Dual-Functional Optical-Transparent Terahertz Metasurface with Tunable Absorption and Polarization Conversion

Abstract With the continuous advancements in material science, research on metamaterials is evolving towards tunability and multifunctionality. This study introduces a novel design methodology for a transparent multifunctional metamaterial that integrates the capabilities of an optical-transparent broadband absorber and a polarization converter, demonstrating its versatility and adaptability in applications. By incorporating a tunable water layer structure, this design allows for the switching of operational modes under different conditions. When the water layer is filled, the material functions as a broadband absorber, achieving absorption exceeding 90% across the frequency bands of 0.65–1.05 THz, 2.23–2.63 THz, and 3.82–4.32 THz. Conversely, when the water layer is emptied, the material exhibits polarization conversion capabilities, achieving a cross-polarization conversion rate exceeding 90% at the frequencies of 1.06 THz and 3.54 THz. This design not only demonstrates new possibilities in functional integration and control within metamaterials but also offers an efficient, cost-effective, and easily manufacturable solution for the practical application of metamaterials.