LD侧面泵浦高功率绿光激光器研究

【作者】 师研；

【导师】 白晋涛；

【作者基本信息】 西北大学 ， 光学， 2010， 硕士

【摘要】 随着高功率半导体激光二极管技术的发展和成熟,采用LD泵浦的全固态激光器已经成为国际上激光技术的研发热点之一。非线性频率变换技术的进步更是极大地拓展了激光器的应用范围,其中采用激光二极管泵浦的全固态绿光激光以其体积小、重量轻、效率高、寿命长和光束质量好等优点在激光显示、工业加工、科学研究以及医学方面得到了广泛的应用。本文正是在这种背景下,针对LD侧面泵浦Nd:YAG腔内倍频高功率准连续绿光激光器进行了系统的理论和实验研究。本文主要完成了以下几个方面的工作：1.对激光二极管泵浦全固态激光器发展历史进行了综述,总结了全固态激光器的特性和优点。对全固态绿光激光器在医学、工业加工、科学研究等方面的应用进行了论述并针对国内外全固态绿光激光器的研究进展分别进行了总结。2.分析了Nd:YAG晶体的物理和激光特性,对激光二极光阵列侧面泵浦棒状Nd:YAG晶体内部的温度分布进行了理论计算,数值模拟了总的热透镜焦距随泵浦功率的变化关系,并对热透镜效应的补偿方法进行了总结。结合谐振腔的稳定性条件对包含热透镜的激光谐振腔进行了分析和研究。3.分析了四能级系统的特性和速率方程,对全固态激光器的连续运转特性进行了理论研究,在理论分析的基础上,采用激光二极管阵列七向侧面泵浦结构,分别用凹面激光棒和螺纹棒进行了1064nm红外激光的实验研究,得出了螺纹棒对于热效应的改善明显优于凹面棒的结论,为后面采用螺纹棒进行倍频实验研究打下了良好的基础。4.从非线性介质中的耦合波方程出发,对光学二次谐波的产生理论和倍频效率的影响因素进行了详细的分析。对比分析了KTP和LBO晶体的特性并对产生二次谐波的倍频方式进行了详细研究。5.对声光调Q腔内倍频绿光激光器进行了理论分析,在此基础上对声光调Q腔内倍频高功率准连续绿光激光器进行了实验研究,在平平腔内采用单声光Q开关获得了173.5W的高功率532nm绿光输出。通过在腔内正交放置同步驱动的两声光Q开关,在泵浦电流14A,重复频率38.7kHz时,获得了平均输出功率达197.5W的532nm绿光,倍频转换效率42%。更多还原

【Abstract】 With the development and maturity of high power laser diode, LD pumped all-solid-state laser has become an international hot research topic in laser technology. Nonlinear optical frequency conversion technique has further expanded the applications of DPL(Diode pumped laser). LD pumped green laser, with its compactness, high efficiency, long lifetime and good beam quality, has been widely used in laser display, industrial process, scientific research and medical treatment. Under this background, theoretical and experimental research has been made on high power LD side-pumped intra-cavity frequency-doubled green laser in the dissertation. The main points can be summarized as follows:1. The development and characteristics of LD-pumped all-solid-state laser are introduced at the beginning. Then the broad applications of all-solid-state green laser are presented and the progresses of high-power LD-pumped green laser are summarized.2. After detailed analysis of the characteristics of Nd:YAG crystal, the temperature distribution within the Nd:YAG rod side-pumped by LD arrays and the resulting thermal lensing are calculated. Then methods for reducing and compensating thermal focal length are summarized. Based on ABCD matrix, the stability condition and beam feature in the resonator are simulated and analyzed.3. Rate equation of four-level laser system are analyzed and the continuous operation characteristics of all-solid-state laser are investigated. Then experimental study by using concave end and grooved rod is made respectively and has laid solid ground for the frequency-doubled 532nm green laser experiments.4. Starting with nonlinear coupled-wave equation, the theory of second harmonic generation is given detailed analysis. Two commonly used frequency doubling cystal, KTP and LBO are comparatively studied. Then two different ways of obtaining second harmonic generation by placing the frequency doubling cystal either in or outside the resonator are discussed.5. Based on theoretical analysis of the acoustic Q-switched intra-cavity frequency doubled green laser system, experimental study on high power qusi-cw all-solid-state green laser are made with single Q switch and dual Q switches. Finally, with single grooved Nd:YAG rod, dual orthogonal placed Q switches, typeⅡcritical phase matched KTP in a plano-plano resonator, a maximum of 197.5W average power 532nm laser ouput was achieved at pumping current of 14A, repetition rate of 38.7kHz, corresponding to a frequency doubling efficiency of 42%.更多还原