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A series of fluorotellurite glasses based on 70TeO2-5MxOy-10P²O5-10ZnO-5PbF2 in mol%, where MxOy = (WO3, Nb2O5) doped with 2400 ppm of Er2O3 have been prepared by the conventional melt quenching method. The influence of modifiers on thermal and optical properties of glasses has been analyzed. Thermal characteristics of glasses like the glass transition temperature Tg, the temperature for the crystallization onset Tx, the maximum crystallization temperature Tc, and the thermal stability parameter were determined by the DSC method. The ellipsometric data have provided Sellmeier-type dispersion relations of the refractive index of the investigated glasses. The optical parameters are used to calculate the molar refractivity, molar polarizability, oxide ion polarizability, molar cation polarizability, and a number of polarizable atoms per unit volume for every glass composition in order to interpret the refractive index of these glasses. [ABSTRACT FROM AUTHOR]

We have investigated the optical and spectroscopic properties of new Er 3+ -doped fluorotellurite glasses with the basic molar composition 75%TeO 2 -10%P 2 O 5 -10%ZnO-5%PbF 2 , modified by replacing 5%TeO 2 by four various metal oxides, namely MgO, PbO, SrO and CdO. The ellipsometric data have provided a Sellmeier-type dispersion relation of the refractive index of the investigated glasses. The optical absorption edge has been described within the Urbach approach, while the absorption and fluorescence spectra have been analyzed in terms of the standard Judd–Ofelt theory along with the photoluminescence decay of the 4 I 13/2 and 4 S 3/2 levels of the Er 3+ ion. The absorption and emission spectra of the 4 I 15/2 ↔ 4 I 13/2 infrared transition have been analyzed within the McCumber theory to yield the peak emission cross-section and figure of merit (FOM) for the amplifier gain. It appears that the glass containing MgO as a modifier is characterized by the largest FOM suggesting that the fluorotellurite matrix with this oxide can be a good novel host for Er 3+ ion doping. Finally, we propose a new simple method to calculate the mean transition energy of the McCumber approach as the arithmetic average of the barycenter wavenumbers of absorption and emission spectra. [ABSTRACT FROM AUTHOR]

We have investigated the thermal and spectroscopic properties of Er3+-doped fluorotellurite glass with the basic molar composition 75%TeO 2 –10%P 2 O 5 –10%ZnO–5%PbF 2 and the glasses modified by substituting 5%TeO 2 by a metal oxide, namely TiO 2 or BaO. As follows from the thermal studies, the glass containing TiO 2 as a modifier exhibits a higher stability against crystallization with respect to two other glasses. The ellipsometric data have provided a Sellmeier-type dispersion relation of the refractive index of the investigated glasses. The absorption and fluorescence spectra, along with the photoluminescence decay of the 4I 13/2 levels of the Er3+ ion, have been analyzed within the Judd–Ofelt and Fuchtbauer-Ladenburg approaches. It appears that the quantum efficiency of the 4I 13/2 → 4I 15/2 transition is quite high (above 70%), being the highest (97%) for the glass containing TiO 2 as a modifier. The absorption and emission cross-section results for the 4I 15/2 ↔ 4I 13/2 transition show that the glass containing TiO 2 is characterized by the largest figure of merit (FOM) for the amplifier gain and indicate this matrix as a promising new host for doping with rare-earth ions. • The DSC data indicate that the glass containing TiO 2 exhibits a much higher stability against crystallization in comparison to B 2 O 3. • Fluorotellurite glass containing TiO 2 and B 2 O 3 are characterized by the largest figure of merit for amplifier gain. • The theory of Judd-Ofelt and Fuchtbauer-Ladenburg approaches are presented. [ABSTRACT FROM AUTHOR]

Abstract: Aromatic polyazomethine (PPI) thin film have been obtained by chemical vapor deposition (CVD) method, via polycondensation process and characterized by X-ray diffraction, AFM, FTIR and detailed UV–Vis–NIR studies. Optical transmission and fundamental reflectivity spectra of the film have been examined within the spectral range 200–2500nm. The refractive index (n), film thickness (d) and parameters of the absorption edge i.e. the optical gap (E G) and the Urbach energy (E U) have been found for the PPI film before and after iodine (I2) doping. Then the annealing effect (from 25°C every 25°C up to 225°C) on the absorption edge have been investigated during “in situ” spectral measurements. Amorphous character of the films allowed us to obtain the E G and E U values, in the way typical for amorphous semiconductors. As a result of iodine doping, the energy gap of the PPI film (2.19eV) distinctly reduces to 1.73eV, due to the polaron states and, simultaneously, the Urbach energy decreases. Thermal stability of the pure PPI film, being the typical feature of polyazomethines, was confirmed, while after iodine doping the film turned out to be thermo-stable only below 100°C; then the distinct changes of the optical gap and the Urbach energy, connected with the iodine releasing process, have been presented and discussed. [Copyright &y& Elsevier]