Terahertz Oscilloscope for Recording Time Information of Ultrashort Electron Beams

Abstract

We propose and demonstrate a Terahertz (THz) oscilloscope for recording time\ninformation of an ultrashort electron beam. By injecting a laser-driven THz\npulse with circular polarization into a dielectric tube, the electron beam is\nswept helically such that the time information is uniformly encoded into the\nangular distribution that allows one to characterize both the temporal profile\nand timing jitter of an electron beam. The dynamic range of the measurement in\nsuch a configuration is significantly increased compared to deflection with a\nlinearly polarized THz pulse. With this THz oscilloscope, nearly 50-fold\nlongitudinal compression of a relativistic electron beam to about 15 fs (rms)\nis directly visualized with its arrival time determined with 3 fs accuracy.\nThis technique bridges the gap between streaking of photoelectrons with optical\nlasers and deflection of relativistic electron beams with radio-frequency\ndeflectors, and should have wide applications in many ultrashort electron beam\nbased facilities.\n