Reconstruction of attosecond pulses using a two-color pumping

Chen, J.*; Itakura, Ryuji; Nakajima, Takashi*

We propose a two-color pumping scheme to characterize attosecond extreme ultraviolet (XUV) pulses. The fundamental and its second harmonic of a fs Ti:Sapphire laser create a coherent superposition of the 4 and 5 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 attosecond pulses.