Photonic crystals proposed (1987)
Eli Yablonovitch and Sajeev John independently proposed photonic crystals, materials whose optical properties repeat in space to control how light moves. The idea started as theory. It took years to build working structures.
The concept guided a new field of nanophotonics and drew skepticism about whether the structures could be built cleanly.
Spatial photonic crystals now shape optical fibers, LEDs, and lasers used across telecom and lighting.
The 2026 device does in time what photonic crystals did in space. If the spatial version reshaped photonics, the temporal version aims at the same targets from a new angle.
