SnSe₂ realizes soliton rain and harmonic soliton molecules in erbium-doped fiber lasers

Two-dimensional layered metal chalcogenides (LMCs) are widely used in battery anode materials, energy conversion, and semiconductor devices, because of their high energy storage characteristics, high thermoelectric characteristics, and large electron mobility. SnSe₂ as a kind of LMC has strong nonlinear optical characteristics. However, its research on dissipative system dynamics as a saturable absorber has not been studied. In this work, we obtained SnSe₂ nanosheets using lithium ion intercalation and we reported a passively mode-locked fiber laser with SnSe₂ as a saturable absorber to achieve the dissipative soliton in a dissipative system. Due to the high third-order nonlinearity of SnSe₂, the evolution of square wave pulses from 2 to 16 ns was obtained in a fiber ring cavity. Through adjusting the polarization state, the evolution phenomenon of soliton rain, the soliton rain phenomenon with a spectrum of dual-wavelengths, and a bound state harmonic phenomenon with a frequency of 313 MHz were obtained. Therefore, the strong nonlinear fiber laser based on SnSe₂ provides a good platform for study the pulsation, explosion, rainfall and other phenomena.