【作者】 蒋鲁杰；

【导师】 戴能利；

【作者基本信息】 华中科技大学 ， 物理电子学， 2007， 硕士

【摘要】 飞秒激光加工技术以其极窄的脉宽与极高的功率密度,可以实现对任何材料的非热熔性加工,具有加工区域小和精度高等优点,在各种材料微细加工中应用日益广泛。采用飞秒激光改性玻璃并结合化学腐蚀的方法可制作光子晶体或微流体芯片,但目前飞秒改性腐蚀机理尚不清楚,如何选择合适的玻璃材料进行改性腐蚀研究也不明确,论文针对这些问题开展深入研究和分析讨论。首先,采用Ti:Sapphire激光器发出的800nm,50fs,1KHz脉宽激光,对三种典型玻璃(石英玻璃,Pb硅酸盐玻璃,碲酸盐玻璃)在开放环境中分别进行烧蚀的实验研究。确定了每种玻璃的阈值,烧蚀面积和脉冲能量成线性关系,三种玻璃烧蚀面积都是随脉冲能量和脉冲数量增多而增大;利用CCD成像技术、扫描电镜技术(SEM)对烧蚀孔表面形貌观察,比较不同单脉冲能量、不同脉冲数量及不同玻璃材料的烧蚀形貌,并分析原因。在上述研究基础上,利用HF酸腐蚀飞秒激光改性后的三种玻璃,研究了玻璃的化学腐蚀特性,对腐蚀前后材料微观结构进行观测,分析了不同材料的腐蚀速率与脉冲能量、腐蚀时间的关系,从材料组成、显微结构、化学键特征讨论了玻璃改性-腐蚀机理。结果表明:飞秒激光改性后的碲酸盐和Pb硅酸盐玻璃不具有选择性腐蚀特性,而石英玻璃的选择性腐蚀比高于50,选择性腐蚀比足够高,就有可能制作出高深宽比,亚微米孔间距的周期微孔结构;在飞秒激光800nm/50fs条件下,存在最佳脉冲能量范围,使得熔石英玻璃选择性腐蚀比达最高;飞秒激光改性玻璃的选择性腐蚀特性与材料结构有关,分子体积大、网络结构不紧密的材料不具有选择腐蚀特性。为改善石英玻璃的结构缺陷,使飞秒激光在石英玻璃中制作的微流通道内壁光滑,进行了热处理和退火的实验研究。在显微镜下观察了热处理后的玻璃表面形貌,研究发现:石英玻璃对温度很敏感,高温会出现析晶现象;表面杂质(比如水)也能促进石英玻璃表面析晶。更多还原

【Abstract】 Due to ultrashort time duration and ultrahigh peak fluence, the technology of femtosecond laser machining can realize the non-thermal processing of almost any materials, the workspace is very small and the accuracy is very high, it has been widely used in micro-machining with different materials. The femtosecond laser modificating chemical etching technique has a good prospect in the application of Micro Total Analysis System (μ-TAS) and photonic crystal, but the mechanisms of glass modifying-chemical and how to select suitable materials are both unknown, the paper is based on the study of above mentioned questions.The ablation of three different typical glass (fused silica, tellurite and lead silicate) has been studied using Ti:Sapphire laser pulses at the wavelength of 800 nm, we report the the measurements of the damage threshold and diameter ablation for three different glass, the ablated diameter increases with increasing laser fluence and shot number, and the reason why laser-induced periodic surface structures grow is analyzed.The femtosecond laser modificating-chemical etching technique is used to study the chemical etching character of three different typical glass respectively. The micro-structure development of three samples before and after etching are observed with CCD camera image and scanning electron microscope (SEM). The dependences of etching rate on micro-structure of glasses, pulses energy and etching duration are exhibited. The mechanisms of glass modifying-chemical etching are discussed. The results show: (1) femtosecond laser modified tellurite and lead silicate have no chemical selective etching,but for fused silica the selective etching rate is higher than 50.(2) With the central wavelength of 800nm and the pulse duration of 50fs, when pulses energy is suitable, silica glass can gain the highest selective etching rate. (3) The character of chemical selective etching of femtosecond laser modified glass is largely depends on the matrix local structures, the glass with lager molecule volume has no properties of chemical selective etching, such as tellurite and lead silicate glass.To polish the etched microchannel surface, annealing processing is used. The microstructure of the silica glass and the influence of heat-treatment on the structure and the thermal properties of the glass are investigated according to the CCD camera image. The results show that: when temperature gets very high, silica glass is sensitive to it, crystallization can be investigated; Impurity of glass surface can promote crystallization, for example, the crystallization tendency is markedly higher if the glass is wet.更多还原