Method of XUV attosecond pulse characterization using two-photon resonant Raman-type transition

Abstract

We suggest a new method of attosecond pulse train measurement based on two-photon Raman-type resonant interaction of the XUV with an atom (Attosecond pulse reconstruction using Raman-type Transitions, ART). We show analytically and numerically that the attosecond pulse auto-correlation function and chirp can be measured using this process. Its resonant nature allows obtaining reasonable signal even for relatively low XUV intensity. The interpretation of the results is remarkably simple for the XUV generated by bi-circular field. The experimental realization of the method can be based either on measuring the excitation of the gas or on four-wave mixing fully optical scheme.We suppose that the parity of the states is such that a two-photon transition from the ground to the excited state is allowed. Transitions to other bound states are assumed to be non-resonant and so they can be neglected.