皮秒激光诱导蓝宝石光丝条纹的研究

发布时间：2022-12-18 19:08

　　蓝宝石是氧化铝（Al₂O₃）的天然晶体,也称为刚玉。由于其优异的耐刮擦性,良好的光学透明性、热稳定性、化学惰性和生物相容性而具有广泛的应用前景。然而,其硬度和脆性对其高质量加工提出了巨大挑战。诸如金刚石锯切,机械切割和断裂等传统方法可导致过度的工具磨损和不必要的微裂纹与损坏。超快激光因其在透明材料中激发的非线性效应在蓝宝石精密加工中表现出巨大的潜力,其中透明材料中的激光成丝效应即是最有趣的现象之一。本论文中,我们研究了皮秒激光在蓝宝石中的成丝实验,系统地研究了皮秒激光脉冲频率、脉冲能量和脉冲数对改性区结构和成丝线迹影响,并基于电离动力学Keldysh理论,分析了激光诱导成丝过程中的电离机制。首先研究了不同的脉冲频率、脉冲能量和脉冲数对皮秒激光诱导成丝对蓝宝石结构改性的影响,在改性区横向尺寸和长度方面进行了比较与讨论。成丝诱导的结构改性中心区域周围有平缓的折射率变化,随后发展为亚微米级微裂纹通道。随着脉冲频率的增加,改性区域的起始位置会远离激光源方向,但成丝线迹的长度却减小。影响改性区域起始位置和成丝线迹长度的还有激光脉冲能量,随着激光脉冲能量... 

【文章页数】：89 页

【学位级别】：博士

【文章目录】：
摘要
Abstract
Chapter1 Introduction
    1.1 Research significance and theoretical background
    1.2 Research status
        1.2.1 Sapphire processing and applications
        1.2.2 Laser filamentation
    1.3 Organization of the dissertation
Chapter2 Materials and methods
    2.1 Laser material interaction
        2.1.1 Nonlinear ionization mechanisms
        2.1.2 Energy transfer
        2.1.3 Modification regimes
        2.1.4 Filamentation
    2.2 Sapphire science
    2.3 Laser processing system
    2.4 Sample characterization systems
    2.5 Chapter summary
Chapter3 Experimental study of the picosecond laser filamentation in sapphire
    3.1 Filamentary tracks induced in sapphire
    3.2 Effect of pulse repetition rate
    3.3 Effect of laser energy
    3.4 Effect of pulse numbers
    3.5 Chapter summary
Chapter4 Ionization dynamics of picosecond laser filamentation in sapphire
    4.1 Laser parameters
    4.2 The growth of free-electron density
        4.2.1 Total electron density
        4.2.2 Photoionization electron density
    4.3 Laser induced damages
    4.4 Chapter summary
Chapter5 Conclusions and significant accomplishments
References
List of research publications and patent applications during the doctoral degree
ACKNOWLEDGEMENTS



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