Superfluorescence, free-induction decay, and four-wave mixing: propagation of free-electron laser pulses through a dense sample of helium ions

Abstract

We report an experimental and numerical study of the propagation of free-electron laser pulses (wavelength 24.3 nm) through helium gas. Ionisation and excitation populates the He${}^{+}$ 4$p$ state. Strong, directional emission was observed at wavelengths of 469 nm, 164 nm, 30.4 nm, and 24.5 nm. We interpret the emissions at 469 nm and 164 nm as 4$p$-3$s$-2$p$ cascade superfluorescence, that at 30.4 nm as yoked superfluorescence on the 2$p$-1$s$ transition, and that at 25.6 nm as free-induction decay of the 3$p$ state.

References in corpus (2)

• Coherent control with a short-wavelength Free Electron Laser
• Controlled free-induction decay in the extreme ultraviolet

Cited by in corpus (8)

• Strong-field extreme-ultraviolet dressing of atomic double excitation
• Atomic, molecular and optical physics applications of longitudinally coherent and narrow bandwidth Free-Electron Lasers
• Extreme Ultraviolet Superfluorescence in Xenon and Krypton
• XUV Spectral Compression by Four-Wave Mixing
• Full characterization of few-cycle superradiant pulses generated from a free-electron laser oscillator
• Propagation-assisted generation of intense few-femtosecond high-harmonic pulses
• Resonant propagation of x-rays from the linear to the nonlinear regime
• Observations of Ultrafast Superfluorescent Beatings in a Cesium Atomic Vapor Excited by Femtosecond Laser Pulses