高功率光纤激光器全内反射型大模场光子晶体光纤设计

Design of large mode area total internal reflection photonic crystal fiber for high power fiber laser

在高功率密度下产生的非线性效应和材料损伤等问题限制了光纤激光器输出功率的进一步提高。利用大模场光纤降低光纤能量密度，提高非线性阈值是一种最为直接和有效的手段。以空气孔尺寸为光波长量级的全内反射型光子晶体光纤为对象，采用等效折射率模型分析了光子晶体光纤的单模特性，利用有限元法分析了结构参数对光子晶体光纤的模场面积和色散等光束质量参数的影响。设计了一种工作波长为0．40～1．55μm，模场面积为112．74~258．87μm。，且在1．27μm附近可补偿色散的大模场光子晶体光纤。该研究可为高功率光纤激光器大模场光纤的进一步参数优化设计及元件加工提供重要参考。

The nonlinear effect and material damage existing in high power fiber lasers restrict their output power. A large mode area fiber, which could reduce the power density and improve the nonlinear threshold, is one of the solutions to the problem. A photonic crystal fiber with air holes at wavelength scales was designed based on the effective index model and finite element analysis. The single-mode properties as well as the influence Of structural parameters on the mode area and dispersion were investigated. Considering practical applications, we designed a large mode area photonic crystal fiber, operating in the range of 0.40~1.55μm, mode area between 112.74~258.87 μm^2 , centering at 1.27μm with dispersion compensation ability. Our investigations may provide new references to the optimization and fabrication of large mode area fiber for high power fiber lasers.