Three‐Dimensional Network Photonic Crystals via Cyclic Size Reduction/ Infiltration of Sea Urchin Exoskeleton

A reduction and infiltration process for a naturally occurring 3D bicontinuous structure is demonstrated. A sea urchin exoskeleton can be engineered in a top–down fashion to create low absorption, high dielectric contrast photonic crystals with a stop band in the mid-IR regime. The Figure shows a sample cut in half where one half (right) has been pyrolyzed, demonstrating the excellent structural fidelity of the replication-reduction process.