【作者】 柯亮；

【导师】 姚宝权；

【作者基本信息】 哈尔滨工业大学 ， 物理电子学， 2010， 硕士

【摘要】 近年来随着全球气候环境的恶化,世界各国对大气风场数据的需求越来越迫切。相干多普勒激光测风雷达以其测风精度高,作用距离远等优点目前已逐渐成为远距离大气风场研究的有效工具。2μm固体激光器因其体积小,大气消光比低,人眼安全等优点目前已成为相干多普勒激光测风雷达的首选光源。与LD泵浦Tm,Ho双掺的2μm激光器相比,采用1.9μm单掺Tm激光器泵浦单掺Ho激光器的技术方案具有量子损耗低、热负载小和转换效率高等优点,易于在常温条件下实现高功率的2μm激光输出。本文从理论和实验两个方面对1.9μm激光泵浦的2.1μm Ho:YAG连续及调Q运行单纵模激光器进行了详细的研究。在理论上,首先建立了Ho:YAG环形腔激光器连续输出的准二能级速率方程以及低重频条件下主动调Q的速率方程。进而推导出了连续运转时激光输出功率与泵浦功率之间关系表达式,调Q输出单脉冲能量,脉冲宽度,峰值功率表达式。采用偏振态匹配理论对单块Ho:YAG半非平面环形腔进行了分析,并进行了实验,以Tm光纤激光器作为泵浦源,在泵浦功率为19.7W时,获得了最高功率6.3W、波长2090.6nm、温度调谐率-1.6GHz/℃、光束质量接近衍射极限单纵模连续激光输出。采用光纤延时自拍频方法测得单纵模激光输出的短期频率不稳定度随时间线性增长,线性增长率为270Hz/μs。以Ho:YAG非平面环形腔激光器为种子光,采用种子注入锁频技术,实现了常温下Ho:YAG环形腔单向运转,获得了重频110Hz、单脉冲能量11mJ、脉宽110ns、线宽4.2MHz、光束质量接近衍射极限的2.1μm单纵模脉冲激光输出。更多还原

【Abstract】 With the deterioration of global climate and environment in recent years, there is growing demand for data on atmospheric wind field all over the world. The use of coherent Doppler lidar for remote measurements of atmospheric wind fields is receiving increasing consideration as a valuable tool for studies of atmospheric dynamics. 2μm solid-state lasers are the primary choice for coherent Doppler wind detection for eye-safe properties and efficient diode-pump operation.Direct laser pumping of the Ho quasi-two-level laser offers several advantages over the sensitized Tm–Ho system: low quantum defect, elimination of energy transfer, reduced upconversion losses, high extraction efficiency. The combined advantages make a 2.1μm laser capable of high-power scaling and high energy output in room temperature. The work discussed in the thesis covers two areas: the single longitudinal mode operation of Tm pumped Ho:YAG CW and Q-switched laser.First, theoretically established CW output quasi two-level rate equations model and the active Q-switched model at low repetition frequency of Ho:YAG ring laser. The relationship between CW output laser output power and pumped power, and the expression of single pulse energy, pulse width, peak power of Q-switched output were derived.The operation of the nonplanar ring osillator is analyzed using polarization match theory. Single frequency output powers up to 6.3W at the wavelength of 2090.6nm with temperature tuning rate of -1.6GHz /℃for 19.7W of pump power are demonstrated. The frequency instability linear growth rate of 270Hz/μs was measured with fiber delayed self-heterodyne method. Taking the nonpanar ring laser as the seed laser using the seed-injection locked technology, the undirectional operation of Ho:YAG ring laser was realized, and a single a pulse energy of 11mJ, pulse width of 110ns, linewidth of 4.2MHz with diffraction limited beam quality of the single longitudinal mode Q-switched operation was achieved.更多还原