Electron bunch length measurements from laser-accelerated electrons using single-shot THz time-domain interferometry

Laser-plasma wakefield based electron accelerators are expected to deliver ultrashort electron bunches with unprecedented peak currents. However, their actual pulse duration has never been directly measured in a single-shot experiment. We present measurements of the ultrashort duration of such electron bunches by means of THz time-domain interferometry. With data obtained using a 0.5 J, 45 fs, 800 nm laser and a ZnTe-based electro-optical setup we demonstrate the duration of laser-accelerated, quasi-monoenergetic electron bunches at a best fit of 32 fs (FWHM) with a 90% upper confidence level of 38 fs.