Search results for "glasses"

Electron microprobe technique for the determination of iron oxidation state in silicate glasses

2018

We present a new calibration for the determination of the iron oxidation state in silicate glasses by electron probe microanalysis (EPMA) with the "flank method." This method is based on the changes in both intensity and wavelength of the FeLα and FeLβ X-ray emission lines with iron oxidation state. The flank method utilizes the maximum difference for the FeLα and FeLβ spectra observed at the peak flanks between different standard materials, which quantitatively correlates with the Fe2+ content. Provided that this correlation is calibrated on reference materials, the Fe2+/ΣFe ratio can be determined for samples with known total Fe content. Two synthetic Fe-rich ferric and ferrous garnet end…

Tellurites fibers for infrared supercontinuum sources : opto-geometric profiles and extrinsic absorptions management

2016

This PhD thesis work focuses on the synthesis and purification of vitreous materials used for the development of waveguides with varied profiles, dedicated to supercontinuum (SC) generation between 1 and 5 μm.Concerning the purification of tellurite glasses, several leads were followed, but best results are obtained for the purification of the TeO2-ZnO-Na2O glassy system by the means of zinc fluoride. Attenuation measurements performed on several meter-long single-index fiber samples reveal the nearly complete elimination of water-related absorptions between 3 and 4 μm (OH ions concentration lower than 1 ppm mass.). Such water-purified glasses were firstly dedicated to microstructured optic…

Fibres optiques à coeur supendu en verre d'oxyde de tellure et génération d'effets non linéaires dans l'infrarouge au-delà de 2 microns

2012

The work reported in this thesis deals with the fabrication of suspended core tellurite microstructured optical fibers (MOFs) for supercontinuum generation beyond 2 µm. In order to reach our aim, we first studied thermal and optical properties of TeO2-ZnO-R2O and TeO2-WO3-R2O (where R = Li, Na and K) glasses. The glass 80TeO2-10ZnO-10Na2O (molar %) has been chosen in order to make MOFs for characterization of the generated non linear optical effects. Synthesis performed under dry and oxidative atmosphere allowed us to reduce the hydroxyl groups concentration by a factor of 30 compared to fabrication in air atmosphere. Use of dehydrating agents (ZnF2 and TeCl4) allowed to reduce again the OH…

2D+1 spatial solitons in heavy metal oxide glass

2007

Two-dimensional self-confinement of near-infrared picosecond pulsed beams is demonstrated in a novel heavy metal-oxide glass, three-photon absorption being the stabilization mechanism to prevent catastrophic collapse.

Nonlinear optical properties of low molecular organic glasses formed by triphenyl modified chromophores

2012

The series of organic molecular glasses have been studied as possible candidates for nonlinear optical (NLO) applications. Amorphous phase formation of investigated materials is ensured by the presence of bulky triphenyl substituents in molecular structure of NLO chromophores. Linear optical properties as well as NLO coefficients and thermal stability of NLO activity for the 13 molecular materials in glassy thin solid films have been determined. For the benzylidene-1,3-indandione chromophore containing compound the highest d33 value equal to 280 pm/V was measured under the 1064 nm excitation. Among the investigated compounds uppermost achieved thermal sustainability of NLO response was 108 …

Dynamics of supercooled liquids and glassy solids

2001

ESR response of watch glasses to neutron irradiation

2012

Abstract In this paper we report the results of the electron spin resonance (ESR) study of the radiation-induced signal of watch glasses exposed to neutrons. This work extends the series of analyses of the response of watch glasses to various radiation beams which our research group is carrying out for possible applications in retrospective dosimetry. We have considered fluences up to about 3 × 1011 cm−2. We evaluated the signal fading and we found that in the first hours after exposure the signal rapidly decreases. After about 1000 h, it decreases much more slowly. The signal was reduced by about 25% in about 5 months. The radiation induced signal is found to be linearly dependent on neutr…

Ultraviolet-induced paramagnetic centers and absorption changes in singlemode Ge-doped optical fibers

2009

We investigated the laser-energy-density dependence of absorption changes and paramagnetic centers induced by a cw Ar+ laser operating at 5.1 eV, in both unloaded and H-2-loaded single mode Ge-doped optical fibers. The induced absorption is measured in the blue and near ultraviolet spectral range by using the 3.1 eV photoluminescence, ascribed to Ge lone pair center (GLPC), as an in situ probe source. We find that the Ge (1) center (GeO4-) is induced upon UV exposure by electron trapping on GeO4 precursors, where the free electrons are most likely produced by ionization of GLPC. Ge (1) is responsible of optical transmission loss of the fiber in the investigated range. Hydrogen loading stron…

Clinical guidelines for diagnosing and managing ocular manifestations in children with mucopolysaccharidosis.

2011

The mucopolysaccharidoses (MPS) are a group of rare lysosomal storage disorders characterized by the accumulation of glycosaminoglycans in several tissues and organs. This accumulation results in an array of clinical manifestations and premature death in severe cases. Ocular problems are very common in children with MPS and may involve the cornea, sclera, trabecular meshwork, retina, optic nerve and also the posterior visual pathways. The aims of this study are to give an overview of ocular problems in MPS and to provide clinical guidelines for paediatric ophthalmologists for early diagnosis and management of ocular manifestations in children with MPS. Diagnostic problems may arise in child…

Glass-Forming Nonsymmetric DWKdyes with 5,5,5-Triphenylpentyl and Piparazine Moieties for Lightamplification Studies

2018

This work has been supported by the European Regional Development Fund within the Activity 1.1.1.2 “Post-doctoral Research Aid” of the Specific Aid Objective 1.1.1 “To increase the research and innovative capacity of scientific institutions of Latvia and the ability to attract external financing, investing in human resources and infrastructure” of the Operational Programme “Growth and Employment” (No. 1.1.1.2/VIAA/1/16/035). Financial support provided by A. Riekstins SIA “Mikrotīkls” donation, administered by the University of Latvia is greatly appreciated. There are no conflicts of interest to declare.