摘要
Femtosecond laser processing is an important machining method for micro-optical components such as Fresnel zone plate(FZP).However,the low processing efficiency of the femtosecond laser restricts its application.Here,a femtosecond laser Bessel beam is proposed to process micro-FZP,which is modulated from a Gaussian beam to a Bessel annular beam.The processing time for FZP with an outer diameter of 60μm is reduced from 30 min to 1.5 min on an important semiconductor material gallium arsenide(GaAs),which significantly improves the processing efficiency.In the modulation process,a central ablation hole that has an adverse effect on the diffraction performance is produced,and the adverse effect is eliminated by superimposing the blazed grating hologram.Meanwhile,the FZP machined by spatial light modulator(SLM)has good morphology and higher diffraction efficiency,which provides a strong guarantee for the application of micro-FZP in computed tomography and solar photovoltaic cells.
飞秒激光是加工菲涅耳波带片等微光学元器件的重要方法,但飞秒激光逐点加工的低效率限制了其应用。空间光调制器(SLM)能灵活地对飞秒激光束进行空间光整形,是提高菲涅尔波带片加工效率的一种有前景的方法,本文对加工方法和工艺参数进行了优化研究。本文对比研究了基于环形光场调制和基于贝塞尔光束调制两种方法,将飞秒激光从高斯光束调制成环形光束,实现单次曝光加工一个波带,并进行了波带片阵列加工。基于贝塞尔光束调制,在重要的半导体材料砷化镓上加工了外径为60μm的菲涅尔波带片,加工时间从30 min缩短到1.5 min,加工效率显著提高。而且,通过叠加闪耀光栅全息图,消除了调制过程中产生的中心烧蚀孔的不利影响。空间光整形后飞秒激光加工的波带片具有良好的形貌和较高的衍射效率,为微型波带片在计算机断层扫描和太阳能光伏电池中的应用中提供了有力的保证。
基金
Projects(51875584,51875585,51975590)supported by the National Natural Science Foundation of China。
作者简介
Corresponding author:ZHOU Fang,PhD,Lecturer,E-mail:csuzhoufang@csu.edu.cn,ORCID:https://orcid.org/0009-0005-2398-8167。
