Emission of globular SiO 2 photonic crystals infiltrated with dielectrics is observed within a wide spectral region under excitation with the light wavelength λ = 400 nm. The first part of the emission spectrum located in the vicinity of the excitation line depends on infiltrated substance and is explained by surface-enhanced Raman scattering effect. The second one lying in the region of 440-650 nm that includes the stop-band is caused by spontaneous parametric down-conversion.
PACS:78.67-n + 78.55.Mb UDC: 535.361
Abstract. 'Opal-tellurium dioxide' nanocomposite has been obtained by filling opal pores with a melt of fine dispersive polycrystalline α-TeO 2 powder. The Raman spectrum of the composite has been measured in the region of 50-1100 cm -1 and compared with the spectra peculiar for polycrystalline α-TeO 2 powder and the corresponding single crystals. Besides of the Raman bands corresponding to α-TeO 2 lattice vibrations, other bands have been detected in the spectrum of the composite. Their spectral positions coincide fairly well with those available in the spectrum of γ-TeO 2 .
Abstract. We study angular dependences of the reflection and fluorescence spectra for the synthetic opal infiltrated with a photo-reactive substance, 2,5-bis(2-benzoxazolyl)hydroquinone (BBHQ). The peak shift observed in the reflection spectra with increasing incidence angle of light is satisfactorily described by the Bragg diffraction law if the effective dielectric constant of the composite obtained by us is taken to be ε eff = 2.10. A suppression of fluorescence inside the stop-band and an increase in the shorter-wavelength fluorescence intensity are identified. The latter effect is explained by increasing role of radiative transitions through the surface states and impurity levels. The concentration of surface states increases essentially for the BBHQ embedded in the opal pores, and the impurity levels are formed by BBHQ molecules with substituted hydroxyl groups or with modified benzazole rings.
Abstract. We demonstrate the influence of structural defects present in opals on the Bragg reflection, the fluorescence and the Raman spectra. Based on the real opal structure, the relative ordering parameter is suggested as a criterion of sample quality. A 1D model of a periodic layered structure containing the defects typical for the synthetic opals is developed. Using a comparison of experimental and simulated reflection spectra, we show that the model can be brought closer to the real conditions if the elastic multiple scattering is taken into account within the model. To study the influence of defects on the spontaneous emission and the inelastic scattering, we have measured the fluorescence spectra of the dye R6G and the Raman spectra of Bi 12 SiO 20 incorporated in the synthetic opal. Amplification of both the fluorescence intensity for R6G and the Raman intensity for Bi 12 SiO 20 is observed for synthetic opal templates.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.