We numerically investigate the power and energy scaling potential of cryogenic Yb:YLF regenerative amplifiers in rod geometry. Our approach is based on solving the coupled set of equations describing thermal behavior of the material and its effect on spectroscopic properties, gain, and overall amplification. The approach is first benchmarked with earlier experimental data. By carefully analyzing the sensitivity of the system to operation parameters, we see that the relatively low gain nature of the Yb:YLF and the onset of thermal effects are the main factors that limited the performance in earlier experimental work. We show that usage of dual-rod geometry promises much improved performance. Specifically, we demonstrate that sub-250 fs pulses with an average power of up to 270 W and a peak power above 500 GW can be extracted directly from a single-stage Yb:YLF regenerative amplifier employing dual Yb:YLF rods. We further show that by adjusting the spot size in the regenerative amplifier, one can operate the amplifier in either high-energy mode (${\gt}{100}\;{\rm mJ}$ at 1 kHz) or high-average-power mode (${\gt}{25}\;{\rm mJ}$ at 10 kHz, with ${\gt}{250}\;{\rm W}$). We also discuss pros and cons of Yb:YLF with respect to Yb:YAG, and underline the need for measurement of population and photo-elastic-effect-induced lensing in Yb:YLF to obtain a better understanding of Yb:YLF systems. The findings presented in this work can be used for the design and development of next-generation high-average and peak-power Yb:YLF amplifier systems.

中文翻译：

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棒型低温Yb：YLF再生放大器的功率和能量缩放

我们用数值方法研究了棒状几何形状的低温Yb：YLF再生放大器的功率和能量定标潜力。我们的方法基于求解描述材料热行为及其对光谱性质，增益和整体放大的影响的方程组的耦合。该方法首先以较早的实验数据作为基准。通过仔细分析系统对操作参数的敏感性，我们发现Yb：YLF的相对较低的增益特性和热效应的出现是限制早期实验工作性能的主要因素。我们证明了使用双杆几何结构有望大大提高性能。特别，我们证明，可以直接从采用双Yb：YLF杆的单级Yb：YLF再生放大器中提取平均功率高达270 W且峰值功率高于500 GW的亚250 fs脉冲。我们进一步证明，通过调整再生放大器中的光斑大小，人们可以在高能量模式下操作放大器（$ {\ GT} {100} \ {\ RM毫焦耳} $在1千赫）或高平均功率模式（$ {\ GT} {25} \ {\ RM毫焦耳} $在10kHz，以$ {\ gt} {250} \; {\ rm W} $）。我们还讨论了Yb：YLF相对于Yb：YAG的利弊，并强调需要对Yb：YLF中的人口和光弹效应诱发的透镜进行测量，以更好地了解Yb：YLF系统。这项工作中提出的发现可用于下一代高平均和峰值功率Yb：YLF放大器系统的设计和开发。