Search

Short laser pulses of femtosecond time scales are in high demand in order to explore the fast electron dynamics in light-matter interactions. Here, the authors demonstrated the compression of free electron laser pulses in the extreme ultraviolet range by using a chirped pulse amplification technique.

X-ray free-electron laser is a power probe for materials, but it is challenging to measure the spectro-temporal characters of individual pulses. Here, De Ninno et al.implement an interferometric method allowing one to characterize and control the ultrashort XUV pulses seeded by a femtosecond laser.

Researchers generated 16.7 nm wavelength extreme-ultraviolet Poincaré beams at the FERMI free electron laser without relying on optical elements. The method of in situ Poincaré beam production in free electron lasers enables straightforward flexibility in the orientation and balance of polarization states, and can be extended to other vector beams and to shorter wavelengths.

Echo-enabled harmonic generation in a free-electron laser enables 45th harmonic pulses from a 264 nm wavelength seed, yielding 5.9 nm wavelength coherent output.

This study presents a method to create nanoscale polarization transient gratings in the EUV range. Unlike intensity gratings, it reduces thermal effects, revealing hidden material dynamics. This enables new insights in chiral materials and ultrafast magnetism.

Two-colour X-ray free electron laser is a powerful tool for pump–probe measurements, but currently constrained by limited tunability. Here, Ferrari et al. develop a configuration that allows tuning both the pump and the probe to specific electronic excitations, providing element selectivity.

Relative synchronization between free-electron laser pulses and a near-infrared field fields is achieved with 24 as resolution by using a correlation analysis of single-shot photoelectron spectra. It is applied to coherently control the photoionization process in neon atom on the attosecond timescale.

By amplifying a soliton in a multistage cascade, few-femtosecond extreme-ultraviolet free-electron laser pulses are achieved.

Light pulses with controllable parameters are desired for studying the fundamental properties of matter. Here the authors generate and use phase-manipulated and highly time-stable XUV pulse pairs to probe the coherent evolution and dephasing of XUV electronic coherences in helium and argon.

The findings that the spatial distribution of an optical field with vortex phase profile can be imprinted coherently onto a propagating electron wave reveal new aspects of light–matter interactions and will help develop future single-photon electron spectroscopy.

Attosecond pulse trains, crucial for ultrafast science, traditionally consist of only odd harmonics due to symmetry constraints in high-order harmonic generation. Here, the authors extend the RABBIT technique to analyze non-consecutive harmonics, enabling the temporal reconstruction of attosecond pulse trains and advancing metrology in extreme ultraviolet spectroscopy.