Study On The Mechanism And Application Of Micro/Nano Structure Prepared By Femtosecond Laser

Solid material would exhibits special physical and chemical properties when the size is reduced to the order of micro-nano structure,so micro-materials such as surface micro-structures and nanoparticles,has been attracted attentions of international academia.The traditional preparation of micro-structure included lithography,self-organizing,micro-mechanical.With the development of ultrafast pulsed laser,many new preparation of micro/nano structure are put forward based on ultrafast pulsed laser,for example laser-induced periodic surface structures and pulsed laser ablation in liquids.Laser processing technology,which is simple step,easy to control and stable,making the laser preparation of micro /nano structure technology has a broad application prospects.But,the above laser preparation technology of micro/nano structure has some difficulties in theory or application,because of complex physical process between laser pulses and solid material.In our paper,we try toThe orientation of laser-induced periodic surface structures(LIPSS)upon irradiation with different po larization pulse sequences has been exploited to investigate initial stage of periodic surface structures on silicon.Our experimental results reveal that an isotropous seed is induced by initial pulses and the LIPSS generate on the isotropous seed subsequently.Through theoretical analysis of surface plasmons(SPs)propagation by Drude model,we consider “lattice-imperfection-layer” as the isotropous seed to increase surface electron density.The single-crystal XRD spectrum on the irradiated silicon surface was present,evidencing existence of lattice-imperfection.Finally,we demonstrate LIPSS formation with a model of laser-SPs coupling based on rough lattice-imperfection-layer.Pulsed laser ablation in liquids(PLAL)have been attracted attentions of international academia for its advances in green and low-selective fabrication of single and composite nanostructure.However,there is still no industrial application due to its low production rate.Here in this paper,we propose a technology of PLAL assisting with microfluidic technology to improve the problem,in which the productivity reached to 87.5 mg/min by improving the efficiency up to 30%.Lattice structures of silicon with size of 400 nm-800 nm and spherical structures with size of 100 nm-300 nm were found in experiments.By analyzing with Scanning electron microscopy(SEM)and photoluminescence spectroscopy,the relationship between production rate and microfluidic flow velocity is presented.