Experimental Studies On Fabrication Of High-aspect-ratio Microgrooves By Femtosecond Laser Based On Electron Dynamics Control

With the development of micro-electromechanical systems (MEMS) andmicro-technology, high-aspect-ratio microchannel structures have also been paid more andmore attention, which have become an important research topic. Conventionalmicrofabrication technology can’t afford to take all of material compatibility, processingefficiency, cost and many other effects into account. As a high-quality, high-efficiency,high-precision machining method, the ultrafast laser micro-nano manufacturing technology,offers the possibility to fabricate high-sapect-ratio microgrooves for large-scale andeffieciently. The innovation of this paper is to fabricate the high-aspect-ratio microgroovesin fused silica and SiC by femtosecond beams-assited chemical etching based on electricaldynamics control.1. Fabrication of high-aspect-ratio microgrooves in SiC by femetoseond Gussianbeams–assisted chemical etching. First, to produce a high-aspect-ratio laser modifiedregions by femtosecond Bessel beams. Then the high-aspect-ratio microgrooves are formedafter laser modified regions being removed by proper chemiacal etching condtions.2. Femtosecond Bessel beams-assisted high-aspect-ratio microgrooves fabrication infused silica. The method consists of two steps:(1) formation of laser modified regions byfemtosecond Bessel beams irradiation and (2) removing laser modified regions through HFetching. The uniform, straight microgrooves can be fabricated and the highest respect ratiocan reach~52.3. Based on hydrodynamic model, we calculate the absorption efficiency during theprocess of femtosecond laser ablation of silicon. First, we improve the multi-fshydrodynamic model, which is based on a numerical model. We calculate the material thedependence of absorption efficiency on laser wavelength and laser intensity. In addition, weget the real-time change map of the absorption efficiency and the electron temperature inthe pulse duration and find the electron temperature has influenced the absorptionefficiency greatly.What’s more, we compare the absorption efficiency between single pulseand double pulse and cacaute the absorption efficiency of the first pulse and second pulsein the condition of double pulse. At the low intensity, the absorption of first pulse can enhance the absorption of the second pulse, while the absorption of first pulse inhibits theabsorption of the second pulse at the high intensity.