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Light-emitting hetero-opals have been synthesized by successive crystallization of one thin opal film on top of the other from beads of two different diameters and selective impregnation of one of films with luminescent CdTe nanocrystals. A strong spectral and spatial anisotropy of the reflectance and the photoluminescence spectra has been observed and attributed to the photonic bandgap mismatch in opal films. Changes of the emission anisotropy with excitation power have been associated with the stimulation of CdTe nanocrystal emission in a host opal film. An interface-related transmission minimum has been revealed and tentatively explained as the consequence of the distractive interference of optical modes of hetero-opal constituents. The idea of the interface resonance has been supported by the observation of the emission modification in this frequency range.

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A light source in a three-dimensional photonic crystal has been realized by depositing CdTe nanocrystals on the inner surface of TiO2 inverted opal films. Two effects, the photonic band gap of inverted opal and the energy exchange between CdTe nanoparticles and the TiO2 framework, have been identified as major sources of emission spectrum modification. An analysis of input-output characteristics of the spontaneous emission demonstrates the saturation of the excitation-to-emission conversion in the emission band and the conversion efficiency improvement associated with the presence of the photonic band gap.