Essentially Transient Raman Amplification in Excited Medium

Jérôme J.-P. Leon, А. В. Михайлов

Michael D. Duncan, John F. Reintjes, Lawrence L. Tankersley +2 more

N. I. Shamrov

V P Pimenov, Vladimir A. Shcheglov

An investigation is reported of the amplification of resonance radiation under conditions of transient and spatially inhomogeneous excitation of a multilevel gaseous medium. Analytic expressions obtained can be used, in particular, in the design of a pulse amplifier and also of a cw amplifier in which mixing of gas streams is utilized.

Naohiro Tanno, Tsukasa Shirahata, Kenichi Yokoto +1 more

In this paper we develop a theoretical analysis which describes a coherent transient effect of two entering pulses---one laser and one Stokes---in a Raman-active medium. The field (Maxwell) and atomic (Schr\"odinger, density-matrix representation) equations are coupled in a self-consistent manner in time and space by virtue of the resultant second-order nonlinear macroscopic polarizations at the two frequencies. This treatment is accomplished under the circumstances where atomic coherence plays a predominant role. The equations derived here may be referred to as "Raman Bloch-Maxwell equations." The resultant equations yield a new aspect of transient stimulated Raman scattering and thus coherent Raman propagation. The transient-pulse behavior may be understood as self-induced modulation of coherent amplification and absorption. The self-induced modulation for the step-function input pulse is described by a combination of Jacobian elliptic functions depending on the input intensity. Computer calculations of transient-pulse evolution reveal interesting pulse breakup phenomena with peak amplification, energy transmission, pulse advance or delay, and pulse-narrowing effects.

R. Wolfson, Kai J. Drühl

An internal phase-shift mechanism can lead to the amplification of Raman solitons even in the presence of coherence decay and detuning. We study here the case of a Raman medium with strong ac Stark shift by using both analytical and numerical methods. Our results also suggest the possibility of propagating stable transient Raman solitons in optical fibers.