Multilayer tungsten-alumina-based broadband light absorbers for high-temperature applications

Abstract

Efficient broadband absorption of visible and near-infrared light by low<br/>quality-factor metal-insulator-metal (MIM) resonators using refractory materials is<br/>reported. Omnidirectional absorption of incident light for broad angles of incidence and<br/>polarization insensitivity are observed for the fabricated MIM resonator. Excellent<br/>thermal stability of the absorber is demonstrated at high operating temperatures (800 °C).<br/>The experimental broadband absorption spectra show good agreement with simulations.<br/>The resonator with 12 nm top tungsten and 100 nm alumina spacer film shows<br/>absorbance above 95% in the range of 650 to 1750 nm. The absorption window is tunable<br/>in terms of the center wavelength, bandwidth, and the value of maximum absorbance<br/>(~98%) by simple variation of appropriate layer thicknesses. Owing to their flexibility,<br/>ease of fabrication and low cost, the presented absorbers have the potential for a wide<br/>range of applications, including the use in commonly used infrared bands or absorbers for<br/>(solar) thermo-photovoltaic energy conversion, where high absorbance and<br/>simultaneously low (thermal) re-radiation is of paramount importance.