Electromagnetically induced transparency and nonlinear pulse propagation in a combined tripod and $\Lambda$ atom-light coupling scheme

TL;DR

This paper explores a complex five-level atomic system combining tripod and Lambda configurations, demonstrating the formation of dark states, EIT, slow light, and stable optical solitons through nonlinear pulse propagation analysis.

Contribution

It introduces a novel combined tripod and Lambda atom-light coupling scheme enabling control over EIT and absorption, and shows the possibility of stable soliton generation.

Findings

Dark states can be formed in the combined scheme.

The system can transition between EIT and absorption.

Stable slow light solitons can be generated.

Abstract

We consider propagation of a probe pulse in an atomic medium characterized by a combined tripod and Lambda ($\Lambda$) atom-light coupling scheme. The scheme involves three atomic ground states coupled to two excited states by five light fields. It is demonstrated that dark states can be formed for such an atom-light coupling. This is essential for formation of the electromagnetically induced transparency (EIT) and slow light. In the limiting cases the scheme reduces to conventional $\Lambda$- or $N$-type atom-light couplings providing the EIT or absorption, respectively. Thus the atomic system can experience a transition from the EIT to the absorption by changing the amplitudes or phases of control lasers. Subsequently the scheme is employed to analyze the nonlinear pulse propagation using the coupled Maxwell-Bloch equations. It is shown that generation of stable slow light optical solitons is possible in such a five-level combined tripod and $\Lambda$ atomic system.