Zhao Yunhe, Liu Zuyao, Liu Yunqi, Mou Chengbo, Wang Tingyun, Yang Yongsheng
Opt Lett. 2019 Dec 15;44(24):5905-5908. doi: 10.1364/OL.44.005905.
We have demonstrated an ultra-broadband fiber mode converter based on -laser inscribed length apodized phase-shifted long-period gratings (LPGs) with a three-section linear length apodization profile, where a -phase shift was introduced between two adjacent grating sections. The grating parameters were optimized theoretically to achieve the broadband mode conversion between the mode and mode. The demonstrated device provides mode conversion efficiency higher than 90% over an ultra- broad bandwidth of ∼182. The insertion loss of the LPGs is negligible. Orbital angular momentum modes with left- and right-handed circular polarization can be generated from the demonstrated ultra-broadband mode converter successfully.
我们展示了一种基于激光写入的具有三段线性长度变迹分布的长度变迹相移长周期光栅（LPG）的超宽带光纤模式转换器，其中在两个相邻光栅段之间引入了π相移。从理论上对光栅参数进行了优化，以实现基模和高阶模之间的宽带模式转换。所展示的器件在约182nm的超宽带范围内提供高于90%的模式转换效率。LPG的插入损耗可忽略不计。从所展示的超宽带模式转换器中能够成功产生具有左旋和右旋圆偏振的轨道角动量模式。
