耦合环辅助多模光纤受激布里渊散射阈值分析

Analysis of the stimulated Brillouin scattering threshold of coupling ring-assisted multi-mode fiber

为了降低模间串扰,提出了一种耦合环辅助多模光纤结构,通过仿真软件对其结构进行建模,并建立了其受激布里渊散射增益谱的数学模型;理论分析了耦合环辅助多模光纤的受激布里渊散射阈值以及光纤参量和模式对受激布里渊散射光谱阈值的影响,并通过了仿真实验验证。结果表明,耦合环辅助多模光纤增大关键模式有效折射率差值为原来的1.75倍,可有效抑制模间串扰;受激布里渊散射光谱阈值跟随光纤长度的增加,从急剧下降变至缓慢,最终在18 km处趋于定值30 dBm;在其它条件不变的情况下,阈值随着衰减系数、纤芯的有效截面积和光纤模式阶数的增加呈线性关系增加,随着纤芯半径的增加呈指数形式增长。该研究为提升光纤通信系统的传输距离和信道容量提供了理论参考。

In order to reduce inter-mode crosstalk,a coupling ring-assisted multi-mode fiber structure was proposed,and the mathematical model of its excited Brillouin scattering gain spectrum was established.Theoretically,the excited Brillouin scattering threshold of the coupling ring-assisted multi-mode fiber was analyzed,as well as the effects of fiber parameters and modes on the excited Brillouin scattering spectral threshold.The results show that the coupling ring-assisted structure increases the effective refractive index difference to 1.75 times that of the conventional type step-index multi-mode fiber.The threshold of the excited Brillouin scattering spectrum in coupling ring-assisted multi-mode fiber follows the increase of the fiber length from a sharp decrease to a slow one and finally converges to a constant value of 30 dBm at 18 km,which is higher than that of the conventional step refractive index multi-mode fiber.Other things being equal,the threshold increases linearly with the attenuation coefficient,the effective cross-sectional area of the fiber core,and the mode order of the fiber;it increases exponentially with the increase of the core radius.This study provides a theoretical reference for enhancing the transmission distance and channel capacity of fiber optic communication systems.