Ultra-broadband Perfect Absorber based on Successive Nano-Cr-film

We have designed and experimentally demonstrated a periodic multilayer structure of SiO2 and Cr thin interlayers to achieve an ultra-broadband perfect absorber based on optical admittance matching method. The successive Nano-Cr-film make significant contribution to improving the absorption intensity of the structure. Measurements reveal high absorption over 85%, when averaged over the range 0.4-7.2 mu m. Remarkably, it is the most broadband planar absorber film without involving lithography in fabrication. Incident angle and polarization dependence of the absorption spectra are also considered. The manufactured absorber also has potential applications for thermal shielding, detecting, imaging, photovoltaics (PVs), sensing, etc.