15-THz pulse generation arising from modulation instability oscillation in a colliding-pulse mode-locking dye laser

Area of Science:

• Optics and Photonics
• Laser Physics
• Nonlinear Optics

Background:

• Modulation instability (MI) is a key phenomenon in nonlinear fiber optics and lasers.
• Generating ultrashort optical pulses requires precise control over laser dynamics.
• Previous methods often struggled with stability and pulse separation.

Purpose of the Study:

• To achieve stable generation of high-repetition-rate optical pulse trains.
• To investigate the conditions for reliable modulation instability in a specific laser system.
• To validate theoretical models of modulation instability with experimental results.

Main Methods:

• Utilized a colliding-pulse mode-locked dye laser operating in the anomalous-dispersion regime.
• Employed a low concentration of saturable absorber to achieve stability.
• Performed autocorrelation measurements to analyze pulse characteristics and separation.

Main Results:

• Successfully generated 15-THz trains of femtosecond optical pulses.
• Achieved a repeatable and stable modulation instability regime.
• Demonstrated complete real-time separation of subpulses via autocorrelation measurements.
• Observed good agreement between experimental variations and modulation instability theory.

Conclusions:

• Stable, high-repetition-rate femtosecond pulse generation is feasible using specific laser parameters.
• The anomalous-dispersion regime and controlled saturable absorber concentration are critical for stable MI.
• Experimental findings strongly support the underlying theory of modulation instability in lasers.