Probing Zeeman coherence in nearly degenerate two-level atomic vapour with four-wave mixing

TL;DR

This paper investigates four-wave mixing in rubidium vapor to understand Zeeman coherence, revealing how different spectral features relate to EIT and EIA phenomena and polarization effects.

Contribution

It introduces a method to distinguish nonlinear processes in atomic vapor using spectral differences under various polarization conditions.

Findings

Spectral differences correlate with EIT and EIA effects.

Polarization influences the four-wave mixing spectra.

Distinct processes contribute to Kerr nonlinearity.

Abstract

We present results of a study of four-wave mixing in Rb vapour with highly nonlinear susceptibility, using both homodyne and heterodyne detection. We demonstrate that the spectra have different appearances for media possessing electromagnetically induced transparency and electromagnetically induced absorption, and for different relative polarizations of the drive and probe fields. We show that these differences allow the contributions of different processes responsible for the enhanced Kerr nonlinearity of the media to be distinguished.