Modulation instability in high power laser amplifiers.
Modulation instability in high power laser amplifiers.
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DOI：
10.1364/oe.18.001380
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发表时间：
2010-01
期刊：
影响因子：
3.8
通讯作者：
A. Rubenchik;S. Turitsyn;M. P. Fedoruk
中科院分区：
文献类型：
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作者：
A. Rubenchik;S. Turitsyn;M. P. Fedoruk
调制不稳定性（MI）是导致高功率激光系统光束质量下降的主要因素之一。所谓的 B 积分限制通常用作无源光学器件中 MI 控制的标准。对于放大器，绝热模型（局部假设 MI 增长的 Bespalov-Talanov 表达式）通常用于估计不稳定性的破坏性影响。我们在此介绍放大器中 MI 开发的精确解决方案。我们确定控制放大器中 MI 影响的参数，并计算 MI 增长率作为这些参数的函数。给出了操作参数的安全范围。将精确计算结果与绝热模型进行比较，确定最新计算结果的有效范围。我们证明，对于实际情况，绝热近似明显高估了 MI。激光系统设计的附加裕度是量化的。
The modulation instability (MI) is one of the main factors responsible for the degradation of beam quality in high-power laser systems. The so-called B-integral restriction is commonly used as the criteria for MI control in passive optics devices. For amplifiers the adiabatic model, assuming locally the Bespalov-Talanov expression for MI growth, is commonly used to estimate the destructive impact of the instability. We present here the exact solution of MI development in amplifiers. We determine the parameters which control the effect of MI in amplifiers and calculate the MI growth rate as a function of those parameters. The safety range of operational parameters is presented. The results of the exact calculations are compared with the adiabatic model, and the range of validity of the latest is determined. We demonstrate that for practical situations the adiabatic approximation noticeably overestimates MI. The additional margin of laser system design is quantified.