High power Tm:YLF & Tm:LuLF slab lasers for pumping Ho:YAG amplifiers (Conference Presentation)
High power Tm:YLF & Tm:LuLF slab lasers for pumping Ho:YAG amplifiers (Conference Presentation)
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高功率 Tm:YLF
DOI：
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发表时间：
2018
期刊：
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通讯作者：
D. Morris
中科院分区：
文献类型：
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作者：
M. Esser;A. Berrou;Michael E. Reilly;K. Tkalcec;D. Morris
光学对抗应用需要2微米的高功率激光器，但也可用于中红外激光波长具有优势的材料加工。这些应用可以从2微米输出功率扩展中受益，但需要保持紧凑的占地面积。特别是，掺Tm的板条激光器设计可以非常紧凑，作为1.9微米高功率Tm：光纤激光器的替代品。它可以直接用于调制的连续波输出，或用于泵浦2.1微米发射的Ho掺杂激光器和放大器。
我们直接比较了半导体端面泵浦激光器配置相同的Tm：YLF和Tm：LLF板条晶体(1.5 mm x 11 mm x 20 mm)，以评估这两种相关材料在150W时的功率比例。我们将分析当从高亮度793 nm激光二极管(Lasertel T6二极管)中以450 W的入射泵浦功率泵浦时，Tm：LLF在板条结构中不能完全抑制的热透镜行为。在双端泵浦的板条激光器结构中，通过仔细考虑板条的几何形状，抑制了寄生的内部激光，进一步将功率扩展到Tm：YLF的300W输出功率水平。
改进后的Tm：YLF激光器将被用于泵浦一块Ho：YLF板条(1.5 mm×10 mm×55 mm)，以放大来自纳秒Q开关振荡器的种子脉冲。建立了一个空间和时间分辨的模型，以确定最佳的泵浦结构和晶体尺寸，以放大平均功率从7 W(重复频率为10 kHz)到150 W(重复频率为2.1µm)的种子脉冲。该模型基于速率方程，确定了热负载在整个晶体中的分布，从而能够准确地预测放大器中饱和和热致像差。
High-power lasers at 2 µm are required for optical countermeasure applications, but can also be used for processing of materials where the mid-infrared laser wavelength provides an advantage. These applications can benefit from power scaling the 2 µm output, with the requirement to maintain a compact footprint. In particular, a Tm-doped slab laser design can be very compact, as an alternative to high power Tm:fiber lasers at 1.9 µm. It can be used directly for modulated continuous-wave output or for pumping Ho-doped lasers and amplifiers that emit at 2.1 µm.
We have directly compared Tm:YLF and Tm:LLF slab crystals (1.5 mm x 11 mm x 20 mm), in an otherwise identical diode end-pumped laser configuration, to evaluate the power scaling to 150 W of these two related materials. We will present the analysis of the thermal lens behaviour of that could not be fully supressed for Tm:LLF in the slab architecture when pumped at 450 W of incident pump power from the high-brightness 793 nm laser diode stack (Lasertel T6 Diode). Further power scaling to the 300 W output power level of Tm:YLF in a dual-end-pumped slab laser configuration will be presented, in which parasitic internal lasing has been supressed through careful consideration of the slab geometry.
The improved Tm:YLF laser will be used to pump a Ho:YAG slab (1.5 mm x 10 mm x 55 mm) to amplify seed pulses from a nanosecond Q-switched oscillator. A spatially and temporally resolved model has been developed to determine the optimal pump configuration and crystal dimensions to amplify seed pulses from 7 W average power at 10 kHz repetition rate, to upwards of 150 W at 2.1 µm. The model is based on rate equations and determines the distribution of thermal load throughout the crystal, permitting accurate prediction of saturation- and thermal-induced aberrations in the amplifier.