Nonperturbative treatments of level shifts of excited states and high-order harmonic generation in strong fields
Journal
Journal of the Optical Society of America B: Optical Physics
Journal Volume
7
Journal Issue
4
Pages
425-432
Date Issued
1990
Author(s)
Abstract
In this paper we accomplish three goals. First, we present new nonperturbative results of complex quasi-energies (shifts and widths) for several low-lying excited states of atomic H in strong fields, using the L2 non-Hermitian Floquet matrix technique. Second, we present a new nonperturbative L2 technique for the treatment of ac Stark shifts of arbitrary excited states. We found that all the Rydberg states in weak fields are upshifted and closely follow the quadratic field dependence described by the ponderomotive potential e2F2/4mw2. Large deviation from the ponderomotive shift and intricate level-shift behaviors, however, occur in strong fields. Finally, we present a classical nonperturbative treatment of the electronic motion in intense laser fields. We show that the spectral analysis of classical trajectories can provide detailed insights regarding the mechanisms responsible for the multiple- harmonic generation recently observed in high-intensity experiments. © 1990 Optical Society of America.
Type
journal article