Transitions between mode-locked and noise-like pulsed states in a multimode fiber laser

Area of Science:

• Laser physics
• Nonlinear optics
• Fiber optics

Background:

• Mode-locked fiber lasers are crucial for various applications.
• Controlling pulse characteristics is essential for optimizing laser performance.
• Kerr spatial self-cleaning is a phenomenon that enhances beam quality.

Purpose of the Study:

• To demonstrate transitions between mode-locked and noise-like pulse states in a ytterbium-doped fiber laser.
• To investigate the role of intracavity spectral filtering in controlling these states.
• To explore the impact of dispersion management on pulse compressibility.

Main Methods:

• Experimental demonstration of state transitions by adjusting spectral filtering.
• Utilizing cavities with different lengths of graded-index fiber.
• Employing external grating pairs for pulse compression.
• Comparison with numerical simulations.

Main Results:

• Achieved controlled transitions between stably mode-locked and noise-like pulse states.
• Kerr spatial self-cleaning ensured high-quality output beams in both regimes.
• Optimized balance between chromatic and modal dispersion maximized pulse compressibility.
• Compressed 6.7-ps pulses to 170 fs with a peak power of 2.1 kW.

Conclusions:

• Intracavity spectral filtering is an effective method for controlling pulse states in fiber lasers.
• Dispersion management is critical for achieving high pulse compressibility.
• The demonstrated laser system offers high-quality beams and significant pulse compression capabilities.