A high-performance light absorber based on a metamaterial nanopyramid array

A high-performance light absorber based on a metamaterial nanopyramid array, which is constructed by alternating aluminum and germanium multilayered thin films, is proposed and numerically studied. The proposed absorber exhibits ultra-flat and nearly 100% absorption performance with the properties of being wide-angle, polarization-insensitive and omnidirectional in the incident waveband ranging from 200 nm to 3.6 µm. The electromagnetic field and Poynting vector distribution of the nanopyramidal structure are analyzed in detail, and it is found that the electric field is enhanced at the edge of the metal-dielectric taper, while the magnetic field is trapped inside the structure. Moreover, the results show that the electromagnetic field absorption position shifts downward with increased incident wavelength, this is accompanied with an enlarged absorption volume. The nearly perfect absorption of the proposed absorber is attributed to the electric dipole resonance and magnetic polaritons. Properties of ultra-broadband perfect absorption and excellent angle-related performance for the pyramidal structure make it an attractive device in the fields of solar photovoltaic devices and thermal emitters.