Multi-physics simulation and experimental study on the structure-performance relationship of stray light absorbing Al-based films

The suppression of near-infrared (NIR) stray light remains a critical challenge in high-energy laser systems, directly impacting the performance and cleanliness of inertial fusion facilities. This study investigates the design, fabrication, and performance optimization of Al-based functional films for enhanced NIR stray light absorption. By controlling the electrolyte temperature during anodization, we precisely tailored the micro-nano characteristic structures—specifically porosity, pore diameter, and spacing—of the anodic oxide layer. A combination of cross-scale electromagnetic and multi-physics irradiation damage simulations, alongside in-situ experimental characterization, was employed to elucidate the correlation between the electrolyte process, micro-nano structure, and the resulting service performance (optical, thermal, mechanical, and tribological properties). The optimized films, fabricated at low electrolyte temperatures (−10 °C to −5 °C), exhibit significantly higher NIR absorptance without compromising the laser irradiation damage threshold (0.4 J/cm²). Furthermore, an empirical model linking surface chromaticity to NIR absorptance was established, enabling rapid, non-destructive assessment of film optical performance. This work provides a comprehensive framework for the structural design and performance enhancement of Al-based functional films, offering a viable surface engineering solution for maintaining high cleanliness in advanced laser systems.