Elliptical Polarization and Probability of Double Ionization

The degree of elliptical polarization of intense short laser pulses is shown to be related to the timing of strong-field nonsequential double ionization. Higher ellipticity is predicted to force the initiation of double ionization into a narrower time window, and this pins'' the ionizing field strength in an unexpected way, leading to the first experimentally testable formula for double ionization probability as a function of ellipticity.