Compact intense extreme-ultraviolet source

TL;DR

This paper introduces a compact, high-intensity extreme-ultraviolet (XUV) source based on high-harmonic generation, capable of reaching intensities suitable for advanced nonlinear and imaging applications in laboratory settings.

Contribution

The authors present a novel, simple method for generating intense XUV pulses using tight focusing of NIR lasers and strategic harmonic generation placement, enabling high intensities in small-scale labs.

Findings

Achieved XUV intensities of 2×10^{14} W/cm^2 with potential for 10^{17} W/cm^2.

Generated XUV pulses refocused to a 600 nm waist, suitable for nonlinear experiments.

The setup fits on a 2-meter laser table, making it accessible for many laboratories.

Abstract

High-intensity laser pulses covering the ultraviolet to terahertz spectral regions are nowadays routinely generated in a large number of laboratories. In contrast, intense extreme-ultraviolet (XUV) pulses have only been demonstrated using a small number of sources including free-electron laser facilities [1-3] and long high-harmonic generation (HHG) beamlines [4-9]. Here we demonstrate a concept for a compact intense XUV source based on HHG that is focused to an intensity of $2 \times 10^{14}$ W/cm$^2$, with a potential increase up to $10^{17}$ W/cm$^2$ in the future. Our approach uses tight focusing of the near-infrared (NIR) driving laser and minimizes the XUV virtual source size by generating harmonics several Rayleigh lengths away from the NIR focus. Accordingly, the XUV pulses can be refocused to a small beam waist radius of 600 nm, enabling the absorption of up to four XUV photons by a single Ar atom in a setup that fits on a modest (2 m) laser table. Our concept represents a straightforward approach for the generation of intense XUV pulses in many laboratories, providing novel opportunities for XUV strong-field and nonlinear optics experiments, for XUV-pump XUV-probe spectroscopy and for the coherent diffractive imaging of nanoscale structures.