单束飞秒激光诱导自组装周期微纳结构形成机理和调控方法研究

Micro/nanostructure arrays have wide applications in various fields such as micro-optics devices, functional materials, information science，etc. Compared to nanoimprinting lithography,electron beam lithography,ion beam lithography and chemical vapor deposition,.femtosecond laser micromaching has a unique advantage of three-dimensional region-selective processing of transparent dielectrics. The traditional fs-laser processing method is to scan the focus on the sample, which belongs to a serial processing style and is usually used in early-stage micromaching.In recent years, to promote the micromaching efficiency, parallel preparation of micro/nanostructure arrays by femtosecond laser has aroused great interest,among which the technique of femtosecond laser inducing self-assembly micro/nanostructures has become a research hotspot in recent years.Although there have been various reports related to femtosecond laser induced self-assembly micro/nanostructures, no widely-accepted physical model has been proposed to elucidate the formation mechanism of femtosecond laser induced self-assembly micro/nanostructures. In this project, based on systematic study of formaton conditions of femtosecond laser induced self-assembly micro/nanostructures on the surface of and in the bulk of transparent dielectrics, we will theoretically simulate the interaction of laser with material, elucidate the formaton mechanism of femtosecond laser induced self-assembly micro/nanostructures and develop new methods for high-speed, reliable and controllable preparation of periodic micro/nanostructures.

微纳结构阵列在微光学器件、功能材料和信息科学等多个领域有着广泛应用。与纳米压印、电子束刻蚀技术、离子束刻蚀技术、化学气相沉积等微纳结构制备方法相比，飞秒激光微加工方法具有对透明材料进行可选区三维体加工的独特魅力。传统的飞秒激光加工方式是焦点直扫法，属于串行加工模式，多用于早期微加工中；近年来，考虑到加工效率的问题，飞秒激光并行制备微纳结构的技术引起人们极大关注。其中飞秒激光诱导自组织周期微纳结构的技术已经成为近年来的研究热点。尽管飞秒激光诱导自组装周期微纳结构的报道已不少，但是目前对飞秒激光诱导自组织周期微纳结构的形成原因并没有一个普遍接受的的统一物理模型。本项目拟在系统研究透明介质表面和内部自组装微纳结构形成条件基础上，理论模拟激光与透明材料表面和内部的相互作用，探索单束飞秒激光诱导自组装周期结构的形成机理，开拓飞秒激光在材料表面及其内部高速地、可靠地以及可控地形成周期性微纳结构的新技术

飞秒激光诱导自组织周期微纳结构已经成为近来的研究热点，但周期结构的自组装形成机制一直存在着争议，周期微纳结构的性能还存在着更多的探索空间。1.本项目首先通过实验设计和理论分析，深入研究了飞秒激光诱导透明材料内部自组装微孔阵列的形成机理，证实了界面球差的各项影响因素也正是调控孔洞阵列的关键参数；2.首次展示了各向同性材料中飞秒激光诱导的自组装微光栅的条纹取向竟与激光偏振方位角密切相关，提出激光偏振面和脉冲前沿倾斜之间的相对方位是这种各向异性现象产生的原因。3.本项目还以硅片、6H-SiC晶体等传统材料为对象，分别采用单脉冲列辐照技术和双脉冲列辐照技术，研究了表面微结构中具有代表性的深亚波长周期微纳结构和近亚波长周期微纳结构的演变过程，理论上运用Sipe-drude理论、电子密度速率方程和麦克斯韦方程，结合材料的物质参数，数值模拟了各级微纳结构的形成，提出表面缺陷、表面波模式的产生、表面等离子体波的激发在各级微纳周期结构形成中的重要作用。4.最后，探索了表面深亚波长周期波纹结构的双折射特性，初步展示了表面深亚波长周期波纹结构在可调谐功率衰减器方面的应用。