藍(lán)寶石是氧化鋁（Al₂O₃）的天然晶體,也稱(chēng)為剛玉。由于其優(yōu)異的耐刮擦性,良好的光學(xué)透明性、熱穩(wěn)定性、化學(xué)惰性和生物相容性而具有廣泛的應(yīng)用前景。然而,其硬度和脆性對(duì)其高質(zhì)量加工提出了巨大挑戰(zhàn)。諸如金剛石鋸切,機(jī)械切割和斷裂等傳統(tǒng)方法可導(dǎo)致過(guò)度的工具磨損和不必要的微裂紋與損壞。超快激光因其在透明材料中激發(fā)的非線(xiàn)性效應(yīng)在藍(lán)寶石精密加工中表現(xiàn)出巨大的潛力,其中透明材料中的激光成絲效應(yīng)即是最有趣的現(xiàn)象之一。本論文中,我們研究了皮秒激光在藍(lán)寶石中的成絲實(shí)驗(yàn),系統(tǒng)地研究了皮秒激光脈沖頻率、脈沖能量和脈沖數(shù)對(duì)改性區(qū)結(jié)構(gòu)和成絲線(xiàn)跡影響,并基于電離動(dòng)力學(xué)Keldysh理論,分析了激光誘導(dǎo)成絲過(guò)程中的電離機(jī)制。首先研究了不同的脈沖頻率、脈沖能量和脈沖數(shù)對(duì)皮秒激光誘導(dǎo)成絲對(duì)藍(lán)寶石結(jié)構(gòu)改性的影響,在改性區(qū)橫向尺寸和長(zhǎng)度方面進(jìn)行了比較與討論。成絲誘導(dǎo)的結(jié)構(gòu)改性中心區(qū)域周?chē)衅骄彽恼凵渎首兓?隨后發(fā)展為亞微米級(jí)微裂紋通道。隨著脈沖頻率的增加,改性區(qū)域的起始位置會(huì)遠(yuǎn)離激光源方向,但成絲線(xiàn)跡的長(zhǎng)度卻減小。影響改性區(qū)域起始位置和成絲線(xiàn)跡長(zhǎng)度的還有激光脈沖能量,隨著激光脈沖能量... 

【文章頁(yè)數(shù)】：89 頁(yè)

【學(xué)位級(jí)別】：博士

【文章目錄】：
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



本文編號(hào)：3722603