Submicrometer focusing of isolated attosecond XUV pulses approaching 10$^{16}$ W/cm$^2$

TL;DR

This paper reports the submicrometer focusing of isolated attosecond XUV pulses using a custom ellipsoidal mirror, achieving near diffraction-limited spot sizes and high peak intensities for potential nonlinear optics applications.

Contribution

The authors demonstrate a practical method to focus attosecond XUV pulses to submicrometer scales with high intensities, enabling advances in attosecond nonlinear optics.

Findings

Achieved focal spot sizes down to 0.46 μm × 0.36 μm (FWHM).

Focusing a 1.1-GW IAP source yields 3×10^{15} W/cm^2 peak intensity.

Pathway to reach 10^{16} W/cm^2 by optimizing beamline throughput.

Abstract

We demonstrate submicrometer focusing of isolated attosecond pulses (IAPs) in the extreme ultraviolet (XUV) region using a custom ellipsoidal mirror. The obtained focal spot sizes were verified using knife-edge measurements with a sharp silicon edge, confirming reproducible dimensions down to 0.46 $\mu$m $\times$ 0.36 $\mu$m (FWHM), approaching the diffraction limit. Focusing a 1.1-GW tabletop IAP source yields a peak intensity of 3 $\times$ 10$^{15}$ W/cm$^2$, and a realistic pathway toward 10$^{16}$ W/cm$^2$ is obtained by optimizing the beamline throughput. These results establish a practical route toward attosecond nonlinear optics in both gas and solid phases, driven by intense XUV fields.