八边形空气孔环绕-双模大模场面积多芯光纤

Dual-mode large mode area multi-core fiber with octagonal distribution of air holes

为实现多芯光纤的严格双模传输和大模场面积,将多芯光纤引入空气孔并排列成八边形结构,利用COMSOL软件建立该光纤的电磁场模型,再采用有限元方法系统地分析相对孔径大小、纤芯与包层折射率差和纤芯之间的间距等3个结构参数对光纤模式特性及有效模场面积的影响,最后讨论了不同弯曲半径下光纤的弯曲损耗。根据分析结果并结合归一化频率常数找到合适的结构参数,此时光纤的基模模场面积在平直状态下可达到1730μm^(2),当弯曲半径大于0.45m时,弯曲损耗小于10^(-3) dB/m,基模模场面积仍可达到1685μm^(2)。该光纤保持少模传输并实现了大模场面积和低弯曲损耗,在大容量、高功率光纤传输系统中具有广阔的应用前景。

In order to realize the strict dual-mode transmission and large mode field area of the multi-core optical fiber,the multi-core fiber is introduced into the air hole and designed into an octagonal structure.First,The electromagnetic field model of the fiber by using COMSOL software is established,and then the finite element method is used to systematically analyze the influence of the three structural parameters of the relative aperture size,the core-clad refractive index difference and the core spacing on the fiber mode characteristics and the effective mode field area.The bending loss of the optical fiber is discussed under different bending radii in the end.According to the analysis results and combined with the normalized frequency constant to find suitable structural parameters,the fundamental mode field area of the fiber can reach 1730μm^(2) in the flat state.When the bending radius is greater than 0.45m,the bending loss is less than 10^(-3) dB/m,the area of the fundamental mode field can still reach 1685μm^(2) at this time.This optical fiber maintains few-mode transmission and achieves a large mode field area and low bending loss,so it has broad application prospects in large-capacity and high-power optical fiber transmission systems.