High-harmonic inverse-free-electron-laser interaction at 800 nm

Area of Science:

• Plasma Physics
• Laser-Electron Interactions
• Nonlinear Optics

Background:

• Inverse-free-electron-laser (IFEL) devices are crucial for generating coherent radiation.
• Higher-order harmonic generation in IFELs is theoretically predicted but experimentally challenging.
• Understanding IFEL harmonic interactions is key to advancing coherent light source technology.

Purpose of the Study:

• To provide the first direct experimental observation of higher-order IFEL interactions.
• To investigate harmonic generation at the fourth, fifth, and sixth harmonics.
• To validate experimental findings against theoretical predictions and simulations.

Main Methods:

• Utilized an 800 nm inverse-free-electron-laser (IFEL) setup.
• Performed direct observation of electron beam dynamics and harmonic radiation.
• Conducted tracking simulations to model the IFEL interaction.

Main Results:

• Successfully observed and documented interactions at the fourth, fifth, and sixth harmonics of the fundamental IFEL frequency.
• Measured harmonic spacing and relative harmonic strengths.
• Confirmed good agreement between experimental data and tracking simulations regarding transverse beam overlap.

Conclusions:

• The study presents the first direct evidence of higher-order IFEL interactions.
• Experimental results strongly support theoretical models and simulation predictions for harmonic generation in IFELs.
• This observation opens new avenues for exploring and controlling nonlinear phenomena in free-electron lasers.