El Sayed Yousef

Raman, green and infrared emission cross-sectionsof Er 3+ doped TZPPN tellurite glass

The spectroscopic properties of Er3‏+ ion in tellurite glass of molar composition 76TeO2∙10ZnO∙9.0PbO∙1.0PbF2∙3.0Na2O∙1.0Er2O3 was investigated experimentally. The three phenomenological intensity parameters Ωk (k = 2, 4, 6) were determined from the absorption spectral intensities using the Judd-Ofelt (J-O) theory. Several radiative properties such as spontaneous transition probabilities, fluorescence branching ratios and radiative life times were determined by using these intensity parameters. The special attention was attributed to the visible emissions that could be obtained by pumping using a blue laser diode. The stimulated emission cross-section and CIE chromaticity coordinates were calculated. The latter were used to evaluate green light emitting by Er:TZPPN glass. Subsequently, the stimulated emission cross-section, around 1.5 μm, was calculated from McCumber theory. Gain cross-section for laser transition 4I13/2→ 4I15/2 of Er3+-ions was obtained. In comparison with other Er-doped laser glasses, the calculated parameters show that Er:TZPPN glass satisfies the fundamental spectral condition for laser emission around 1.5 μm. Moreover the Raman gain coefficient of the present glass was obtained from Raman scattering experiments using 532 nm excitation [(532 nm Laser type Diode-pumped, solid state (DPSS)]. The developed glass showed the widest bandwidths of gain cross section from 249 to 1,106 cm−1.

Thermal stability and UV–Vis-NIR spectroscopy of a new erbium-doped fluorotellurite glass

A new transparent bulk glass from the system 76TeO2 · 10ZnO · 9.0PbO · 1.0PbF2 · 3.0Na2O doped with Er3+ (TZPPN doped with Er3+) has been prepared using the conventional melt-quenching method. Results of differential thermal analysis (DTA) measurements indicate good thermal stability of this glass. The refractive indices at different wavelengths, the optical energy gap, the Sellmeier gap energy and the dispersion energy have been estimated. The Judd–Ofelt parameters, Ω t (t = 2, 4, 6) of Er3+ were evaluated from optical absorption spectra. Electric dipole, magnetic dipole type transition probabilities, spectroscopic quality factors, branching ratio and radiative lifetimes of several excited states of Er3+ have been predicted using intensity Judd–Ofelt parameters. The spectroscopic properties indicate that TZPPN glass doped with Er3+ is a promising candidate for laser applications and may be suitable for upconversion fibre optical devices.

Spherical NiO Nanoparticles (SNPs): Synthesis, Characterization, and Optical Properties

Spherical NiO nanoparticles have been synthesized by a simple and modified solvothermal method using NiCl2·6H2O and urea. After the precursor was calcined in the air, NiO could be obtained. Structural, optical, and morphological characterizations were done by x-ray powder diffraction, ultraviolet–visible (UV–vis) spectroscopy, and scanning electron microscopy. Fourier-transform infrared (FTIR) studies show a broad absorption around 422–425 cm−1 corresponding to a surface-active mode, indicating the nanocrystalline nature of the oxide. The values of some important physical parameters of material are determined, such as refractive index (n), dielectric constant (ϵ), ratio of molar volume (Vm) and molar refraction (Rm), and metallization criterion (M(n)).