Periodic silicon nanostructure arrays play crucial role in the fields of the optics, nanophotonics and biotechnology. It’s imperative to fabricate controllable silicon nanostructures with high precision and cost-efficiency. In this study,an elegant approach was proposed for fabricating morphology controllable periodic 3D silicon nanostructure arrays through chemical etching assisted femtosecond laser near-field modification. The employed transparent dielectric microsphere monolayer acted as micro-lens array to confine laser pulse energy in subwavelength region transforming crystalline silicon into amorphous silicon. Based on the etching rate difference between the two phase state in etchant, 3D silicon nanostructure arrays were fabricated. Nanostructures with elliptical and circular shape formed under linearly and circularly polarized laser irradiation and with subsequent wet chemical etching. Various surface nanostructure were prepared including disk-like, ring-like, cone-like and volcano-like nanostructures by tuning laser fluence and chemical etching duration.
As micro-supercapacitors are more and more widely used in the field of energy storage, how to fabricate microsupercapacitors simply and quickly is very important. We demonstrated a one-step and effective method for the fabrication of flexible micro-supercapacitors. Irradiated by the double-pulse femtosecond laser, the polyimide was converted to a conductive holey carbon with uniform pore size distribution. At the same time, the scribing of the electrode is completed. Compared with the single-pulse femtosecond laser, the specific capacitance of holey carbon electrode prepared by doublepulse femtosecond laser was higher than that by single-pulse femtosecond laser. This one-step approach of the fabrication of holey carbon electrodes with excellent capacitive properties makes it possible to integrate micro-supercapacitors as miniaturized energy storage units with other micro/nano portable electronic devices in the future.
Laser-induced forward transfer of liquid film is widely used, and the viscosity of liquid directly affects the jet formation and deposition results. In this paper, the femtosecond (fs) laser-induced forward transfer of medium viscosity (0.3 Paꞏs) liquid film was observed by time-resolved shadowgraph imaging, and it is found that the jet changed from a stable state to an explosive state with the increase of laser fluence. However, the deposition results show that when the driving laser fluence increased, the deposition droplet height first increased, then decreased, and then increased. Combined with the observation results, it is proved that the change of jet state is the reason for the above-mentioned trend of the deposition height. These results provide a reference for the observation and deposition results of femtosecond laser-induced medium viscosity liquid films transfer.
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