New Electromagnetic Modes in Space-Time Modulated Dispersion-Engineered Media

TL;DR

This paper introduces novel electromagnetic modes in space-time modulated media with unique dispersion and scattering properties, created through coupled harmonic pairs, and explores their potential applications in optical devices.

Contribution

It reports the discovery of new electromagnetic modes in space-time modulated media, detailing their properties and generation mechanisms, which were not previously known.

Findings

Modes exhibit unusual dispersion relations and field profiles.

Energy transfer occurs between incident and shifted frequencies in subluminal modulation.

Superluminal modulation leads to exponentially growing frequencies.

Abstract

We report on new electromagnetic modes in space-time modulated dispersion-engineered media. These modes exhibit unusual dispersion relation, field profile and scattering properties. They are generated by coupled codirectional space-time harmonic pairs, and occur in space-time periodic media whose constituent materials exhibit specific dispersion. Excitation of a slab of such a medium with subluminal modulation results in periodic transfer of energy between the incident frequency and a frequency shifted by a multiple of the modulation frequency, whereas superluminal modulation generates exponentially growing frequencies. These modes may find applications in optical mixers, terahertz sources and other optical devices.