Transition Of Yb3 Research Articles

Near-infrared quantum cutting in Pr3+/Yb3+ co-doped transparent tellurate glass via two step energy transfer

A series of Pr3+/Yb3+ co-doped transparent tellurate glass samples were prepared by high-temperature melting method. The optical properties and energy transfer process from Pr3+ to Yb3+ were investigated. On excitation of Pr3+ ions with a blue visible photon at 449nm, a near infrared emission at 1001nm were observed in the Pr3+/Yb3+ co-doped tellurate glass, which is attributed to 2F2/5→2F2/7 transition of Yb3+ ions. The feeding of Yb3+ ions is shown to be two step energy transfer from Pr3+ through 1G4 multiplet by excitation and emission spectra. The maximum total quantum efficiency reaches 136.7% when the co-doped Yb3+ mole concentration is 5%. The efficient down-conversion near infrared emission of Pr3+/Yb3+ co-doped tellurate glass has potential application in enhancing the conversion efficiency of crystalline silicon based solar cells.

Growth, luminescence and energy transfer studies of Pr3+, Yb3+ co-doped CaYAlO4 single crystal

Abstract Pr3+, Yb3+ co-doped CaYAlO4 (Pr, Yb: CYA) single crystal was grown using the Czochralski (CZ) method. For near-infrared quantum-cutting system, a quantum efficiency of 145% for Pr3+, Yb3+-codoped CYA crystal has been obtained by ignoring the nonradiative losses. Under excitation at 940 nm, high intensities of 502 nm, 555 nm, 628 nm, 661 nm and 729 nm emissions turn up. Fluorescence decay time of 3P0→3F2 emission of Pr3+ ions and 2F5/2→2F7/2 transition of Yb3+ ions were also studied as evidences for energy transfer.

Upconversion emission in a carbon-implanted Yb:YAG planar waveguide

Light confinement and spectroscopic properties of a Yb:YAG planar waveguide fabricated by ion implantation were investigated. Under 970nm excitation, cooperative upconversion and near infrared luminescence were observed. The interaction between Yb3+ ion pairs was responsible for the appearance of a blue–green band centered at 514nm. However, several more bands in the blue, green and red regions were detected and are related to Er3+ and Tm3+ ion impurities. The upconversion emission of such ion impurities is explained in terms of an efficient energy transfer from Yb3+ to Er3+ and Tm3+ due to high Yb3+ concentration. The stimulated emission cross section for the 2F5/2→2F7/2 transition of Yb3+ was 1.9×10−20cm2. The fluorescence lifetime of the 2F5/2 level and that of the blue–green band were 1.28ms and 593μs respectively. The self-convolution of IR emission was calculated and the result shows that the main peak is centered at 514nm. Such self-convolution and the fact that the blue–green band lifetime is half the IR lifetime are good evidences for cooperative emission of Yb3+ ion pairs.

Yb^3+ ion concentration effects on ∼1 μm emission in tellurite glass

The effects of Yb3+ ion concentration on physical, optical, and spectroscopic properties have been studied in a low phonon (∼590 cm−1) barium-lanthanum-tellurite glass. Due to the unfeasibility of Judd-Ofelt theory Yb3+-doped systems, the oscillator strength of absorption transition, F27/2→F5/22 has been evaluated by using the Smakula equation. The nature of emission from F25/2→F7/22 transition of Yb3+ ions is described theoretically by using a rate equation in comparison with experimental results. By applying reciprocity (RM) and Fuchtbauer-Ladenburg methods on emission spectra as well as the excitation random walk model on measured fluorescence lifetimes, the radiation trapping and concentration quenching effects have been discussed. Considering all the spectroscopic and laser performance parameters, an optimum Yb-ion doping concentration (YT1) has been determined, and the gain measurements performed on the sample revealed a flat gain over a broad wavelength range could be achieved even with a low (∼20%) excitation population density. A comparative study with other hosts revealed the potentiality of the present glass for ∼1 micron emission.

Preparation of Yb3+ doped GdPO4 nanoparticles by solution-based processing

Yb3+ doped GdPO4 (GdPO4:Yb3+) nanoparticles are prepared in glycol solvent by autoclave treatment at 230 °C for 120 min. According to X-ray diffraction (XRD) patterns, the sample prepared in ethylene glycol is monazite-type GdPO4:Yb3+ without crystal water, while the sample prepared in 1,4-butanediol is rhabdophane-type GdPO4:Yb3+ with crystal water. The former shows more intense near infrared photoluminescence due to the f-f transition of Yb3+ in comparison with the latter. These results indicate that quenching of Yb3+ emission is attributed to energy dissipation due to the O-H vibration of crystal water. When the samples are prepared in ethylene glycol by autoclave treatment at 230 °C for different aging time, the crystallization degree estimated from integrated intensities of XRD peaks increases with increasing aging time. At the same time, the Yb3+ emission becomes strong. We found out that the photoluminescence intensity is linearly related with the crystallization degree.

Effects of magnetic field and pressure on the intermediate valence state of YbPd

High field magnetization, magnetoresistance and pressure effects of magneticsusceptibility, thermal expansion and electrical resistivity were examined for theintermediate valence system YbPd, which undergoes two first-order transitions atT1 = 125 K andT2 = 105 K. Analyses of high field magnetization suggest that half of the Yb atomshave magnetic moments below 100 K up to 55 T. The Yb valence stateand the first-order transitions are stable up to 55 T. On the other hand,T1 andT2 decrease with increasing pressure and the first-order transitions disappear ataround 4 GPa. Above the critical pressure, the experimental results suggest that theintermediate valence state persists down to the lowest temperature or a heavyfermion state is formed. We will show that most experimental results are explainedreasonably by assuming the first-order transitions as a valence order transition ofYb. The magnetic ordering temperature is decreased with increasing pressure,in contrast to other Yb intermediate valence or Kondo systems. This may becorrelated with the instability of the valence ordered state in this compound.

Cooperative Quantum Cutting in Yb$^{3+}$–Tb$^{3+}$ Codoped Borosilicate Glasses

Quantum cutting down-conversion (DC) with the emission of two near-infrared photons for each blue photon absorbed is realized in Yb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -Tb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> codoped borosilicate glasses. With the excitation of Tb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ion by a 484-nm monochromatic light, emission from the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5/2</sub> rarr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7/2</sub> transition of Yb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions is observed and this emission is proved to originate from the DC between Tb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions and Yb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions. Results shows that maximum quantum efficiency reach as high as 153%, which is comparable with that in oxyfluoride glass ceramics in this system. With the advantages of excellent transparence, easy shaping, good stability, and low cost, Yb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -Tb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> codoped borosilicate glasses are potentially used as down-converter layer in silicon-based solar cells.

Energy transfer in Pr3+/Yb3+ codoped tellurite glasses

Resonant energy transfer between Pr3+ and Yb3+ ions has been studied in tellurite glasses. The energy absorbed by Pr3+ is transferred efficiently to Yb3+, and fluorescence at around 1μm wavelength is observed. The energy transfer efficiencies for the 3P0→3F2 and 1D2→1G4 transitions in 0.5wt% Pr3+–1.0wt% Yb3+ codoped tellurite glasses are ∼68% and ∼84%, respectively, and the emission intensity of the 1G4→3H5 transition of Pr3+ does not show any significant change, due to a possible back transfer energy from the 2F5/2→2F7/2 transition of Yb3+ to the 1G4 level of Pr3+.

Lasing parameters of ytterbium-doped fibres doped with P2O5 and Al2O3

Absorption and emission cross sections are measured for the 2F5/2 → 2F7/2 transition in Yb3+ ions in silica fibres doped with Al2O3 and P2O5. The measurements were performed by methods based on spectroscopic data and by more direct methods based on laser-transition saturation. Possible lasing ranges of ytterbium-doped double-clad fibre lasers are calculated from the measured spectral dependences of stimulated transition cross sections.

From optical spectroscopy to a concentration quenching model and a theoretical approach to laser optimization for Yb3+-doped YLiF4 crystals

A spectroscopic characterization was carried out to identify crystal-field levels for magnetic-dipole transitions of Yb3+ ions located in the Y3+ dodecahedral S4 crystallographic site in YLiF4 (YLF) crystals which were grown either by the Czochralski technique or by the laser heated pedestal growth (LHPG) technique. The concentration dependence of the measured decay time of the 2F5/2 excited level of Yb3+ was analysed in order to understand relevant concentration quenching mechanisms. Under Yb3+ ion infrared pumping, self-trapping and up-conversion non-radiative energy transfer to trace rare-earth impurities (Er3+, Tm3+) has been observed over the visible region and interpreted by a limited-diffusion process within the Yb3+ doping ion subsystem to the impurities. The principal parameters useful for a theoretical approach for potential laser applications of Yb3+-doped YLiF4 crystals have also been given.

Nonmagnetic–magnetic transition inYb(Cu1−xNix)2Si2 studied by muon-spin relaxation

The muon-spin relaxation technique has been used to investigatethe transition from a nonmagnetic to a magnetic ground state inYb(Cu1−xNix)2Si2.The effect of the chemical substitution of Cu by Ni on the magnetic properties isevidenced by an unusual occurrence of magnetic ordering, characterized by anx-dependentmagnetic volume fraction. Both the magnetic transition temperature and the magneticvolume fraction are observed to increase with Ni concentration. It is found that thesize of the magnetic volume fraction depends on the probability of an Yb ionpossessing at least two Ni ions as nearest neighbours. The transition temperature ofYbNi2Si2 is shown to be reduced compared to that of the pressurizedYbCu2Si2 at equivalent volume and is related to electron doping effects. Using a scaling law for thetemperature dependence of the relaxation rates of the Yb-moments, the Kondotemperature is deduced and found to decrease, as expected, with increasing Niconcentration.

Hysteretic behaviour in the fluorescence of Yb3+ in LiNbO3:MgO crystals

Hysteretic behaviour in the luminescence of Yb3+ ions in LiNbO3:MgO crystals at low temperatures is observed as a function of the excitation power inside the 2F7/2(0)→2F5/2(1) transition of Yb3+ ions. The results are tentatively explained in terms of the laser heating effect on the thermal distribution between the crystal field levels of the 2F5/2 excited state which varies along the hysteresis loop. This fact would be responsible for the nonlinear population change needed for the observation of bistability.

Matrix effect on local structure surrounding Yb3+and spontaneous emission probability in oxide glasses

Extended X-ray absorption fine structure measurements have been performed on Yb3+ in silicate, borate, phosphate, and gallate glasses in order to investigate the local structures surrounding Yb3+. The local structures of Yb3+ ions in silicate, borate, and phosphate glasses were similar to those of Er3+ ions. Yb3+ ions do not occupy the network structural sites, but sit around the terminal region of the network or the region between the networks in these glasses. On the other hand, Yb3+ ions substitute the Ga3+ sites in complex anion structural units of the K2O-Ga2O3-Nb2O5 glasses. We classified the local structures surrounding Yb3+ ions in oxide glasses into two types: the former and the latter are interstitial and substitutive types, respectively. The relationship between the spontaneous emission probability for 2F5/2 – 2F7/2 transition of Yb3+ and the local structure of Yb3+ in oxide glasses are discussed in terms of these two types.

Photoluminescence study of CuInS2:: Yb3+ under high magnetic fields

Photoluminescence spectra of a bulk single crystal of Yb-doped CuInS2 have been investigated in a high magnetic field up to 25T. Sharp luminescence peaks are assigned to the intra-4f-shell transitions of Yb3+. A crystal-field level diagram has been proposed from the peak energy of the spectra. These peaks are found to split into several peaks on applying magnetic field due to the Zeeman effect. The splitting of peaks increases linearly to the field up to 20T, and deviates from the linearity above 20T, which is interpreted as a result of mixing between the crystal-field levels.

Photoluminescence of Yb3+-doped CuInS2 crystals in magnetic fields

Single crystals of Yb3+-doped CuInS2 were isolated by an In-flux technique. The Yb3+ concentration is estimated to be 4.5×1019 cm−3 in terms of the Curie–Weiss behavior of magnetic susceptibilities. The intra-4f-shell transitions of Yb3+ were resolved at low temperatures by photoluminescence peaks at 1.2–1.25 eV. The Yb-related peak intensities are weak in comparison with those arising from defect and impurity centers in the host. The magnetic field dependence of photoluminescence spectra shows interesting differences among the Yb-related peaks, with only part of them being Zeeman split. An energy level scheme on the basis of a single type of Yb3+ center in a tetragonal crystal field is proposed to explain the temperature- and magnetic-field dependence of the optical spectra.

Yb:Niobosilicate Glass with High‐Emission Cross Section

The emission cross section for the 2F5/2–2F7/2 transition of Yb3+ has been determined from absorption and emission measurements of niobosilicate glasses at room temperature. Using systematic variations in the spectroscopic properties, relative to composition, a glass host with emission cross sections of &gt;2.00 pm2 and fluorescence lifetimes of &gt;0.8 ms is obtained. This glass has advantages over some laser glasses that have been reported in other published papers.

Yb:phosphate laser glass with high emission cross-section

The emission cross-section for the 2F5/2–2F7/2 transition of Yb3+ has been determined from absorption and emission measurements of phosphate glasses at room temperature. By systematic variations in the spectroscopic properties with glass composition, the glass composition with emission cross-section more than 1.0pm2 and fluorescence lifetime longer than 2.00 ms is obtained which has advantage over some laser glasses reported in published papers.

On the Excitation Mechanism of Erbium and Ytterbium in the Quaternary Compounds InGaAsP

AbstractAn efficient transfer of excitonic energy to rare earth (RE) ions is crucial for possible optoelectronic applications of RE doped semiconductors. In order to investigate the energy transfer mechanism to RE ions after optical above bandgap excitation we studied the intensity of the 4I13/2 →4 4I15/2-transition of Er3+ (1.54μm) and the one of the 2F5/2 →2F7/2 -transition of Yb3+ (lμm) (loped into InGaAsP-layers lattice matched to InP. By varying the composition of the quaternary compoun ds, the bandgap energy together with the RE bound exciton energy were tuned relative to the RE excitation energy, and the effect on the RE luminescence intensity was observed. The results can be interpreted by stating a) that the energy transfer to the RE proceeds via the RE bound exciton, and b) that the intensity of the RE luminescence is essentially determined by the rate of back transfer of the RE excitation energy ERE to the bound exciton (with excitation energy Ebe). In this back transfer the energy of the excited RE ion plus the energy of 0, 1, 2 ... L0-phonons (energy Elo) is used to reexcite the bound exciton, instead of being emitted as an RE luminescence photon. For compositions where Ebe = ERE + n. Elo (n = 0, 1, 2...) we have a maximum of back transfer and correspondingly a, minimum in RE luminescence. In between the intensity has a, maximum.

Ho3+ Doped 2.84.MU.m Laser Glass for Laser Knives, Sensitized by Yb3+.

The fluorescence properties of the Ho3+5I6→5I7 transition in Yb3+-Ho3+codoped aluminozircofluoride glasses were investigated. The emission wavelength of Ho3+ (5I6→→5I7) at 2.84 μm is almost the same as the vibration oscillation absorption of hydroxyl (OH-1) at 2.89 μm. The emission intensity of Ho3+(5I6→→5I7) transition in Yb3+-Ho3+codopedaluminozirco-fluoride glass is 4.5 times higher than commercial 2.7μm Er3+laser glass. As thelifetime of 5I7 level is longer than 5I6 level, the Nd3+, Eu3+, Pr3+, Sm3+ and Tb3+ were investigatedas deactivator for decreasing the lifetime of 5I7 level. Eu3+and Tb3+ are good candidates for deactivator because they have energy levels which are close to the Ho3+5I7 level todecrease the population of Ho3+5I7 level by energy transfer and have not energy levels whichare close to the Ho3+5I6 level or Yb3+2F5/2 level.

Time Resolved Photoluminescence of Yb in InP

ABSTRACTTime resolved photoluminescence (PL) measurements of the internal 4f-4f transitions of Yb3+ have been carried out in InP and GaP. In InP a nonexponential component is observed in the PL decay, and is interpreted in terms of carrier capture by nonequilibrium Yb3+. At low temperatures the exponential component is found to be much faster (≈12.5 μsec) than expected, and is tentatively associated with a weak coupling to resonant valence band states. As the temperature is increased, the PL intensity and the exponential component of the excited state lifetime are quenched with a thermal activation energy of ≈0.1 eV. This is interpreted as being due to the emission of a hole into the valence band by the neutral Yb acceptor.