  An analytical expression of a Floquet operator, which describes the evolution
of a wave packet in combined atomic and an intense laser field,is obtained
approximately in the stabilization regime. Both the classical and quantum
versions of the Floquet operator are used to study the phase-space dynamics of
atomic stabilization, and the 'fringe structure' in the phase-space is clearly
demonstrated. Furthermore, we investigate the dynamical mechanism and
characters of this striking structure, and find that this structure is very
closely related to the classical invariant manifolds.
