Vectorial optical field reconstruction by attosecond spectral interferometry

An electrical pulse E(t) is defined completely by its time-dependent amplitude and polarization direction. For optical pulses the manipulation and characterization of the light polarization state is fundamental because of its relevance in several scientific and technological fields. In this work, we demonstrate the complete temporal reconstruction of the electric field of few-cycle pulses with a complex time-dependent polarization. Our experimental approach is based on extreme ultraviolet interferometry with isolated attosecond pulses and on the demonstration that the motion of an attosecond electron wave packet is sensitive to perturbing fields only along the direction of its motion. By exploiting the sensitivity of interferometric techniques and by controlling the emission and acceleration direction of the wave packet, pulses with energies as low as a few hundreds of nanojoules can be reconstructed. Our approach reveals the possibility to characterize completely the electric field of the pulses typically used in visible pump-probe spectroscopy.