Frequency-resolved optical gating for complete reconstruction of attosecond bursts

We describe a method for the complete temporal characterization of attosecond extreme. Ultraviolet, (xuv) fields. An electron wave packet is generated in the continuum by photoionizing. atoms with the attosecond field; and a low-frequency dressing laser pulse is used as a phase gate for frequency-resolved-optical-gating-like measurements on this wave packet. This method is valid for xuv fields,of an arbitrary temporal structure, e.g., trains of nonidentical. attosecond pulses. It establishes a direct connection between the main attosecond char. acterization techniques demonstrated experimentally so far, and considerably extends their. scope, thus providing a general perspective on attosecond metrology.