Tuning the Photonic Bandgap Properties of Crystalline Arrays of Polystyrene Beads by Annealing at Elevated Temperatures

A 3D photonic crystal that operates in the visible regime is presented. The bandgap properties of this photonic crystal, fabricated from ∼230 nm polystyrene beads, can be tuned in a controllable way by annealing the sample at elevated temperatures (see Figure). It is demonstrated that shrinkage and a change in the shape of the beads are responsible for the change in bandgap properties.