谐振泵浦2.1μm单频脉冲激光振荡与放大技术研究

This project will study oscillation and amplification of 2.1 μm single frequency pulse solid state laser. The 1.9 μm laser diode (LD) will be used to pump Ho-doped laser mediums (including Ho:YAG crystal and Ho:YAG ceramics).By using the resonant pump technique high efficiency 2.1 μm laser output can be obtained. To achieve stable 2.1 μm single frequency narrow line-width laser output, the LD-pumped monolithic Ho:YAG non-planar ring resonator (NPRO) is desinged and experimentally investigated. Then the single frequency laser generated from the Ho:YAG NPRO will be used as a seed laser and injected into a slave Q-switched Ho:YAG ceramics laser, to get 2.1μm single frequency Q-switched laser output. The technique to amplify the 2.1 μm single frequency Q-swithed laser will be investigated. A high power 1.9 μm LD stack pumped Ho-doped ceramic slab amplifier with a multi-pass configuation will be used to get efficient amplification. The results of this project will offer new technical routes for highly efficient pumping of 2.1 μm solid state lasers and 2.1 μm single frequency laser oscillation and amplification, and solve key scientific and technical problems concerning 2.1 μm single frequency solid state lasers in higer energy levels.

本项目将研究谐振泵浦的2.1μm单频脉冲固体激光振荡与放大技术。本项目计划以波长为1.9μm的激光二极管(LD)泵浦掺Ho激光介质（包括Ho:YAG激光晶体和Ho:YAG激光陶瓷）,通过谐振泵浦的方式实现2.1μm固体激光的高效输出；计划设计LD谐振泵浦的单块Ho:YAG非平面环形腔(NPRO)实现高稳定性的2.1μm的单频窄线宽激光运转；然后以该NPRO激光器输出的单频激光为种子光注入到以Ho:YAG陶瓷为增益介质的从动调Q激光器中，实现2.1μm的单频调Q激光振荡；将研究2.1μm单频调Q激光的放大技术，计划采用1.9μm的大功率LD叠阵谐振泵浦掺Ho:YAG板条，通过多程放大的方式实现单频调Q激光脉冲的高效放大。本项目的研究结果将为2.1μm固体激光器的高效泵浦、单频调Q激光振荡与能量放大提供新的技术途径，解决制约2μm激光器实现较大能量单频激光输出的关键科学技术问题。

波长为2.1μm的单频激光在激光测风雷达、差分吸收激光雷达等领域具有重要的应用价值。本项目开展了谐振泵浦2.1μm 波段Ho:YAG激光器的理论和实验研究，对Ho:YAG激光介质（晶体和陶瓷）的特性、2.1μm波段激光能级跃迁过程等进行了理论分析，研究了上转换效应对于转换效率的影响，对2.1μm 波段激光器的泵浦方式进行了研究，研究了谐振泵浦情况下泵浦光参数、Ho:YAG的掺杂浓度、长度等参数与2.1μm激光器的阈值、效率、输出功率的关系。设计和研制了谐振泵浦2.1μm 波段单块非平面环形腔Ho:YAG激光器，实现了高效率、窄线宽、高光束质量的2.1μm单频种子激光输出。开展了2.1μm波段注入锁定单频调Q激光器理论及实验研究，以Ho:YAG单块非平面环形腔激光器作为种子源，采用1908nm半导体激光器泵浦Ho:YAG晶体，利用Ramp-Hold-Fire注入锁定技术，在重复频率200Hz下实现了15mJ的单频脉冲输出。开展了Ho:YAG单频激光功率放大（MOPA）的技术研究，对激光功率放大系统进行了理论分析，计算了最优的放大级晶体参数，对单频Ho:YAG激光器输出的脉冲激光进行功率放大实验研究，在重复频率为200Hz时获得了55mJ的单频调Q激光。本项目的研究结果具有重要的科学意义和应用前景。