Spectroscopic properties of Sm3+ doped sodium-tellurite glasses: Judd-Ofelt analysis

Modifying the optical response of rare earth doped inorganic glasses for diverse optical applications is the current challenge in materials science and technology. We report the enhancement of the visible emissions of the Sm3+ ions doped sodium-tellurite (TNS) glasses. The impacts of varying Sm3+ ions concentration on the spectroscopic properties of such glass samples are evaluated. Synthesized glass samples are characterized via emission and absorption measurements. The UV–Vis–NIR absorption spectra revealed nine absorption peaks which are assigned to the transitions from the ground level (6H5/2) to 6P3/2, 4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6F1/2 excited energy levels of Sm3+ ions. Emission spectra of the prepared glass under 404 nm excitation wavelength consisted of four bands centered at 561 nm, 598 nm, 643 nm and 704 nm which are originated from 4G5/2→6HJ (J = 5/2, 7/2, 9/2 and 11/2) transitions. The experimental oscillator strengths, fexp are calculated from the area under absorption bands. Using Judd-Ofelt theory and fit process of least square, the phenomenological intensity parameters Ωλ (λ = 2, 4, 6) are obtained. In order to evaluate potential applications of Sm3+ ions in telluride glasses, the spectroscopic parameters: radiative transition probability AR, branching ratio BR, radiative life time τr and stimulated emission cross section σλ for each band are calculated. These glass compositions could be a potential candidate for lasers

Plasmon-enhanced luminescence of samarium doped sodium tellurite glasses embedded with gold nanoparticles: Judd-Ofelt parameter

A series of samarium doped sodium tellurite glass embedded with gold nanoparticles (Au NPs) in the composition (79-x)TeO2−20Na2O-1Sm2O3-xAuCl3 (x=0, 0.2, 0.4, 0.6, 0.8, 1 mol%) are prepared using conventional melt quenching technique. The UV–Vis–NIR absorption spectra shows 9 bands corresponding to transition bands from ground state 6H5/2 to excited states 6P3/2, 4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6F1/2 in which the most intense bands are 6F9/2, 6F7/2, 6F5/2 and 6F3/2. The homogeneous distribution of spherical and non-spherical Au NPs (average size ~3.36±0.076 nm) in the glassy matrix is evidenced from the transmission electron microscopy (TEM). The absorption spectrum of Sm3+ ions free glass sample containing Au NPs displays a two prominent surface plasmon resonance (SPR) band located at ~550 nm and ~590 nm. The infrared to visible frequency down conversion emission under 404 nm excitation shows four emission bands centered at 577 nm, 614 nm, 658 nm and 718 related to the transitions 4G5/2→6H5/2, 4G5/2→6H7/2, 4G5/2→6H9/2 and 4G5/2→6H11/2 respectively, corresponding to Sm3+ transitions. An enhancement in down conversion emission intensity of both green and red bands is observed in the presence of gold NPs either by increasing annealing time or by NPs concentration, the enhancement in photoluminescence (PL) intensity of glass containing 0.4 mol% Au (as to be compared with glass without Au) shows the maximum enhancement by a factor of 1.90:1.82:1.97:2.25 times for all transitions band. The enhancement is mainly ascribed to the highly localized electric field of Au NPs positioned in the vicinity of Sm3+ ion. The enhancement of down conversion emission is understood in terms of the intensified local field effect due to gold NPs. The Judd-Ofelt parameters (Ωλ, λ= 2, 4, 6) are calculated that is used to estimate the important parameters such as total radiative transition probability (AT), stimulated emission cross-section (σpE), radiative lifetime (τR) and branching ratio (βR) for the excited levels of Sm3+ ions in the glass. Furthermore, the value of Ω2 for the studied glasses is found higher than that of glasses reported in the literature. These relatively higher values of Ω2 reflect low symmetry and high covalency around the Sm3+ ions. We assert that these tellurite glass nanocomposites can be used for developments of the solid-state lasers and nanophotonics applications

Spectroscopic investigations of near-infrared emission from Nd3+-doped zinc-phosphate glasses: Judd-Ofelt evaluation

Zinc-phosphate glasses doped with different concentrations of Nd 3+ ions have been prepared by the melt quenching technique and characterized the spectroscopic properties. The physical properties by means of density and molar volume are determined. The amorphous nature of the glasses has been confirmed by X–ray diffraction analysis. FTIR spectra exhibited the fundamental stretching vibrations modes of glass network. In order to study the spectroscopic properties of fabricated glasses, absorption and emission spectroscopy has been performed. Additionally, the spectroscopic properties of Nd 3+ ions were analyzed using J–O theory. UV–Vis–NIR absorption spectra of glass samples divulged twelve significant peaks. Considerable enhancement of Ω 2 values with increasing neodymium content indicated an improvement in the covalency and asymmetry of Nd 3+ ions environment. Under the excitation of 808 nm laser diode, two near-infrared emission bands at around 890 and 1060 nm from 4 F 3/2 → 4 I 9/2 and 4 I 11/2 radiative transitions respectively were observed in the Nd 3+ single doped glasses. The major intensity is observed for 1060 nm for such glass samples. Nd 3+ ions dopant is found to augment the luminescence intensity by a factor as much as 2.23 times as the concentration of Nd 3+ ions increase up to 1.5 mol%. The lifetimes of this level has been experimentally determined through decay profile studies. The developed glass possesses high fluorescence quantum efficiency (η = 96%). The results indicate that the prepared glass system could be a suitable candidate for using it as laser gain media around 1060 nm, solid-state lasers and fiber amplifiers