Long range surface plasmon resonance induced mid-infrared Fano resonance and the mediated nonreciprocal thermal radiation

Abstract

Nonreciprocal thermal radiation (NTR) has attracted significant attention, which offers a broader control over radiative heat transfer beyond conventional limits. Manipulating NTR involves creating systems with various strategy where heat transfer depends on the direction of energy flow, breaking traditional reciprocity. Here, we consider a Kretschmann configuration that consists of a germanium (Ge) prism, barium fluoride (BaF₂), Weyl semimetal (WSM) layer, BaF₂ and zinc selenide (ZnSe). Long range surface plasmon resonance (LRSPR) is expected to be excited at resonance of $10.8\mu m$ with a narrow resonance dip. Asymmetric Fano resonance (FR) will be achieved by the strong coupling between waveguide mode (WGM) and long-range surface plasmon polaritons (LRSPPs). This FR can bring about narrowband and directional thermal emission, which can also boost the contrast between the emissivity and absorptivity in a broad range of structural parameters. The underlying physical principles of the device are elucidated through the examination of magnetic field distributions. The proposed configuration shows great potential mid-IR thermal radiation regulation.