高斯镜的设计、制备及应用
文献类型：学位论文
| 作者 | 邓德刚 |
| 学位类别 | 博士 |
| 答辩日期 | 2007 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 邵建达 |
| 关键词 | 渐变反射率膜 高斯镜 光束质量 传输特性 空心高斯光束 |
| 其他题名 | Design,Fabrication and Application of Gaussian mirror |
| 中文摘要 | 渐变反射率输出镜非稳腔可以输出分布光滑的激光束，使大部分能量集中在中央亮斑，是谐振腔技术的重大进展，实现高功率、高光束质量激光输出较理想的优化条件。本文围绕高斯镜渐变反射膜设计、制备及应用的一些核心问题，分别从以下几方面开展了基础性研究： 利用真空镀膜技术，在基片上沉积一定厚度分布的介质膜，是实现反射率渐变的比较现实和经济的方式。利用Tfcalc膜系设计软件，介绍了单波长和可调谐波长反射率渐变膜膜系的设计方法。位相均匀镜可以看作是高级次的超高斯镜，利用电子束蒸发，制备了应用波长1064nm、351nm的位相均匀镜薄膜。 利用薄膜光学的光学导纳和单层介质膜的反射率，建立了非均匀膜的单层膜模型，其它复杂的膜系都可等效为此模型。在单层膜的基础上，推导出了膜厚与反射率之间的关系。假设基片处在蒸发源分子的均匀辐射场中，利用膜厚与反射率的关系，建立了沉积膜厚满足轴对称关系的渐变膜的挡板模型。在单层膜模型和挡板设计模型的基础上，搭建了厚度渐变薄膜的制备装置，制备了简单的超高斯膜。 介绍了（超）高斯镜谐振腔产生的光束，在几何光学近似下，超高斯镜谐振腔产生光束的基模场分布与超高斯镜上反射率分布是相似的。利用M2因子理论和相干光通过傍轴光学系统的衍射理论，研究了高斯镜谐振腔产生光束的光束质量以及在自由空间的传输和聚焦特性。根据瑞利－索末菲衍射理论的夫琅和费近似，讨论了高斯光束通过位相均匀镜衍射后的远场光强分布，比较了位相均匀镜不同参数下的能量分布，为谐振腔的设计提供一定的理论依据。 空心光束在激光加工和原子冷却等方面都有广泛的应用。在描述空心光束的模型——空心高斯光束的基础上，研究了超高斯谐振腔产生的光束，通过理论推导，得到其可以看着是一系列空心高斯光束的叠加。并给出了在超高斯镜谐振腔产生的空心光束。利用角谱分析的方法，把光在单轴晶体中的场分布表示为寻常光（o光）和非常光（e光）的场的叠加，计算分析了空心高斯光束在单轴晶体中的传输特性，并从偏振度的角度，讨论了其偏振特性。最后在非傍轴近似下，研究了空心高斯光束在自由空间的传输，并和近轴近似、远场近似的结果进行比较和分析。 |
| 英文摘要 | Variable reflectance mirrors (VRM) can be used as the output coupler of an unstable resonator which is an optimum solution for designing high beam quality laser system. Comparing with the hard-edge mirror resonator, the Gaussian mirror resonator has some main advantages: 1) refraining laser diffraction loss, 2) enhancing conversion efficiency, 3) improving transverse mode discrimination and mode volume; 4) perfecting uniformity of output beam in the near field and reducing sidelobe in the far field. In this dissertation, focusing on some key problems, we have carried out a fundamental research in the following respects: Achieving graded-reflectance, variable-thickness coatings were deposited on substrate in vacuum deposition system. Using the software Tfcalc, these coatings were designed for single and tunable wavelength lasers, and the same design could be easily adapted to other wavelength by a proper change in the layer optical thicknesses. The PU mirrors coatings were produced at 1064nm and 351nm. In some meaning, the phase-unifying(PU) mirrors could regard as higher order Gaussion mirror. Employing the admittance matrix and single-layer coating, the single-variable-thickness layers model was built. Based on the model, the function between reflectivity and thickness of coating was derived. Several multilayer types and masking techniques can be used for manufacture of VRM. Using the masking model, the coating setup for graded-thickness films was designed and fabricated, and produced a Gaussian mirror. Based on the scalar diffraction theory, the far-field intensity distribution of the beams generated by a Gaussian mirror resonator was investigated. An analytical expression of the M2 factor of the beams was derived on the basis of the second-order moments. Moreover, the propagation and focusing properties of a hard-edged diffracted the beam were investigated. Explicit expressions for the field distribution of the truncated beam that propagates through a paraxial optical ABCD system were derived in detail. Numerical examples are given to illustrate our analytical results. In Fraunhofer approximation, the far-field intensity distribution of beam generated by a PU mirror resonator was investigated based on Rayleigh diffraction theory. Attention was paid to the parameters, such as obscuration ratio and reflectivity of the PU mirror. The dark-hollow beams have attracted much attention because of their of increasing application in laser processing and cooling atom. The hollow Gaussian beams (HGBs) is a new mathematical model to describe the dark-hollow Gaussian beams. The beams generated by super-Gaussian mirror resonator can be decomposed into a linear combination of HGBs. Based on the paraxial vectorial theory of beams propagating in uniaxially anisotropic media, we have derived the analytical propagation equations of HGBs in uniaxial crystals. Due to the anisotropy crystals, the ordinary and extraordinary beams originated by incident HGBs propagate with different diffraction lengths, thus the linear polarization state and axial symmetry of incident HGBs do not remain during propagating in crystals. Based on the vectorial Raleigh-Sommerfeld diffraction integral, the nonparaxial propagation of vectorial HGBs in free space is studied. The far-field and paraxial cases can be treated as special cases of our general results. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15488]  |
| 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 | 邓德刚. 高斯镜的设计、制备及应用[D]. 中国科学院上海光学精密机械研究所. 2007. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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