Publications

2007

• OPTICS OF SUBWAVELENGTH GRADIENT NANOFILMS
  
  • Shvartsburg A.B.
  • Kuzmiak V.
  • Petite G.
  Physics Reports, Elsevier, 2007, 452 (2-3), pp.33-88. Propagation and tunneling of light through subwavelength photonic barriers, formed by dielectric layers with continuous spatial variations of the dielectric susceptibility across the film are considered. Effects of giant heterogeneity-induced non-local dispersion, both normal and anomalous, are examined by means of a series of exact analytical solutions of the Maxwell equations for gradient media. Generalized Fresnel formulae, showing a profound influence of the gradient and curvature of dielectric susceptibility profiles on the reflectance/transmittance of periodic photonic heterostructures, are presented. Depending on the cutoff frequency of the barrier, governed by the technologically managed spatial profile of its refractive index, propagation or tunneling of light through it is examined. Non-attenuative transfer of electromagnetic energy by evanescent waves, tunneling through dielectric gradient barriers characterized by real values of the refractive index decreasing into the interior of the medium, is shown. Scaling of the results obtained for different spectral ranges of visible, IR and THz waves is illustrated. The potential of gradient optical structures for the design of miniaturized filters, polarizers and frequency–selective interfaces of subwavelength thickness is considered
• Optical properties and valence state of Sm ions in aluminoborosilicate glass under β-irradiation
  
  • Malchukova E.
  • Boizot B.
  • Petite G.
  • Ghale D.
  Journal of Non-Crystalline Solids, Elsevier, 2007, 353 (24-25), pp.2397-2402. Sm-doped borosilicate glasses exposed to β-irradiation with doses from 8 × 105 up to 4 × 109 Gy have been studied by luminescence, Raman and electron paramagnetic resonance (EPR) spectroscopies. The luminescence spectra for pristine and irradiated glasses reveal that the β-irradiation process affects valence state of samarium ions. Intense emission at 684 and 727 nm excited by Ar+ laser (514.5 nm) due to the transition of Sm2+ ion was observed after irradiation. Relative proportion of Sm2+ ions estimated as a function of both Sm2O3 content and irradiation dose has the tendency to increase with increasing irradiation dose. In contrast, the EPR spectra of the studied samples reveal a decrease of the defect content, which are mostly hole defects, produced during irradiation, as a function of Sm2O3 content. Finally, the addition of Sm2O3 leads to a decrease of the Si–O–Si bending vibration modes shift and polymerisation changes under irradiation