飞秒贝塞尔光束直写铌酸锂高深径比光子晶体结构  

High-Aspect-Ratio Photonic-Crystal Structure of Lithium Niobate Fabricated via Femtosecond Bessel Beam Direct Writing

作　　者：孙伟高 季凌飞[1,2] 郑锦灿 温亚楠 王冠强 Sun Weigao;Ji Lingfei;Zheng Jincan;Wen Yanan;Wang Guanqiang(Institute of Laser Engineering,Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China;Key Laboratory of Trans-Scale Laser Manufacturing Technology of Ministry of Education,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学材料与制造学部激光工程研究院,北京100124 [2]北京工业大学跨尺度激光成型制造技术教育部重点实验室,北京100124

出　　处：《中国激光》2022年第10期143-151,共9页Chinese Journal of Lasers

基　　金：国家自然科学基金(51975017);北京市教委重点科研项目(KZ202110005012);国家重点研发计划(2018YFB1107500)。

摘　　要：具有深微孔结构的铌酸锂晶体可以成为具有优良光波选择性调制功能的光子晶体器件。然而,目前使用的聚焦离子束刻蚀、化学刻蚀或常规激光制孔等方法很难获得光子晶体所需的高深径比微孔。本文基于飞秒脉冲高峰值功率、超短脉宽的基本特点,通过对光束进行贝塞尔整形以及对光束与铌酸锂晶体的相互作用进行调控和研究,用飞秒单脉冲在铌酸锂晶体内部一步制备出深径比约为700∶1的大面积均匀微孔阵列。测试结果表明,设计并制备的高深径比微孔阵列光子晶体结构对450~510 nm波长范围内的光束具有明显的选择透过性。Objective Lithium niobate crystals with deep microhole structures are excellent photonic-crystal devices with modulation properties of wavelength selection.However,current fabrication methods,such as focused ion beam etching,chemical etching,or conventional laser drilling,remain a considerable challenge for obtaining microholes with high-aspect-ratios in lithium niobate crystals.This paper presents a strategy for the one-step fabrication of uniform deep microhole arrays with a 700∶1 aspect ratio within lithium niobate crystals using the ultrafast laser temporal Bessel shaping technique.This efficient and high-quality strategy for fabricating deep microhole arrays has excellent process stability.The prepared lithium niobate microhole array has remarkable selective beam transmittance,and we hope that this strategy can be used as a promising method for fabricating lithium niobate photonic-crystals.Methods In this study,the original femtosecond Gaussian beam was transformed into a zero-order Bessel beam using a series of beam shaping units and the energy distribution of the femtosecond Bessel beam was calculated via COMSOL simulations.The one-step fabrication of deep microholes was realized using the high peak power of the femtosecond laser and by adjusting the spatial energy distribution of the Bessel beam.By matching the pulse frequency and the speed of the moving stage,stable and uniform fabrication of large-area deep microhole arrays could be achieved by varying beam energy and the relative focal position.The resulting microhole morphology and aspect ratio were evaluated using scanning electron microscope,confocal laser scanning microscope,and optical microscope.Additionally,the beam transmission test was performed on the microhole arrays,verifying the structure’s excellent selective beam transmission ability.Results and Discussions The femtosecond Bessel beam obtained after beam shaping successfully realized the fabrication of microhole arrays with a 700∶1 aspect ratio.Varying the laser power can effective

关 键 词：激光技术 超快激光 贝塞尔光束 铌酸锂 深径比 光子晶体 

分 类 号：TN249[电子电信—物理电子学]