Pulse splitting in short wavelength seeded free electron lasers

Area of Science:

• Physics
• Quantum Optics
• Laser Science

Background:

• Seeded free electron lasers (FELs) are crucial for generating coherent radiation in the vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) ranges.
• Optimizing FEL output energy is a key objective for advanced scientific applications.
• Understanding limitations in FEL performance is essential for future development.

Purpose of the Study:

• To investigate a fundamental limitation in VUV and XUV seeded FELs.
• To analyze the effect of seed pulse duration on FEL output energy and pulse characteristics.
• To elucidate the underlying mechanisms causing pulse deformation and splitting.

Main Methods:

• Numerical simulations based on the Colson-Bonifacio free electron laser equations.
• Analysis of spatiotemporal dynamics of the amplified radiation pulse.
• Investigation of the role of slippage length and seed laser pulse wings.

Main Results:

• An increase in seed pulse duration can enhance FEL output energy at saturation.
• A complex spatiotemporal deformation of the amplified pulse is observed.
• Pulse splitting occurs as a consequence of increased seed pulse duration and specific dynamic factors.

Conclusions:

• Seed pulse duration is a critical parameter influencing FEL performance and stability.
• Spatiotemporal pulse deformation and splitting represent a fundamental limitation in seeded FELs.
• Slippage length and seed laser pulse wings are key factors governing this limitation.