The coherent propagation of four optical pulses through a multilevel resonant medium is investigated theoretically. We present a self-consistent analytic solution without steady-state or adiabatic approximations and use numerical simulations to indicate that the analytic formulas can be used as a guide in an experimental setting.
(Submitted 14 February 1986) Zh. Eksp. Teor. Fiz. 92,46-55 (January 1987) The coherent resonant interaction between multifrequency light and a multilevel system is considered together with the N-wave interaction of wave packets in a medium with a quadratic nonlinearity. The Lax representation of the self-consistent set of Maxwell-Bloch equations for this interaction is found. Soliton solutions resulting from the parametric transformation of ultrashort pulses in three- and four-level system (N = 3, and N
Coherent propagation of a circularly polarized pulse which is two-photon quasi-resonant with a medium of multi-level atoms is considered in the adiabatic following limit. The relevant pair of non-linear coupled partial differential equations are solved exactly for arbitrary pulse shapes. The development of the envelope and the phase of the pulse as it propagates through the medium is described analytically. Perturbation theoretical results are shown to apply only for small intensity or small distance of propagation or both. Qualitatively different results apply for higher intensities and longer distances of propagation. These include strong self-phase-modulation effects as well as reshaping of the pulse envelope.
We investigate short pulses propagation through multilevel atomic vapors. The medium is composed of an ensemble of four atomic levels generated by the hyperfine structure of the D1 transition in Rubidium-87 atoms. The pulses are resonant to their respective optical transitions, in order to have a well-defined pulse area definition. We discuss local stabilization of the pulse area with or without energy stabilization and as a function of the prolonged distance. Furthermore, we explore some new features for the propagation dynamics in multilevel atomic media which are beyond the traditional framework of McCall and Hahn area theorem and self-induced transparency.
The coherent propagation of two optical short pulses through a resonant medium consisting of two three-level atoms in the configuration is investigated. A self-consisting analytical solution without steady state or adiabatic approximations is presented. The electric field in the model studied consists of two co-propagating plane waves, each of which is in near resonance with a transition in the absorber. The density matrix of two three level atoms is studied. Also, the reduced density matrices are stated. The present approach for the semiclassical treatment of resonant coherent interactions in three-level atoms represents a generalization of the Maxwell- Bloch equations for a two-level system. The Maxwell-Bloch equations reduced to the non-linear pendulum equation. The solution shows that the two pulses can propagate simultaneously without loss under some conditions about the pulses and the medium. The propagation of the two pulses through the medium without any constrains approves the self -induced transparency (SIT) phenomenon.
The ultrabroad spectrum of few-cycle and especially subcycle pulses requires multiple energy levels in a medium to be properly considered in order to describe the pulse propagation effects. In this paper we go beyond the standard two-level or related few-level approximations and theoretically analyze the propagation of subcycle pulses in a nonequilibrium multilevel resonant medium. We specifically address the case of pulse durations, smaller than the periods of resonant transitions in a medium, where the appropriate analytical models can be provided, and assume accordingly a slow dissipation in the medium. We demonstrate a number of nonlinear phenomena, arising under such conditions, in particular the formation of stable subcycle dissipative solitons of various profiles in a nonequilibrium medium, including superluminal ones, as well as study possible scenarios of their collision.