Abstract

Single crystals of yttrium orthoaluminate activated with Yb³⁺ ions (YAlO₃:Yb) are of high interest for diode pumped high-power ultrafast lasers emitting in the spectral range around 1 µm. The major parameters of lasers achieved so far can be improved by optimizing the activator concentration and improvement of the structural and optical quality of crystals. One of the problems is occurrence of color centers giving rise to absorption bands in the visible range with tails extending to the near IR. In the present work single crystals of YAlO₃:Yb were grown by the Bridgman and Czochralski methods. It is found that under the applied growth conditions absorption associated with color centers in the visible range is much lower in YAlO₃:Yb crystals grown by the Bridgman method. The differences in optical quality are attributed to the growth atmosphere (Ar/H₂ for Bridgman and Ar in the case of Czochralski), and to crystal cooling conditions. The influence of gamma-ray irradiation and thermal annealing on optical absorption in YAlO₃:Yb grown by the two methods is studied. The lifetime of Yb³⁺ is measured in crystals grown by the two methods.

中文翻译：

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YAP：Yb单晶用于超短脉冲激光器

摘要

由Yb ³⁺离子激活的原铝酸钇单晶（YAlO ₃：Yb）对于在约1 µm光谱范围内发射的二极管泵浦大功率超快激光器非常感兴趣。到目前为止，通过优化活化剂的浓度以及改善晶体的结构和光学质量，可以改善激光器的主要参数。问题之一是色中心的出现，导致在可见光范围内出现吸收带，并且尾部延伸到接近IR。在本工作中，通过Bridgman和Czochralski方法生长YAlO ₃：Yb单晶。发现在所应用的生长条件下，YAlO ₃中与可见范围内的色心有关的吸收要低得多。：通过Bridgman方法生长的Yb晶体。光学质量的差异归因于生长气氛（对于Bridgman而言为Ar / H _2，对于Czochralski而言为Ar），以及晶体冷却条件。研究了γ射线辐照和热退火对两种方法生长的YAlO ₃：Yb中光吸收的影响。在通过两种方法生长的晶体中测量Yb ³⁺的寿命。