Anomalous Optical Drag

Abstract

A moving dielectric medium can displace the optical path of light passing through it, a phenomenon known as the Fresnel-Fizeau optical drag effect. The resulting displacement is proportional to the medium's velocity. In this article, we report on an anomalous optical drag effect, where the displacement is still proportional to the medium's speed but along the direction opposite to the medium's movement. We conduct an optical drag experiment under conditions of electromagnetically-induced transparency and observe the transition from normal, to null, to anomalous optical drag by modification of the two-photon detuning.

A practical guide to electromagnetically induced transparency in atomic vapor

“…Notably, the diffusion here is of a complex quantity (a 'coherent diffusion' of both the argument and the phase of the field) and it therefore demonstrates interference phenomena, such as self-similar expansion and contraction of the probe field [68][69][70]. More intriguing results occur slightly off the EIT resonance, such as negative drag and negative diffraction [71,72].…”