Ultra long infrared metamaterial absorber with high absorption and broad band based on nano cross surrounding

Long wavelength infrared (LWIR) wideband absorption is an important target in the research of middle infrared band. In this work, we study the absorption characteristics of Cr-Ge-Si3N4-Ti metamaterial absorber based on nanowire cross surrounding. The absorber has polarization independence when the light wave is incident vertically. Due to the coupling of surface plasmon resonance and the intrinsic absorption of lossy material, the numerical simulation calculation shows that the bandwidth with absorptivity greater than 90 % reaches 7.23 μm, and the average absorptivity in the LWIR band (8.98–16.21 μm) is 94.1 %. The absorption spectrum can be adjusted independently by changing the geometric parameters of the structure. Moreover, the absorber has excellent incident angle insensitivity in TE and TM modes. The designed absorber is simple in structure, easy to configure, and suitable for infrared imaging, thermoelectronic devices and thermal detection applications.