Femtosecond laser inscribed parallel long-period fiber gratings for multi-channel core mode conversion

Chen Jiang, Kaiming Zhou, Bing Sun, Zhiqiang Wang, Ying Wan, Yuehui Ma, Chengbo Mou, Lei Shen, Lei Zhang, Jie Luo, Yunqi Liu

Research output: Contribution to journalArticlepeer-review


We propose and demonstrate the inscription of parallel long-period gratings (LPGs) in a few-mode fiber (FMF) using femtosecond lasers. Mode conversion from the fundamental (LP01) mode to high-order core modes, including LP11, LP21, LP31, LP02, and LP12, is achieved by controlling the inscription period of the gratings. Taking advantage of the highly focused femtosecond laser, LPGs with different off-axis offsets were fabricated, and the resonance wavelength and the inscription efficiency of the gratings versus the offset were investigated. Based on the off-axis writing technique and using the femtosecond laser source, we wrote parallel LPGs that contain multi-gratings in a single FMF and achieved a multi-channel core mode converter in a single FMF with flexibility in terms of the resonant wavelength and mode conversion among different modes. This approach offers a new, to the best of our knowledge, option for implementation with high integration, and a multi-channel mode converter, which could find potential applications in FMF multi-wavelength laser systems, and wavelength/mode division multiplex communication systems. Furthermore, these microstructured LPGs integrated into an optical fiber can be used as a multifunctional sensor.
Original languageEnglish
Pages (from-to)3207-3210
Number of pages4
JournalOptics Letters
Issue number13
Early online date22 Jun 2022
Publication statusPublished - 1 Jul 2022

Bibliographical note

© 2022 Optica Publishing Group. This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: https://doi.org/10.1364/OL.461547. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.


  • Atomic and Molecular Physics, and Optics


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