Coherence creation in an optically thick medium by matched propagation of a chirped laser pulse pair

TL;DR

This paper demonstrates a method for nearly lossless propagation of chirped laser pulse pairs in an optically thick medium, enabling robust creation of atomic coherence for enhanced nonlinear optical processes.

Contribution

It introduces a self-organization effect for chirped pulses in a dense medium, leading to controlled coherence creation and improved wave mixing efficiency.

Findings

Achieves quasi-lossless propagation of chirped pulses in thick media.

Creates robust atomic coherence controllable by laser amplitudes.

Enhances efficiency of nonlinear optical processes.

Abstract

We consider the simultaneous propagation of a pair of Raman-resonant, frequency-modulated (chirped) laser pulses in an optically thick medium, modeled by an ensemble of $\Lambda$-atoms. A self-organization ('matching`) effect is shown for the chirped pulse pair, which leads to a quasi-lossless propagation. Furthermore, we demonstrate that a well-defined coherent superposition of the atomic ground states and, correspondingly, a coherence is robustly created in the medium that can be controlled by amplitudes of the laser pulses. The proposed scheme can be applied to substantially increase the efficiency of the optical wave mixing processes, as well as in other nonlinear processes where the initial preparation of a spatially extended medium in a coherent superposition state is required.