Research On Femtosecond Laser Micro-fabrication Of Transparent Material And Biological Molecule

Femtosecond laser has unique ultra-intense and ultra-fast specialities.Ultrahigh peak intensity can be achieved by femtosecond（fs）laser with low pulse energy.So fs laser can induce multiphoton absorption of transparent materials and realize micro-fabrication with high precision inside them.Fs laser has so short pulse duration that thermal effect is little during the fabrication.So fs laser micro-fabrication is a focus in fs laser field nowadays.Studies of fs laser propagating and focusing in transparent materials are theoretical foundation of fs laser micro-fabrication and precondition of investigating and optiminzing the fs laser micro-fabrication system.Under the direction of the theory,fs laser micro-fabrication system and fs laser tweezer and surgery system were established, which could carry out micro-fabrication inside transparent materials and micro-surgery on cultured cells.With this fs laser micro-fabrication system,refractive-index change was achieved inside K9 glass.The influence to the fabrication was studied,of scanning speed,laser power and numerical aperture（NA）.The filamentation was also studied.Void with 0.4μm diameter was abtained in K9 glass.10×10 arrays of voids were gained,which testified the possibility of 3D light data storage.And 1-to-2 and 1-to-4 waveguide splitters and three-dimensional logpile photonic crystal were successfully obtained with this system.Based on plasma-induced ablation of cells by fs laser,protuberances of SH-SY5Y cells were successfully dissected.The influence to the dissection and target cell’s activity were studied,of laser power under NAs of 0.60 and 1.35.Protuberances were dissected at different locations.And it finds that the farside the dissection location is, the smaller the dissection effect is.Under un-intact dissection,the longer the dissection length is,the larger the effect is;but the self-recovery of un-intactly dissected cell started earlier than intactly dissected ones.It is calculated that under dissection speed of 2μm/s,when the peak density(I_peak)is ranged from 2.55×10¹⁴W/cm² to 0.26×10¹⁴W/cm²,the fs laser can realize the dissection of cells’ protuberances by plasma-induced ablation.It proved that this fs laser micro-surgery facilitated the research on human nerve’s recovery.