Gain-driven spectral-temporal noise-like pulse dynamics in a passively mode-locked fiber laser

Area of Science:

• Physics
• Nonlinear Optics
• Laser Physics

Background:

• Passively mode-locked fiber lasers generate complex pulse dynamics.
• Erbium-doped fiber lasers are crucial for optical communications.
• Understanding noise-like pulse (NLP) formation is essential for laser stability.

Purpose of the Study:

• To numerically investigate complex noise-like pulse dynamics in erbium-doped fiber lasers.
• To model wavelength-dependent gain dynamics influencing laser instabilities.
• To explain experimentally observed puzzling phenomena in NLPs.

Main Methods:

• Numerical simulation of passively mode-locked erbium-doped fiber laser.
• Modeling wavelength-dependent gain using three-level and four-level systems.
• Approximating erbium gain spectrum deformation during saturation.

Main Results:

• Qualitative reproduction of experimentally observed puzzling NLP dynamics.
• Simulation of slow quasi-periodic energy variations.
• Observation of emergence and walkoff of wavelength-shifted radiation components.

Conclusions:

• Wavelength-dependent gain dynamics are critically involved in the onset of complex temporal and spectral instabilities.
• Numerical modeling provides insights into the mechanisms behind NLP formation.
• The study clarifies the role of gain saturation in laser dynamics.