Reconstruction of attosecond pulses using two-color pumping

Abstract

We propose a two-color pumping scheme to characterize attosecond extreme ultraviolet (XUV) pulses. The fundamental and its second harmonic of a femtosecond Ti:sapphire laser create a coherent superposition of the 4p and 5p states of K, and we retrieve the spectral phase of the XUV pulse from the phase offset of the photoelectron signal as a function of time delay after the pump pulse. The scheme is technically simple and efficient to characterize ∼100 as pulses.