【作者】 陈娜；

【导师】 丁欣；

【作者基本信息】 天津大学 ， 光电子技术， 2010， 硕士

【摘要】 热效应是实现全固态激光器高功率、高效率和高光束质量运转的瓶颈。由激光介质内热沉积产生的物理机制可知,解决热效应最根本的办法就是减小泵浦光和振荡光之间的量子缺陷,基态高斯塔克能级热助推泵浦方式（Thermally boosted pumping from high Stark sublevel of the ground state）是采用特定波长泵浦光把能量直接转化到激光上能级,而不是泵浦到更高的能带然后再驰豫到激光上能级,这种泵浦方式可将量子缺陷降到最低并消除量子效率损耗,能够最大程度地提高量子效率并最大限度降低热沉积,是一种可根本性解决固体激光器热效应的方案。在本论文中,分别采用全固态准连续可调谐钛宝石激光器和连续914nm Nd:YVO₄激光器作为泵浦源,选用不同掺杂浓度和长度的Nd:YVO₄晶体作为激光增益介质,主要研究晶体温度、掺杂浓度和长度对基态高斯塔克能级热助推泵浦的Nd:YVO₄激光器输出特性的影响。主要内容和创新点如下:1.介绍了Nd:YAG和Nd:YVO₄晶体的高斯塔克能级热助推泵浦特性;对端面泵浦固体激光器中的热效应进行了理论研究,并从热助推泵浦四能级激光系统的速率方程出发,研究了热助推泵浦的机理。2.对热助推泵浦Nd:YVO₄激光器的泵浦源——全固态准连续可调谐钛宝石激光器进行了实验研究,获得的钛宝石激光器的调谐范围为675-970nm,输出谱线宽度为2nm,脉冲宽度为17.6ns,在780nm处的最大功率为6.2W,相应的光-光转化效率为28.2%。其中,钛宝石激光器在914nm处的最大输出功率为3.7W。3.对增益开关固体激光器的物理模型和时间特性进行了理论研究,同时在研究全固态准连续可调谐钛宝石激光器的基础上,使用钛宝石激光器作为泵浦源,把其输出调至Nd:YVO₄的热助推泵浦带,进行了准连续914nm钛宝石激光器热助推泵浦的Nd:YVO₄激光器1064nm运转实验研究,得到的最大输出功率为230 mW,相应的光-光转化效率为23.7%,斜率效率为79%。使用钛宝石激光器泵浦的Nd:YVO₄激光器同样具有增益开关的性质,获得了3.1ns的窄脉宽输出。4.对连续914nm Nd:YVO₄激光器基态高斯塔克能级热助推泵浦的Nd:YVO₄激光器1064nm、1342nm运转进行了实验研究,重点研究了晶体的温度、晶体的掺杂浓度和晶体长度对激光器输出特性的影响。当晶体温度为50oC时,使用掺杂浓度为1.0 at.%、尺寸为3mm×3mm×10mm的Nd:YVO₄作为激光介质时,获得了最大功率为2.2W的1064nm输出,相应的斜率效率为83.9%。当晶体温度为50oC时,使用两块掺杂浓度为1.0 at.%、尺寸为3mm×3mm×4mm的晶体作为激光介质时,获得了最大功率为1.05W的1342nm输出,相应的斜率效率为66.4%。更多还原

【Abstract】 The thermal effect is the bottleneck of the operation of solid-state lasers with high power, high efficiency, and high beam quality. According to the mechanism of the heat generation in solid-state lasers, the most fundamental way to deal with the thermal effect is to reduce the quantum defect between a pump photon and a laser photon. The thermally boosted pumping from the high Stark sublevel of the ground state is to pump the active ions from the high Stark sublevel of the ground-state level directly to the sublevel of the upper lasing level without a relaxation process and it can reduce the quantum defect to the minimum and eliminate the quantum efficiency loss, increase the quantum efficiency and reduce the heat generation to a greatest extent, which makes it become an ultimate technology to deal with the thermal effect.In this dissertation,using an all-solid-state quasi-continous tunable Ti:Sapphire laser and a continues 914 nm Nd:YVO₄ laser, respectively, as the pump source, the impact of the temperature, the doped concentration and the length of the laser crystal on the thermally boosted pumped Nd:YVO₄ laser from the high Stark sublevel of the ground state is to be researched. The main contents and key creation points are as follows:1. The characteristics of the thermally boosted pumping in Nd:YAG and Nd:YVO₄ crystal were introduced. And the thermal effect of the end-pumped solid state lasers was theoretically researched. Based on the rate equations of four-level system, the mechanism of the thermally boosted pumping was studied.2. High power all-solid-state quasi-continuous widely tunable titanium-doped sapphire laser was experimentally researched. The tuning range from 675 to 970 nm with the linewidth of 2 nm and the pulse width of 17.6 ns was obtained. The maximum output power of this laser system was 6.2 W at 780 nm corresponding to all optical-to-optical conversion efficiency of 28.2%. And the output power at 914nm is 3.7 W.3. The physical model and time properties of the gain-switched solid state lasers was theoretically researched. The Nd:YVO₄ laser under 914nm thermally boosted pumping by the Ti:Sapphire laser was experimentally researched. A high slope efficiency of 79% and pulse width of 3.1 ns were obtained, which is the verification of the gain-switching effect of the Nd:YVO₄ laser.4. Based on the experiment of continuous 914nm thermally boosted pumped 1064nm and 1342nm Nd:YVO₄ laser from the high Stark sublevel of the ground state, the impact of the temperature, the doped concentration and the length of the laser crystal on the output characteristics of the laser was reasearched. When the temperature of the crystal was 50oC, a maximum output power at 1064nm of 2.2W was achieved in a 1.0 at.% Nd:YVO₄ crystal with the dimension of 3 mm×3 mm×10 mm, leading to a high slope efficiency of 83.9%. In two 1.0 at.% Nd:YVO₄ crystals with the dimension of 3 mm×3 mm×4 mm, a maximum output power of 1.05W and a high slope efficiency of 66.4% were obtained at 1342nm.更多还原