中文题目: 高功率激光终端KDP晶体非共线高效三倍频及远场色分离方案数值模拟分析
外文题目: Numerical simulation analysis of high efficient SFG and color separation in far field in high power laser facility based on noncollinear phase matching by KDP crystal
作者: 刘崇; 季来林; 朱宝强; 林尊琪
刊名: 物理学报
年: 2016 卷: 65 期: 14 文章编号：144202
中文关键词:
高功率激光装置; 激光损伤; 非共线和频; 远场色分离
英文关键词:
high power laser facility; laser induced damage; noncollinear sum frequency generation; harmonic wave separation at far field
中文摘要:
为满足高功率激光装置对终端光学系统的改进要求, 控制3omega光路透射元件厚度以降低激光损伤风险, 避免3omega非对称聚焦与色分离元件对靶场调靶产生不利影响, 本文利用非共线相位匹配原理讨论了KDP晶体I类和II类两种和频产生351 nm(3omega)激光及其远场色分离过程. 模拟结果表明, 室温20 ℃环境中除目前常用的共线和频外, 1053 nm(omega)与526.5 nm(2omega)激光可选择I类或II类两种非共线和频方式实现高效3omega激光输出并在激光远场实现色分离, 且具有足

英文摘要:
Asymmetric property of wedge lens in 3 omega optical path which is used as frequency separation, and focusing element is considered to be an unfavourable factor for target alignment in inertial confinement fusion (ICF). Furthermore, the thickness of wedge lens in 3 omega optical path will lead to laser induced damage inevitably. For the purpose of scheme improvement of final optical assembly, types I and II noncollinear sum frequency generation in KDP crystal at room temperature are discussed based on nonlinear coupled wave theory. As illustrated by simulated result, in addition to type II collinear SFG used in ICF recently, 351 nm (3 omega) waves can be generated by type I or II noncollinear SFG process. This method can realize color separations of omega, 2 omega, 3 omega in far field without asymmetric element such as wedge lens and posses adequate tolerance of matching angle corresponding to the high efficiency conversion. As calculated, for type I SFG, when the noncollinear angle alpha is in the interval from 0 degrees to 19.99 degrees, phase matching condition can be satisfied in KDP crystal. The noncritical phase matching angle theta(3) is 90 degrees and the corresponding noncollinear angle alpha is about 19.99 degrees. The tolerance of mismatching angle is about +/- 20 mrad. For type II SFG, the noncollinear angle interval that can satisfy phase matching process is about 0 degrees-13.55 degrees. Like type I SFG, there is also an noncritical solution in type II process whose matching angle is about theta(3 omega) = 86.53 degrees. Because of the smaller effective nonlinear coefficient in this case, high efficiency conversion needs about 5 cm thick SFG crystal under 1 GW/cm(2). Correspondingly, tolerance of mismatching angle is about +/- 20 mrad. Because of the harsh tolerance of noncollinear angle between omega and 2 omega and for the purpose of compactness of final optical assembly, another method of noncollinear SFG is proposed: a piece of silica wedge with 12 degrees wedged angle is mounted behind the SHG crystal in order to produce a 3.5 mrad intersection angle between ! and 2 omega, and after type II noncollinear SFG process, omega, 2 omega, 3 omega will be frequency separated in far field automatically by using thin lens. The tolerance of incident angle corresponding to high efficient conversion is about +/- 1.0 mrad. This scheme can improve the the final optical assembly used recently.


文献类型: 期刊论文
正文语种: Chinese
收录类别: SCIEI
DOI: 10.7498/aps.65.144202


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