光纤制备工艺的理解和进一步降低损耗的一些设想

Understanding Fabricating Process of Optical Fiber and Some Approaches on Further Reducing the Loss

描述二氧化锗，五氧化磷和氟化物在沉积和烧结过程中的机理．由于掺杂物在高温下的特性差异，有可能产生许多不利因素，如掺杂物的挥发、局部应力、缺陷中心和不完整波导结构．这些因素有损于传输特性．随着光纤通讯的发展，低损耗光纤在长距离，大容量通讯系统中起着越来越重要的作用．经过１０多年的努力，接近理论值的，低损耗的光纤已经商品化．但由于不完善工艺条件所引起的损耗，仍需要研究．１９７４年出现了ＭＣＶＤ工艺，由于实施相对容易，得到广泛使用．许多研究工作者对这一工艺中四个主要阶段：即沉积，烧结，固化和缩棒，提出满意的解释．为进一步改善包层内，包层和芯子之间，芯子内的浓度梯度和应力结构以便获得低损耗光纤，本文分析了几种掺杂物在高温下相互作用的机理。

This report described mainly a mechanism of GeO 2, P 2O 5 and fluorine deposit and sintering. Due to difference of several dopants properties at high temperature, it may give rise to many disadvantageous factors, such as the volatilization of dopants, the residual stress, the defect center and the imperfection waveguide structure, which affect the transmission properties. In this report, first, understanding of the effect of some factors on the dopant incorporation are reviewed, second, a reduction of concentration gradient is fully discussed, and another explanation on a characteristic of fluorine particle during sintering is given, third, the dependence of defect center on dopant species and drawing tension are analyzed, finally, from the point of view of the process, some suggestions are offered to improve the fabricating process conditions for obtaining extremely low-loss fibers.