Broadband Midinfrared ZnSe Metasurface Absorption Device Based on Surface Plasmon Resonance

In the infrared band, numerous substances show distinct absorption spectral line features. This characteristic can be utilized for spectral analysis of different objects. Because of the subwavelength structure and tunable properties of metamaterials, a broadband mid‐infrared absorbing material with a surface metal cross‐array structure is designed in this article. The substrate is metallic Ti, the middle layer is a Ti–ZnSe stack, and the top cross‐array structure is metallic Ti. This absorber architecture exhibits a remarkable average absorption efficiency of 96.14% throughout the wavelength spectrum spanning from 7.23 to 21.49 μm. Through a detailed analysis of electromagnetic field distributions at the resonant peaks, the physical mechanisms underlying the realization of broadband high absorption are systematically investigated. Finally, the spectral response of this structure under TM/TE mode and oblique incidence of the source is analyzed. The results highlight the superior absorption performance with compelling experimental evidence remains unchanged at large incident angles. This structure has wide applications in molecular imaging, infrared stealth, infrared detection, thermal radiation sources, and gas sensing.