Research and development of high-power, high-repetition rate, ultrashort pulse Yb-doped ceramic lasers

为了获得更短的脉冲宽度和更高的功率，我们研究了激光二极管泵浦的飞秒掺Yb陶瓷激光器。倍半氧化物(Re_2O_3，Re=Y，Lu，Sc)克尔透镜锁模的成功使短脉冲锁模突破了一般带宽的限制。以Yb：Sc_2O_3为例，获得了输出功率为850 mW的92fS脉冲输出。研究了单谐振腔内多个陶瓷的陶瓷激光器。利用Yb：Y_2O_3和Yb：Sc_2O_3展宽增益带宽，同时实现了53ps和1W的输出，这是Yb固体振荡器直接产生最短脉冲的记录。结果表明，在小于100fS的范围内，该材料的功率和效率远远超过其他材料，大大提高了Yb固体激光器的性能指标。此外，我们还研制了各种复合陶瓷，并展示了脉冲宽度237ps、脉冲能量172μJ、峰值功率…为0.72 mW自调Q微片激光器为了研制温度调谐的高功率有源镜激光器，我们系统地研究了Yb：YAG和Re_2O_3陶瓷的光谱、热和力学性能。我们建立了一个包括受激发射截面、流形内布居数分布、增益介质内温度分布和浓度猝灭的温度依赖关系的模型，并建立了如何从温度调谐的Yb：YAG激光器中最佳地提取能量的模型。在较薄的介质中进行较高的掺杂对有源镜激光器的功率调节是有效的。然而，我们发现，当高掺Yb材料被强泵浦时，它们被合作上转换激发到电荷转移带，并产生超宽带发射，这就给出了限制。在高掺Yb的Yb：YAG激光器中，陶瓷比单晶具有更高的效率，其中20%Yb：YAG获得了高达60.6%的斜效率。我们可以得出结论，陶瓷比单晶更适合于高掺杂，因为陶瓷中的杂质较少，因此上述非线性损耗较小。较少

We studied laser-diode-pumped femtosecond Yb-doped ceramic lasers for shorter pulse durations and higher powers. The success of Kerr-lens mode locking by use of sesquioxides (Re_2O_3, Re=Y, Lu, Sc) enables short-pulse mode-locking beyond general bandwidth limitations. For example, 92fs pulses with 850mW of output power from Yb:Sc_2O_3 was achieved. Ceramic lasers with multiple ceramics in a single resonator were also investigated. Broadening the gain bandwidth by use of Yb:Y_2O_3 and Yb:Sc_2O_3 simultaneously realized an output of 53fs and 1W, the record shortest pulse generation directly from an Yb solid-state oscillator. The series of our results show the powers and efficiencies are far beyond other materials in a sub-100fs region, and advanced the specifications of Yb solid-state lasers significantly. In addition, we have developed various composite ceramics and demonstrated a self-Q-switched microchip laser with 237ps of pulse duration, 172μJ of pulse energy, and 0.72MW of peak pow … More er by Yb:YAG/Cr:YAG.For the development of temperature-tuned high-power active-mirror lasers, we investigated systematically the spectroscopic, thermal, and mechanical properties of YAG and Re_2O_3 ceramics. We developed a model including the temperature dependences of the stimulated emission cross section, population distribution within manifolds, temperature distribution in a gain medium and concentration quenching, and established how we optimally extract the energy from a temperature-tuned Yb:YAG laser. Higher-doping in a thinner medium is effective for power scaling of active-mirror lasers. We discovered, however, that when highly Yb-doped materials are pumped strongly, they are excited to a charge-transfer band by cooperative up-conversion and ultra-broadband emission is generated, giving the limitation. In highly Yb-doped Yb:YAG lasers, ceramics showed higher efficiency than single crystals, and as high as 60.6% Slope efficiency was obtained by 20% Yb:YAG. We can conclude that ceramics are suitable than single crystals for high doping since ceramics will have less impurity and hence the aforementioned nonlinear loss. Less