Multiband selective absorbers made of 1D periodic Ag/SiO2/Ag core/shell coaxial cylinders horizontally lying on a planar substrate

Direction-independent dual-band perfect absorption induced by fundamental magnetic polaritons

In this paper, we designed a single sized Metal-Insulator Pair-Metal hybrid grating for dual-band perfect absorption from 8 μm to 14 μm utilizing both nondispersive insulators and dispersive phonic insulators. The hybrid grating was composed of Al/ZnTe-SiC pair/Al, which incorporated an ultrathin phononic SiC layer between the nondispersive ZnTe dielectric spacer and Al substrate. The physical mechanisms responsible for the dual-band perfect absorption were elucidated by the resonance of fundamental magnetic polaritons (MPs). Dual-band perfect absorption with incident angle insensitive feature was enabled. An equivalent LC circuit model predicting the dual-band resonant absorption peaks wavelengths was proposed and verified. Furthermore, the effects of grating period, strip width, nondispersive dielectric spacer thickness and polar phononic dielectric spacer thickness on the absorption were explored.

A Review of Tunable Wavelength Selectivity of Metamaterials in Near-Field and Far-Field Radiative Thermal Transport

Radiative thermal transport of metamaterials has begun to play a significant role in thermal science and has great engineering applications. When the key features of structures become comparable to the thermal wavelength at a particular temperature, a narrowband or wideband of wavelengths can be created or shifted in both the emission and reflection spectrum of nanoscale metamaterials. Due to the near-field effect, the phenomena of radiative wavelength selectivity become significant. These effects show strong promise for applications in thermophotovoltaic energy harvesting, nanoscale biosensing, and increased energy efficiency through radiative cooling in the near future. This review paper summarizes the recent progress and outlook of both near-field and far-field radiative heat transfer, different design structures of metamaterials, applications of unique thermal and optical properties, and focuses especially on exploration of the tunable radiative wavelength selectivity of nano-metamaterials.