Sandwich-Multilayer-Film Perfect Absorber Spanning the Entire Visible Spectrum

High-efficiency perfect absorption, spanning the entire visible region, plays an increasingly significant role in applications such as solar energy harvesting, photodetection, and thermal radiation management. However, the complexity and manufacturing difficulty of the currently proposed structures hinder large-scale application. In this work, we propose a broadband perfect absorber based on a tungsten–silicon nitride–tungsten (W-Si3N4-W) sandwich multilayer film. We combine the unique broadband absorption capability and high-temperature stability of material W with the low-loss characteristic of material Si3N4. By optimizing the geometrical parameters of the structure, we successfully achieved an average absorption efficiency exceeding 94% across a wide wavelength ranging from 500 nm to 900 nm. This work paves the way for developing high-performance, stable, and broadband absorption devices.