V. G. Solovyev

Structure-related optical properties of luminescent hetero-opals

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.

Modification of the spontaneous emission of CdTe nanocrystals in TiO2 inverted opals

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.

Light extinction in bulk and thin film opal photonic crystals

Transmission, scattering and reflectance of bulk opals and thin opal films have been studied using a micro-optical set-up. Spectra of transmitted and scattered light are similar and complementary to reflectance spectrum. Long- and short-range attenuation mechanisms have been identified and related to the scattering on lattice defects.

Photonic Crystals Based on Two-Layer Opaline Heterostructures

Optical properties of several heterostructures representing two-layer opaline photonic crystals have been examined. Two separate stop-bands have been observed both in transmission and emission spectra. The effect of the interface disorder on the optical spectra was not observed, probably, due to the insufficient degree of order of the opaline layers.

Optical Characterization of Cadmium Telluride Doped Heterostructured Opaline Photonic Crystal

A double-layer photonic crystal (PhC) possessing incomplete photonic band gap (PBG) has been prepared by successive formation of one opaline film on top of another and subsequent impregnation with CdTe colloidal nanocrystals as the light source. Transmission, reflection and photoluminescence (PL) spectra of this nanocomposite have been measured from 1.8 to 2.5 eV at different angles of the light incidence and detection. The suppression of emission intensity has been found at both stop bands of the PhC heterostructure. Depending on the excitation power, either suppression or enhancement of the emission rate at the stop band has been observed.

Emission in the ballistic propagation regime of colloidal photonic crystals

Summary form only given. Luminescent CdTe nanocrystals were integrated with thin opal films. Increase of the saturation threshold in a photonic bandgap was interpreted in terms of emission stimulation. Modeling of resonating inhomogeneous eigenmodes justified the bandgap emission properties.

Photoluminescence of CdTe quantum dots in TiO/sub 2/-based opaline photonic crystals

TiO/sub 2/ -based inverted opaline films filled with luminescent CdTe nanocrystals have been prepared and optically characterized. The manifestation of a photonic band gap structure in this system representing a photonic crystal with embedded light sources has been demonstrated. An angular dispersion of the Bragg resonances has been obtained from reflectance measurements. Photoluminescence emission spectra have been measured in the spectral region from 1.8 to 2.7 eV at different values of the angle of incidence, temperature, excitation wavelength and laser pump power.