Role of surface plasmon polaritons on the enhancement of the near-field thermal radiation from fishnet metamaterial

We study the near-field thermal energy density of the metal-dielectric-metal sandwich-like fishnet metamaterial (FMM) in the near infrared region by fluctuational electrodynamics. In addition to the electric response peaks of the near-field thermal radiation within the metamaterial, the other magnetic response peaks are observed, which are associated with the excitations of the surface plasmon polaritons (SPPs) propagating on the outer surface of the metal (external SPPs) and along the inner metal-dielectric interface (internal SPPs). It is shown that the external and internal SPPs are related to the macroscopic magnetic responses of the FMM and open new frequency channels of the near-field thermal radiation compared with that of conventional materials. This study will assist in the designing of innovative structures for thermal management at the nanoscale level.