First all-optical photonic time crystal demonstrated in Nature study

An international team has experimentally demonstrated an all-optical photonic time crystal, a material whose optical behavior can be altered strongly and repeatedly over extremely short periods, SciTechDaily reported. Scientists from École Polytechnique, Collège de France, and Helmholtz-Zentrum Dresden-Rossendorf published the work in Nature. They used HZDR's TELBE superradiant terahertz source to drive light-matter interaction in the terahertz range. Unlike conventional photonic crystals, whose spatial lattice shapes how photons move, a photonic time crystal changes optical properties such as reflectivity and resonance frequency dynamically over picosecond timescales comparable to the oscillation period of the light itself. The writeup says the approach could support ultrafast optical computing, advanced telecommunications, and new types of terahertz lasers. Lead author Tingwen Guo and assistant professor Yannis Laplace describe extending photonic crystals from space to time as a path toward amplification and lasing at terahertz frequencies. The paper carries DOI: 10.1038/s41586-026-10825-9.