A common model for superluminal propagation in absorbing atomic media and lossy metastructures

TL;DR

This paper presents a unified analysis of superluminal pulse propagation in absorbing media and lossy metastructures, revealing how interference of scaled replicas causes time-advanced signals.

Contribution

It introduces a common model explaining superluminal effects in both dissipative bulk media and lossy micro-ring resonators, enhancing understanding of underlying physical mechanisms.

Findings

Superluminal pulses are attenuated and undistorted with a time advance.

Interference of scaled input replicas explains superluminal propagation.

Model applies to both electronic resonances and dielectric waveguides.

Abstract

We analyse the superluminal propagation of narrow-band pulses at resonances in dissipative media. The output waveform is an attenuated, undistorted, time-advanced version of the input which can be interpreted as the result of the interference of two scaled replicas of the input having a positive relative delay. The proposed analysis applies both to the propagation in a passive bulk medium at an electronic resonance and in a dielectric waveguide coupled to a lossy micro-ring resonator. This latter case provides a clear insight of the underlying physical phenomena.