Modelocking of a thin-disk laser with the frequency-doubling nonlinear-mirror technique

Area of Science:

• Laser Physics
• Nonlinear Optics

Background:

• Mode-locking techniques are crucial for generating ultrashort laser pulses.
• Existing methods like SESAM and KLM have limitations in stability or pulse duration.
• Thin-disk lasers offer high power scalability but face challenges in achieving ultrashort pulses.

Purpose of the Study:

• To demonstrate a novel frequency-doubling nonlinear-mirror (NLM) mode-locking technique for thin-disk lasers.
• To achieve robust and stable ultrashort pulse generation in Yb:YAG thin-disk lasers.
• To develop a theoretical model for the NLM technique to predict performance and limitations.

Main Methods:

• Implementation of an intracavity second harmonic crystal and a dichroic output coupler for NLM mode-locking.
• Utilizing a diode-pumped Yb:YAG thin-disk laser architecture.
• Development of a theoretical model to analyze loss modulation and predict minimum pulse duration.

Main Results:

• Achieved 21 W of average power with a pulse duration of 323 fs using the NLM technique.
• Demonstrated a pulse duration an order of magnitude shorter than previously reported for NLM in bulk lasers.
• Developed a theoretical model that accurately predicts NLM performance without fitting parameters.

Conclusions:

• The NLM technique provides a robust alternative to SESAM and KLM for mode-locking thin-disk lasers.
• The developed NLM laser overcomes pulse duration limitations of SESAM mode-locking without requiring stringent cavity stability.
• Future NLM thin-disk lasers are predicted to exceed 100 W average power with sub-200 fs pulses.