Enhancement of nonsequential double ionization in counter-rotating two-color circularly polarized laser fields

Nonsequential double ionization is theoretically investigated in the counter-rotating two-color [frequencies (omega(1); omega(2))] circularly polarized laser fields with classical ensemble approach. It is found that remarkable ionization enhancement is obtained by adjusting the relative electric field amplitude ratios (gamma(E)). The result indicates that there is a broader steerable range of gamma(E) to obtain higher ionization enhancement for omega(2) = 3 omega(1) than that for omega(2) = 2 omega(1). Through the analysis of trajectories, the recollision picture for omega(2) = 3 omega(1) is complicated leading to slow change of double ionization, which is benefit to gentle control mechanism. However, the recollision ionization channel is easily distinguishable and sensitive to control double ionization in omega(2) = 2 omega(1) laser fields and the travel time can be controlled in the order of magnitude of 100 attoseconds. (C) 2018 Elsevier B.V. All rights reserved.