1 kHz, 10 mJ, sub-200 fs regenerative amplifier utilizing a dual-crystal configuration of Yb:CaGdAlO₄ featuring exceptional beam quality

Area of Science:

• Laser Physics
• Materials Science

Background:

• Femtosecond lasers require high pulse energy for applications.
• Regenerative amplifiers (RA) are crucial for amplifying laser pulses.
• Yb:CaGdAlO4 (Yb:CGA) crystals offer potential for high-power lasers.

Purpose of the Study:

• To develop a high-energy femtosecond regenerative amplifier.
• To investigate the performance of Yb:CGA crystals in a dual-crystal RA.
• To achieve high pulse energy while maintaining beam quality and stability.

Main Methods:

• Chirped pulse amplification (CPA) technique.
• Martinez stretcher for pulse stretching.
• Specially designed dual-crystal regenerative cavity using Yb:CGA crystals.
• Precise control of cavity mode size to prevent component damage.

Main Results:

• Achieved 11.3 mJ pulse energy at a 1 kHz repetition rate.
• Demonstrated power stability of 0.35% over 1 hour.
• Obtained a compressed pulse duration of 198 fs with a 9 nm FWHM spectrum.
• Output beam exhibited near-diffraction-limited performance (M² ≈ 1.05).

Conclusions:

• The dual-crystal Yb:CGA RA design successfully achieved record energy output.
• The system demonstrates excellent power stability and beam quality.
• This development advances high-energy femtosecond laser technology.