Impact of pump power on Lyot filtering effect in mode-locked fiber lasers

Filtering effects, which can achieve multi-wavelength in mode-locked fiber lasers, are currently being investigated, including communications and industry. In this study, we systematically investigate the impact of pump power on the operation of the filter in mode-locked fiber lasers. An all-normal dispersion ytterbium-doped fiber laser was employed to investigate hybrid filtering structures combining a Lyot filter and a nonlinear optical loop mirror (NOLM), both experimentally and theoretically. Furthermore, we identified a specific pump power range, from 570.5 mW to 748.9 mW, within which the Lyot filter operates effectively, facilitating transitions between single- and multi-wavelength outputs. We theoretically explain how pump power governs the operational state of the Lyot filter, enabling precise control over spectral modulation. This work demonstrates the influence of power on filtering and presents a versatile nonlinear system for generating and analyzing multi-wavelengths, facilitating the optimization and customization of the output spectrum.