Eu 3+ ions have been incorporated into the silica skeleton of synthetic opal. The effect of the anisotropic photonic band gap structure upon the emission characteristics has been studied in the case where the emission bandwidth is narrower than the stop-band. Either suppression or enhancement of the spontaneous emission at the wavelength of the radiative transition has been observed, depending on the relative position of the emission band and the stop-band.

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The “semimetallic” photonic band gap formed in a synthetic opal has been increased by depositing a layer (InP or TiO2) with high refractive index on the inner surface of opal voids. Reflectance spectra of the composites (nanolayers assembled within grating voids) are correlated with both the photonic structure of the opal and electronic structure of the semiconductor.

Photonic bandgap (PGB) structures based on synthetic opal have been modified by in‐situ growth of CdS. The resulting structures show an enhanced stop‐band as determined from transmission and reflection measurements. Photoluminescence from the structures is squeezed to the low‐energy side of the stop‐band, with the effect increasing with higher fraction of CdS.

The stop-band width and angular dispersion have been traced by angle-resolved reflectance spectroscopy for two opposite configurations of opal-based photonic crystals where either the silica balls possess a higher refractive index than the voids or vice versa. It has been demonstrated that filling the empty voids of opal with a material of higher refractive index than silica results in widening of the stop-band and squeezing of its dispersion, thus improving the stop-band of the opal grating towards the omnidirectional photonic band-gap situation.