梳状大模场光纤结构的优化设计

Optimum design for comb-index core fiber with large mode area

通过在周期性梳状折射率结构的最外层增加一个高折射率平台的方法,对梳状折射率分布大模场光纤的波导结构进行了优化,使其在模场面积、模场分布及抗弯曲性能方面都有明显提升。模拟研究结果表明,与已有单一梳状折射率分布的光纤相比,优化后的大模场光纤的模场面积提高了700μm^2以上,且在相同弯曲半径下,基模弯曲损耗由6 dB/m降低为0.1 d B/m。此外,通过对最外层高折射率平台的参数进行调制可实现不同的模场分布,包括高斯分布、平坦化分布和环状分布,满足特殊激光加工工业的应用需求。

The wave-guide structure of the large mode area fiber with a comb-index core was optimized by adding a high refractive index platform in the outer layer of the fiber core,which provided a performance promotion on the parameters of mode field area,mode field distribution and bending resistance.The simulation results show that the optimized refractive index distribution increases the fiber’s mode field area by more than 700μm2,and reduces bending loss of the fundamental mode from 6 dB/m to0.1 d B/m at the same bending radius compared with the original comb-index distribution.Moreover,the mode field distributions including Gauss-like distribution,flattened distribution and hollow distribution,can be obtained by simply modulating the refractive-index parameters of the outermost platform,which may meet the needs of special laser processing industry.