High-power coherently combined femtosecond laser based on InnoSlab amplifiers.

Area of Science:

• Laser Physics
• Optics
• Materials Science

Background:

• High-power ultrafast lasers are crucial for scientific and industrial applications.
• Coherent beam combination is a key technique for scaling laser power.
• Yb: YAG lasers offer advantages in efficiency and thermal management.

Purpose of the Study:

• To develop and demonstrate a high-power, ultrafast coherent beam combination system.
• To achieve kilowatt-class average power with excellent beam quality and stability.
• To investigate the performance of InnoSlab chirped pulse amplifiers (CPAs) for power scaling.

Main Methods:

• Utilized two InnoSlab CPAs based on Yb: YAG crystals.
• Employed coherent beam combination techniques.
• Optimized spatial mode filtering and pulse compression using a grating compressor.

Main Results:

• Achieved 306 W average power and 1.53 mJ pulse energy at 200 kHz repetition rate.
• Improved combined beam quality from M²=1.24×1.41 to M²=1.1×1.18.
• Compressed the combined beam to 460 fs with near-diffraction-limited spatial quality.
• Demonstrated excellent spatiotemporal performance and long-time stability (0.52% RMS power fluctuation).

Conclusions:

• The developed system represents a novel kilowatt-class average power amplifier.
• The results demonstrate the potential of coherent beam combination for high-power ultrafast lasers.
• The system's performance will significantly benefit applications requiring high-energy, ultrashort laser pulses.