Fluorescence properties of Nd3+-doped tellurite glasses

Novel Multicomponent Titanate-Germanate Glasses: Synthesis, Structure, Properties, Transition Metal, and Rare Earth Doping

Novel multicomponent titanate-germanate glasses singly doped with transition metal (Cr³⁺) and rare earth ions (Eu³⁺) were synthesized and the glass transition temperatures and thermal stability parameters were determined using DSC measurements. X-ray diffraction analysis confirmed fully amorphous nature of the received samples. Their structural and optical properties were compared with germanate glasses without TiO₂. Correlation between local structure and optical properties in titanate-germanate glasses is well evidenced by FT-IR, Raman, EPR, and luminescence spectroscopy. In particular, luminescence spectra and their decays are examined for glass samples, where GeO₂ was partially substituted by TiO₂.

Rare earth-doped barium gallo-germanate glasses and their near-infrared luminescence properties

Near-infrared luminescence properties of Nd³⁺ and Ho³⁺ ions in barium gallo-germanate glasses have been reported. Several spectroscopic parameters for Nd³⁺ and Ho³⁺ ions have been determined from the Judd-Ofelt analysis and absorption/luminescence measurements. Quite large luminescence lifetime, quantum efficiency and stimulated emission cross-section have been obtained for the main ⁴F_3/2 → ⁴I_11/2 (Nd³⁺) and ⁵I₇ → ⁵I₈ (Ho³⁺) laser transitions of rare earths in barium gallo-germanate glasses. It suggests that barium gallo-germanate glass is promising for near-infrared laser application at emission wavelengths 1064 nm (Nd³⁺) and 2020 nm (Ho³⁺).

Spectroscopy and enhanced frequency upconversion in Nd3+-Yb3+ codoped TPO glasses: energy transfer and NIR to visible upconverter

TeO₂-Pb₃O₄ (TPO) glasses codoped with Nd³⁺ and Yb³⁺ ions have been fabricated by conventional melting technique. The absorption, emission and excitation spectra of the samples have been recorded. The optical band gap in both the doped/codoped glasses is found to be ∼3.31 eV. Judd-Ofelt analysis has been carried out by using the absorption spectrum of 0.8 mol% Nd³⁺ doped glass to determine the radiative properties viz radiative transition probabilities, branching ratios, radiative lifetimes, quality factor and emission cross sections of some emitting levels for Nd³⁺ ions. The radiative transition probability for the ⁴G_7/2 → ⁴I_9/2 transition (∼1926 Hz) is found to be maximum compared to other ⁴G_5/2 → ⁴I_9/2 (∼1622 Hz) and ⁴F_5/2 → ⁴I_9/2 (∼865 Hz) transitions. Upconversion (UC) luminescence of the samples has been examined by the 980 nm CW diode laser excitation. Effect of addition of Yb³⁺ ions in the Nd³⁺ doped glasses on UC emission intensity has been discussed. The UC emission intensity corresponding to the green, red and NIR bands in the codoped glass has been enhanced by ∼17, ∼12 and ∼42 times as compared to that of the Nd³⁺ singly doped glass. The quantum efficiency for the ⁴G_7/2 level is found to be ∼32%. The nephelauxetic ratio, bonding parameter and covalency of Nd³⁺ ions have been found positive which represents the covalent bonding between Nd³⁺ ion and oxygen atom. The colour tunability from yellowish-green to dominant green region has been obtained in the optimized codoped TPO glass.

Optical spectroscopy, 1.06μm emission properties of Nd3+-doped phosphate based glasses

Neodymium doped phosphate based glasses with composition of (P₂O₅+K₂O+Al₂O₃+CaF₂) were prepared. The samples were analysed through differential thermal analysis (DTA), Fourier transform infrared (FTIR), absorption, emission and decay measurements. Judd-Ofelt parameters (Ω_λ) have been determined from the spectral intensities of absorption bands in order to calculate the radiative parameters like radiative transition probabilities (A_R), radiative lifetime (τ_R) and branching ratios (β_R) for the ⁴F_3/2→⁴I_11/2 laser transition of Nd³⁺ ion. The effective emission bandwidths (Δλ_eff), experimental branching ratios (β_exp) and stimulated emission cross-sections (σ_e) have been determined from the emission spectrum. The decay curves of the ⁴F_3/2 level exhibited almost single exponential nature for all the Nd³⁺ ion concentrations.

Optical properties of Nd3+ doped bismuth zinc borate glasses

Glasses with compositions of (100-x) (Bi2ZnOB2O6) -x Nd2O3 (where x=0.1, 0.3, 0.5, 1 and 2 mol%) were prepared by melt quenching method and characterized through optical absorption, emission and decay curve measurements. Optical absorption spectra have been analyzed using Judd-Ofelt theory. The emission spectra exhibit three peaks at 919, 1063 and 1337 nm corresponding to (4)F3/2 to (4)I9/2, (4)I11/2 and (4)I13/2 transitions in the near infrared region. The emission intensity of the (4)F3/2 to (4)I11/2 transition increases with increase of Nd(3+) concentration up to 1 mol% and then concentration quenching is observed for 2 mol% of Nd(3+) concentration. The lifetimes for the (4)F3/2 level are found to decrease with increase in Nd2O3 concentration in the glasses. The decay curves of the glass up to 0.3 mol% of Nd(3+) exhibit single exponential nature and thereafter the curves become nonexponential nature (0.5, 1 and 2 mol%). The nonexponential curve has been fitted to the Inokuti-Hirayama model to understand the nature of energy transfer process.

Spectral study of the stimulated emission of Nd3+ in fluorotellurite bulk glass

In this work we present, for the first time to our knowledge, laser emission under wavelength selective laser-pulsed pumping in Nd(3+)-doped TeO(2)-ZnO-ZnF(2) bulk glass for two different Nd(3+) concentrations. The fluorescence properties of Nd(3+) ions in this matrix which include, Judd-Ofelt calculation, stimulated emission cross-section of the laser transition and lifetimes are also presented. The site-selective emission and excitation spectra along the (4)I(9/2)→(4)F(3/2) absorption band show the inhomogeneous behaviour of the crystal field felt by Nd(3+) ions in this fluorotellurite glass which allows for spectral tuning of the laser output pulse as a function of the pumping wavelength. The emission cross-section obtained from the Judd-Ofelt analysis and spectral data (4.9x10(-20) cm(2)) is in fairly good agreement with the value obtained from the analysis of the laser threshold data (4x10(-20) cm(2)).

Simple and sensitive detection method for Cobalt(II) in water using CePO4:Tb3+ nanocrystals as fluorescent probes

A simple and sensitive method for detecting cobalt by synchronous fluorescence spectrometry technique with a novel fluorescence probe CePO4:Tb(3+) has been developed. CePO4:Tb(3+) nanocrystals were synthesized in aqueous solutions and characterized by transmission electron microscopy, electron diffraction pattern spectroscopy and spectrofluorometry. When Δλ=210 nm, the selected synchronous fluorescence is produced at 284 nm. CePO4:Tb(3+) nanocrystals were negatively charged under weakly basic conditions (pH=8.2), which can interact with Co(2+) via electrostatic interaction. Moreover, there is the spectrum overlap between the emission wavelength of CePO4:Tb(3+) NCs and the absorbance of Co(2+). So the energy transfer would occur, leading to the quenching phenomenon. The quenching equation of the system was agreed with the Stern-Volmer equation. The linear range and detection limit of Co(2+) were 5-1.8 μM and 3.5 nM, respectively. The method is successfully applied to the quantification of Co(2+) in water samples.

Optical evaluation on Nd3+-doped phosphate glasses for O-band amplification

We have fabricated and characterized optically Nd3+-doped phosphate [Li2O-CaO-BaO-Al2O3-La2O3-P2O5 (LCBALP)] glasses for drawing single-mode glass fiber. The 4F3/2→4I13/2 transition emission from the Nd3+ is at the 1.327 μm wavelength with a full width at half-maximum of 43 nm, and the spontaneous transition probability and quantum efficiency are calculated to be 1836 s-1 and 52%, respectively. The maximum stimulated emission cross sections for 4F3/2→4I11/2 and 4F3/2→4I13/2 transitions are derived to be 1.82×10(-20) cm2 and 6.97×10(-21) cm2, respectively, and the theoretical gain coefficient at the 1.327 μm wavelength is evaluated to be 0.182 dB/cm when the fractional factor of the excited neodymium ions equals 0.6, which indicates that Nd3+-doped LCBALP phosphate glasses are potential candidates in developing O-band optical fiber amplifiers.

Spectroscopic characterization of alkali modified zinc-tellurite glasses doped with neodymium

Neodymium doped zinc-tellurite glasses of composition TeO(2)-ZnO-Na(2)O-Li(2)O have been prepared and characterized for their thermal, structural and optical properties. Differential thermal analysis revealed reasonably good forming tendency of the glass composition. FTIR spectra were used to analyze the functional groups present in the glass. Judd-Ofelt intensity parameters were derived from the absorption spectrum and used to calculate the radiative lifetime, branching ratio and stimulated emission cross-section for (4)F(3/2)-->(4)I(9/2, 11/2, 13/2) transitions. The quantum efficiency of the (4)F(3/2) level is comparable to the typical values obtained for the Nd(2)O(3)-doped glasses. The decay properties for higher concentration of Nd(2)O(3) were analyzed using Inokuti-Hirayama model to investigate the non-radiative relaxation of the (4)F(3/2) emitting level. The experimental values of branching ratio and saturation intensity of (4)F(3/2)-->(4)I(11/2) transition and calculated spectroscopic quality factor indicate the favourable lasing action in these glasses.

Investigation of concentration quenching and 1.3 microm emission in Nd(3+)-doped bismuth glasses

Nd(2)O(3)-doped 70Bi(2)O(3)-20B(2)O(3)-10SiO(2)-xNd(2)O(3) (x=0.1, 0.3, 0.5, 0.7, 1.0, 1.5 mol%) bismuth glasses were prepared by the conventional melt-quenching method, and the Nd(3+):(4)F(3/2)-->(4)I(13/2) fluorescence properties had been studied for different Nd(3+) concentrations. The Judd-Ofelt analysis for Nd(3+) ions in bismuth boron silicate glasses was also performed on the base of absorption spectrum. The transition probabilities, excited state lifetimes, the fluorescence branching ratios, quantum efficiency and the stimulated emission cross-sections of (4)F(3/2)-->(4)I(13/2) transition were calculated and discussed. Based on the electric dipole-dipole interaction theory, the interaction parameters: C(DD), for the energy migration rate (4)F(3/2), (4)I(9/2)-->(4)F(3/2), (4)I(9/2) and C(DA), for cross-relaxation rate (4)F(3/2), (4)I(9/2)-->(4)I(15/2), (4)I(15/2), and/or (4)F(3/2), (4)I(9/2)-->(4)I(13/2), (4)I(15/2) in bismuth boron silicate glasses were about 18.4 x 10(-40)cm(6)/s and 3.4 x 10(-40)cm(6)/s, respectively.