Nm For Yb Research Articles

Efficient near-infrared down-conversion in KCaGd(PO_4)_2:Ce^3+,Yb^3+

Abstract: A novel near-infrared (NIR) quantum cutting KCaGd(PO4)2:Ce3+,Yb3+ phosphor was successfully developed. Due to the cooperative energy transfer from one Ce3+ to two Yb3+, an intense NIR emission around 1021 nm of Yb3+:2F5/2-2F7/2 transition was obtained under 324 nm excitation. Yb3+ concentration dependent quantum efficiency has been calculated and the theoretical maximum efficiency approaches up to 158.2%. Because the emission of Yb3+ around 1021 nm is matched with the band gap of crystalline Si, the phosphors could be a potential candidate for silicon-based solar cells.

Synthesis of Chlorin-Sensitized Near Infrared-Emitting Lanthanide Complexes

Lanthanide (Yb(3+), Nd(3+)) complexes equipped with red-absorbing hydroporphyrin (chlorin) antennae were synthesized and characterized. The syntheses are scalable, highly modular, and enable the introduction of different chlorins functionalized with a single reactive group (COOH or NH(2)). Absorption maxima were dependent on chlorin substitution pattern (monomeso aryl or dimeso aryl) and metalation state (free base or zinc chelate). The complexes benefit from dual chlorin (610-639 nm) and lanthanide (980 or 1065 nm for Yb- or Nd-complexes, respectively) emission in the biologically relevant red and near IR region of the spectrum.

Structural and luminescent study in lanthanide doped sol–gel glass–ceramics comprising CeF3 nanocrystals

Sol–gel derived glass–ceramics containing CeF3 nanocrystals have been developed for the first time, to the best of our knowledge, by adequate heat treatments of precursor bulk glasses with composition 95SiO2–5CeF3 doped with 0.1 Eu3+ or 0.1 Sm3+ and co-doped with 0.3 Yb3+ and 0.1 Er3+ ions (in mol%). X-Ray Diffraction and High Resolution Transmission Electron Microscopy confirm the precipitation of CeF3 nanocrystals. Moreover, this structural analysis is completed using Eu3+ and Sm3+ as probe ions of the different local environments for rare-earth ions in the nano-structured glass–ceramics. Luminescence measurements led us to discern the final environments for the ions, revealing the partition of a large fraction of these ions into like-crystalline environment of the precipitated CeF3 nanocrystals. Near infrared emission at 1.5 μm was observed after excitation at 980 nm in Yb3+–Er3+ co-doped samples for potential applications in telecommunications.

High efficient near-infrared quantum cutting in Ce 3+,Yb 3+ co-doped LuBO 3 phosphors

High efficient near-infrared (NIR) quantum cutting (QC) LuBO 3:Ce 3+,Yb 3+ phosphors had been synthesized by hydrothermal method with further heat treatment. Due to the cooperative energy transfer (CET) from one Ce 3+ to two Yb 3+ ions, an intense NIR emission around 971 nm of Yb 3+: 2F 5/2 → 2F 7/2 transition was obtained under 369 nm excitation. Yb 3+ concentration dependent quantum efficiency has been calculated and the maximum efficiency approaches up to 181% before reaching the critical concentration quenching threshold. Because the 971 nm emission of Yb 3+ is matched with the band gap of crystalline Si, the phosphors may be applied potentially in silicon-based solar cells.

Energy transfer rates and population inversion investigation of 1G4 and 1D2 excited states of Tm3+ in Yb:Tm:Nd:KY3F10 crystals

In this work we present the spectroscopic properties of KY3F10 (KY3F) single crystals activated with thulium and co-doped with ytterbium and neodymium ions. The most important processes that lead to the thulium up-conversion emissions in the blue and ultraviolet regions were identified. A time-resolved luminescence spectroscopy technique was employed to measure the luminescence decays and to determine the most important mechanisms involved in the up-conversion process that populates 1G4 and 1D2 (Tm3+) excited states. Analysis of the energy-transfer processes dynamics using selective pulsed-laser excitations in Yb:Tm:Nd, Tm:Nd, and Tm:Yb KY3F crystals show that the energy transfer from Nd3+ to Yb3+ ions is the mechanism responsible for the enhancement of the blue up-conversion efficiency in the Yb:Tm:Nd:KY3F when compared with the Yb:Tm system. A study of the energy transfer processes in Yb:Tm:Nd:KY3F crystal showed that the 1G4 excited level is mainly populated by a sequence of two nonradiative energy transfers that starts well after the Nd3+ and Tm3+ excitation at 797 nm according to: Nd3+ (4F3/2) → Yb3+ (2F7/2) followed by Yb3+ (2F5/2) → Tm (3H4) → Tm3+ (1G4). Results of numerical simulation of the rate equations system showed that a population inversion for 483.1 nm laser emission line is attained for a pumping rate threshold of 98 s−1, which is equivalent to an intensity of 3.3 KW cm−2 for a continuous laser pumping at 797 nm for Yb(30 mol%):Tm(0.5 mol%):Nd(1 mol%):KY3F. Nevertheless, best Yb3+ concentration for the laser emission near 483.1 nm was estimated to be within 40 and 50 mol%. On the other hand, a population inversion was not observed for the case of 960 nm (Yb3+) pumping.

All-fiber ultrashort Yb3+ doped fiber laser self-started by spectral filter

Theory of the passively mode-locked Yb3+ doped fiber ring laser self-starting through spectral filter is presented. The all-fiber Yb3+ doped fiber ring laser generating ultrashort pulses are designed and fabricated. High concentration Yb3+ doped fiber was employed as gain medium, which was pumped by a 980 nm diode laser. In the all-normal-dispersion cavity, a spectral filter was spliced to reduce the large emission peak at 1030 nm of Yb3+ ion and to generate an additional pulse shaping through spectral filtering of chirped pulse. Self-starting and stable mode-locking centered at 1053 nm was achieved by nonlinear polarization evolution along with spectral filtering from the filter. The mode-locking threshold was 300 mW, with the slope efficiency of 18.3%, the maximum output power was 53.07 mW, corresponding to the maximum pulse energy of 3.2 nJ. The center wavelength of the mode-locked pulse was 1053.6 nm, with 3 dB bandwidth of 10.84 nm at the repetition rate of 16.45 MHz. The picosecond mode-locked pulse can be dechirped to 188 fs using grating pair outside the cavity.

Broadband UV excitable near-infrared downconversion luminescence in Eu 2+/Yb 3+:CaF 2 nanocrystals embedded glass ceramics

Cooperative downconversion was realized in glass ceramics containing Eu 2+/Yb 3+:CaF 2 nanocrystals with Eu 2+ greatly absorbing ultraviolet photons. Upon excitation of Eu 2+ ions to the 5 d level with an ultraviolet photon at 320 nm, emission of two near infrared photons at 976 nm of Yb 3+ were achieved. The dependence of the visible and near-infrared emissions, decay lifetime, and quantum efficiency on the Yb 3+ doping content has been investigated. The maximum energy transfer efficiency and the corresponding downconversion quantum efficiency were estimated to be 51% and 151%, respectively.

Preparation and photoluminescence properties of RE:Na 3La 9O 3(BO 3) 8 ( RE=Er, Yb) crystals

Using Na 2CO 3–H 3BO 3–NaF as fluxes, transparent RE:Na 3La 9O 3(BO 3) 8 (abbr. RE:NLBO, RE=Er, Yb) crystals have been grown by the top seed solution growth (TSSG) method. The X-ray powder diffraction analysis shows that the RE:NLBO crystals have the same structure with NLBO. The element contents were determined by molar to be 0.64% Er 3+ in Er:NLBO, 2.70% Yb 3+ in Yb:NLBO, respectively. The polarized absorption spectra of RE:NLBO have been measured at room temperature and show that both Er:NLBO and Yb:NLBO have a strong absorption bands near 980 nm with wide FWHM (Full Wave at Half Maximum) (21 nm for Er:NLBO and 25 nm for Yb:NLBO). Fluorescence spectra have been recorded. Yb:NLBO has the emission peaks at 985 nm, 1028 nm and 1079 nm and the emission peak of Er:NLBO is at 1536 nm. Spectral parameters have been calculated by the Judd–Ofelt theory for Er:NLBO and the reciprocity method for Yb:NLBO, respectively. The calculated values show that Er:NLBO is a candidate of 1.55 μm laser crystals and Yb:NLBO is a candidate for self-frequency doubling crystal.

Magnetic tunnel contacts to silicon with low-work-function ytterbium nanolayers

Unambiguous proof of spin transport in semiconductor spintronic devices requires a control experiment to exclude spurious signals that arise from the presence of the ferromagnetic contacts. It is shown here that insertion of a low-work-function Yb nanolayer in ferromagnetic tunnel contacts to silicon allows a selective suppression of the tunnel spin polarization for 2 nm of Yb and simultaneous control of the Schottky barrier height. The insertion of a nonmagnetic nanolayer provides a versatile method to exclude artifacts and a solution for nanoscale devices or other geometries in which the frequently employed Hanle effect cannot be applied and a control experiment did not exist.

Optical properties of PMMA doped with erbium(III) and ytterbium(III) complexes

AbstractIn this article, we report the fabrication and optical/spectroscopic properties of polymethylmethacrylate (PMMA) doped with rare earth (RE) (Er3+ and Er3+/Yb3+) ions. Infrared spectroscopy revealed only very weak OH stretching vibration peaks in the samples, which is important if satisfactory photoluminescence is to be observed at 1530 nm. Measurement of transmission spectra in the wavelength ranges from 300 to 700 nm for Er3+‐doped samples and from 900 to 1050 nm for Yb3+‐doped samples enabled us to observe the 4G11/2 (377 nm) and 2H11/2 (519 nm) transmission bands typical for Er3+‐doped samples, as well as the 2F5/2 (975 nm) band typical for Yb3+‐doped samples. Under excitation at 980 nm, at room temperature, the characteristic Er3+ emission at 1530 nm was also observed with improving trend when the higher RE concentrations were applied. The results indicate that the PMMA reveals very low tendency to the RE clustering, which together with low cost and easy fabrication make it a material with a great potential in the active photonics devices. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Energy transfer between silicon–oxygen-related defects and Yb3+ in transparent glass ceramics containing Ba2TiSi2O8 nanocrystals

We report on the conversion of near-ultraviolet radiation of 250–350 nm into near-infrared emission of 970–1100 nm in Yb3+-doped transparent glass ceramics containing Ba2TiSi2O8 nanocrystals due to the energy transfer from the silicon–oxygen-related defects to Yb3+ ions. Efficient Yb3+ emission (F25/2→F27/2) was detected under the excitation of defects absorption at 314 nm. The occurrence of energy transfer is proven by both steady state and time-resolved emission spectra, respectively, at 15 K. The Yb2O3 concentration dependent energy transfer efficiency has also been evaluated, and the maximum value is 65% for 8 mol % Yb2O3 doped glass ceramic. These materials are promising for the enhancement of photovoltaic conversion efficiency of silicon solar cells via spectra modification.

Spectra, temporal structure, and angular directivity of laser radiation of a Yb:YAG crystal and ytterbium glass pumped by low-coherence radiation from a F2+:LiF colour centre laser

By focusing radiation from a F2+:LiF colour centre laser (emitting in the range from 0.89 to 0.95 μm) on plates of a Yb:YAG crystal with the 20% concentration of Yb and of ytterbium glass with the 10% concentration of Yb, we observed nanosecond radiation pulses of Yb3+ ions in the spectral region from 1.00 to 1.06 μm with the spectral width up to 20 nm in Yb:YAG and up to 50 nm in the ytterbium glass. Lasing appeared in the active medium in the region of excitation of the SBS of pump radiation with a diameter less than 200 μm. The angular divergence of the broadband laser radiation (10-3—10-4 rad) was one—two orders of magnitude smaller than the diffraction limit. The mechanism of generation of short broadband high-directional laser pulses in the spatial structure of thin layers with inversion produced in the region of propagation of an intense acoustic wave in the medium is discussed. The interpretation of experimental data on the angular divergence of radiation is based on a new concept of the spatial distribution of the electromagnetic field of a photon not in the form of a travelling wave but with the field structures located in fixed positions along the propagation direction. The features of the temporal picture and narrowband lasing spectra of Yb:YAG and ytterbium glass in a resonator upon relaxation of the SBS excitation region in the active medium are considered. The possibility of diagnostics of medium parameters using the shift of spectra of the lasing at the resonator modes in different sites of the SBS excitation region is discussed.

Wide colour gamut generated in triply lanthanide doped sol–gel nano-glass–ceramics

The generation of a wide colour gamut, based on up-conversion of cheap near-infrared photons into the visible range, is of great importance for general lighting appliances and integrated optical devices. Here, we report for the first time on up-conversion luminescence under infrared excitation at 980 nm in Yb3+–Er3+–Tm3+ triply doped sol–gel derived SiO2–LaF3 based nano-glass–ceramics (SOL-YET), containing LaF3 nanocrystals with a size about 13 nm. Efficient simultaneous up-conversion emission of the three primary colours (blue, green and red) gives rise to a balanced white overall emission. The ratio between up-conversion emission bands can be varied by changing pump power intensity resulting in colour tuneable up-conversion phosphor.

Luminescence behavior of Yb3+heavy-doped yttrium lanthanum oxide transparent ceramics

Yb 3+ heavy-doped yttrium lanthanum oxide transparent ceramics were fabricated and their spectroscopic properties were investigated. The absorption bands of (Yb x Y 0.9 − x La 0.1 ) 2 O 3 ( x = 0.05–0.15) ceramics are broad at wavelength of 900–1000 nm. The absorption cross-sections centered at 974 nm and the emission cross-sections at 1031 nm of Yb 3+ ion are 0.89–1.12 × 10 −20 cm 2 and 1.05 × 10 −20 cm 2 , respectively. The up-conversion luminescence intensity of Yb 3+ -doped yttrium lanthanum oxide ceramics increased firstly, then decreased with the increase of Yb 3+ ion content.

Efficient diode-pumped Yb^3+:Y_2SiO_5 and Yb^3+:Lu_2SiO_5 high-power femtosecond laser operation

We report the mode-locked operation of two new Yb-doped oxyorthosilicates, Y2SiO5 (YSO) and Lu2SiO5 (LSO), that are longitudinally diode pumped. Yb:YSO supplied pulses as short as 122 fs with 410 mW of output power at 1041 nm. More than 2.6 W of average output power, for pulse durations of 198 fs at 1044 nm and 260 fs at 1059 nm for Yb:YSO and Yb:LSO, respectively, were provided. These are, to our best knowledge, the highest values ever obtained and the most efficient mode-locked laser in such a classic fiber-coupled diode-pumping configuration.

Effects of Yb concentration on the fluorescence spectra of Yb-doped YAlO 3 single crystals

0.5 at.% Yb:YAlO 3(YAP), 5 at.% Yb:YAP and 15 at.% Yb:YAP were grown using the Czochralski method. Their absorption and fluorescence spectra were measured at room temperature and their emission line shape was calculated using the method of reciprocity. It was observed that the fluorescence spectra changed appreciably with the increasing of Yb concentration. For 0.5 at.% Yb:YAP, the line shape of fluorescence is very similar with the calculated emission line shape; with the increasing of Yb doping concentration, the line shape of fluorescence is very different from the calculated emission line shape. These phenomena are caused by the strong self-absorption at 979 and 999 nm for Yb:YAP.

Refine Yttria Powder and Fabrication of Transparent Yb,Cr:YAG Ceramics

Commercial Y2O3 powders were subjected to high energy ball milling in a planetary ball mill using high purity alumina balls and vial. The refined Y2O3 power ,with commercial high-purity Al2O3, Cr2O3 and Yb2O3 powders, were used as raw materials. Transparent ytterbium and chromium codoped yttrium aluminum garnet (Yb,Cr:YAG) ceramics were fabricated by a solid-state reaction method. The Yb,Cr:YAG ceramics exhibit a pore free structure and the average grain size is about 10 micron. The strong absorptions at 940 and 968 nm of Yb3+ are suitable for InGaAs diode laser pumping, and there is an absorption band at 1030 nm, which is suitable for passive Q-switch laser output at 1030 nm. Transparent Yb,Cr:YAG ceramics may be a potential material for compact, efficient, high-stability diode-laser-pumped passive Q-switched solid-state lasers.

Simultaneous cw dual-wavelength laser action and tunability performance of diode-pumped Yb 3+:Sr 5(VO 4) 3F

Simultaneous cw laser operation at 1044 and 1120 nm in Yb 3+:Sr 5(VO 4) 3F (SVAP) under diode pumping has been achieved for the first time. Output powers of 29.9 mW at 1044 nm and 26.5 mW at 1120 nm were obtained under simultaneous operation. A maximum output for each transition operating separately was 103 mW at 1044 nm and 157 mW at 1120 nm. In addition, we demonstrate over 27 nm of wavelength tunability of the 1120 nm band.

Near-Infrared Photoluminescence and Electroluminescence of Neodymium(III), Erbium(III), and Ytterbium(III) Complexes

Tris(dibenzoylmethanato)(monobathophenanthroline)lanthanide(III) complex [Ln(DBM)3 bath (Ln: Nd, Er and Yb)] both in solutions and thin films at room temperature showed narrow band photoluminescence (PL) due to the f–f transitions in the near-IR region: 890, 1070 and 1350 nm for Nd(III), 980 and 1540 nm for Er(III), and 985 nm for Yb(III). The PL efficiencies in solution were determined [φPL=3.3×10-3 for Nd(III), 7.0×10-5 for Er(III), and 1.4×10-2 for Yb(III)]. Organic electroluminescent (EL) devices having the structure of glass substrate/indium-tin oxide/N,N′-diphenyl-N,N′-di(m-tolyl)benzidine/Ln(DBM)3bath(Ln: Nd, Er and Yb)/bathocuproine/Mg:Ag/Ag were fabricated, giving the EL bands around 900–1600 nm at room temperature. The external near-IR EL efficiencies at low current density were estimated by comparing with that of the Eu(III) device having the same structure. The saturation of near-IR EL intensity observed at the high current density suggested that the near-IR EL should suffer the T–T annihilation.

Synthesis and thermal reactions of rhabdophane-(Yb or Lu)

Poorly crystalline rhabdophane-(Yb or Lu) was synthesized by precipitation from mixed aqueous solutions of Ln(NO 3) 3 (Ln = Yb or Lu), (NH 4) 2HPO 4, and citric acid with the mixing mole ratios of (NH 4) 2HPO 4/Ln(NO 3) 3 = 4 and citric acid/Ln(NO 3) 3 = 5 to 30, at pH 7 and 90°C for 7 to 30 days. However, unknown XRD peaks and C–O bond FTIR absorption peaks were observed for the precipitates. These peaks disappeared with increasing heating temperature up to 400°C in air, and single phase rhabdophane-(Yb or Lu) was obtained when heated at 400 to 800°C in air. Chemical formulas of the single phase rhabdophane were YbPO 4·0.4H 2O and LuPO 4·0.5H 2O, respectively. The water corresponding to 0.4H 2O (or 0.5H 2O) was zeolitic water. The lattice constants are a = 0.676 and c = 0.626 nm for Yb, and a = 0.674 and c = 0.630 nm for Lu. Rhabdophane-(Yb or Lu) changed into the xenotime structure above 860°C, which was stable even at 1800°C in air.