【作者】 蔡艳芳；

【导师】 李强；

【作者基本信息】 北京工业大学 ， 光学工程， 2009， 硕士

【摘要】 二极管泵浦的薄片激光器相比于传统的全固态激光器有两个明显的优势,一是薄片激光器增益介质的热流平行于激光腔腔轴,近一维的热流分布导致腔内的热透镜效应大大减弱,热应力诱导双折射可忽略;二是薄片激光器增益介质冷却表面大,增益介质薄片的热耗散功率大大提高。使得薄片激光器在获得高功率激光输出的同时保持高效率和高光束质量,成为近二十年来全固态激光器的重要进展之一。薄片激光器有端面泵浦与侧面泵浦两种方式,端面泵浦方式采用光纤耦合输出、或聚焦于石英棒输出的泵浦光,产生均匀分布的光束包络,从端面泵浦薄片增益介质,未被吸收的泵浦光经多次反射后,可实现90%以上的泵浦吸收。侧面泵浦方式是直接将泵浦光从薄片增益介质的几个侧面传输入。比较两种泵浦方式,侧面泵浦不仅光学系统结构简化、泵浦光无需光纤耦合,有利于激光器整体效率的提高,而且可通过增大介质薄片的面积,增加通光口径,避免由于口径限制而引起过大的热负荷,进而降低晶体单位面积内的热耗散功率密度,进一步发挥薄片激光器的潜力。本文通过二极管侧面泵浦薄片激光器晶体内光分布的数值模型计算了晶体内光斑实现均匀分布情况下的Nd:YAG晶体尺寸,然后将Nd:YAG晶体与非掺杂的YAG晶体热键合,再将热键合晶体镀膜,铟焊于铜热沉上,最后将激光器组装。为了实现高的功率及好的光束质量的激光输出,我们还设计了不同的实验,对各种参数进行优化,同时还进行了相关的理论研究。获得了光光转换效率为33.5%,峰值功率为230W,光束参数乘积为21.6 mm*mrad的激光输出。更多还原

【Abstract】 Comparing with traditional all-solid laser, thin-disk laser has two significant advantages. One advantage is the direction of cooling flow is the same with cavity resonant oscillation of light, making cooling flow similar to one-dimensional heat distribution, which effectively reduces the thermal lens effect; the other is the large cooling area of gain medium for disc-laser, making the heat dissipation power density of the material being pumped per area very small. These two advantages make the side-pumped thin-disk laser have very high power and good beam quality.Disk laser has two kind of pump style, side-pumping and end-pumping. The end-pump mode use fiber-coupled beam, generating homogeneous beam distribution. After multiple reflections, about 90% pumping light can be absorbed. The side-pump mode is making the pumped light into the crystal directly. Compared to end-pump mode, the side-pump mode not only has very simple structure, no coupled fiber and high efficiency, but also can reduce the heat dissipation power density of the material per area by enlarging the area of gain medium, which highlight the development potential of disc-laser.By numerical simulation of the light distribution in crystal, we achieve the crystal size under the situation of uniform distribution of light. Then after bonding, film coating of the bonded crystal, and soldering on the copper heat sink, we finally realize the side-pumped thin disk-laser. Besides, we designed different experiments, for optimizing the various parameters, and at the same time, related theoretical research is done. Finally, we achieved the laser output with 33.5% of opt.-opt. effect, 230W of peak power and 21.6 mm*mrad of the beam parameter product.更多还原