Two broad absorption bands in infrared atmosphere transparent windows by trapezoid multilayered grating
Yulian Li, Linzhi Li, Fang Wang, Haonan Ge, Runzhang Xie, Bowen An
Abstract
We proposed a metamaterial absorber composed of an array of trapezoid multilayered grating Au and InP on top of an opaque substrate, which covers two atmosphere-transparent-window bands with appropriate modulation of geometric parameters. The absorption higher than 0.8 is from 3.5 to 4.8 µm and 7 to 14.3 µm. From the effective medium theory and dispersion relation, the reason of the broad-band absorption is the first and third order slow light effect respectively, which is verified by the electromagnetic and thermal loss distribution further. This absorber may greatly promote the practical application of absorbers in double-color infrared imaging, detecting, infrared stealth and sub-ambient passive radiative cooling by thermal emitting.