激光作用下薄膜中的电子-声子散射速率

激光功率密度达到太瓦级时，光学激光薄膜破坏中雪崩机制占主导地位．研究雪崩破坏机理，必然涉及到电子吸收激光能量的速率和电子损耗能量的速率，这些都与电子和声子的散射有密切的联系．所以，电子受到的散射速率是研究雪崩机制的前提和基础．本文分析了截断散射声子波矢对散射速率的影响，得到散射速率与电子能量的依赖关系，与其他理论及实验结果一致．同时还对耦合参数进行了修正，得到了依赖声子波矢的耦合参数，修正结果表明在不改变散射速率与高能电子能量依赖关系的基础上，散射速率整体降低了．

Avalanche ionization is a dominant damage mechanism of optical films if laser power density reaches to TW/cm(2) level. In order to study avalanche ionization mechanism, it is inevitable to deal with rates of electrons absorbing and losing energy. Both of these relate to the rate of collision between electrons and phonons. So it is important to study the collision of electrons and phonons. In this paper, we discuss the effect of truncating the maximum phonon vector on collision rate, and find the relation between scattering rate and electron kinetic energy. The conclusion is consistent with that obtained from other theories and experiments. At the same time, we also modify the coupling parameter, and obtain the connection of the coupling parameter with phonon vector. After modification, the curve shape of scatter rate versus electronic energy does not change, but the overall value decreases.