Control of superluminal transit through a heterogeneous medium

TL;DR

This paper investigates how pulse propagation through a composite metal-dielectric medium can exhibit superluminal or subluminal transmission, depending on conditions like cavity presence and metal volume fraction, with implications for controlling light speed.

Contribution

It demonstrates the control of pulse transit times in heterogeneous media using localized plasmon resonance and cavity effects, providing new insights into superluminal and subluminal light transmission.

Findings

Superluminal pulse transmission achieved in thin slabs at plasmon resonance.

Cavity presence can switch transmission from subluminal to superluminal.

Phase time is independent of system width and metal volume fraction under certain conditions.

Abstract

We consider pulse propagation through a two component composite medium (metal inclusions in a dielectric host) with or without cavity mirrors. We show that a very thin slab of such a medium, under conditions of localized plasmon resonance, can lead to significant superluminality with detectable levels of transmitted pulse. A cavity containing the heterogeneous medium is shown to lead to subluminal-to-superluminal transmission depending on the volume fraction of the metal inclusions. The predictions of phase time calculations are verified by explicit calculations of the transmitted pulse shapes. We also demonstrate the independence of the phase time on system width and the volume fraction under specific conditions.