Tailored terahertz pulses from a laser-modulated electron beam.

Area of Science:

• Physics
• Laser Science
• Materials Science

Background:

• Terahertz (THz) radiation generation is crucial for spectroscopy and imaging.
• Existing methods often lack tunability and coherence.
• Controlling electron beam properties is key to advanced radiation generation.

Purpose of the Study:

• To present a new method for generating steady, tunable, coherent, broadband terahertz radiation.
• To demonstrate this method using a relativistic electron beam modulated by a femtosecond laser.
• To explore the flexibility in shaping terahertz pulses.

Main Methods:

• Modulating a relativistic electron beam with a femtosecond laser pulse in a wiggler.
• Utilizing the dispersion of electron trajectories to create a longitudinal density perturbation.
• Measuring the intensity and spectra of the emitted terahertz pulses.

Main Results:

• Successfully generated steady and tunable coherent broadband terahertz radiation.
• Observed short pulses of temporally and spatially coherent terahertz radiation synchronized to the laser.
• Demonstrated the technique in the electron storage ring at the Advanced Light Source.

Conclusions:

• The presented technique enables flexible generation and shaping of terahertz pulses.
• This method provides a new pathway for producing synchronized, coherent terahertz radiation.
• The findings have implications for advanced terahertz spectroscopy and applications.