Nd：LuVO₄、Nd：GdVO₄晶体微片LD端面泵浦激光性质研究

【作者】 徐方华；

【导师】 邵宗书； 王正平；

【作者基本信息】 山东大学 ， 凝聚态物理， 2006， 硕士

【摘要】 激光二极管泵浦的固体激光器（Laser-diode pumped solid-state laser，简称DPSSL）现已成为固体激光器的发展主流，是迄今唯一不需维护的激光系统，具有转换效率高、输出的光束质量好、性能稳定可靠、体积小、结构紧凑等特点，在医学、科研、军事、工业和娱乐装饰等领域获得了广泛的应用。 DPSSL的发展与相应新晶体的探索密切相关。目前最实用的激光晶体Nd：YAG存在着一些性能缺陷，如Nd：YAG具有窄的泵浦吸收带宽和较低的泵浦吸收截面等特点，这些特点限制了它在DPSSL领域，特别是LD泵浦微片激光器中的应用。掺钕钒酸盐晶体是顺应DPSSL发展而开发的新型激光晶体材料。LuVO₄和GdVO₄两种典型激光晶体，它们不仅具有宽的吸收带和高的吸收截面，而且具有目前发现的钒酸盐中最高的热导率，尽管其热导率的大小大致与Nd：YAG相比拟，但它们的增益截面比Nd：YAG高得多，尤其是它们能均匀的掺入较高浓度的钕离子，使LD泵浦微片激光性能有更大提高，因而引起人们的特别关注。目前，这两种新晶体的LD泵浦微片激光性能已有一些报道，但对不同钕离子浓度，不同厚度微片等条件下系统的研究LD泵浦的激光性能尚未见报道。 本论文主要对Nd：LuVO₄和Nd：GdVO₄两种激光晶体在中小泵浦功率LD端面下的多种激光性能进行了系统的测试和理论分析。实验使用了不同钕离子浓度，不同厚度微片样品60余块，实验结果表明该类晶体具有广阔的应用前景。 本论文主要研究内容包括： 1．简要介绍了DPSSL主要特性、优势、应用及发展现状；对DPSSL制作中目前比较常用的固体激光材料的特点进行了分析对比，并指出了掺钕钒酸盐系列的激光晶体，特别是LuVO₄和GdVO₄两种新型晶体，具有优良的LD泵浦微片激光性能。 2．从增益介质中饱和光强的微分方程出发，导出了对LD泵浦微片激光器的基频输出功率、阈值泵浦功率和斜效率的理论表达式；采用高、低功率两种LD分别对多种Nd：GdVO₄和Nd：LuVO₄微片样品的基频输出进行了系统测试，确定了微片的最佳基频输出所对应的钕浓度、厚度以及透过率；研究了LD温度变化和微片热效应对晶体基频输出功率的影响。在2W泵浦功率条件下，Nd：GdVO₄和更多还原

【Abstract】 Laser-diode pumped solid-state lasers ane now becoming the mainstream in the developing field of solid state lasers and are the only maintainless laser system,. They have been widely applied in medical treatment, scientific research, military, industry and so on for its advantages in high conversation efficiency, excellent stability, high credibility, high quality beam, small volume and compact structure.At present, Nd:YAG the most practical laser crystal has got some defects, such as narrow in absorption bandwidth and low emission cross-section etc, all of which have restricted it from the application of LD pumped microchip lasers. They have not only high absorption bandwidth and high absorption cross-section, but also the highest thermal conductivity in all the crystals of orthovanadates ever found. Despite of a little less than Nd:YAG in thermal conductivity, they have much higher than Nd:YAG in emission cross-section, especially they can be well-proportioned doped with high neodymium ions and greatly increased the properties of LD pumped microchip lasers. System investigations on LD pumped laser properties at different conditions of Nd concentrations, length of samples have not been appeared yet.This dissertation has made systematic researches and conclusions on many laser properties of Nd:LuVO₄ and Nd:GdVO₄. More than 60 samples of microchips with different Nd ions and length have been studied. The experiments proved that the kinds of this crystals have a vast application field. The main contents are as follows:1. The main properties, advantages, applications and developments of DPSSL were introduced briefly. Several typical solid-state laser materials for DPSSL were summarized. A few Nd-doped laser crystals of series of orthovanadates were mainly mentioned to have excellent laser characteristics, especially for two new crystals of LuVO₄ and GdVO₄ LD pumped microchip lasers.2. Based on the differential of saturated intensity in gain media, the output characteristics of DPSSL were theoretically analyzed, the analytical expressions of the output power, threshold pump power and slope efficiency were derived respectively. A vast mount Nd:GdVO₄ and Nd:LuVO₄ crystals were tested in high and low pumped power to find out the output and its change affected by the different concentrations, length, and transmission. The dependence of output power on the LD’s change and更多还原