Papers by Keyword: Erbium

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Authors: Valeriy V. Galutskiy, Elena V. Stroganova, Nikolay A. Yakovenko
Abstract: To increase efficiency of continuous 1.5 μm laser radiation crystal laser media should be used instead of the glass ones. Generation efficiency in major laser crystals with ytterbium and erbium is at a disadvantage in relation to phosphate glasses. A cause of this phenomenon is a reverse energy transfer. Could be found crystals comparable in efficiency with Yb-Er phosphate glasses? At present a number of investigations on the use of ions relaxators Се 3+ in crystals Ca2Al2Si07 with ytterbium and erbium have been carried out to solve the problem of the reverse energy transfer in crystals [1,2]. It has been determined [1-3] that high content of cerium is needed to depress the reverse energy transfer. But cerium and ytterbium are in different ends of a lanthanide series, so silicate crystals with more isomorphic capacity such as Yb,Er,Ce:CaGdSiO (CGCS) have been proposed [3]. A sufficient solubility of Се 3+ ions in these crystals gives fast excitation relaxation on a laser level and guards against the reverse energy transfer from Er3+ to donor ions. Furthermore, a number of crystal media on the base of borate crystals with a developed phonon spectrum have been proposed [4,5]. They lack the reverse energy transfer, fast multiphonon nonradiative relaxation shunts the 4I11/2 – 4I13/2 Er3+ transfer. New crystals on the base of anhydrous borates – calcium-yttrium oxyorthoborates - Ca4YO(BO3)3 (YCOB) with ytterbium appeared recently [6], which showed high efficiency of generation, as well as calcium-barium fluor-orthoborates YbEr:Ca BaFBO3 (CBFB), in which ytterbium ions formed centers of luminescence with excellent characteristics [6]. Unfortunately, erbium ions in YCOB are characterized by high three level parameter [6], therefore the efficiency of generation Er,Yb:YCOB is not high. It has been determined recently that erbium ions in crystals CBFB have outstanding spectroscopic parameters, besides, between ytterbium and erbium ions fast energy transfer of electronic excitation takes place [7]. Since the efficiency of a sensitized laser medium depends on joint characteristics of the Yb and Er centres and the efficiency of their interactions, then available data allow considering crystals CBFB as a considerably promising matrix for an effective 1.5 μm laser. In order to obtain the most promising laser crystals and to answer the question cited above, it should be made their comparative analysis on basic spectroscopic and generative parameters. One of the important parameters related directly to the efficiency of the laser medium is an energy density of the generation threshold. Given spectroscopic parameters of active centers in crystals, the generation threshold of the one-activated laser medium (in an idealized model without passive losses) with a tree-level or quasi-four-level scheme of generation is specified by properties of active centers and can be easily determined by a simple formula [8]. The results obtained by this method are often used for determination of limiting parameters of the three-level laser media, the ytterbium media, for instance, and their comparative analysis [8]. There are known calculations of sensitized media generation parameters, among them the ytterbium-erbium glasses with a tube pumping [9], which although can be used for a diode pumping, nonetheless they are too unwieldy for simple estimation and comparative analysis. Hence there is a demand for simple analytical expressions such as [8] to calculate the lower limit of generation of the sensitized two-activated laser media with a diode pumping. The work reports the growing of single crystals CBFB and YCOB doped with erbium and ytterbium with erbium, and single crystals Yb,Er,Ce:CGS as well. We have made a comparative analysis of an ytterbium-erbium media for 1.5 μm lasers with a diode pumping on the base of simple expressions for limiting generation thresholds of the idealized sensitized media with a three-level scheme of generation, obtained in the approximation of balance equations without considering nonlinear and cumulative processes.
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Authors: G. Pasold, F. Albrecht, Joachim Grillenberger, Ulrike Grossner, C. Hülsen, R. Sielemann, W. Witthuhn
487
Authors: L.F. Santos, H.C. Vasconcelos, M.I. Barros Marques, Rui M. Almeida
545
Authors: Yasufumi Fujiwara, Atsushi Koizumi, Kazuhiko Nakamura, Masato Suzuki, Yoshikazu Takeda, Masayoshi Tonouchi
Abstract: We have fabricated GaInP/Er,O-codoped GaAs (GaAs:Er,O)/GaInP double heterostructure (DH) light-emitting diodes (LEDs) and successfully observed 1.5 µm electroluminescence (EL) due to an Er-2O center under forward bias at room temperature. Er excitation cross section by current injection decreased with increasing GaAs:Er,O active layer thickness, implying reduced diffusion length of injected carriers in the active layer. Carrier dynamics in GaAs:Er,O have also been investigated by means of a pump and probe reflection technique. Time-resolved reflectivity of GaAs:Er,O exhibited a characteristic dip after a steep decrease to negative in less than 10 ps. The analysis of the characteristic dip revealed short lifetime in range of ps for photoexcited carriers. The extremely short lifetime is quite coincident with the reduced diffusion length of injected carriers, and suggests that a trap induced by Er and O codoping would play an important role in dynamics of nonequilibrium carriers in GaAs:Er,O.
159
Authors: Xiao Liu, Quan Shen, Hai Lin, Dian Lai Yang
Abstract: In Er3+/Yb3+ codoped Na2O-ZnO-PbO-GeO2-TeO2 (NZPGT) glasses, effective ~1.5mm infrared (IR) emission was investigated under 980nm excitation. Judd-Ofelt intensity parameters Wt (t = 2, 4, 6) had been calculated to be 6.78´10-20, 1.54´10-20, and 1.17´10-20cm2, respectively. The IR emission full width at half maximum (FWHM) is 73nm, and the maximum stimulated emission cross-section (se) is derived to be 7.53×10-21cm2. A figure of merit (FOM) as the product FWHM´se is adopted to evaluate the gain bandwidth. The comparison of FOM in different glasses indicated that Er3+/Yb3+ codoped NZPGT glasses were potential materials in developing broadband optical amplifier.
538
Authors: Kenichiro Takahei, Yoshiji Horikoshi, Akihito Taguchi
639
Authors: Elisabetta Gariboldi, Marco Colombo
Abstract: The role played by transition elements and rare earths, added in small quantities (fractions of unity in weight percent) was proved by several authors to be beneficial for the age-hardening response and for the microstructural stability at high temperature of Al-based alloys. The paper illustrates the results of an experimental investigation on the effects of erbium (Er) additions on the microstructural features, microstructural stability and mechanical properties of an Al-7Si-0.4Mg alloy of wide industrial use. The effects are multifold: in the cast microstructure, a silicon (Si) eutectic modification was observed with the formation of several Er-containing intermetallic phases. After solution treatment and aging, an increase in peak hardness and an enhanced microstructural stability were obtained. In this preliminary study, the beneficial effects of Er additions were confirmed.
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Authors: Nélito Bernardes Pereira Junior, André Felipe Henriques Librantz, Wonder Alexandre Luz Alves, Alessandro Melo Deana
Abstract: Different laser designs may require high-concentration erbium lasers. The laser efficiency can be measured by the small signal gain (SSG) of the laser media. In this paper an investigation of the SSG for a Er:YLF with 40 mol % of erbium concentration were carried out by means of computational simulation considering several pumping rates and different pulse duration . Results showed that the maximum SSG values for 40% Er concentration are reached for lower pulse durations and high pumping rates. In addition, results suggest that the performance of such lasers can be significantly enhanced by the adjustment of pulse duration and the interval between two consecutive pulses.
450
Authors: Wen Yan Zhang, Chun Hua Lu, Ya Ru Ni, Yan Zhang, Zhong Zi Xu, Jian Bin Song
Abstract: For the first time, nano-scale rods of NaLaxYb9-x(SiO4)6O2 (x=1,3,5,7,9) crystals (NLS) activated with Er3+ have been synthesized through a mild hydrothermal conditions with subsequent calcination. The as-obtained products were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results indicate that the compound has an apatite structure and crystallizes in the hexagonal system, space group P63/m. The excitation spectrum and emission spectrum were also emplyed to investigate the optical properties of the nano-rods. The Er3+ doped NLS exhibit green/red up-conversion luminescence under excitation with a diode laser at 980 nm.
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Authors: Marc Dietrich, P. Thurian, I. Loa, S. Gronemeyer, A.P. Litvinchuk, C. Thomsen
1589
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