Mu X, Ding Y J
Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
Appl Opt. 2000 Jun 20;39(18):3099-103. doi: 10.1364/ao.39.003099.
We have developed a simple method that uses cw irradiation from an argon laser to measure the damage threshold of KTP crystals. Our experimental results show that there are two types of damage in KTP crystal, depending on the polarization of the incident laser beam. One type of optical damage is the appearance of gray tracks, including both dark tracks and orange dots, when the pump polarization is perpendicular to the z axis. The other type is invisible damage when the polarization is parallel to the z axis. In addition, we have also observed weak photorefractive two-wave mixing in KTP crystals in each of these polarization states. After a systematic analysis we have concluded that the first type of damage is due to the formation and absorption of Ti3+ and Fe3+ centers and the second is due to the drift of K+ ions. The weak photorefractive effect is the result of screening of the electric field by the drifted K+ ions.
我们开发了一种简单的方法，利用氩离子激光器的连续波辐照来测量磷酸钛氧钾（KTP）晶体的损伤阈值。我们的实验结果表明，根据入射激光束的偏振情况，KTP晶体存在两种类型的损伤。一种光学损伤是当泵浦光偏振垂直于z轴时出现灰色轨迹，包括暗轨迹和橙色点。另一种是当偏振平行于z轴时的不可见损伤。此外，我们还在这两种偏振状态下的KTP晶体中观察到了微弱的光折变二波混频。经过系统分析，我们得出结论，第一种损伤是由于Ti3+和Fe3+中心的形成和吸收，第二种损伤是由于K+离子的漂移。微弱的光折变效应是漂移的K+离子对电场进行屏蔽的结果。
