Seiboth, F.F.SeibothKahnt, M.M.KahntLyubomirskiy, M.M.LyubomirskiySeyrich, M.M.SeyrichWittwer, F.F.WittwerUllsperger, T.T.UllspergerNolte, S.S.NolteBatey, D.D.BateyRau, C.C.RauSchroer, C.G.C.G.Schroer2022-03-062022-03-062019https://publica.fraunhofer.de/handle/publica/26125110.1364/OL.44.004622In this Letter, we report on the creation of hard x-ray beams carrying orbital angular momentum of topological charge −ℏ and −3ℏ at a photon energy of 8.2 keV via spiral phase plates made out of fused silica by ultrashort-pulsed laser ablation. The phase plates feature a smooth phase ramp with a 0.5 mm nominal step height and a surface roughness of 0.5 mm. The measured vortex beams show submicrometer-sized donut rings and agree well with numerical modeling. Fused silica phase plates are potentially suited to manipulate the electromagnetic field in highly intense x-ray beams at x-ray free-electron laser sources.en620535journal article