Research On Femtosecond Laser Microfabrication For Various Materials And Their Applications

For an advanced micro/nano-fabrication method,the ability to adapt to the fabrication of various materials is one of the most key indicators to measure the method.In this work,we use the unique advantages of femtosecond laser processing which can fabricate most materials to further explore the micro/nano fabrication process on a variety of new materials.Based on the optimized fabrication parameters,we successfully made different functional microdevices,and further investaged their applications.The details are shown below:(1)Based on the highly sensitive to damp and fragile properties of single crystal CH3NH3PbI3,we put forward a femtosecond laser ablating approach.We systematically investigate the relationship between resolution and fabrication parameters including laser power density and exposure time.Furthermore,we realized colored perovskite by changing the repetition rate of laser.In the end,we investigated the influence of laser on the fluorescence property of perovskite.(2)Conventional fabrication methods are hard to fabricate 3D microstructures inside LiNbO3.Here we put forward a femtosecond laser direct writing method for 3D nonlinear photonic crystal fabrication inside LiNbO3.First,we measured the refraction index change of LiNbO3 after femtosecond laser processing by fabricating 1D grating and dealing with diffraction intensity.Then,we designed and fabricated 2D nonlinear photonic.Confocal scanning results verified the change of second-order nonlinear coefficient in the processed area.The change was further proved by the second harmonic wave output image generated by the fundamental wave.It shows nonlinear Talbot effect by changing the incident direction of fundamental wave.In the end,we processed cubic 3D nonlinear photonic crystal based on the optimized fabrication parameter and experimentally verified second harmonic generation through quasi-phase matching.We also initial investigated the nonlinear structural light generated by nonlinear photonic crystal.(3)We put forward a rapid and flexible 3D fabrication method of SZ 2080 based on structural light.We first generated the Mathiu beam via spatial light modulator(SLM).Then investigated the influence of optical parameters and optical setup on tightly focused laser pattern using Debye vectorial diffraction theory.On this basis,we realized high efficiency fabrication of 3D microcages by dynamically changing the hologram.The fabrication speed were increased by 2 orders of magnitude compared with conventional single-point direct laser writing.Finally,effective trapping/sorting of SiO2 particles and trapping/culturing of yeasts using the resultant 3D microcages were demonstrated,which is promising in microfluidics and biomedical study.(4)We realized an all-in-one fabrication approach of Foturan glass and Su-8 photoresist based on femtosecond laser-assisted wet etching.We first optimized the laser power based on the depth of fabrication area to ensure similar morphology.Then we used control layer to guarantee the uniformity of 3D structures in chemical etching.In the end,we optimized the pre-baking time,laser power and developing time based on the unique enclosed fabrication environment.This work will be a basic work for further fabrication of 3D multi-functional microfluidic chips.