High temperature plasmonics: Narrowband, tunable, near-field thermal sources

Abstract: We propose multiple approaches for controlling Wien's displacement law in the near-field leading to narrowband, tunable, spatially-coherent high temperature thermal sources. We show that narrowband super-planckian thermal emission relevant to the wavelength ranges for near-field thermophotovoltaics can be achieved by utilizing engineered plasmonic states of metals with a high melting point. Along with conventional thin film surface plasmon polaritons of high temperature plasmonic metals, we also introduce multiple different approaches to narrowband near field thermal emission a) epsilon-near-zero metamaterials b) tunable surface-plasmon-polaritons of anisotropic metamaterials and c) photonic van hove singularities. Our work solves the critical issue of a narrowband thermal source for near-field thermophotovoltaics.