Few-Femtosecond XUV Pulse Pairs with Independently Tunable Topological Properties

Area of Science:

• Physics
• Quantum Optics
• Materials Science

Background:

• Externally seeded free-electron lasers (FELs) are crucial for generating coherent radiation.
• Producing extreme-ultraviolet (XUV) pulse pairs with controlled properties is challenging.
• Existing methods like superradiance have limitations in flexibility and configuration.

Purpose of the Study:

• To propose a novel method for generating few-femtosecond XUV pulse pairs.
• To enable tunable topological properties and adjustable temporal delays for these pulses.
• To offer a more flexible alternative to existing XUV pulse generation techniques.

Main Methods:

• Leveraging a slippage-compensation scheme in externally seeded free-electron lasers (FELs).
• Utilizing simulations to demonstrate control over pulse properties.
• Implementing independent setting of topological charge (l=-1, 0, 1) and pulse delay.

Main Results:

• Successfully demonstrated the generation of few-femtosecond XUV pulse pairs.
• Achieved independent tunability of topological charge (l=-1, 0, 1) for each pulse.
• Showcased adjustable temporal delays ranging from a few to several tens of femtoseconds.

Conclusions:

• The proposed slippage-compensation scheme offers greater flexibility than superradiance for XUV pulse pair generation.
• This method avoids the need for FEL saturation and complex cascade configurations.
• Potential applications include advanced studies of circular/helical dichroism and high-resolution imaging in the few-femtosecond regime.