谐振泵浦单掺Ho:SSO激光器的实验研究

发布时间：2018-05-04 08:36

本文选题：2μm激光器 + Ho:SSO激光介质　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：2μm波段处于大气窗口,是众多原子和分子(如H2O等)的吸收峰,且处于人眼安全波段。2μm激光器还可以作为中远红外波段激光OPO的泵浦源。因此2μm波段激光在军事国防、工农业生产等方面具有重要的应用价值。本文对新型Ho:SSO激光器的输出特性开展了研究,以期为相关领域的拓展做出贡献。首先,阐述了2μm波段激光器的发展现状与应用前景,通过对不同基质的掺Ho~(3+)离子固体激光器的介绍和对比,指出2μm硅酸盐激光器的优势。同时,介绍了近五年来掺Ho~(3+)离子固体激光被动调Q运转的发展状况,指出Cr~(2+):ZnS晶体作为被动Q开关在中红外激光器中的应用价值与发展潜力。其次,介绍了Ho:SSO晶体的物化特性与光谱特性,根据其吸收光谱和发射光谱,得到其吸收、发射截面,并计算了Ho:SSO晶体的强度参数,并从理论上分析了不同反转粒子数比率下Ho:SSO的增益截面,讨论其可能的振荡波长。建立了Ho:SSO激光器的准二能级速率方程模型,结合其晶体参数,对速率方程进行数值求解,为单端泵浦Ho:SSO激光器的设计奠定理论基础。再次,讨论了谐振腔腔长和输出镜曲率对Ho:SSO激光器谐振腔内振荡光斑分布的影响,为单端泵浦Ho:SSO激光器的设计提供理论依据。结合理论计算,对Ho:SSO激光器进行设计,讨论了输出镜透过率、谐振腔长度、Ho:SSO增益介质温度对激光器输出性能的影响。在输出镜透过率为T=20%、曲率R=-100mm,谐振腔长度L=60mm,晶体温度为290K时,获得最大输出功率1.71W;晶体温度为281K时,得到最大输出功率2.1W,连续运转激光输出波长为2113.5nm。最后,对Ho:SSO固体激光器的被动调Q输出特性进行了探究。首先介绍了Cr~(2+):ZnS晶体的物化特性和光谱特性,分析其作为2μm波段激光器的被动调Q开关的可行性。再从理论上建立掺Ho~(3+)调Q激光器的速率方程模型,理论分析被动Q开关的工作过程。在实验上,探究了Ho:SSO固体激光器被动调Q脉冲运转过程中各参数随泵浦功率变化的趋势。在实验温度T=284K时,泵浦功率为14.1W的情况下,获得最小脉冲宽度615.56ns,最大重复频率24.54kHz。
[Abstract]:The 2 渭 m band is located in the atmospheric window, which is the absorption peak of many atoms and molecules (such as H2O), and the 2 渭 m laser at the human eye safe band can also be used as the pump source of OPO. Therefore, the 2 渭 m band laser has important application value in military defense, industry and agriculture production and so on. In this paper, the output characteristics of new Ho:SSO lasers are studied in order to contribute to the development of related fields. Firstly, the development status and application prospect of 2 渭 m band laser are described. The advantages of 2 渭 m silicate laser are pointed out by introducing and comparing different matrix doped Ho~(3) ion solid state lasers. At the same time, the development of passive Q-switched operation of Ho~(3 doped solid-state laser in recent five years is introduced, and the application value and development potential of Cr~(2 / ZnS crystal as a passive Q-switch in mid-infrared laser are pointed out. Secondly, the physicochemical and spectral properties of Ho:SSO crystal are introduced. According to its absorption and emission spectra, the absorption and emission cross sections are obtained, and the strength parameters of Ho:SSO crystal are calculated. The gain cross sections of Ho:SSO at different inversion population ratios are analyzed theoretically and the possible oscillatory wavelengths are discussed. The quasi-two-level rate equation model of Ho:SSO laser is established, and the rate equation is solved numerically with its crystal parameters, which lays a theoretical foundation for the design of single-end pumped Ho:SSO laser. Thirdly, the influence of cavity length and output mirror curvature on the distribution of oscillatory spot in Ho:SSO laser resonator is discussed, which provides a theoretical basis for the design of single-ended pumped Ho:SSO laser. Based on the theoretical calculation, the effects of the transmittance of the output mirror and the temperature of the gain medium of the resonator (cavity) on the output performance of the Ho:SSO laser are discussed. The maximum output power of 1.71W is obtained when the transmission rate of the output mirror is Tn20, the curvature is Rn-100mm, the length of the resonator is 60 mm, the crystal temperature is 290K, the maximum output power is 2.1W and the CW laser output wavelength is 2113.5nmm. Finally, the passive Q-switched output characteristics of Ho:SSO solid-state lasers are investigated. Firstly, the physicochemical and spectral characteristics of Cr~(2: ZnS crystal are introduced, and the feasibility of using it as a passive Q-switched switch for 2 渭 m band laser is analyzed. Then the rate equation model of Ho~(3) Q-switched laser is established theoretically, and the working process of passive Q-switch is analyzed theoretically. In the experiment, the variation trend of the parameters with pump power during the passive Q-switched pulse operation of Ho:SSO solid-state laser is investigated. The minimum pulse width of 615.56 ns and the maximum repetition rate of 24.54 kHz were obtained at the experimental temperature of T _ (284K) and the pump power of 14.1 W.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN248

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