Improved the anti-reflection performance and stability of hierarchical micro-nano hybrid structures by annealing method

The stability and durability of micro-nano structures is the key to influence the structural materials surface towards practical engineering applications. In this paper, the stability of micro-nano structures fabricated by femtosecond laser is systematically studied. It is found that the hierarchical micro-nano hybrid structures seriously affect absorbing properties and stability of the material surface due to the poor crystallinity. In order to enhance efficient optical absorption and stability, the annealing method is applied to further crystallization of the micro-nano structures. As a result, hierarchical micro-nano hybrid structures with large depth-to-width ratios are fabricated. The experimental results demonstrate that an average reflectance of 3.43% is realized in the waveband of 300-2400nm, and the reduction rate of the reflectance reaches 39.6%. Meanwhile, the water jet impact experiment verifies that the stability of the structure is further improved.