Dual-Band and Polarization-Free Metamaterial Perfect Absorber for MIR/NIR Applications

We present a novel design of a metamaterial perfect absorber (MPA) operating at mid-infrared (MIR) and near-infrared (NIR) regimes. The proposed MPA is formed by a crossed ellipse in the center of a thick circular ring with both made of silver. A dielectric layer is sandwiched between this metallic structure and a silver ground plan. The geometrical dimensions are carefully optimized such that two absorption bands at $2.7~\mu \text{m}$ and $6~\mu \text{m}$, whose peaks are over 99%, are created. The horizontally and vertically symmetric design allows polarization-free operation. The proposed concept offers a tunable design for detection, imaging, energy harvesting, and stealth applications.