Spatiotemporal self-mode-locked operation in a compact partial multimode Er-doped fiber laser

We report spatiotemporal self-mode-locked operation at 1.55 mu m with a low pump threshold of 32 mW in a compact partial multimode fiber laser system. Spatial filtering and the saturable absorber, both of which originate from the multimode interference (linear or nonlinear) of the single mode-multimode structure in this hybrid configuration, are well suited to the spatiotemporal self-mode-locked operation. Not only stable multimode conventional solitons with different spectral bandwidths but also a multimode soliton molecule complex with different structural bound-state patterns are obtained. It is found that the spatiotemporal evolution of the multimode solitons is dependent on many factors, such as the operating state, the involved frequency component, and the interaction between solitons. Further-more, an unstable spatiotemporal mode-locked (STML) state where the beam profiles of the solitons change spontaneously is also observed for a specific multimode fiber state and pump power. (C) 2022 Optica Publishing Group

Automated summary

In this study, spatiotemporal self-mode-locked operation at 1.55 um was investigated. A compact partial multimode fiber laser system was used to achieve this operation at a low pump threshold. The results showed that stable multimode conventional solitons and complex multimode soliton molecule complexes could be obtained through the application of spatial filtering and saturable absorbers.