Extreme-ultraviolet structured beams via high harmonic generation

TL;DR

This paper demonstrates the generation of structured extreme-ultraviolet beams with controlled polarization and phase properties via high harmonic generation, enabling advanced applications in high-resolution imaging and ultrafast science.

Contribution

It introduces a method to produce EUV structured beams with tailored polarization and phase, including vector, vortex, and vector-vortex beams, using high harmonic generation in a tabletop setup.

Findings

EUV vector beams with spatially-dependent polarization were generated.

EUV vortex beams with twisted phase were produced.

EUV vector-vortex beams combining both properties were demonstrated.

Abstract

Vigorous efforts to harness the topological properties of light have enabled a multitude of novel applications. Translating the applications of structured light to higher spatial and temporal resolutions mandates their controlled generation, manipulation, and thorough characterization in the short-wavelength regime. Here, we resort to high-order harmonic generation (HHG) in a noble gas to upconvert near-infrared (IR) vector, vortex, and vector-vortex driving beams that are tailored respectively in their Spin Angular Momentum (SAM), Orbital Angular Momentum (OAM), and simultaneously in their SAM and OAM. We show that HHG enables the controlled generation of extreme-ultraviolet (EUV) vector beams exhibiting various spatially-dependent polarization distributions, or EUV vortex beams with a highly twisted phase. Moreover, we demonstrate the generation of EUV vector-vortex beams (VVB) bearing combined characteristics of vector and vortex beams. We rely on EUV wavefront sensing to unambiguously affirm the topological charge scaling of the HHG beams with the harmonic order. Interestingly, our work shows that HHG allows for a synchronous controlled manipulation of SAM and OAM. These EUV structured beams bring in the promising scenario of their applications at nanometric spatial and sub-femtosecond temporal resolutions using a table-top harmonic source.