Superradiant terahertz free-electron laser driven by electron microbunch trains.

Area of Science:

• Physics
• Quantum Optics
• Accelerator Physics

Background:

• Superradiance enhances radiation intensity quadratically with emitter number through phase synchronization.
• Generating superradiance from free electrons is key for intense radiation from THz to X-ray.
• Achieving THz superradiance has been limited by microbunching technique challenges.

Purpose of the Study:

• Demonstrate an ultra-widely tunable superradiant THz free-electron laser (FEL).
• Improve emission efficiency for THz radiation generation.
• Enhance THz pulse energy to millijoule levels.

Main Methods:

• Utilized high-peak-current electron microbunch trains to drive the FEL.
• Employed an undulator for strong interaction between microbunches and generated THz waves.
• Implemented a tapered undulator configuration to boost emission intensity.

Main Results:

• Achieved efficient superradiance in the THz spectral range.
• Demonstrated a two-fold enhancement in emission intensity with a tapered undulator.
• Generated millijoule-level pulse energy for narrow-band THz radiation within a 1-meter undulator.

Conclusions:

• This work presents a significant advancement in realizing compact, high-power, narrow-band THz sources.
• The developed FEL technology bridges the 'THz gap', enabling broad scientific applications.
• The findings pave the way for new opportunities across diverse scientific disciplines.