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题名	准分子激光线宽压窄技术研究
作者	张海波
学位类别	博士
答辩日期	2012
授予单位	中国科学院上海光学精密机械研究所
导师	楼祺洪
关键词	准分子激光器 线宽压窄 带宽测量 棱镜扩束器 中阶梯光栅 激光感生荧光
其他题名	Excimer Laser Linewidth Narrowing Techniques
中文摘要	准分子是激发态结合而基态离解的受激二聚体。准分子激光作为一种能够精确聚焦和控制的紫外光源，由于其波长短、均匀性好和脉冲能量高的特点，在集成电路光刻、材料加工、受激拉曼散射、光栅刻写和激光医学等领域具有重要的应用。本文在腔色散理论分析和线宽压窄模块光学设计的基础上，对准分子激光线宽压窄技术、激光中心波长精密调谐和带宽测量技术进行了系统研究。 第一章综述了准分子激光的基本原理及其发展历史，概述了窄线宽准分子激光在工业和科研领域的应用，介绍了准分子激光线宽压窄的主要技术方案，包括棱镜法、标准具法、光栅法及这三种元件的组合法。 第二章介绍了适用于准分子激光的紫外光学材料的评估方法和原理。一方面研究了ArF准分子激光辐照紫外光学材料的激光感生荧光光谱特性，分析了熔融石英内光致缺陷形成的物理机制，并比较了不同光学材料所表现的荧光特性。高纯熔融石英在281nm、478nm和650nm波长处辐射荧光峰，并且其荧光光谱具有角向分布特性。激光调制的熔融石英的显微图像显示，激光感生荧光被光致损伤中心散射是荧光光谱强度分布呈现角向分布的主要原因。荧光信号强度与功率密度平方相关说明光致缺陷主要由双光子吸收过程形成。另一方面，不同材料的荧光特性迥异，掺锗熔融石英比高纯熔融石英的的荧光信号强，而氟化钙晶体的荧光光谱几乎探测不到。 第三章设计了一种准分子激光线宽压窄模块。首先给出了消色差棱镜扩束器的设计方案。随后根据几何光学原理，数值分析了入射角、顶角和出射角对棱镜扩束倍数的影响。分析表明扩束倍数随着棱镜入射角的增大而迅速提高。光束垂直出射时不仅可以提高扩束倍数，而且可以减少腔内光程。而采用直角棱镜可有效提高棱镜尺寸的使用效率。最后基于利特罗腔结构，推导了激光器线宽压窄模块实现一定激光线宽输出所需的总扩束倍数，由此可以确定入光束入射角和直角棱镜的顶角。利用优化得到的结果，设计了扩束倍数为31.8的四棱镜扩束器，对2.1mm宽的光斑扩束后尺寸为66mm，该值与理论吻合的很好。, 第四章系统地研究了准分子激光线宽压窄和激光中心波长的调谐技术。首先基于棱镜扩束器加光栅结构，研究了激光线宽和脉冲能量与入射角的关系，以及腔内狭缝宽度对线宽的影响。实验发现激光线宽和脉冲能量均随着光束入射角的增加或者狭缝宽度变窄而减小，利用三棱镜扩束器加光栅结构获得了FWHM为0.6pm的窄线宽激光输出。实验结果表明，对于目标激光线宽可以通过优化设计棱镜扩束器来提高激光脉冲能量。其次，比较了光栅法和标准具法压窄激光线宽输出特性，在双棱镜加光栅压窄的基础上用标准具滤光获得了FWHM 为0.29pm光谱。最后，通过转动棱镜扩束器的第一块棱镜调谐波长具有较好的调谐精度和线性。 第五章分别利用光栅法和标准具法测量了压窄的准分子激光光谱。介绍了测量线宽的基本技术方案，利用光栅光谱仪分析了各线宽压窄模块的激光输出稳定特性。并根据设计的标准具测量系统对激光线宽进行了测量。
英文摘要	The name excimer comes from excited dimer, a class of molecules formed by the combination of two identical constituents in the excited state. As an ultraviolet light source characterized with short wavelength and inherent high photon energy, which allows high resolution imaging and precision controlling. With the high peak intensity available, strong nonlinear interactions may be achieved and utilized for highly precise semiconductor lithography, material microstructuring, stimulated Raman scattering, fiber grating writing and laser medicine. Based on theories of cavity dispersion and optimal optics design of linewidth narrowing module, linewidth narrowing, center wavelength tuning and bandwidth measurement of excimer laser are investigated systematically. In the first chapter, the development history and basic principles of the excimer lasers are reviewed. The applications of excimer lasers in industry and scientific research are introduced. The main techniques of excimer laser line width narrowing, which include prism, etalon, grating and the combination of the three ones are presented. In the second chapter, the estimation methods and principles for excimer laser applicable UV materials are reported. Laser-induced fluorescence (LIF) of UV materials irradiated by ArF excimer laser is studied experimentally. The physical mechanisms of the laser-induced defects formation in high-purified fused silica are analyzed. The LIF characteristics of the difference materials are compared. LIF bands of the high-purified fused silica centered at 281 nm, 478 nm, and 650 nm are observed simultaneously. Microscopic image of the laser modified fused silica indicates that scattering of the generated fluorescence by laser-induced damage sites is the main reason for the angular distribution of LIF signals. LIF signals show a squared power density dependence, which indicates that laser-induced defects are formed mainly via two-photon absorption processes. Finally, LIF are varied from different optics materials. LIF signals of Ge-doped fused silica are much stronger than that of high-purified fused silica. However, the LIF signal of CaF2 is hardly detectable. In the third chapter, a linewidth narrowing module in the cavity of excimer laser is optimized and designed. Firstly, the achromatic prism beam expander (PBE) is designed. Furthermore, based on principles of geometry optics, the impact of the incidence angle, apex angle and exit angle of the prism on magnification are analyzed by numerical simulation. The beam magnification can be improved and the cavity losses could be decreased with the beam exit angle by the value of the zero. The prism size can be smaller with right angle design. Then, based on littrow cavity, to achieve a given laser linewidth, the minimal magnification of the line narrowing module is deduced. Finally, the incidence angle and the apex angle of the prism can be fixed. In the fourth chapter, linewidth narrowing and center wavelength tuning of excimer lasers are investigated systemically. Firstly, theoretical simulation and experiments are carried out to study the dependence of linewidth and pulse energy on incidence angle as well as slit width based on prism beam expander and echelle grating. FWHM with 0.6pm spectral is obtained with three-prism beam expander and echelle configurations. The results show that both linewidth and pulse energy are decreased with increasing incidence angles or decreased slit width. It’s noteworthy to mention that, for the given linewidth, the pulse energy can be improved through optimal designing of the prism beam expander. Furthermore, the output characteristics of the linewidth narrowing laser between grating and etalon are compared and analyzed. Based on linewidth narrowing with two-prism beam expander and echelle grating configurations, FWHM with 0.29pm is obtained using an etalon. Finally, the laser center wavelength tuning presents high resolution and good linearity through rotation the first prism of the PBE. In the fifth chapter, the measurement of line width narrowed excimer laser spectrum bandwidth through grating spectrometer and optical etalon are described. Linewidth and the spectral stability of the difference linewidth narrowing modules are investigated. And the bandwidth of the linewidth narrowed excimer laser is studied through designed etalon.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15717]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	张海波. 准分子激光线宽压窄技术研究[D]. 中国科学院上海光学精密机械研究所. 2012.

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