Generation of Coherent Extreme-Ultraviolet Vector-Vortex beams

Optical vortex and vector beams are two paradigmatic examples of structured light. While the first ones carry orbital angular momentum (OAM), and thus their wavefront spirals along the propagation direction, the second ones present spatially inhomogeneous distributions of polarization. Harnessing structured light is opening new perspectives in communications, quantum information, processing, high-resolution imaging, or particle trapping. Among them, the generation of coherent structured beams in the extreme-ultraviolet (EUV)/soft x-ray regime is of high interest due to their unique ability to interact with matter at the nanometer and sub-femtosecond scales. During the last years, high-order harmonic generation (HHG) has opened a new paradigm to up-convert infrared vortex [1] , [2] and vector beams [3] into the EUV, circumventing the use of inefficient optical converters. Previous results proved that a synchronous control over the polarization and the OAM is possible through HHG [4] , [5] .