【摘要】 本文用双折射貌相法和化学腐蚀法测定了六根晶体棒中的位错分布和位错密度,用光学方法检验了晶体的光学质量,晶体的激光性能是在一台Q开关YAG激光装置上测定的。实验表明当位错密度增加到一定程度时,位错形成的应力场会引起明显的双折射,以致探测光通过晶体时波面会发生畸变。在干涉仪上可观察到干涉条纹的增加。同样,在位错应力场区消光比亦下降。因此,作为结构缺陷的位错也是晶体光学不均匀的来源之一。晶体激光性能的实验结果指出:位错对激光输出特性有很大的影响,从激光近场光斑图看出,在位错应力场区,因为高的激光阈值而不能产生激光振荡,并且由于应力双折射效应产生光的退偏性。由于存在高位错密度,晶体的激光发散度增加,倍频效率下降。当晶体中存在缀饰位错(decorated dislocation)时,激光输出特性的变化尤为明显.更多还原

【Abstract】 The dislocation of distribution and density in six crystal rods were determined by birefringence topography and chemical etching. Their optical quality were also inspected by optical method. Laser measurement of output performances of these crystal were conducted in a Q-switched YAG laser device.The experiment result is shown that the dislocations can form stress field causing strong birefringence when the dislocation density increases to considerable extent. As a result, light wavefront passing through the crystal is distorted and the interference fringes areincreased. As well as extinction ratio in region of high dislocation density is also decreased. Therefore, the dislocation structural defect will also be origin of optical inhomogeneity in crystals.By experimental results of laser performance of these crystal, it is pointed out that there are great influence of dislocation on laser output characteristics. From laser near-field patterns, the laser oscillation can not take place in the region of high dislocation density due to high laser threshold and the light is depolarized by birefringence effect. Because of high dislocation density, the laser divergence is increased and the frequency doubling efficiency is also decreased. The laser output performances changed more obviously when existing decorated dislocations in these crystals.更多还原