High-energy pulse stacking via regenerative pulse-burst amplification

Area of Science:

• Laser physics and optics
• Materials science for optical components

Background:

• Solid-state femtosecond chirped pulse amplifiers are crucial for high-intensity laser applications.
• Scaling amplifier energy is limited by intracavity optical damage thresholds.
• Existing methods for energy scaling often involve complex setups or lower repetition rates.

Purpose of the Study:

• To develop and demonstrate a coherent pulse stacking approach for enhancing the energy output of a solid-state femtosecond chirped pulse amplifier.
• To investigate the damage thresholds associated with pulse-burst amplification.
• To enable energy upscaling without compromising beam quality or increasing amplifier complexity.

Main Methods:

• A coherent pulse stacking technique was developed.
• Femtosecond laser pulses were split into four replicas.
• Amplification was performed in a burst-mode regenerative Ytterbium-doped Calcium Fluoride (Yb:CaF2) amplifier.
• Pulse replicas were made to collide to mitigate intracavity optical damage.
• The amplified replicas were coherently combined into a single high-energy pulse.

Main Results:

• A single-stage stacker cavity achieved an energy enhancement factor of 2.62.
• Millijoule-level pulse energy was demonstrated through coherent combining.
• Experimental investigation into the damage thresholds of optical elements under pulse-burst conditions was conducted.
• The method proved effective in overcoming intracavity optical damage limitations.

Conclusions:

• The coherent pulse stacking approach offers a viable strategy for significantly upscaling the energy of femtosecond chirped pulse amplifiers.
• The demonstrated technique is scalable, with potential for much higher energy enhancement using cascaded stacking configurations.
• Understanding and mitigating pulse-burst-induced damage is critical for practical implementation and further development.