• Chinese Optics Letters
  • Vol. 20, Issue 1, 010602 (2022)
Xiao Chen, Liangjin Huang*, Yi An, Huan Yang, Zhiping Yan, Yisha Chen, Xiaoming Xi, Zhiyong Pan, and Pu Zhou**
Author Affiliations
  • College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
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    Abstract

    We found the beam quality factor M2 of the fundamental mode as a function of wavelength is U-shaped in the working photonic bandgap (PBG) of an all-solid PBG fiber (AS-PBGF) for the first time, to the best of our knowledge, and our simulation results also match well with the phenomenon. The normal band that is near the high-frequency edge of the third PBG integrates the lowest M2 and single-mode operation simultaneously, while the other two edge regions suffer from anomalous variation of M2 versus wavelength. The general applicability of this finding can be further extended to other PBGs and also other representative structures in the AS-PBGF field.

    1. Introduction

    Large-mode-area (LMA) fibers working with advanced mechanisms have been established as promising candidates for next-generation high-power fiber lasers, benefitting from their potentials in mode area scaling, higher nonlinear threshold, and feasibilities for some functional applications[16]. More recently, a kind of bandgap-guided microstructure fiber, called the all-solid photonic bandgap fiber (AS-PBGF), has become an emerging research focus[712]. Free of air-holes structures, AS-PBGF exhibits excellent practical convenience for the high-power platform[13] and portability for the double-cladding design or polarization-maintaining scheme[11]. The all-solid structure ensures the ease of cleaving and splicing, making a compact all-fiber configuration possible. Robust single-mode (SM) operation with high loss ratio between the fundamental mode (FM) and high-order modes (HOMs) is achievable due to the open-cladding of AS-PBGF[7]. By combining the stack-and-draw method with rare-earth doping technology, the production of active AS-PBGF has gradually become an internal technology mastered by only a few organizations[8,9,11,12,14,15]. Over kilowatt-level emission by using double-cladding active AS-PBGF has been successfully demonstrated[16]. Besides, the multi-resonant and hetero-structured designs further open a new path for the super LMA AS-PBGF design[8,17,18]. With all of the above advantages integrated, the controllable distribution of photonic bandgaps (PBGs) of AS-PBGF additionally provides a novel approach for selective wavelength filtering[13,19]. Therefore, AS-PBGF takes most of the prerequisites for high-power laser applications. Currently, the physics of AS-PBGF optical guidance is a fascinating and ongoing topic of research.

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    Xiao Chen, Liangjin Huang, Yi An, Huan Yang, Zhiping Yan, Yisha Chen, Xiaoming Xi, Zhiyong Pan, Pu Zhou. Spectrally U-shaped profile of beam propagation factor in all-solid photonic bandgap fiber[J]. Chinese Optics Letters, 2022, 20(1): 010602
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    Category: Fiber Optics and Optical Communications
    Received: Aug. 30, 2021
    Accepted: Oct. 19, 2021
    Posted: Oct. 19, 2021
    Published Online: Nov. 25, 2021
    The Author Email: Liangjin Huang (hlj203@nudt.edu.cn), Pu Zhou (zhoupu203@163.com)