Shaping polarization of attosecond pulses via laser control of electron and hole dynamics

Summary form only given. We present [1] a way to control and shape the polarization of attosecond pulses generated by HHG by using the combination of the fundamental radiation and its second harmonic, both linearly polarized, in perpendicular geometry. By extending the multi-electron analysis done in the CO₂ molecule in previous works [2] to treat the two-color laser fields, we explore the rich possibilities that this control mechanism offers.The second color component of the field allows to control the angle of recombination of the electron which, in turns, controls the relative magnitudes of different recombination channels as each of these channels have preferred recombination angles. At the same time, this second field also induces dynamics in the molecular ion upon ionization, that leads to population transfer between the different ionic states. Therefore the magnitude of additional recombination channels can be controlled by the relative intensity and the phase delay between the two driving fields. This manipulation of amplitude and phases of several interfering HHG channels results in fine control of polarization properties of the XUV emission, as can be seen in Figure 1, where three examples of such control are shown. The instantaneous rotation of the time-dependent polarization ellipse is plotted, and, as it can be seen, one of the pulses of each example is close to circulary polarized virtually everywhere, while the other one has almost linear polarization, with a pronounced rotation of the polarization ellipse. This control scheme is ready for experimental tests as the setup has already been implemented in recent experiments [3-4].