Multi-wavelength Coexisting with the Continuous Wave-Induced Resonant Spectral Sidebands in a Hybrid Mode-Locked Fiber Laser

Continuous-wave (CW) induced resonance spectral sidebands, a novel type of sub-sideband, are asymmetrically located around the CW. Their emergence has enriched the complex spectral dynamics. However, the fundamental research on these sidebands coexisting with solitons is still in its infancy, and the exploration of soliton dynamics could potentially advance this field. In this study, we introduced the Sagnac loop into the nonlinear polarization rotation (NPR) mode-locked fiber laser to form a hybrid mode-locked structure. We found that the Sagnac loop can effectively narrow the soliton spectrum. In the experiment, we obtained the result of the four-wavelength soliton spectrum coexisting with the CW sidebands, which has not been reported in previous literature. These findings have not only enriched our understanding of the diverse spectral dynamics of fiber lasers but also laid a foundation for studying CW-induced generation of resonant sidebands in a multi-wavelength mode-locked regime, hinting at the untapped potential of fiber lasers.