Propagation of videopulse through a thin layer of two-level atoms   possessing permanent dipole moments
  The excitation of a thin layer of two-level permanent dipole moment atoms by ultimately short (less than field oscillation period) electromagnetic pulses (videopulse) is observed. The numerical analysis of matter equations free of rotating wave approximation and relaxation reveals a strong affect of local field and Stark effect on temporal behavior of transmitted field. Specifically it is demonstrated that a dense film irradiated by videopulse emits a short response with a delay much longer even than the characteristic cooperative time of atom ensemble. It is supposed that the local field in the thin layer of permanent dipole atoms is able to re-pump the atomic subsystem. The close analogy to nonlinear pendulum motion is discuused. 
Sergei O. Elyutin and Andrei I. Maimistov