High-order mode conversion in a few-mode fiber via laser-inscribed long-period gratings at 1.55 µm and 2 µm wavebands

Xinyi Zhao; Yunhe Zhao; Yunqi Liu; Zuyao Liu; Chengbo Mou; Lei Shen; Lei Zhang; Jie Luo

doi:10.1364/AO.408782

High-order mode conversion in a few-mode fiber via laser-inscribed long-period gratings at 1.55 µm and 2 µm wavebands

Appl Opt. 2020 Dec 1;59(34):10688-10694. doi: 10.1364/AO.408782.

Authors

Xinyi Zhao, Yunhe Zhao, Yunqi Liu, Zuyao Liu, Chengbo Mou, Lei Shen, Lei Zhang, Jie Luo

PMID: 33361887
DOI: 10.1364/AO.408782

Abstract

We demonstrate high-order mode conversion in a few-mode fiber (FMF) via CO₂ laser inscribed long-period fiber gratings (LPFGs) at both the 1.55 µm and 2 µm wavebands. At the 1.55 µm waveband, five high-order core modes (the LP₁₁, LP₂₁, LP₀₂, LP₃₁, and LP₁₂ modes) can be coupled from the LP₀₁ mode with high efficiency by the FMF-LPFGs. The orbital angular momentum beams with different topological charges (±1,±2,±3) are experimentally generated by adjusting the polarization controllers. At the 2 µm waveband, three high-order modes (the LP₁₁, LP₂₁, and LP₀₂ mode) can be coupled by the FMF-LPFGs with different grating periods. The proposed LPFG-based mode converters could have a potential prospects in mode-division multiplexing and multiwindow broadband optical communication applications.