提出一种采用少模阶跃光纤与单模光纤连接的方法, 实现低弯曲损耗传输的新型光纤通信系统。采用有限元法研究了在模场直径相同的情况下少模光纤纤芯半径与折射率差的关系, 以及不同参数下光纤的弯曲损耗; 采用光束传播法计算了少模光纤的各种模式与普通单模光纤的基模的连接损耗。证明了采用少模光纤可以利用模式间的正交性实现有效的单模传输, 并具有低的弯曲损耗和连接损耗。

A novel optical fiber system composed of single-mode optical fiber and few mode step-index optical fiber is investigated. The relationship between the core radius and index difference for the few mode optical fiber with the same mode field diameter is analyzed using the finite-element method. The low bending loss characteristics of the few mode optical fiber is also demonstrated. The splicing losses of the few-mode optical fiber with the single-mode optical fiber are investigated by the beam propagation method. Numerical results demonstrate the low bending loss transmission and effectively single-mode guiding using the few-mode optical fiber.