Optimized Polarization-Independent, Wide-Band Metamaterial Perfect Absorber for Infrared Energy Harvesting

We present a gradient-based optimization approach to design a metamaterial perfect absorber (MPA) operating at infrared (IR) wavelengths, specifically around 10.6 μm. The optimal design supports a wide-band absorptivity and its symmetry results in a polarization-insensitive operation. The proposed MPA is composed of a split-ring resonator concentric with crossed-ellipses. This MPA represents the top metallic layer of a metal-insulator-metal (MIM) structure. Magnetic polaritons (MP) at 10 μm leads to a wide reception-angle performance. The ease of forming thin insulator layers inside the gaps of the proposed MPA enables building an IR-energy harvester element similar to the rectenna’s operation. Also, the strong electric field enhancement at these gaps improves the performance of MIM rectifiers. Moreover, the coupling between these MPAs and MIM rectifiers is studied and shows that our proposed design is a good candidate for energy harvest application with capability of scaling the design to different wavelengths.