Ultra-broadband, polarization-insensitive, high-efficiency metamaterial absorber for solar harvesting and solar sailing with thermal analysis

This study introduces a novel ultra-broadband metamaterial absorber (MMA) consisting of a titanium (Ti) substrate, a silicon dioxide (SiO₂) dielectric spacer, and an array of flat-top pyramid resonators composed of alternating titanium (Ti) and tungsten (W). The absorber achieves an average absorption of 99.56 % across the 300 −3000 nm range, with near-unity peaks at 1060 nm and 2870 nm , while maintaining polarization insensitivity up to 90° and stable absorption up to 70° incidence . The performance of the proposed structure was analyzed through full-wave electromagnetic simulations in CST Microwave Studio and optical force calculations in COMSOL Multiphysics. Solar-thermal conversion efficiency, evaluated against the standard AM1.5 solar spectrum, was confirmed over a broad temperature range of 400–1200 K, demonstrating strong potential for energy harvesting. Time-averaged optical force analysis demonstrated measurable radiation pressure on the absorber, yielding forces on the order of 10⁻¹ ² N per unit cell, thereby confirming its suitability for solar sail propulsion. To ensure a comprehensive evaluation, this study includes a comparative thermal analysis of Ti-only, W-only, and alternating Ti-W resonators. Simulation results of temperature distribution, heat-flow density, and thermal volume loss at 300 nm, 700 nm, and 2000 nm indicate that Ti-only resonators develop elevated thermal profiles due to low conductivity, while W-only resonators exhibit reduced heating but suffer from excessive mass. In contrast, the alternating Ti-W configuration balances localized heating with efficient dissipation, achieving thermal stability and favorable mass distribution. This optimized design effectively supports dual functionality, enabling high-efficiency solar harvesting and stable solar sailing.