First realistic Photonic Time Crystals

Viktar Asadchy et al. from Aalto University published article “Expanding momentum bandgaps in photonic time crystals through resonances” in Nature Photonics, where they report that by introducing temporal variations in a resonant material, the momentum bandgap, normally requiring a substantial modulation strength, can be drastically expanded in resonant bulk media and optical metasurfaces.

News releases at
https://optics.org/news/15/11/18

https://www.kit.edu/kit/english/pi_2024_090_space-time-crystals-an-important-step-toward-new-optical-materials.php