In this paper, a new photonic crystal fiber (PCF) for long-distance transmission of orbital angular momentum (OAM) is proposed. The rectangular air holes are distributed in the cladding and a circular air hole is distributed in the core. The designed PCF can support 88 OAM modes over S + C + L + U wavelength band. The characteristics of the PCF are analyzed by using the finite element method systematically. The results show that the nonlinear coefficient is lower than 2.8 km⁻¹W⁻¹ over S + C + L + U wavelength band, and the minimum value is as low as 0.9 km⁻¹W⁻¹. The confinement loss of each mode is between 10⁻¹⁷–10⁻¹⁰ dBm⁻¹, and the stable transmission distance of the OAM modes is up to 60 km. Additionally, the effective mode filed area and dispersion of the PCF are also analyzed. In general, the PCF can be used in modular division multiplexing which can effectively improve the capacity and transmission distance of communication system.

在本文中，提出了一种用于轨道角动量（OAM）长距离传输的新型光子晶体光纤（PCF）。矩形气孔分布在包层中，圆形气孔分布在纤芯中。设计的PCF可支持S+C+L+U波段的88种OAM模式。采用有限元方法系统地分析了PCF的特性。结果表明，非线性系数在S+C+L+U波段小于2.8km ^-1 W ^-1，最小值低至0.9 km ^-1 W ^-1。每种模式的限制损耗在 10 ^-17 –10 ^-10 dBm ^{-1 之间}，OAM模式稳定传输距离可达60公里。此外，还分析了PCF的有效模场面积和色散。一般而言，PCF可用于模分复用，可有效提高通信系统的容量和传输距离。