Photonic time-crystals-fundamental concepts [Invited]

Photonic Time-Crystals (PTCs) are materials in which the refractive index varies periodically and abruptly in time. This medium exhibits unusual properties such as momentum bands separated by gaps within which waves can be amplified exponentially, extracting energy from the modulation. This article provides a brief review on the concepts underlying PTCs, formulates the vision and discusses the challenges. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

Photonic Time-Crystals (PTCs) are materials with periodically and abruptly varying refractive index in time. This medium exhibits unique properties, such as momentum bands separated by gaps where waves can be exponentially amplified, extracting energy from the modulation. This article provides a brief review of PTC concepts, formulates the vision, and discusses the challenges.