Femtosecond laser induced simultaneous functional nanomaterial synthesis, in situ deposition and hierarchical LIPSS nanostructuring for tunable antireflectance and iridescence applications

Abstract

Femtosecond laser induced periodic surface structures (LIPSSs) are excellent biomimetic iridescent antireflective interfaces. In this work, we demonstrate the feasibility to develop tunable iridescent antireflective surfaces via simultaneous synthesis of functional metal-oxide nanomaterials, in situ deposition and hierarchical LIPSSs nanostructuring by means of femtosecond laser ablation (fs-LA) of tungsten (W) and molybdenum (Mo) in air. Adjusting the scanning interval from 1 μm to 20 μm allows the modulation of particle deposition rates on LIPSSs. Diminishing the scan interval enables a higher particle deposition rate, which facilitates the development of better UV-to-MIR ultrabroadband antireflective surfaces with a less pronounced iridescence. Through comparing the reflectance of hierarchical LIPSSs with different densities of loosely/tightly deposited particles, it is found that the deposited WOx and MoOx particle aggregates have high UV-to-MIR ultrabroadband absorbance, especially extraordinary in the MIR range. Loosely deposited particles which self-assembly into macroporous structures outperform tightly deposited particles for ultrabroadband antireflective applications. The presence of loosely deposited MoOx and WOx particle absorbers can cause up to 80 % and 60 % enhancement of antireflectance performances as compared to the tightly particle deposited LIPSSs samples. One stone of “fs-LA technique” with three birds of (particle generation, in situ deposition and LIPSS hierarchical nanostructuring) presented in this work opens up new opportunities to tune the reflectance and iridescence of metallic surfaces.