Broadband visible absorber with enhanced infrared emissivity for infrared scene generation

An Al-Cr alloy absorber is proposed for light absorption in the visible and infrared bands. The absorber was fabricated on a 3-inch silicon wafer and quartz glass using magnetron sputtering and wet-etching techniques. Owing to its disordered nanocone structure, the absorber achieves an average absorption of up to 98.45% in the 400-1100 nm band. When the wavelengths are broadened to 3-5 µm and 8-12 µm, the average absorptions still reach 81.8% and 69.4%, respectively. Compared to a plain Al-Cr film without nanostructures, the absorption increases by approximately 70%. The infrared emission spectrum of the Al-Cr absorber is fully controllable, and an effective 3D FEM model is proposed to predict the peaks and valleys of its infrared spectrum with a prediction deviation of less than 7%. Al-Cr alloy absorbers offer advantages such as low cost, no requirement for photolithography, scalability in preparation, and controllable infrared emissivity. These advantages make the Al-Cr absorber a promising candidate for efficient infrared scene generation devices.