmons is opened to become hyperbolic, leading to broadband singularities of density of states. Extremely high-k evanescent waves can now couple with hyperbolic graphene plasmons. Consequently, a giant enhancement of the near-field radiative heat flux, by more than one order of magnitude, is demonstrated in this study using rigorous numerical simulations. The findings may open promising pathways for highly efficient thermal management, energy harvesting, and sub-wavelength thermal imaging.