Author Affiliations
Abstract
1 Chinese Academy of Sciences Shanghai Institute of Optics and Fine Mechanics National Laboratory on High Power Laser and Physics Shanghai 201800, China
2 Electronics Technology Group Corporation No. 23 Research Institute Shanghai 200437, China
A theoretical method to analyze four-layer large flattened mode (LFM) fibers is presented. The influence of the second cladding on the properties of four-layer LFM fiber, including the fundamental and higher-order modal fields, effective area, bending loss, and dispersion, are studied by comparison. At the same time, the reasons for the different characteristics are considered. The obtained results indicate that the effective area of the four-layer LFM fiber is about 1.6 times larger than that of the conventional standard step-index fiber and the fibers have better bend-induced filtering ability than three-layer LFM fibers.
large flattened mode (LFM) fiber modal fields effective area bending loss Collection Of theses on high power laser and plasma physics
2007, 5(1): 218
提出里兹－伽略金方法的一个近似或改进，即里兹－伽略金方法仅仅用来得到梯度型光纤的传播常量和纤芯中的模式场．包层场用修正贝塞尔函数以及已经求得的两个参量：包层径向衰减常量和场在纤芯－包层界面上的值重新构建．计算结果表明包层场准确度的改进是相当显著的，将这一近似方法应用于计算两根光纤之间的耦合系数，其结果与准确值几乎没有办法区分．
光纤光学 梯度型光纤 拉盖尔－高斯函数展开 模式场 耦合系数 Fiber optics Graded-index optical fibers Laguerre-Gauss expansion Modal fields Coupling coefficient
Author Affiliations
Abstract
National Laboratory on High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800, China
Theoretical method to analyze three-layer large flattened mode (LFM) fibers is presented. The modal fields, including the fundamental and higher order modes, and bending loss of the fiber are analyzed. The reason forming the different modal fields is explained and the feasibility to filter out the higher order modes via bending to realize high power, high beam quality fiber laser is given. Comparisons are made with the standard step-index fiber.
High power fiber laser Large flattened mode fiber Modal fields Bending loss Collection Of theses on high power laser and plasma physics
2006, 4(1): 140
应用量子力学的超位力定理(HVT)和赫尔曼费恩曼(Hellmann-Feynman)定理 (HFT),导出了用微扰法计算渐变折射率平面波导传播常数各级近似值的代数递推公式,并给出了由传播常数近似值计算模场近似表达式的代数公式.计算了几个典型实例.此法的特点是便于直接计算任意级近似的传播常数及模场分布,且可推广到二维波导的计算.
渐变折射率波导 传播常数 模场 微扰方法 代数递推公式
