面向模分复用的偏振保持领结型椭圆芯少模光纤的设计

Design of polarization-maintaining bow-tie elliptical-core few-mode fiber for mode-division-multiplexing

提出了一种弱耦合领结型椭圆芯应力保偏少模光纤(PM-FMF),通过使用高折射率纤芯,所提出的光纤可在1505~1585 nm波段下,支持32个独立的本征模式。椭圆纤芯和领结型应力区的引入,有效地分离了相邻的本征模式。采用有限元法对领结型椭圆芯应力PM-FMF的纤芯及领结型应力区的结构参数进行优化。评估了光纤参数对模式数量、模式间的最小有效折射率差、模态双折射、应力双折射以及弯曲损耗的影响。此外还分析了该光纤的带宽性能,包括模式间的有效折射率、有效折射率差、差分模式时延(DMD)。经数据分析,在1505~1585 nm波段下,该光纤支持的32个本征模式是完全分离的,相邻模式之间的最小有效折射率差大于1.295×10^(−4)。所提出的弱耦合保偏少模光纤能够提高传输容量,在本征模式复用传输中具有潜在的应用前景。

We propose a weakly coupled polarization-maintaining few-mode fiber(PM-FMF)design with elliptical-core and bow-tie stress-applying areas.Using a high refractive index core,the proposed fiber can support 32 independent eigenmodes in the 1505−1585 nm band.The combination of the elliptical-core and bow-tie stressapplying area effectively separates the adjacent eigenmodes.The structural parameters of the elliptical-core and the bow-tie stress-applying area of the PM-FMF are optimized using the finite element method.The effects of fiber parameters on the number of modes,the minimum effective refractive index difference(Δneff,mim)between modes,the mode birefringence Bm,the stress birefringence Bs,and the bending loss are evaluated.The bandwidth performance of the fiber is also analyzed,including the effective refractive index neff,Δneff and differential mode delay(DMD)between adjacent modes.The results indicate that 32 eigenmodes supported by the fiber are completely separated withΔneff,min between adjacent modes larger than 1.295×10^(−4) in the 1505−1585 nm band.The fiber proposed can improve the transmission capacity and has potential applications in eigenmode multiplexing transmission.