Cooperative emission of a pulse train in an optically thick scattering medium

TL;DR

This paper demonstrates that an optically thick cold atomic cloud can produce a train of high-contrast, high-efficiency light pulses through cooperative emission triggered by abrupt phase changes, even in dilute conditions.

Contribution

It introduces a method to generate pulse trains via cooperative emission in dilute, optically thick atomic clouds, highlighting the role of cooperativity in controlling emission dynamics.

Findings

Pulse train with high intensity contrast achieved

Emission duration shorter than atomic excited lifetime

Cooperative effects dominate even in dilute media

Abstract

An optically thick cold atomic cloud emits a coherent flash of light in the forward direction when the phase of an incident probe field is abruptly changed. Because of cooperativity, the duration of this phenomena can be much shorter than the excited lifetime of a single atom. Repeating periodically the abrupt phase jump, we generate a train of pulses with short repetition time, high intensity contrast and high efficiency. In this regime, the emission is fully governed by cooperativity even if the cloud is dilute.