Near-Perfect Photon Tunneling by Hybridizing Graphene Plasmons and Hyperbolic Modes

Abstract

Excitation of surface plasmon polaritons helps to increase the near-field heat flux by orders of magnitude beyond the limit governed by Stefan–Boltzmann law. However, the photon tunneling probability is rather low, except for modes satisfying the resonance condition of surface plasmon polaritons. Broadband hyperbolic metamaterials can broaden the frequency region for the enhancement of near-field heat transfer, but can hardly maintain a high tunneling probability for large wavevectors since no resonances are excited to overcome the inherent exponential decay. In this letter, perfect photon tunneling with near-unity probability across broad frequency and k-space region is demonstrated based on the hybridization of graphene plasmons and hyperbolic modes. As a result, the near-field heat transfer coefficient between doped-silicon-nanowire hyperbolic metamaterials can be further improved several fold when covered by a graphene sheet, approaching to a theoretical limit.