超快贝塞尔光束在硫化锌晶体表面制备纳米孔

Writing nanopores on a ZnS crystal with ultrafast Bessel beams

硫化锌(ZnS)晶体是重要的宽光谱红外窗口材料,高深径比纳米孔的超快激光制造技术为中红外波导傅立叶变换光谱仪等光子器件的实现提供了重要的技术途径。本文采用中心波长为1030 nm、重复频率为100 kHz、脉冲宽度为223 fs~20 ps可调的Yb:KGW激光光源,用石英锥镜产生高斯-贝塞尔光束,并用4f系统构建了40倍缩束的超快激光直写系统。在能量为36~63μJ,脉宽为12.5~20 ps的情况下,在ZnS晶体上成功刻写了直径为80~320 nm的纳米孔结构。通过聚焦离子束(FIB)剥蚀和扫描电子显微镜(SEM)成像确定了纳米孔隙表面形貌、直径及深度信息。研究了激光脉冲能量、脉冲宽度对纳米孔隙的影响。结果表明,在20 ps脉冲宽度、48μJ脉冲能量的激光参数下,纳米孔隙的深度约为270μm。

Zinc sulfide(ZnS)crystal is one of the important materials used to make the wide-spectrum infrared window.The ultrafast laser technology for manufacturing the nanopores with high aspect ratio provides an important approach to fabricate the photonic devices such as mid-infrared waveguide Fourier transform spectrometer etc.In this paper,a 40-times-demagnification ultrafast laser direct-writing system was built with a 4f system and a Gaussian-Bessel beam generated by a quartz axicon and a Yb:KGW laser source that operated at a wavelength of 1030 nm,a repetition rate of 100 kHz and a pulse width tunable from 223 fs to 20 ps.When the pulse energy was changed from 36μJ to 63μJ and the pulse duration was changed from 12.5 ps to 20 ps,the nanopore structure with a diameter of 80~320 nm was successfully written on the ZnS crystal.The surface morphology,diameter and depth of the nanopores were determined by FIB(Focused Ion Beams)ablation and SEM(Scanning Electron Microscopy)imaging.The influence of laser pulse energy and pulse width on the nanopores was studied.The results show that when the pulse width is 20 ps and the pulse energy is 48μJ,the depth of a nanopore is about 270μm.