摘要
为了进一步探讨大模场光纤激光的模式控制方法,需要研究大模场光纤的弯曲特性。从亥姆霍兹方程出发,通过对比直光纤和弯曲光纤的模场分布,确定大模场光纤直弯过渡中的模场演变方式。应用模场的叠加和激发理论,推导得到光纤直弯过渡中的模场耦合效率公式。应用耦合公式和有限元方法,计算了阶跃折射率分布的大模场光纤在直弯过渡中的模场耦合效率。结果表明:在光纤的直弯过渡中,存在模式的自耦合和互耦合过程,耦合程度随着弯曲程度和模场阶次的变化而变化,其中基模的耦合效率始终最大,高阶模的耦合损耗大于低阶模。光纤的直弯过渡以总能量的损耗为代价换取对高阶模的有效抑制。
For further investigating the fiber laser mode control, the bending properties of large mode area fibers need to be studied. Begining with the Helmholtz equation, by comparing the field distributions of straight fiber and bent fiber modes, the mode evolution ways between straight and curved large mode area fibers transition are determined. Based on mode superposition and excitation theory, the mode coupling efficiency formula about straight and bent fiber transition is derived. With the help of coupling formula and finite element method, the mode coupling efficiencies of a step-index large mode area fiber in straight and curved state transition are calculated. The results show that self-coupling and cross-coupling processes exist when fiber transits between straight and curved states, and the coupling degree varies with the degree of bending and mode order, in which the coupling efficiency of the fundamental mode is always higher than that of other modes and the coupling loss of higher order mode is larger than that of lower order mode. The fiber transition between straight and curved states costs the total power to exchange for the effective inhibition of higher order mode.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2013年第3期141-146,共6页
Chinese Journal of Lasers
基金
广西自然科学基金(2011GXNSFA018148)资助课题
关键词
光纤光学
大模场光纤
直弯过渡
模场演变
耦合效率
fiber optics
large mode area fibers transition between straight and curved states
mode fieldevolution
coupling efficiency
作者简介
廖素英（1972-），女，博士，副教授，主要从事光纤激光技术方面的研究。E—mail：liaosuying@gmail．com
