Frontiers in laser science-cryogenically cooled lasers: editorial
Frontiers in laser science-cryogenically cooled lasers: editorial
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激光科学前沿——低温冷却激光器：社论
DOI：
10.1007/s00340-021-07603-y
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Mackenzie J
中科院分区：
文献类型：
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作者：
Mackenzie J
在这期低温冷却激光器特刊中，我们捕捉到了最先进的激光系统的快照，这些激光系统利用了在低温下操作增益材料的好处。在极低的温度下操作活性介质的固态激光器的原理并不新鲜，因为第二种激光器就是基于这种技术[1]。然而，低温的复杂性，加上激光工程，似乎抑制了该技术的显著吸收。克服这些挑战的原因是在DC Brown创造的低温冷却激光器“现代时代”的黎明时实现的[2]。这个现代时代是由Lacovara等人不协调地宣布的。[3]作者用二极管泵浦掺镱钇铝石榴石（Yb：YAG）激光器，以证明其在室温下工作的潜力。与此同时，他们证明Yb：YAG是功率缩放的典型活性介质，不久之后以薄盘的形式体现[4]。在此过程中，还显示了将晶体冷却到低温温度所带来的光谱和激光性能优势。从那时起，Yb：YAG一直是功率缩放二极管泵浦低温冷却激光器的支柱[2，5]。虽然镱是活性离子的选择，其简单的能量方案和有效的二极管泵浦配置的适用性，在收集的论文在这个特殊的问题，我们有报告的系统，涵盖了几乎所有的关键稀土离子和半导体二极管激光器。Fibrich等人从已报道的最轻的镧系元素离子开始，对原铝酸钇（YAlO3）类钙钛矿基质中的镨进行了系统研究。除了对其在低温下的光谱进行严格研究外，作者还展示了0.5 W的输出功率工作在493-nm处，来自带内GaN二极管泵浦单片激光器[6]。接下来，在镧系元素中，报道了带内二极管泵浦的掺钕YAG低温激光器，在946 nm处产生60 W，光-光效率接近50%[7]。对于常用的稀土离子，接下来是钬。再次，作为YAG主体的掺杂剂，在这种情况下，在板状几何形状中。报道的激光器也是带内泵浦的，利用高功率Tm光纤激光器，Ho：YAG激光器在Q开关模式下工作，它产生了> 130 mJ的脉冲，重复率超过200 Hz时斜率效率> 60%[8]。最后选择的论文在稀土离子激光器都是基于替代主机媒体，即倍半氧化物和氟化钇锂（YLF）。首先，研究了掺铥氧化钇（Tm：Y2O3）的光谱和二极管泵浦操作[9]，突出了与冷却晶体相关的关键光谱含义。同样来自捷克共和国的HiLase中心，对于相同的基质材料，也报道了低温陶瓷Yb：Y2O3激光器的高效性能[10]。该激光器在CW和被动Q开关配置中操作，表明与在低温下操作相关的输出功率的显着改善。佩雷韦津采夫等也调查Yb：Y2O3在[11]中，建议其潜在的替代主力Yb：YAG的低温冷却磁盘放大器的ps脉冲。此外，他们报告了多通放大器方案的演示，并表明在液氮温度下，增益光谱带宽几乎是Yb：YAG的两倍。在提出的最后一个倍半氧化物宿主中，Brown et.报告的吸收光谱的综合研究.
In this Special Issue on Cryogenically Cooled Lasers, we capture a snapshot of the state-of-the-art laser systems that capitalise on the benefits of operating the gain material at cryogenic temperatures. The principle of operating a solidstate laser with the active medium held at extremely low temperatures is not new, as the second laser ever reported was based upon this technique [1]. However, it appears that the complexity of cryogenic, coupled with, laser engineering, has dampened significant uptake of the technology. Reasons to overcome the challenges were realised at the dawn of the “modern era” of cryogenically cooled lasers, as coined by DC Brown [2]. This modern era was heralded, incongruently, by Lacovara et al.[3], with the authors diode-pumping an ytterbium-doped Yttrium Aluminium Garnet (Yb: YAG) laser to demonstrate its potential for room-temperature operation. At the same time, they proved Yb: YAG is an exemplar active medium for power-scaling, epitomised soon after in the form of a thin disk [4]. In the process, also showing the spectroscopic and laser-performance advantages derived from cooling the crystal to cryogenic temperatures. Since that time, Yb: YAG has been the mainstay in power-scaling diode-pumped cryogenically cooled lasers [2, 5]. While ytterbium is the active ion of choice, for its simple energy scheme and suitability for efficient diode-pumping configurations, in the collection of papers in this special issue, we have reports for systems covering nearly all of the key rare earth ions and a semiconductor diode laser. Starting with the lightest of the reported lanthanide ions, Fibrich et al. present a systematic study of praseodymium in the Yttrium Orthoaluminate (YAlO3) perovskite-like host.In addition to a rigorous study of its spectroscopy at cryogenic temperatures, the authors demonstrate 0.5 W of output power operating at 493-nm, from an in-band GaN-diodepumped monolithic laser [6]. Next in the line of the lanthanides, a neodymium-doped YAG cryogenic laser in-band diode-pumped is reported, producing 60 W at 946 nm with an optical to optical efficiency approaching 50%[7]. Moving toward the other end of the series for commonly used rare earth ions, holmium is next. Again, as a dopant of the YAG host, in this case in a slab geometry. The reported laser was also in-band-pumped, exploiting a high-power Tm-fibre laser, with the Ho: YAG laser operated in Q-switching mode, it generated> 130 mJ pulses with a> 60% slope efficiency for repetition rates over 200 Hz [8]. The final selection of papers on rare-earth-ion lasers is all based upon alternate host media, that is sesquioxides and Yttrium Lithium Fluoride (YLF). First, there is a study of the spectroscopy and diode-pumped operation of thulium-doped yttria (Tm: Y2O3)[9], highlighting the key spectroscopic implications associated with cooling the crystal. Also from the HiLase Centre in the Czech Republic and for the same host material, efficient performance of a cryogenic ceramic-Yb: Y2O3 laser is also reported [10]. This laser was operated in CW and in passively Q-switched configurations, demonstrating significant improvements in output power associated with operating at cryogenic temperatures. Perevezentsev et. al. also investigate Yb: Y2O3 in [11], recommending its potential for replacing the workhorse Yb: YAG for cryogenically cooled disk amplifiers for ps-pulses. Furthermore, they report a demonstration of a multi-pass amplifier scheme and show that the gain spectral bandwidth is almost double that of Yb: YAG at liquid nitrogen temperatures. In the last sesquioxide host presented, Brown et. al. report a comprehensive study of the absorption spectroscopic …