Photonics of Time-Varying Media

TL;DR

This review explores recent advances in photonic time-varying media, including concepts, applications, and experimental developments, highlighting their potential for wave manipulation and novel photonic phenomena.

Contribution

It provides a comprehensive overview of the state-of-the-art in time-modulated photonic metamaterials, including theoretical insights, applications, and future directions.

Findings

Discussion of temporal switching and spatial scattering

Review of photonic time-crystals and topological physics

Analysis of spatiotemporal modulation applications

Abstract

Time-varying media have recently emerged as a new paradigm for wave manipulation, thanks to thesynergy between the discovery of novel, highly nonlinear materials, such as epsilon-near-zero materials, and the questfor novel wave applications, such as magnet-free nonreciprocity, multi-mode light shaping, and ultrafast switching. Inthis review we provide a comprehensive discussion of the recent progress achieved with photonic metamaterials whoseproperties stem from their modulation in time. We review the basic concepts underpinning temporal switching and itsrelation with spatial scattering, and deploy the resulting insight to review photonic time-crystals and their emergentresearch avenues such as topological and non-Hermitian physics. We then extend our discussion to account for spa-tiotemporal modulation and its applications to nonreciprocity, synthetic motion, giant anisotropy, amplification andother effects. Finally, we conclude with a review of the most attractive experimental avenues recently demonstrated,and provide a few perspectives on emerging trends for future implementations of time-modulation in photonics.