Photonic crystals - Opal

Opals are self-assembled fcc-packed colloidal crystals with sphere diameters in the nonometer and submicrometer region. The periodic dielectric structure leads to the opening of photonic band gaps that suppress the propagation of light with wavelengths at the lattice constant scale. This explains e.g. the opals' brilliant color impression. Synthetic opals can be prepared from polymer or metaloxide spheres in a bottomup approach that allows for chemical functionalization and processing. Also, they can be used as templates to fabricate inverted structures. Fields of application reach from optical chips, color displays and effect pigments to biosensors.