Robust 700 MHz mode-locked Yb:fiber laser with a biased nonlinear amplifying loop mirror

Area of Science:

• Laser Physics
• Optical Engineering

Background:

• Mode-locked fiber lasers are crucial for ultrafast science and technology.
• Developing stable, self-starting lasers with high repetition rates remains a key challenge.

Purpose of the Study:

• To demonstrate a self-starting Yb:fiber laser with a 700 MHz repetition rate.
• To utilize a phase-biased nonlinear amplifying loop mirror (NALM) as an artificial saturable absorber.
• To characterize the laser's performance, including output power, pulse width, noise, and environmental stability.

Main Methods:

• Incorporation of a phase-biased NALM into a Yb:fiber laser cavity.
• Characterization of output power and pulse width at varying pump powers.
• Measurement of integrated relative intensity noise (RIN) and phase noise.
• Assessment of mode-locking stability in open air over an extended period.

Main Results:

• Achieved self-starting mode-locking at a 700 MHz repetition rate.
• Delivered a maximum output power of 150 mW with a pulse width of 215 fs.
• Obtained a minimum integrated RIN of 0.015% (10 Hz–10 MHz).
• Demonstrated sustained mode-locking for over two weeks in open air, indicating high environmental stability.

Conclusions:

• The phase-biased NALM effectively acts as an artificial saturable absorber for robust mode-locking.
• The developed Yb:fiber laser exhibits excellent performance metrics and remarkable environmental stability.
• This laser system is a promising candidate for applications requiring stable, high-repetition-rate ultrashort pulses.