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Researchers have long sought materials in which light behaves the way electrons do in semiconductors. A workable approach for growing such materials in bulk now seems at hand, and could lead to advances in computing.
In 1987, the physicist Eli Yablonovitch predicted that materials called photonic bandgap crystals (PBCs) would enable light to be handled in the way existing microcircuits handled electrical signals1. Since then, one- and two-dimensional cousins of PBCs have been microfabricated2, for which several applications have been found. Although some small PBCs have been formed by direct microfabrication3, a bulk 3D PBC material has been elusive, along with its potential applications — including next-generation computing technology. Writing in Nature, He et al.4 report the growth of opal-like crystals that have the unusual structure required for PBCs: transparent micro-particles arranged in a manner akin to the carbon atoms in a diamond crystal. For a working PBC, these materials will need to be used as moulds to form Swiss-cheese-like ‘inverse opals’ that have holes where the current crystals have particles.