Reflection and transmission of ultrashort light pulses through a thin resonant medium: Local-field effects

We investigate the problem of resonant reflection and transmission of an ultrashort light pulse passing through a thin layer consisting of two-level atoms. The local-field correction that leads to an inversion-dependent resonance frequency generates a new mechanism of nonlinear transparency. When the excitation frequency is somewhat larger than the original resonant frequency, then the transmission of the layer exhibits a transient bistable behavior on the time scale of superradiation, which can be much shorter than the relaxation times. This type of bistability is essentially different from the ordinary stationary intrinsic bistability investigated earlier by other authors.