Three-dimensional photonic band gap structure of a polymer-metal composite

A three-dimensional photonic band gap structure based on self-assembled crystals of polystyrene microspheres was fabricated by filling the pores with metallic silver. An almost complete stop band at 580-600 nm is observed in the optical transmission spectra. In comparison with pure polystyrene colloid crystals, the absorption band of Bragg diffraction in the composite was much more intense and broader, due to an enlargement of the contrast between the spheres and the background. A shift to shorter wavelengths in the band occurred because of a decrease in the average refractive index.