Coherent Manipulation of Extreme-Ultraviolet Bessel Vortex Beams from Solids by Active Wavefront Shaping of Driving Fundamental Beams
Abstract
High-harmonic generation (HHG) of extreme ultraviolet (EUV) radiation enables ultrafast spectroscopy and nanoscale coherent imaging with timing resolutions down to the attosecond regime. However, beam manipulations such as steering and focusing remain a major challenge for handy implementation of such applications toward the achievement of a wavelength-scale spatial resolution. Here, we present a solid-based noncollinear HHG scheme mediating the propagation control and helical wavefront generation commanded via a spatial light modulator. The coherent multifold conversion of wavefronts in HHG enabled active control of the EUV harmonic beam propagation. Further, EUV harmonics generated by double-annular beams were converted to the Bessel vortex beam, for the first time, narrowing the beam diameter to 3.4 wavelengths with a long millimeter-level depth-of-focus without extra EUV-dedicated optical components. Our results will suggest the wavefront manipulation of the fundamental beam in HHG as a powerful tool for beam shaping of high photon-energy applications with a nanoscale spatial resolution.