An unprecedented feat: Printing 3D photonic crystals that completely block light

https://phys.org/news/2024-09-unprecedented-feat-3d-photonic-crystals.html

"transparent complete photonic bandgap blocking light at all visible wavelengths/ directions... allows precise light control... high resolution 3D printed photonic crystals, high refractive index... 2-photon polymerization lithography heating shrinks crystals 6X oxidizing titanium ions within crystals, turning ions into titanium dioxide resin... 180 nm distance between layers enhancing resolution... color generation, waveguides, telecommunications, sensing, single-photon emitters, quantum information processing"