Compositional effects and spectroscopy of rare earths (Er3+, Tm3+, and Nd3+) in tellurite glasses

Sulfophosphate Glass Doped with Er3+ and TiO2 Nanoparticles: Thermo-Optical Characterization by Photothermal Spectroscopy

In this work, time-resolved thermal lens and beam deflection methods were applied to determine the thermo-optical properties of Er3+ doped sulfophosphate glass in which different concentrations of Titanium dioxide (TiO2) nanoparticles (NPs) were embedded. Thermal diffusivity (D), thermal conductivity (κ), and the temperature coefficient of the optical path length (ds/dT) were determined as a function of NPs concentrations. Moreover, the growth of TiO2 NPs inside the amorphous glass matrix was evidenced by Transmission Electron Microscopy (TEM) images as well as through optical effects such as refractive index change of the glass. The outcomes indicated relatively high values for D and κ as well as a low ds/dT as required for most optical components used for laser media. The addition of TiO2 NPs with concentration of dopants up to 0.6 mol% improved the optical properties of the glass samples but did not affect its thermal properties. The results indicate that the enhanced optical and thermal performance of the proposed co-doped glass fits the quality standards for materials used in photonic devices.

Highly NIR-emissive lanthanide polyselenides

Ln(SePh)(3) (Ln = Ce, Pr, Nd), prepared by reduction of PhSeSePh with elemental Ln and Hg catalyst, reacts with excess elemental Se to give (py)(11)Ln(7)Se(21)HgSePh, an ellipsoidal polyselenide cluster. The molecular structure contains two square arrays of eight- or nine-coordinate Ln fused at one edge to form a V shape that is also capped on the concave side by a centrally located nine-coordinate (Se(3))pyLn(Se(3)) and on the convex side by a 2-fold disordered SeHgSePh. The central Ln coordinates to selenido, triselenido, and pyridine ligands, while all other Ln coordinate to selenido, diselenido, triselenido, and pyridine ligands. Thermal treatment of the Pr compound at 650 °C gave Pr(2)Se(3) and Pr(3)Se(4). NIR emission studies of the Nd compound show four transitions from the excited-state (4)F(3/2) ion to (4)I(9/2), (4)I(11/2), (4)I(13/2), and (4)I(15/2) states. The (4)F(3/2) ion to (4)I(11/2) transition (1075 nm emission) exhibited 43% quantum efficiency. This is the highest quantum efficiency reported for a 'molecular' Nd compound and leads a group of selenide-based clusters that has shown extraordinary quantum efficiency. In terms of efficiency and concentration, these compounds compare favorably with solid-state materials.

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.

Lanthanide clusters with chalcogen encapsulated Ln: NIR emission from nanoscale NdSe(x)

Ln(SePh)(3) (Ln = Ce, Pr, Nd) reacts with elemental Se in the presence of Na ions to give (py)(16)Ln(17)NaSe(18)(SePh)(16), a spherical cluster with a 1 nm diameter. All three rare-earth metals form isostructural products. The molecular structure contains a central Ln ion surrounded by eight five-coordinate Se(2-) that are then surrounded by a group of 16 Ln that define the cluster surface, with additional μ(3) and μ(5) Se(2-), μ(3) and μ(4) SePh(-), and pyridine donors saturating the vacant coordination sites of the surface Ln, and a Na ion coordinating to selenolates, a selenido, and pyridine ligands. NIR emission studies of the Nd compound reveal that this material has a 35% quantum efficiency, with four transitions from the excited state (4)F(3/2) ion to (4)I(9/2), (4)I(11/2), (4)I(13/2), and (4)I(15/2) states clearly evident. The presence of Na(+) is key to the formation of these larger clusters, where reactions using identical concentrations of Nd(SePh)(3) and Se with either Li or K led only to the isolation of (py)(8)Nd(8)Se(6)(SePh)(12).

Index matching between passive and active tellurite glasses for use in microstructured fiber lasers: erbium doped lanthanum-tellurite glass

Active and passive variants of La-containing tellurite glasses have been developed with matched refractive indices. The consequences of adding lanthanum to the glass was studied through measurements of the crystallization stability, glass viscosity and the loss of unstructured fibers. Doping the glass with erbium allowed for any spectroscopic changes to be observed through measurements of the absorption and energy level lifetimes. The fluorescence emission spectra were measured at 1.5 microm and, to the best of our knowledge, for the first time in tellurite glass at 2.7 microm.

Enhanced broadband near-infrared emission and energy transfer in Bi-Tm-codoped germanate glasses for broadband optical amplification

Bi-Tm-codoped, and Tm- and Bi- singly doped germanate glasses were prepared, and their luminescent properties were investigated. Intense broadband near-IR emission with FWHM of 300 nm was observed in the Bi-Tm codoped glass. The emission intensity of Tm(3+):(3)H(4)-(13)F(4) and (3)F(4)-(13)H(5) transitions in the Bi-Tm-codoped glass was highly increased and reduced, respectively. The fluorescence lifetime of Tm(3+) at 1470 nm increased from 204 micros to 301 micros after codoping. These should be due to the efficient energy transfer from Bi-related centers to Tm(3+) ions. The highest energy transfer efficiency is estimated to be approximately 50%.

Tm(3+)/Yb(3+)co-doped tellurite glass for broadband optical amplifying over S+L bands

A kind of novel fluorescence which possesses a potential application in wide-band optical amplifying is reported in this paper. With 975-nm LD laser pumping and Yb(3+)-assisted energy transferring, the fluorescence of Tm(3+)in the tellurite glass can be measured with emission spectra in 1.4- and 1.6- microm bands, which would be continued to the 1.53 microm of the Er(3+). The full-width at half-maximum (FWHM) is 170 nm(110 + 60nm), and the lifetimes come up to 0.66 and 1.46 ms. Then, an interpretation was given to the mechanism of IR fluorescence emission which is based on the energy transferring and up-conversion of Tm(3+), Yb(3+) and Er(3+).

Oxoselenido Clusters of the Lanthanides: Rational Introduction of Oxo Ligands and Near-IR Emission from Nd(III)

Reactions of Ln(SePh)3 with SeO2 in THF give octanuclear oxoselenido clusters with the general formula (THF)8Ln8O2Se2(SePh)16 (Ln = Ce, Pr, Nd, Sm). In this isomorphous series, the eight Ln(III) ions are connected in the center by a pair of mu3-O2- ligands and mu5-Se2- ligands, with 14 bridging and two terminal selenolate ligands capping the cluster surface. Thermal decomposition at 700 degrees C of the Nd compound in vacuo led to the formation of a phase mixture of NdSe2, Nd2Se3, and Nd2O3. Near-IR emission experiments on the (THF)8Nd8O2Se2(SePh)16 and the fluorinated thiolate compound (DME)2Nd(SC6F5)3 demonstrate that clusters with oxo ligands are not only highly emissive, but also they emit at wavelengths not found in conventional oxides.

Study of luminescence properties of novel Er3+ single-doped and Er3+/Yb3+ co-doped tellurite glasses

The novel Er(3+) single-doped and Er(3+)/Yb(3+) co-doped tellurite glasses were prepared. The effect of Yb(2)O(3) concentration on absorption spectra, emission spectra and upconversion spectra of glasses were measured and investigated. The emission intensity, fluorescence full width at half maximum (FWHM) and upconversion luminescence of Er(3+) go up with the increasing concentration of Yb(3+) ions. The maximum FWHM of (4)I(13/2) --> (4)I(15/2) transition of Er(3+) is approximate 77 nm for 1.41 x 10(21)ions/cm(3) concentration of Yb(3+)-doped glass. The visible upconversion emissions at about 532, 546 and 659 nm, corresponding to the (2)H(11/2) --> (4)I(15/2), (4)S(3/2) --> (4)I(15/2) and (4)F(9/2) --> (4)I(15/2) transitions of Er(3+), respectively, were simultaneously observed under the excitation at 970 nm. Subsequently, the possible upconversion mechanisms and important role of Yb(3+) on the green and red emissions were discussed and compared. The results demonstrate that this kind of tellurite glass may be a potentially useful material for developing potential amplifiers and upconversion optical devices.