【作者】 周波；

【导师】 祖小涛；

【作者基本信息】 电子科技大学 ， 光学， 2017， 硕士

【摘要】 在高功率固体激光装置中,熔石英光学元件有着大量的应用。为了提升熔石英的透光性,往往会在熔石英表面镀制增透膜,但这些光学膜层容易受到激光损伤和环境污染。此外,在利用CO2激光器修复熔石英表面大尺寸缺陷过程中,因使用的激光功率较大,修复坑周围会形成烧蚀碎片和凸起圆环。如果不及时去除这些存在较大安全隐患的光学膜层、烧蚀碎片和凸起圆环,在强激光辐照下很容易诱发新的损伤和加速损伤增长,从而极大地降低了元件的损伤阈值。因此,如何提高熔石英元件的激光损伤阈值,成为了目前高功率固体激光器的一个研究热点。本文利用离子束刻蚀技术去除熔石英表面的三倍频膜层以及熔石英元件修复区周围的烧蚀碎片和凸起圆环,对熔石英元件表面进行微区修饰,以提高熔石英光学元件的损伤阈值。工作内容主要有以下几个方面:(1)从物理刻蚀机制的角度分析离子束刻蚀的基本原理,掌握了离子束刻蚀的物理过程,对离子束刻蚀效果起主要作用的因素包括离子束束压、离子束入射角度、离子束流密度以及离子的原子序数。(2)利用TRIM软件仿真了Ar+离子束刻蚀熔石英表面的物理过程,分别获得了离子束压、离子束入射角度、离子束流密度与离子束刻蚀速率、刻蚀深度、损伤大小之间的变化规律。(3)探究了K9玻璃表面Si O2膜去除实验的离子束刻蚀去除规律,所得实验结果与TRIM仿真结果有一定的偏差,但总体变化规律相一致。(4)以TRIM仿真结论和K9玻璃表面SiO2膜去除实验为指导,完成了利用离子束去除熔石英表面三倍频膜层的实验,验证了利用离子束刻蚀技术较好去除熔石英表面三倍频膜层的可行性,同时获得了最佳的离子束压大小。(5)根据烧蚀碎片和凸起圆环的结构特点构建物理几何模型,并结合前期探索出的离子束刻蚀规律,从理论上获得了最佳离子束刻蚀参数。再通过离子束去除熔石英修复区烧蚀和凸起的实验,验证了利用离子束刻蚀技术去除熔石英表面修复区烧蚀和凸起圆环的可行性。更多还原

【Abstract】 Fused silica optical components are widely used in high power solid-state laser devices.However,the anti-reflective film coated on surface of fused silica to enhance its transmittance tends to be susceptible to damage by laser and be polluted by the service environment.In addition,it is easy to form ablated debris and raised ring around the mitigated pit because of the large power when CO2 laser is used to mitigate large defects on surface of fused silica.It is susceptible to damage and accelerate the growth of the damage under intense laser irradiation if these large potential safety hazard in the optical film,ablated debris and raised ring do not be removed.Thus,the damage threshold of components will be reduced greatly.Therefore,how to improve the laser damage threshold and prolong its service life has become a hot topic in the research of high power solid-state laser.In this thesis,ion beam etching technology is used to remove tripled-frequency film coated on surface of fused silica and ablation fragments or raised ring around the mitigated area of fused silica optical components to obtain a clean and smooth surface.It can improve its damage threshold when the surface of fused silica optical components was modified.The main contents of this work are carried out from the following aspects:(1)The basic principle of ion beam etching is analyzed from the perspective of physical etching mechanism,to master the process of ion beam etching.The main influence factors for ion beam etching include energy,incident angle,flux of ion beam and atomic number of ions.(2)TRIM software is used to simulate the physical process of surface etching by using Ar+ ion beam to obtain the correlations between ion energy,incident angle and etching rate,etching depth,damage degree,respectively after simulating the physical process of using Ar+ to etch the surface of quartz by TRIM software.(3)The experiments of Si O2 film removal from the surface of K9 glass are conducted and it is found that there is some deviation between the experimental results and simulated results,their overall variation trend is consistent.(4)The experiments of removing tripled-frequency films coated on surface of fused silica has been accomplished based on the results of TRIM simulation and the experimental results of removing Si O2 film coated on surface of K9 glass.it was verified that ion beam etching technology used to remove tripled-frequency films from the surface of fused silica was feasible.At the same time,the energy of ion beam for the best etching effect has been obtained.(5)The geometric model is constructed on the basis of the structural characteristics of ablation debris and raised ring.The ion beam etching parameters are theoretically obtained according to the geometric model and the previous etching resutls.Then the experiment of ion beam to remove ablation fragments and raised ring around the mitigated area of fused silica was carried out and it verified the feasibility of using the ion beam etching technique to remove ablation and raised rings of the mitigated area on the surface of fused silica.更多还原