Thermal lensing in diode-pumped ytterbium Lasers-Part II: evaluation of quantum efficiencies and thermo-optic coefficients
Thermal lensing in diode-pumped ytterbium Lasers-Part II: evaluation of quantum efficiencies and thermo-optic coefficients
复制标题
DOI：
10.1109/jqe.2004.833203
复制
发表时间：
2004-08
影响因子：
2.5
通讯作者：
S. Chénais;F. Balembois;F. Druon;G. Lucas-Leclin;P. Georges
中科院分区：
文献类型：
--
作者：
S. Chénais;F. Balembois;F. Druon;G. Lucas-Leclin;P. Georges
本文对掺Yb晶体的热透镜效应进行了理论和实验研究。本文介绍了第一部分的理论考虑和实验波前测量。在本文中，我们研究了热透镜效应随泵浦光吸收功率的变化规律，得到了两个对激光器设计和功率定标有价值的参数。测量了掺Yb的YAG、GGG、GdCOB、YCOB、KGW和YSO的量子效率和热光系数。在激光和非激光条件下的热透镜之间的明显区别是无辐射效应发生在所有研究中的晶体中的证据。考虑到激光提取效率的分析模型能够解释所有的实验特征，并允许推断样品的荧光量子效率（在0.7-0.96的范围内）。在非激光条件下，热透镜的屈光力经历了一个滚降，对此，我们提出了一个基于第一部分理论的解释。这些结果然后被用来产生的晶体的热光系数。最后，我们提出了一个简单的分析公式，用于粗略估计的焦距。
A theoretical and experimental study of thermal lensing in Yb-doped crystals is presented. This papers follows the presentation of theoretical considerations and experimental wavefront measurements, which have been the subject of Part I. In this paper, we study the evolution of thermal lensing versus absorbed pump power, and we derive two parameters valuable for laser design and power scaling. The quantum efficiency and the thermo-optic coefficient, in Yb-doped YAG, GGG, GdCOB, YCOB, KGW and YSO. The clear difference between thermal lensing under lasing and nonlasing conditions is the proof that nonradiative effects occur in all the crystals under investigation. An analytical model which takes into account the laser extraction efficiency enables to explain all the experimental features and allows to infer the fluorescence quantum efficiency of the samples (in the range 0.7-0.96). Under nonlasing conditions, the thermal lens dioptric power experiences a roll-off, for which we propose an explanation based on the theory presented in Part I. These results are then used to yield the thermo-optic coefficient of the crystals. At last, we propose a simple analytical formulation useful for a rough estimation of the focal length.