Broadband Mid‐Infrared Metamaterial Absorption Device With High Absorption and Angular Stability

ABSTRACT

This study proposes a Ni‐Si ₃ N ₄ ‐Ge infrared metamaterial absorber. The absorption performance was analyzed using the Finite‐Difference Time Domain (FDTD) method. Numerical simulation results indicate that the absorber achieves an average absorption rate of 93.94% within the wavelength range of 5.5–16.5 µm, demonstrating excellent broadband absorption capability. FDTD‐based electromagnetic field analysis indicates that the material's high absorption is due to the combined effects of multiple modes, such as Surface Plasmon Resonance (SPR), Localized Surface Plasmon Resonance (LSPR), and Fabry–Pérot cavity resonance. These modes collectively enhance the efficiency of capturing incident infrared radiation through the localized electromagnetic field enhancement effect. Although the absorber exhibits slight dependence on polarization state and incident angle, it maintains stable absorption efficiency within a wide angular range, making it well‐suited for non‐normal incidence scenarios commonly encountered in practical applications. Additionally, its absorption performance can be optimized by adjusting key structural parameters such as the thickness of each functional layer, period, and geometric dimensions, providing flexibility for tailored adjustments in specific application scenarios. This Ni‐Si ₃ N ₄ ‐Ge absorber features a simple structure, reliable mid‐infrared broadband absorption performance, and good environmental adaptability, thus holding significant application potential in fields including thermoelectric devices, infrared imaging systems, and thermal detection technologies.