Mirrorless Optical Bistability of Thin Layer with Resonant Two-Level Atoms in Ultrashort Light Pulse Field

We investigate the problem of resonant re flection and transmission of an ultrashort light pulse passing through a medium consisting of two-level atoms. We show that for a thin layer it is important to take into account the difference between the external macroscopic field and the field acting on the individual atoms within the medium. The local field correction leads to an inversion dependent resonant frequency. In thin layers this generates a new mechanism of nonlinear transparency induced by the dynamical frequency shift. When the excitation frequency is larger than the original resonant frequency, then the transmission of the layer exhibits bistable behavior.