Rigrod laser-pumped-laser resonator model: I. Theoretical considerations
Rigrod laser-pumped-laser resonator model: I. Theoretical considerations
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Rigrod 激光泵浦激光谐振腔模型： I. 理论考虑
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
D. Brown
中科院分区：
文献类型：
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作者：
D. Brown
其离子掺杂被最小化的稀激光材料是有吸引力的，因为俄歇上转换被最小化，产生显著较低的热分数，并且横向或纵向增益和热沉积梯度被减小。此外，放大自发辐射（ASE）效应也被最小化。然而，由于在合理长度的激光晶体中难以获得有效吸收，使用稀释激光材料的激光器往往具有降低的效率。这主要是因为使用了简单的单程或双程泵浦吸收方案。虽然这个困难可以通过使用多通吸收泵浦光束来克服，但是如结合薄盘激光器的开发已经成功地证明的那样，在增加复杂性和成本的情况下获得更高的吸收和效率。在本文中，我们提出了一种替代的方法，其中一个稀释或薄的吸收激光材料放置在腔内的泵浦激光谐振腔。随着吸收激光晶体作为一个有效的外耦合器，我们发现，最高的吸收和谐振腔提取效率获得最稀或最薄的材料时，使用近单位反射率的谐振腔反射镜。这种违反直觉的结果可以通过激光谐振腔内部相应的长光子寿命来解释，这有效地多次通过吸收激光晶体，从而导致非常高的吸收效率。
Dilute laser materials whose ion doping is minimized are attractive because Auger up-conversion is minimized, substantially lower heat fractions result and transverse or longitudinal gain and heat deposition gradients are reduced. In addition, amplified spontaneous emission (ASE) effects are minimized as well. Lasers using dilute laser materials, however, tend to have lowered efficiencies due to the difficulty in obtaining efficient absorption in laser crystals of reasonable length. This is primarily because of the use of simple single or double-passed pump absorption schemes. While this difficulty may be overcome using multi-passed absorption pump beams, as has been successfully demonstrated in connection with the development of thin-disc lasers, higher absorption and efficiency are obtained with added complexity and cost. In this paper, we present an alternative method in which a dilute or thin absorbing laser material is placed intra-cavity to a pump laser resonator. With the absorbing laser crystal acting as an effective outcoupler, we find that the highest absorption and resonator extraction efficiencies are obtained with the most dilute or thin materials when resonator mirrors of near unity reflectivity are used. This counter-intuitive result is explained by a corresponding long photon lifetime inside the laser resonator, which effectively multi-passes the absorbing laser crystal, leading to a very high absorption efficiency.