Shen Dongya, Ma Chuan, Yuan Hong, Ren Wenping, Zhang Xiupu
Appl Opt. 2019 Feb 1;58(4):1185-1192. doi: 10.1364/AO.58.001185.
This paper proposes a novel all-optical fiber mode converter for mode conversion from LP to LP and vice versa. The mode converter is formed by connecting a single-mode fiber, a taper-core multi-mode fiber, and a few-mode fiber (FMF) together. The taper fiber core is designed to convert LP mode to LP. The few-mode fiber is used to cut off the modes that are higher than LP. It is shown that the proposed mode converter provides 20 dB extinction ratio and low insertion loss in a very broad optical bandwidth of 200 nm, from 1465 to 1665 nm. By further optimizing the FMF radius only for each of the O-, E-, S-, C-, U-, etc. bands, the mode converter can apply to any band of interest with higher performance. It is found that the performance of the mode converter has a large tolerance to structural parameters. The mode converter has the same performance in reciprocal operation, i.e., LP to LP.
本文提出了一种新型的全光纤模式转换器，用于实现从低阶模（LP）到低阶模的模式转换，反之亦然。该模式转换器通过将单模光纤、锥形芯多模光纤和少模光纤（FMF）连接在一起构成。锥形光纤芯被设计用于将LP模式转换为LP模式。少模光纤用于截止高于LP的模式。结果表明，所提出的模式转换器在1465至1665nm的200nm非常宽的光带宽内提供20dB的消光比和低插入损耗。通过仅针对O、E、S、C、U等每个波段进一步优化少模光纤半径，该模式转换器可以以更高的性能应用于任何感兴趣的波段。研究发现，该模式转换器对结构参数具有很大的容差。该模式转换器在反向操作（即LP到LP）中具有相同的性能。
