• Photonics Research
  • Vol. 9, Issue 10, 10001898 (2021)
Kewei Liu1, Xiaosheng Xiao2、4、*, Yihang Ding1, Hongyan Peng3, Dongdong Lv3, and Changxi Yang1、5、*
Author Affiliations
  • 1State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China
  • 2State Key Laboratory of Information Photonics and Optical Communications, School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China
  • 3School of Physics and Electronic Engineering, Hainan Normal University, Haikou 571158, China
  • 4e-mail: xsxiao@bupt.edu.cn
  • 5e-mail: cxyang@tsinghua.edu.cn
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    Abstract

    Spatiotemporal mode locking is a nonlinear process of multimode soliton self-organization. Here the real-time buildup dynamics of the multiple solitons in a spatiotemporal mode-locked multimode fiber laser are investigated, assisted by the time-stretch technique. We find that the buildup processes are transverse mode dependent, especially during the stages of relaxation oscillation and Q-switching prior to multiple soliton formation. Furthermore, we observe that the transverse modal composition of these generated pulses among the multiple solitons can be different from each other, indicating the spatiotemporal structure of the multiple soliton. A simplified theoretical model based on pulse energy evolution is put forward to interpret the role of 3D saturable absorber on spatiotemporal structures of spatiotemporal mode-locking multiple solitons. Our work has presented the spatiotemporal nonlinear dynamics in multimode fiber lasers, which are novel to those inside the single transverse mode fiber lasers.

    1. INTRODUCTION

    The multiple soliton in mode-locked lasers is a widely observed phenomenon that has been extensively investigated over the years [15]. Assisted by the ultrafast single-shot measurement dispersive Fourier transform (DFT, or time stretch) [6,7], a plethora of transient dynamics of different kinds of multiple solitons, including soliton molecules and harmonic mode locking have been revealed in detail. For example, the internal interactions [810] and buildup dynamics [11,12] of soliton molecules, the birth and collision of multiple solitons [13], the entire birth of harmonic mode locking [14,15] and multiple solitons [16], as well as the transition between different multipulsing states [17], were characterized in real time, having provided much insight on comprehending the complexities of dissipative solitons. These investigations are based on mode-locked lasers with a single transverse mode, which have been the mainstream area of scientific exploration and applications in recent decades.

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    Kewei Liu, Xiaosheng Xiao, Yihang Ding, Hongyan Peng, Dongdong Lv, Changxi Yang. Buildup dynamics of multiple solitons in spatiotemporal mode-locked fiber lasers[J]. Photonics Research, 2021, 9(10): 10001898
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    Category: Lasers and Laser Optics
    Received: Apr. 22, 2021
    Accepted: Aug. 3, 2021
    Published Online: Sep. 7, 2021
    The Author Email: Xiaosheng Xiao (xsxiao@bupt.edu.cn), Changxi Yang (cxyang@tsinghua.edu.cn)