The Modulation Properties of Local-Field Effect on a Dense Two-Level System

In this paper we investigate the evolutions of Bloch vector in a dense two-level system with near-dipole-dipole (NDD) interactions driven by ultrafast incident pulses, whose duration is far less than the relaxation times. The results show that the evolutionary relationships between dispersion (absorption) and inversion, as function of NDD parameter, are reciprocal. And the pulse width and pulse area effect on the final state of inversion (FSI) are sensitive and obvious for nonzero NDD parameter. Furthermore, we demonstrate a way to eliminate the NDD interactions effect on the FSI by adding an appropriate detuning.