All-fiber spatiotemporal mode-locking lasers with large modal dispersion
Huaiwei Zhang, Yunhong Zhang, Jiying Peng, Xinyang Su, Xiaosheng Xiao, Dongjian Xu, Junhao Chen, Tianran Sun, Kai Zheng, Jianquan Yao, Yi Zheng
Abstract
It is a challenging problem to balance the modal walk-off (modal dispersion) between multiple transverse modes and chromatic dispersion in long step-index multimode fibers (MMFs). By properly designing the oscillator, we have overcome the difficulty and successfully obtained an all-fiber spatiotemporal mode-locked laser based on step-index MMFs with large modal dispersion for the first time, to our knowledge. Various proofs of spatiotemporal mode-locking (STML) such as spatial, spectral, and temporal properties, are measured and characterized. This laser works at a fundamental frequency of 28.7 MHz, and achieves a pulse laser with single pulse energy of 8 nJ, pulse width of 20.1 ps, and signal-to-noise ratio of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m1"> <mml:mrow> <mml:mo form="prefix">∼</mml:mo> <mml:mn>70</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>dB</mml:mi> </mml:mrow> </mml:math> . In addition, we observe a dynamic evolution of the transverse mode energy during the STML establishment process that has never been reported before.