基于Yb:YAG/Cr4+:YAG复合材料的高峰值功率被动调Q微片激光器研究

Laser-diode end-pumped passively Q-switched microchip lasers have potential applications in laser ignition for automobile, material processing, new light sources generated by efficient frequency conversion and so on owing to their compactness, robustness, high beam quality and high peak power achievable. Theoretical design, fabrication and performance of Yb:YAG/Cr4+:YAG composite materials are proposed in this project. Effects of diffusions of Yb3+ ions and Cr4+ ions between interface on the mechanical properties, optical and laser properties of Yb:YAG/Cr4+:YAG composite materials will be investigatead in detail. The key parameters of doping concentrations, thickness of Yb:YAG and Cr4+:YAG parts in Yb:YAG/Cr4+:YAG composite materials will be otained for constructing passively Q-switched microchip lasers with high energy and high peak power. Yb:YAG/Cr4+:YAG composite materials with high opitcal quality, low scattering, perfect interface will be fabricated with thermal bonding technology. Under 940 nm quasi-CW laser-diode pumping, choosing suitable pump light parameters, stable laser output will be obtained from Yb:YAG/Cr4+:YAG composite laser materials based on the mechanism of mode selection techique of combining Yb:YAG and Cr4+:YAG thin plates. The investigation will provide a solid foundation on theory and experimental data for developing high energy, high peak power passively Q-switched microchip lasers based on Yb:YAG/Cr4+:YAG composite materials.

激光二极管端面泵浦的被动调Q微片激光器具有结构紧凑、坚固耐用、高光束质量、高峰值功率等优点，在机械加工、激光点火、高效非线性频率转换产生新光源等领域有着非常广阔的应用前景。本项目拟通过开展Yb:YAG/Cr4+:YAG复合材料的理论设计、制备及性能研究，阐明Yb3+离子和Cr4+离子相互之间扩散特性对复合材料界面机械、光学及激光性能影响的关系，获得实现大能量、高峰值功率激光输出所需的Yb:YAG/Cr4+:YAG复合材料的掺杂浓度、晶片厚度等关键参数，利用热键合技术制备出性能优良、低散射、键合面平整完美的Yb:YAG/Cr4+:YAG复合材料。利用Yb:YAG及Cr4+:YAG晶片组合选模实现Yb:YAG/Cr4+:YAG复合材料被动调Q微片激光器的输出脉冲稳定化。为今后推动基于Yb:YAG/Cr4+:YAG复合材料的大能量、高峰值功率被动调Q微片激光器的发展提供理论依据和实验数据。

激光二极管端面泵浦的被动调Q微片激光器具有结构紧凑、高光束质量、高峰值功率、高光学转换效率等优点，在机械加工、内燃机激光点火、高效非线性频率转换产生新光源等领域有着非常广阔的应用前景。资助项目系统研究了用于研制Yb:YAG/Cr4+:YAG复合激光晶体的Yb:YAG、Cr4+:YAG光谱性能。获得了制备Yb:YAG/Cr4+:YAG复合晶体的优化设计参数和材料设计理论。利用三明治方式，通过不同晶体组合研究了Cr,Yb:YAG双掺过渡层对Yb:YAG/Cr4+:YAG复合晶体被动调Q激光器激光性能的影响。利用Yb:YAG及Cr4+:YAG晶片组合选模实现Yb:YAG/Cr4+:YAG复合晶体被动调Q微片激光器的输出脉冲稳定化。阐明了纵模模式特性与输出激光脉冲序列之间的内在联系，提出了实现多纵模振荡Yb:YAG被动调Q微片激光器实现脉冲稳定化的物理机制。在连续激光二极管泵浦的Yb:YAG/Cr4+:YAG复合晶体被动调Q激光器中获得了平均输出功率1.75 W、光学转换效率高达36%的激光输出。在高亮度单管激光二极管泵浦的Yb:YAG/Cr4+:YAG复合晶体被动调Q微片激光器中获得了光学转换效率高达41%、平均输出功率1.5 W、脉冲宽度为665 ps的激光脉冲输出。系统地研究了准连续激光二极管泵浦光参数、复合晶体材料参数输出耦合镜透过率等对Yb:YAG/Cr4+:YAG复合晶体被动调Q激光器激光性能的影响，获得了优化的泵浦光参数以实现高光学转换效率和高峰值功率激光输出。在优化准连续激光二极管泵浦光参数的情况下，在初始透过率为70%的Yb:YAG/Cr4+:YAG复合晶体被动调Q激光器中获得了光学转换效率高达22%、单脉冲能量为1.6 mJ、脉冲宽度为1.46 ns、峰值功率为1.08 MW的被动调Q激光脉冲输出。在激光二极管泵浦的KTP腔内倍频Cr,Nd:YAG小型化绿光器获得了性能稳定、光学转换效率高达17%的瓦级绿光激光输出，为海底激光通信、激光显示等应用领域提供了新型光源。高光学转换效率、高峰值功率被动调Q激光器的研究成果为研制基于Yb:YAG/Cr4+:YAG复合材料的高光学转换效率、大能量、高峰值功率被动调Q微片激光器提供理论依据和实验数据，同时也为激光加工、激光点火、非线性光学转换产生新型激光光源以及激光诱导击穿光谱仪等小型化仪器的研制提供了可靠的激光源。