Observation of narrow fluorescence from doubly driven four-level atoms at room temperature

TL;DR

This paper reports the observation of unusually narrow fluorescence peaks from Rubidium-85 atoms driven by two lasers in a molasses setup, with detailed analysis of peak splitting and additional features at various detunings.

Contribution

It presents experimental evidence of narrow fluorescence features in a four-level atomic system under dual laser excitation, supported by a simple explanatory model.

Findings

Narrow fluorescence peaks observed at room temperature

Peak splitting increases with cooling laser detuning

Additional small peaks appear at large detunings

Abstract

Unusually narrow fluorescence peaks are seen from Rubidium-85 atoms under the action of two driving laser fields that are in a three dimensional molasses configuration. One of the lasers is held at a fixed detuning from the "cooling" transition, while the other is scanned across the "repumping" transitions. The fluorescence peaks are split into symmetric pairs, with the seperation within a pair increasing with the detuning of the cooling laser. For large detunings additional small peaks are seen. A simple model is proposed to explain these experimental observations.