Design, fabrication and characterization of a dielectric multilayer broadband infrared metamaterial absorber

Dielectric metamaterials rationally engineered in both bulk and quasi-infinite planar fashions with optical properties beyond natural materials have emerged as promising platforms for developing resonant architectures with sub-wavelength dimensions. The main criterion that distinguishes all-dielectric metamaterials from their plasmonic counterparts is that they exhibit negligible losses in the infrared and visible spectral regions, possessing an immense potential to be employed in developing ultradense and efficient devices. Advances in the nanofabrication and design of dielectric metamaterials enabled the miniaturization of photonic metadevices for coming generation technologies. In particular, dielectric-metamaterial coatings possess strategic applications such as high-resolution imaging and thermal camouflage in diverse technologies through controlling the characteristic reflection/transmission responses. In this study, the design, fabrication, and characterization of Al2O3/Ge/ITO/Soda Lime Glass stack meta-absorbers consisting of dielectric layers to provide broadband absorption of mid-infrared (MWIR) and long-infrared light (LWIR) are presented. The structure was produced by coating with an e-beam thermal evaporation system, one of the highly developed microfabrication techniques, sequentially without vacuum breaking. Through computational investigations and experimental assessments, the geometric parameters of the metastructure were judiciously selected, where the absorbance of over ~92% was achieved in the conducted analyses. To mechanically understand the properties of these customized all-dielectric meta-absorbers, we performed extensive numerical calculations to investigate the effect of the thickness of the used Al2O3 layer on the medium and LWIR absorption performance. Notably, the projected meta-absorber is polarization-insensitive and performs consistently over a wide range of incidence angles.