Search

Highlights: [•] Two-photon absorption of TlInSnSe single crystals. [•] Maximal TPA was achieved for x =0.1. [•] Size enhancement of TPA was up to 4 times. [ABSTRACT FROM AUTHOR]

Abstract: We have discovered an occurrence of optical second harmonic generation at 1064nm fundamental wavelength for the α-BaB2O4 (ABO) crystal illuminated by 7ns nanosecond nitrogen laser of 337nm. The effect is observed only during illumination and achieves the maximum SHG output after 15–20min of treatment. After switching off of the UV laser treatment the SHG decreases during about 5min. The maximum second order susceptibility achieved was equal to about 2.1pm/V at 1064nm after about 20min of UV laser treatment. The observed SHG is explained by local photothermal heating of the crystals and photo stimulated photothermal anisotropy that favors an occurrence non-centrosymmetry of the local charge density. An additional investigations of the low-power (cw) He–Ne laser light indicate the absence of additional light scattering, which unambiguously indicates an absence of any additional microcrystalline states including non-cenrosymmetrical β-BaB2O4 phases. Probably photostimulated enhancement of thermal expansion anisotropy the main reason for the observed non-centrosymmetry. [Copyright &y& Elsevier]

Highlights: [•] PbO–Al2O3–SiO2:Ho2O3 glasses with varying concentration of Al2O3 were synthesized. [•] Optical absorption, luminescence spectra and decay profiles were recorded. [•] The intensity of all Ho3+ emission bands increased with increasing Al2O3 content. [•] Increase is attributed to declustering of Ho3+ ions by Al3+ ions and self up-conversion. [ABSTRACT FROM AUTHOR]

Abstract: Complex refractive indices N = n +ik for a-cut Sr x Ba1−x Nb2O6 single crystals with four nominal values of composition x =0.40; 0.50; 0.61; 0.75 were studied by spectroscopic ellipsometry in the photon energy range 2–5eV of crystal transparency and fundamental electronic absorption. The ellipsometric data were evaluated taking into account an uniaxial anisotropy and an unintentional surface roughness. We use a global composition dependent Sellmeier fit as a reference for monitoring the crystals composition. The optical model yields indirect and direct optical band gap energies E g in the spectral range 3.77–4.03eV and 4.28–4.55eV, respectively, depending on the Sr/(Ba+Sr) content ratio x and light polarization. The congruently melting composition Sr0.61Ba0.39Nb2O6 shows distinct dispersion features in the imaginary part of the UV complex refractive index with respect to other compositions. [Copyright &y& Elsevier]