Dark rectangular noise-like pulses in a figure-nine fiber laser based on a nonlinear amplifying loop mirror

Area of Science:

• Optics and Photonics
• Laser Physics

Background:

• Mode-locked fiber lasers are crucial for generating ultrashort pulses.
• Noise-like pulses (NLPs) represent a distinct class of ultrashort pulse phenomena.
• Understanding NLP formation dynamics is key to controlling laser output.

Purpose of the Study:

• To experimentally observe and characterize dark rectangular noise-like pulses (NLPs) in a novel figure-nine fiber laser.
• To investigate the influence of nonlinear and birefringent effects on NLP generation.
• To explore the spectral evolution of dark rectangular NLPs with varying pump power.

Main Methods:

• Utilized a novel figure-nine fiber laser configuration incorporating a nonlinear amplifying loop mirror.
• Engineered the laser cavity to enhance nonlinear and birefringent effects.
• Experimentally investigated pulse dynamics and spectral characteristics under different pump power levels.

Main Results:

• Successfully observed dark rectangular noise-like pulses (NLPs) for the first time in this laser configuration.
• Achieved fundamental and high-order harmonics of dark rectangular NLPs under net anomalous dispersion.
• Demonstrated a unique operational regime of the fiber laser with distinct pulse dynamics.

Conclusions:

• The experimental observation of dark rectangular NLPs in this novel fiber laser expands the known dynamics of mode-locked pulses.
• The findings highlight the potential for controlling and generating complex pulse structures by manipulating nonlinear and birefringent effects.
• This work contributes to the fundamental understanding of ultrafast laser dynamics and opens avenues for new laser applications.