Coherent manipulation of extreme-ultraviolet Bessel vortex beam from solids by active wavefront shaping of driving fundamental beam

Abstract

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 towards the achievement of a wavelength-scale spatial resolution. Here, we present a solid-based non-collinear HHG scheme mediating the propagation control and helical wavefront generation commanded via a spatial light modulator. The phase-matching-insensitive nature of the solid-HHG leads to the coherent multi-fold conversion of wavefronts enabling 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 millimetre-level depth-of-focus without extra EUV-dedicated optical components. Our results will suggest a solid-HHG as a powerful tool for high photon-energy applications with a nanoscale spatial resolution.