Abstract

Solitons can self-assemble into stable bound states, also denoted as soliton molecules that exhibit striking molecule-like dynamics. To date, diatomic soliton molecules that bound states of only two solitons have been the most studied multisoliton structure [1]. Contrary to the significant progress in the diatomic soliton molecules, the controllable multiple-state switching of soliton molecular complexes (SMC) with different temporal spacing and phases is still largely unexplored, especially in the 2 μm fiber lasers. The development of mode-locked fiber lasers in wavelength ranges from 2 μm and beyond is accelerating. However, the fundamental studies of soliton dynamics in 2 μm fiber lasers are far from being explored. As we know, the differences in the medium gain characteristics in different wavelength ranges (Thulium and Erbium-doped fiber), especially gain bandwidth and excited-state relaxation timescales could play a vital role in the dynamical soliton interaction. For instance, the strong anharmonicity could be observed in the vibration soliton-pair molecule at the wavelength of 2 μm while not being observed at 1.5 μm [2,3], which calls for additional comparisons with dynamics observed at different operating wavelengths. Moreover, the controllable temporal spacing and phase in SMC can achieve higher dimensional encoding compared to the diatomic soliton molecule, which is beneficial for performing dense encoding in optical communications, imaging, and computations.

© 2023 IEEE