Ultrashort light pulse generation under coherent interaction of a field with a medium

We consider the dynamics of propagation and compression of ultrashort electromagnetic-wave pulses in a multicomponent two-level field, one component of which emits or absorbs light in a regime of coherent interaction of the radiation with the substance. We consider also the question of the dynamics of the field in planar superconducting structures (such as, e.g., layered high-temperature superconductors of the YBa₂Cu₃O_7=x type). With Josephson tunneling of the electrons between the layers it becomes possible here to describe the field-induced current in a model using Bloch equations for particles with near-zero frequency of the transition between levels and with infinite relaxation times, i.e., to reduce the problem to that of the dynamics of a field coherently interacting with a two-level medium.Lebedev Physics Institute, Academy of Sciences of the USSR. University Center for Laser Research, Oklahoma State University. translated from Preprint No. 69, Lebedev Physics Institute, Moscow, 1991.