Achievement of essentially full spatial coherence in a high-average-power soft-x-ray laser

Abstract

We report an observation of essentially full spatial coherence in a high average power soft-x-ray laser. Rapid coherence buildup due to strong refractive antiguiding in a long plasma column is experimentally demonstrated. This allows the generation of fully coherent, milliwatt-level average power soft-x-ray radiation by a tabletop device. The peak brightness of this laser reaches $2\ifmmode\times\else\texttimes\fi{}{10}^{25}{\mathrm{photons}\mathrm{}\mathrm{s}}^{\ensuremath{-}1}{\mathrm{mm}}^{\ensuremath{-}2}{\mathrm{mrad}}^{\mathrm{\ensuremath{-}}2}$ within 0.01% spectral bandwidth, making it one of the brightest soft-x-ray sources available.