Growth of Fibrous Single Crystals of Oxides by the Floating Zone Method

浮区法生长氧化物纤维单晶

• 批准号: 09650917
• 负责人: HIGUCHI Mikio
• 金额: $ 1.98万
• 依托单位: HOKKAIDO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650917/
• 关键词: fiber crystal; floating zone method; oxide; laser material; yttrium orthovanadate; dislocation density; ファイバー結晶; 小傾角粒界

In various optical devices, efficient laser oscillation or wavelength conversion is expected using a fiber crystal, in which laser beam is encapsulated. In this study, the floating zone method, which had been employed to grow bulk crystals, was applied to grow fiber crystals of oxides Neodymium-doped yttrium orthovanadeate (Nd : YVO_4), which has attracted the attention as a laser material with laser-diode pumping, was chosen as a model material. Growth conditions to obtain thinner crystals were examined and the relation between the crystal diameter and quality was clarified.To keep a stable molten zone, the feed diameter should be decreased with decreasing crystal diameters and the ratio of the feed diameter to the crystal one should be less than three. In the case of less than 1 mmphi. the ratio should be about two. To realize these conditions, a single crystalline feed rod with a uniform diameter was used by cutting and grinding after the zone pass. The minimum diameter obtained was 0.8 mm. Thinner crystals are expected by using a four-ellipsoidal type apparatus. Which has much higher convergence efficiency than in the present apparatus. A drastic decrease in dislocation density was found in the crystals below 3 mmphi, in which dislocations were spontaneously decreased with continuing crystal growth. The decrease in the thermal stresses because of the decrease in the crystal diameter would contribute to the quality improvement.In this study, a basic technique for growing fiber crystals of oxides by the floating zone method was established and the quality of the crystals was improved with decreasing crystal diameters. This technique is also applicable to grow other kinds of fiber crystals that were difficult to grow by the conventional methods.

在各种光学器件中，期望使用其中封装有激光束的光纤晶体进行有效的激光振荡或波长转换。本研究采用浮区法生长块体晶体，以激光二极管泵浦的激光材料掺钕钒酸钇（Nd：YVO_4）为模型材料，研究了掺钕钒酸钇光纤晶体的生长。研究了获得较细晶体的生长条件，阐明了晶体直径与质量的关系，指出为保持稳定的熔区，进料直径应随晶体直径的减小而减小，进料直径与晶体直径之比应小于3。在小于1 mmphi的情况下。比例应该是2左右。为了实现这些条件，在区域通过之后通过切割和研磨使用具有均匀直径的单晶进料棒。获得的最小直径为0.8 mm。通过使用四椭球型装置，预期晶体更薄。其具有比本装置高得多的收敛效率。在低于3 mmphi的晶体中发现位错密度急剧下降，其中位错随着晶体的继续生长而自发地减少。由于晶体直径的减小而减小的热应力将有助于质量的改善。在本研究中，建立了用浮区法生长氧化物纤维晶体的基本技术，并且随着晶体直径的减小，晶体的质量得到改善。该技术也适用于生长其他类型的纤维晶体，这是很难通过传统的方法生长。