Just as electronic devices rely upon electronic band gaps in semiconductors to control the flow of electrical current, future photonic devices will depend upon materials endowed with photonic band gaps to provide tight control over light transmission. Sending signals via light instead of electrons is expected to result in extremely fast circuits.

But coming up with photonic materials that can cage light in the technologically important visible and near-IR regions has proven challenging. Theoretical investigations conducted a decade ago pointed to crystals with structures related to diamond as good candidates, but those materials have been tough to synthesize.

Some success has been reported with LincolnLogs type crystals that have a diamondlike structure, but the layer-by-layer microlithography procedures used to make them are painstaking and complex.

Alternatively, University of Toronto physics professor Sajeev John and graduate student Ovidiu Toader propose that a structure of synthetic crystals built from square spiral posts on a tetragonal lattice (left) can function as an effective photonic band gap material and is amenable to large-scale microfabrication techniques. The scientists note that an even more effective material can be prepared by inverting the crystal (right) using established synthesis procedures.

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