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Sample records for 30w 1178nm yb-doped

  1. 1178 nm all Yb-fiber laser source power-scaled by solid-core photonic bandgap fiber for 589nm generation

    Maruyama, H.; Shirakawa, A.; Ueda, K.I.;

    2009-01-01

    Here we report an 1178 nm all Yb-fiber laser source power-scaled by solid-core photonic bandgap fiber (SC-PBGF) for 589 nm generation. A 1.4 W output at 589 nm with an input power of 9 W at 1178 nm were obtained. One important advantage of PBGF is distributed filtering. Hence the gain spectrum can...... be designed artificially in an active-ion-doped SC-PBGF, desirable for long-wavelength Yb fiber laser operation. At first, 1178 nm amplification seeded with a non-polarized and linearly-polarized FRL was carried out with the core launched powers of 4 W and 2 W, respectively. As a result, an output...... power of 30 W at 1178 nm with was obtained with the slope efficiency of 58% and ASE free. A 25 W linearly-polarized output with dimensions. Thereby one can obtain lasing or amplification at longer avelengths (1100 nm - 1200 nm) as the amount of amplification in the fibre is shown to scale with the power...

  2. Large-mode-area hybrid photonic crystal fiber amplifier at 1178 nm

    Petersen, Sidsel Rübner; Chen, Mingchen; Shirakawa, Akira; Olausson, Christina Bjarnal Thulin; Alkeskjold, Thomas Tanggaard; Lægsgaard, Jesper

    2015-01-01

    Amplification of 1178 nm light is demonstrated in a large-mode-area single-mode ytterbium-doped hybrid photonic crystal fiber, relying on distributed spectral filtering of spontaneous emission at shorter wavelengths. An output power of 53 W is achieved with 29 dB suppression of parasitic lasing...

  3. Laser and spectroscopic properties of Yb-doped apatite crystals

    Favorable spectroscopic and laser properties were measured in several Yb-doped apatite crystals: Ca5(PO4)3F, Sr5(PO4)3F, and Ca5-xSrx(PO4)3F (x=1-3). The properties included absorption and emission spectra, and laser pumping (slope efficiency)

  4. 100-fs-level diode-pumped Yb-doped laser amplifiers

    Delaigue, M.; Pouysegur, J.; Ricaud, S.; Hönninger, C.; Mottay, E.

    2013-03-01

    Ultrashort pulse lasers with pulse duration on the level of 100 fs can be used for à variety of interesting applications that rely on multiphoton processes or ultrafast dynamics. Up to now, this field was reserved to Ti:sapphire-based laser systems that exhibit a quite complex laser architecture and relatively low laser efficiency. This may be an important reason why such applications could not yet penetrate into large scale industrial applications. We have realized an Yb-doped tungstate-based regenerative amplifier in innovative amplifier architecture. We succeeded to produce 106-fs-pulses at 70μJ and 140 fs at 40 μJ pulse energy, respectively. The average power is on the level of several Watts. The optimized management and exploitation of dispersive and nonlinear effects during the amplification process inside the regenerative amplifier cavity enabled the generation of such short pulses with excellent temporal quality and in an extremely simple and robust laser architecture that is well suited for industrial environments. Applying the same amplifier architecture to an Yb:YAG thin disk regenerative amplifier enabled the generation of pulses as short as 360-fs at high pulse energies exceeding 200 μJ and high average powers of more than 30 W.

  5. Guided mode gain competition in Yb-doped rod-type photonic crystal fibers

    Poli, Federica; Passaro, Davide; Cucinotta, Annamaria;

    2009-01-01

    The gain competition among the guided modes in Yb-doped rod-type photonic crystal fibers with a low refractive index core is investigated with a spatial model to demonstrate the fiber effective single-mode behaviour.......The gain competition among the guided modes in Yb-doped rod-type photonic crystal fibers with a low refractive index core is investigated with a spatial model to demonstrate the fiber effective single-mode behaviour....

  6. Synthesis and characterization of (Ba,Yb doped ceria nanopowders

    Branko Matović

    2011-06-01

    Full Text Available Nanometric size (Ba, Yb doped ceria powders with fluorite-type structure were obtained by applying selfpropagating room temperature methods. Tailored composition was: Ce0.95−xBa0.05YbxO2−δ with fixed amount of Ba − 0.05 and varying Yb content “x” from 0.05 to 0.2. Powder properties such as crystallite and particle size and lattice parameters have been studied. Röntgen diffraction analyses (XRD were used to characterize the samples at room temperature. Also, high temperature treatment (up to 1550°C was used to follow stability of solid solutions. The mean diameters of the nanocrystals are determined from the full width at half maxima (FWHM of the XRD peaks. It was found that average diameter of crystallites is less than 3 nm. WilliamsonHall plots were used to separate the effect of the size and strain in the nanocrystals.

  7. Novel materials for Yb and Er-Yb doped microchip lasers

    Hellström, Jonas

    2006-01-01

    The objective of this thesis has been to investigate novel host material configurations for high-power end-pumped Er-Yb co-doped, or Yb doped microchip lasers and try to increase their performance. In Er-Yb co-doped systems, the main limitation is the thermal shortcomings of the phosphate glass host material. The thesis presents some novel results that contribute to the search for a crystalline replacement. In Yb doped systems, most end-pumped schemes reported have been using relatively low-p...

  8. Mass fabrication of homogeneously Yb-doped silica nanoparticles and their spectroscopic properties

    A large number of homogeneously Yb-doped silica nanoparticles were continually fabricated in a vapor synthesis route, in which the Yb doping level can be well controlled by varying either the heating temperature or the carrier gas flow rate of the Yb precursor. The sizes, shapes, and morphologies of the nanoparticles were examined, and no crystallites and no Yb2O3 clusters were observed in the nanoparticles. These nanoparticles exhibit a clear Yb3+-derived absorption at around 973-975 nm and a dependence of the emission intensity and decay time on the doping level, much different from that of sintered pellets.

  9. Multi-Frequency Soliton Complex in Er/Yb-Doped Fiber Amplifier

    Kang, Jin U.; Kim, Do-Hyun; Khurgin, Jacob B.; Akhmediev, Nail N.; Han, Haewook; Shaw, Harry; Day, John H. (Technical Monitor)

    2001-01-01

    We experimentally investigated presence of multi-frequency soliton complex that exist in high power Er/Yb-doped Fiber Amplifier. The complex with the spectral bandwidth in excess of 100 nm is bound by the Kerr nonlinearity and exhibit stable propagation.

  10. Thermal effects in Yb-doped double-cladding Distributed Modal Filtering rod-type fibers

    Coscelli, Enrico; Poli, Federica; Jørgensen, Mette Marie; Laurila, Marko; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard; Leick, Lasse; Broeng, Jes; Cucinotta, Annamaria; Selleri, Stefano

    2012-01-01

    The effects of thermally-induced refractive index change in Yb-doped Distributed Modal Filtering (DMF) photonic crystal fibers are investigated, where high-order mode suppression is obtained by resonant coupling with high index elements in the cladding. The temperature distribution on the fiber...

  11. Femtosecond pulse generation and amplification in Yb-doped fibre oscillator–amplifier system

    P K Mukhopadhyay

    2010-11-01

    In recent times ytterbium (Yb) doped fibre-based mode-locked master oscillator and power amplifier have attracted a great deal of interest because of their inherent advantages like flexibility, reliability, compactness, high power handling capability and diffraction limited output beam quality as compared to the solid-state counterpart. But, to successfully develope of high-power femtosecond oscillator–amplifier system based on Yb- doped fibre, an appropriate choice of the mode-locking regime and the amplifier geometry are required. Development of an all-fibre integrated high-power Yb-doped fibre oscillator–amplifier system in which the advantages of a fibre-based system can be fully exploited remained a challenge as it requires the careful optimization of dispersion, nonlinearity, gain and ASE contribution. In this article, femto-second pulse generation in Yb-doped fibre oscillator in different mode-locking regimes are reviewed and the details of development and characterization of an all-fibre, high-power, low-noise amplifier system seeded by an all-normal-dispersion mode-locked Yb-doped fibre laser oscillator is described. More than 10 W of average power is obtained from the fibre oscillator–amplifier system at a repetition rate of 43 MHz with diffraction-limited beam quality. Amplified pulses are de-chirped to sub-160 fs duration in a grating compressor. This is the first 10 W-level source of femtosecond pulses with completely fibre-integrated amplification comprised of commercially available components.

  12. Tunable passively harmonic mode-locked Yb-doped fiber laser with Lyot-Sagnac filter.

    Li, Ming; Zou, Xin; Wu, Jian; Shi, Jindan; Qiu, Jifang; Hong, Xiaobin

    2015-10-10

    A novel passively harmonic mode-locked dissipative soliton Yb-doped fiber laser with all normal dispersion is proposed and experimentally demonstrated based on a semiconductor saturable absorption mirror and tunable Lyot-Sagnac filter. By only tuning the bandwidth of the filter at fixed pump power, the repetition rate of 9.87 to 167.8 MHz (corresponding to 17th-order harmonic) is obtained. This is the highest repetition rate and harmonic order for a passively harmonic mode-locked dissipative soliton Yb-doped fiber laser with all-normal dispersion to the best of our knowledge. The signal-to-noise ratio and super-mode suppression ratio for all harmonic orders are higher than 65 and 35 dB, respectively, which shows the high stability of the fiber laser. PMID:26479821

  13. Properties of Yb-doped scintillators: YAG, YAP, LuAG

    Belogurov, S. E-mail: belogurov@pd.infn.it; Bressi, G.; Carugno, G.; Grishkin, Yu

    2004-01-01

    A big number of Yb:YAG samples is analyzed. Emission and transmittance spectra are measured. Light output and decay time vs. temperature are measured for charge transfer (CT) and IR scintillation. Light yield (LY) of the best laser crystals is by a factor 2.4 higher than the value measured for the samples of typical scintillator quality. A pulse shape dependence on e-beam energy density is observed for the IR scintillation. A new efficient Yb doped scintillator is found-Yb:YAP. CT scintillation in a high Z material Yb:LuAG is confirmed. A new scintillation material, potentially interesting for neutrino physics, is proposed: Yb doped garnet or perovskite containing indium in the host lattice. Some prospective research directions are indicated.

  14. Properties of Yb-doped scintillators: YAG, YAP, LuAG

    A big number of Yb:YAG samples is analyzed. Emission and transmittance spectra are measured. Light output and decay time vs. temperature are measured for charge transfer (CT) and IR scintillation. Light yield (LY) of the best laser crystals is by a factor 2.4 higher than the value measured for the samples of typical scintillator quality. A pulse shape dependence on e-beam energy density is observed for the IR scintillation. A new efficient Yb doped scintillator is found-Yb:YAP. CT scintillation in a high Z material Yb:LuAG is confirmed. A new scintillation material, potentially interesting for neutrino physics, is proposed: Yb doped garnet or perovskite containing indium in the host lattice. Some prospective research directions are indicated

  15. Experimental observation of soliton molecule evolution in Yb-doped passively mode-locked fiber lasers

    We have observed soliton molecules with variable modulation depth of spectra in a passively mode-locked dispersion-managed Yb-doped fiber laser. The soliton molecule we experimentally investigated presents diatomic and tetratomic types. With the enhancement of pump power, the laser alternately operates at solitons molecule, temporal-separation-oscillation solitons, and harmonic mode-locked states. Moreover, the phase of solitons molecule is only locked at low pump, and excess pump would cause phase vibration. (letters)

  16. High-power Yb-doped continuous-wave and pulsed fibre lasers

    B N Upadhyaya

    2014-01-01

    High-power laser generation using Yb-doped double-clad fibres with conversion efficiencies in excess of 80% have attracted much attention during the last decade due to their inherent advantages in terms of very high efficiency, no misalignment due to in-built intracore fibre Bragg gratings, low thermal problems due to large surface to volume ratio, diffraction-limited beam quality, compactness, reliability and fibre-optic beam delivery. Yb-doped fibres can also provide a wide emission band from ∼1010 nm to ∼1170 nm, which makes it a versatile laser medium to realize continuous-wave (CW), Q-switched short pulse, and mode-locked ultrashort pulse generation for various applications. In this article, a review of Yb-doped CW and pulsed fibre lasers along with our study on self-pulsing dynamics in CW fibre lasers to find its role in high-power fibre laser development and the physical mechanisms involved in its generation has been described. A study on the generation of high-power CWfibre laser of 165Woutput power and generation of high peak power nanosecond pulses from acousto-optic Q-switched fibre laser has also been presented.

  17. Effective pulse recompression after nonlinear spectral broadening in picosecond Yb-doped fiber amplifier

    Zaytsev, A. K.; Wang, C.-L.; Lin, C.-H.; You, Y.-J.; Tsai, F.-H.; Pan, C.-L.

    2012-02-01

    We report the performance of a picosecond master-oscillator power amplifier (MOPA) system based on a diode-pumped solid-state (DPSS) seed laser and Yb-doped fiber amplifier. An average power of 28 W at ˜200 MHz repetition rate is achieved by using only one amplification stage. We found that positive nonlinear phase shift induced by nonlinear effect in the active fiber can be effectively compensated by a grating pair. A pulse duration of ˜1.6 ps is shown after recompression.

  18. Yb-doped phosphate double-cladding optical fiber laser for high-power applications

    Mura, Emanuele; Lousteau, Joris; Boetti, Nadia Giovanna; Scarpignato, Gerardo Cristian; Milanese, Daniel

    2013-01-01

    A Yb-doped phosphate glass double cladding optical fiber was prepared using a custom designed glass composition (P2O5 - Al2O3 - Li2O - B2O3 - BaO - PbO - La2O3) for high-power amplifier and laser applications. The preform drawing method was followed, with the preform being fabricated using the rotational casting technique. This technique, previously developed for tellurite, fluoride or chalcogenide glass preforms is reported for the first time using rare earth doped phosphate glasses. The mai...

  19. High-energy, kHz, picosecond hybrid Yb-doped chirped-pulse amplifier.

    Chang, Chun-Lin; Krogen, Peter; Hong, Kyung-Han; Zapata, Luis E; Moses, Jeffrey; Calendron, Anne-Laure; Liang, Houkun; Lai, Chien-Jen; Stein, Gregory J; Keathley, Phillip D; Laurent, Guillaume; Kärtner, Franz X

    2015-04-20

    We report on a diode-pumped, hybrid Yb-doped chirped-pulse amplification (CPA) laser system with a compact pulse stretcher and compressor, consisting of Yb-doped fiber preamplifiers, a room-temperature Yb:KYW regenerative amplifier (RGA), and cryogenic Yb:YAG multi-pass amplifiers. The RGA provides a relatively broad amplification bandwidth and thereby a long pulse duration to mitigate B-integral in the CPA chain. The ~1030-nm laser pulses are amplified up to 70 mJ at 1-kHz repetition rate, currently limited by available optics apertures, and then compressed to ~6 ps with high efficiency. The near-diffraction-limited beam focusing quality is demonstrated with M(x)(2) = 1.1 and M(y)(2) = 1.2. The shot-to-shot energy fluctuation is as low as ~1% (rms), and the long-term energy drift and beam pointing stability for over 8 hours measurement are ~3.5% and <6 μrad (rms), respectively. To the best of our knowledge, this hybrid laser system produces the most energetic picosecond pulses at kHz repetition rates among rod-type laser amplifiers. With an optically synchronized Ti:sapphire seed laser, it provides a versatile platform optimized for pumping optical parametric chirped-pulse amplification systems as well as driving inverse Compton scattered X-rays. PMID:25969056

  20. Unidirectional dissipative soliton operation in an all-normal-dispersion Yb-doped fiber laser without an isolator.

    Li, Daojing; Shen, Deyuan; Li, Lei; Chen, Hao; Tang, Dingyuan; Zhao, Luming

    2015-09-10

    We demonstrate self-started unidirectional dissipative soliton operation and noise-like pulse operation in an all-normal-dispersion bidirectional Yb-doped fiber laser mode-locked by nonlinear polarization rotation. The laser works unidirectionally once mode-locking is achieved due to the cavity directional nonlinearity asymmetry along with the nonlinear polarization rotation mode-locking mechanism. PMID:26368963

  1. Unidirectional dissipative soliton operation in an-normal-dispersion bidirectional Yb-doped fiber laser without an isolator

    Li, Daojing; Li, Lei; Chen, Hao; Tang, Dingyuan; Zhao, Luming

    2015-01-01

    We demonstrate self-started unidirectional dissipative soliton operation and noise-like pulse operation in an all-normal-dispersion bidirectional Yb-doped fiber laser mode-locked by nonlinear polarization rotation. The laser works unidirectional once mode locking was achieved due to the cavity directional nonlinearity asymmetry along with the nonlinear polarization rotation mode locking mechanism.

  2. All-normal-dispersion multi-wavelength dissipative soliton Yb-doped fiber laser

    We propose and demonstrate an all-normal-dispersion multi-wavelength dissipative soliton Yb-doped fiber laser with a periodic birefringence fiber filter, for the first time to our best knowledge. Numerical simulations show that single-, dual-, and multi-wavelength dissipative solitons can be generated under appropriate filter bandwidth and saturation power. Under a certain filter bandwidth, the generated wavelength number of multi-wavelength mode-locked dissipative solitons is related to the saturation power, decreasing with increasing saturation power. The maximal and minimal attainable wavelength spacing of multi-wavelength dissipative solitons are also investigated, which are 21 nm and 4.6 nm, respectively, according to our simulations. Furthermore, the generation of multi-wavelength dissipative solitons has been verified by experiments. Dual- and three-wavelength dissipative solitons with a wavelength spacing of 16.4 nm have been achieved. (letter)

  3. Smoothing of the inversion profile in Nd- and Yb-doped solid-state laser elements

    A solid state selectivity pumped laser is considered now seriously as a candidate to the driver for the future power plant based on a ''pure'' fusion or a ''hybrid'' nuclear-thermonuclear reactor. In connection with an elaboration of selective pumping techniques for solid-state laser-drivers, a stored energy formation in solid state media under absorption of a narrow-band pumping radiation has been considered. The calculations demonstrate the possibility of the inversion profile smoothing in the slab-like Nd- and Yb-doped active elements pumped from excited levels of activator's or sensitizer's ions. A possibility of the Nd:glass and iodine lasers usage to carry out modelling experiments on selective pumping at the several kJ energy level is discussed

  4. Recent developments in polycrystalline oxide fiber laser materials: production of Yb-doped polycrystalline YAG fiber

    Lee, HeeDong; Keller, Kristin; Sirn, Brian; Parthasarathy, Triplicane; Cheng, Michael; Hopkins, Frank K.

    2011-09-01

    Laser quality, polycrystalline oxide fibers offer significant advantages over state-of-the-art silica fiber for high energy lasers. Advanced ceramic processing technology, along with a novel powder production process, has potential to produce oxide fibers with an outstanding optical quality for use in the fiber laser applications. The production of contaminant-free green fibers with a high packing density, as well as uniform packing distribution, is a key factor in obtaining laserquality fibers. High quality green fibers are dependent on the powder quality combined with the appropriate slurry formulation. These two fundamental technologies were successfully developed at UES, and used to produce Yb-doped yttrium aluminum garnet (YAG) fibers with high optical quality, high chemical purity, and suitable core diameters down to 20-30 microns.

  5. Hybrid femtosecond fiber laser outcrossing Er-doped fiber and Yb-doped fiber

    Kim, Yunseok; Park, Sanguk; Kim, Seung-Woo

    2014-07-01

    A hybridized scheme of a fiber femtosecond pulse laser was devised with the aim of grafting the frequency comb of an Er-doped fiber oscillator, stabilized around a 1.550 μm center wavelength, onto the 1.0 μm emission range of an Yb-doped fiber amplifier. Test results showed that the frequency comb is successfully transferred to a new 1.034 μm center wavelength with a spectral bandwidth of 21 nm, upholding an original frequency stability of 3.71 × 10-13 at 10 s averaging. This work demonstrates the feasibility of outcrossing different kinds of fibers to shift the spectral range of the frequency comb over a large operating span without loss of stability.

  6. Sintering and optical quality of highly transparent yb-doped yttrium lanthanum oxide ceramics

    Ivanov, Maxim; Zayats, Sergey [Institute of Electrophysics UrB of RAS, Amundsen st 106, 620016 Ekaterinburg (Russian Federation); Kopylov, Yury; Kravchenko, Valery [Institute of Radioengineering and Electronics named after V.A. Kotelnikov, RAS, Vvedensky Sq. 1, 141120 Fryazino, Moscow region (Russian Federation)

    2013-06-15

    To produce highly transparent Yb-doped yttrium lanthanum oxide (Yb{sup 3+}:(La{sub x}Y{sub 1-x}){sub 2}O{sub 3}) ceramics two original technologies were used: laser synthesis of nanopowder and pulsed magnetic compacting. Sintering of the compacts in vacuum 3 x 10{sup -4} Pa at 1600-1700 C during 13 hours led to transparent ceramics fabrication. The ceramics with relative density higher than 99.99% and grain size about 40 {mu}m were fabricated. Full transmittance of 1.8 mm thick Yb{sub 0,11}La{sub 0,23}Y{sub 1,66}O{sub 3} ceramics reaches 82.5% rate at 800 nm. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Q-Switched Large-Mode-Area Yb-Doped Fibre Laser Using GaAs as Saturable Absorber

    FU Sheng-Gui; GUO Zhan-Cheng; SI Li-Bin; ZHAO Ying; YUAN Shu-Zhong; DONG Xiao-Yi

    2007-01-01

    A passive Q-switched large-mode-area Yb-doped fibre laser is demonstrated using a GaAs wafer as the saturable absorber. A high Yb doping concentration double-clad fibre with a core diameter of 30 μm and a numerical aperture of 0.07 is used to increase the laser gain volume, permitting greater energy storage and higher output power than conventional fibres. The maximum average output power is 7.2 W at 1080nm wavelength, with the shortest pulse duration of 580ns and the highest peak power of 161 W when the laser is pumped with a 25 W diode laser operating at 976 nm. The repetition rate increases with the pump power linearly and the highest repetition rate of 77kHz is obtained in the experiment.

  8. Long-period fiber grating as wavelength selective element in double-clad Yb-doped fiber-ring lasers

    Peterka, P; Dussardier, Bernard; Slavik, R; Honzatko, P; Kubecek, V

    2009-01-01

    Selection of operating wavelength of the Yb-doped fiber-ring lasers using longperiod fiber gratings (LPFGs) is suggested. In the proposed method, customized LPFG that sustains high powers serves as a broad-band rejection filter. It modifies the net gain profile of the laser, enabling the peak gain to occur at a designed wavelength. Spectral range of oscillation between 1050-1110 nm was experimentally demonstrated. This range can be extended to both shorter and longer wavelengths with proper design of the LPFG and length of the Yb-doped fiber. The gratings were inscribed by CO2 laser and the grating period down to 175 ?m was achieved being, to our best knowledge, the shortest reported LPFG period using this technique.

  9. Effect of pump wavelength on self-induced laser line sweeping in Yb-doped fiber laser

    Navrátil, Petr; Peterka, Pavel; Kubeček, V.

    Vol. 8775. BELLINGHAM: SPIE-INT SOC OPTICAL ENGINEERING, 2013 - (Kalli, K.; Kanka, J.; Mendez, A.) ISBN 978-0-8194-9577-8. ISSN 0277-786X. [Conference on Micro -structured and Specialty Optical Fibres II. Prague (CZ), 15.04.2013-17.04.2013] R&D Projects: GA MŠk(CZ) ME10119 Institutional support: RVO:67985882 Keywords : Laser line sweeping * fiber lasers * Yb-doped Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  10. Low-repetition-rate all-fiber all-normal-dispersion Yb-doped mode-locked fiber laser

    We demonstrate a low-repetition-rate all-fiber all-normal-dispersion Yb-doped mode-locked fiber laser. Stable mode-locking is achieved by nonlinear polarization rotation and its spectral-filtering effect. Nanosecond pulses with steep edges spectrum at repetition rate 217.4 kHz are achieved. Our preliminary experiment shows that it is a promising seed for all-fiber amplifier system

  11. Structural characterization and EXAFS wavelet analysis of Yb doped ZnO by wet chemistry route

    Highlights: • Optical and electrical properties of ZnO are influenced by lanthanide doping. • Optical and electrical properties of ZnO are influenced by lanthanide positioning. • Yb is incorporated in the Oh sites of the wurtzite structure. • There is not Yb2O3 clustering or segregation for treatments below 800 °C. - Abstract: Lanthanide doped ZnO are interesting materials for optical and electrical applications. The wide band gap of this semiconductor makes it transparent in the visible range (Egap = 3.2 eV), allowing a sharp emission from intra shell transition from the lanthanides. From the electrical side, ZnO is a widely used material in varistors and its electrical properties can be tailored by the inclusion of lanthanides. Both applications are influenced by the location of the lanthanides, grain boundaries or lattice inclusion. Yb doped ZnO samples obtained by wet chemistry route were annealed at different temperatures and characterized by Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Rietveld refinement of XRD data, and X-ray Absorption Fine Structure (XAFS). These techniques allowed to follow the changes occurred in the matrix and the Yb environment. The use of the Cauchy continuous wavelet transform allowed identifying a second coordination shell composed of Zn atoms, supporting the observations from XRD Rietveld refinement and XAFS fittings. The information obtained confirmed the incorporation of Yb in Oh sites of the wurtzite structure without Yb2O3 clustering in the lattice

  12. Structural characterization and EXAFS wavelet analysis of Yb doped ZnO by wet chemistry route

    Otal, Eugenio H., E-mail: eugenio.otal@citedef.gob.ar [Division of Porous Materials, UNIDEF, CITEDEF, CONICET, S.J.B de la Salle 4397, Villa Martelli (B1603ALO), Buenos Aires (Argentina); Laboratory for Materials Science and Technology, FRSC-UTN, Av. Inmigrantes 555, Río Gallegos 9400 (Argentina); Sileo, Elsa [INQUIMAE, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Aguirre, Myriam H. [Dept. of Physics Condensed Matter, University of Zaragoza (Spain); Laboratory of Advanced Microscopy (LMA), Institute of Nanoscience of Aragón (INA), University of Zaragoza (Spain); Fabregas, Ismael O. [Division of Porous Materials, UNIDEF, CITEDEF, CONICET, S.J.B de la Salle 4397, Villa Martelli (B1603ALO), Buenos Aires (Argentina); Kim, Manuela [Division of Porous Materials, UNIDEF, CITEDEF, CONICET, S.J.B de la Salle 4397, Villa Martelli (B1603ALO), Buenos Aires (Argentina); Laboratory for Materials Science and Technology, FRSC-UTN, Av. Inmigrantes 555, Río Gallegos 9400 (Argentina)

    2015-02-15

    Highlights: • Optical and electrical properties of ZnO are influenced by lanthanide doping. • Optical and electrical properties of ZnO are influenced by lanthanide positioning. • Yb is incorporated in the O{sub h} sites of the wurtzite structure. • There is not Yb{sub 2}O{sub 3} clustering or segregation for treatments below 800 °C. - Abstract: Lanthanide doped ZnO are interesting materials for optical and electrical applications. The wide band gap of this semiconductor makes it transparent in the visible range (E{sub gap} = 3.2 eV), allowing a sharp emission from intra shell transition from the lanthanides. From the electrical side, ZnO is a widely used material in varistors and its electrical properties can be tailored by the inclusion of lanthanides. Both applications are influenced by the location of the lanthanides, grain boundaries or lattice inclusion. Yb doped ZnO samples obtained by wet chemistry route were annealed at different temperatures and characterized by Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Rietveld refinement of XRD data, and X-ray Absorption Fine Structure (XAFS). These techniques allowed to follow the changes occurred in the matrix and the Yb environment. The use of the Cauchy continuous wavelet transform allowed identifying a second coordination shell composed of Zn atoms, supporting the observations from XRD Rietveld refinement and XAFS fittings. The information obtained confirmed the incorporation of Yb in O{sub h} sites of the wurtzite structure without Yb{sub 2}O{sub 3} clustering in the lattice.

  13. Single-mode amplification in Yb-doped rod-type photonic crystal fibers for high brilliance lasers

    Poli, F.; Lægsgaard, Jesper; Passaro, D.; Cucinotta, A.; Selleri, S.; Broeng, Jes

    2009-01-01

    higher-order mode (HOM), stressing the difference between their spatial distributions, with respect to the uniform refractive index core. In the present analysis a rod-type PCF with a 19-missing air-hole core, whose radius is 30 mum, has been considered. Initially, a PCF step-index model has been applied...... to identify a proper ring characteristic that is width, position and refractive index. Then rod-type PCF designs have been optimized with a full-vector modal solver based on the finite-element method. Then, the amplification properties of the Yb-doped rod-type PCFs have been investigated by assuming...

  14. Multiple Dissipative Solitons in a Long-Cavity Normal-Dispersion Mode-Locked Yb-Doped Fiber Laser

    ZHAO Guang-Zhen; XIAO Xiao-Sheng; MEI Jia-Wei; YANG Chang-Xi

    2012-01-01

    Transitional operations of multiple dissipative solitons in a long-cavity normal-dispersion Yb-doped fiber laser are experimentally investigated.Multiple dissipative solitons,including a stable soliton pair and a soliton triplet are observed by increasing the pump power or adjusting the polarization controllers.Two main boundaries of the stable asymmetric soliton and oscillating soliton are found between steady mode-locking.Moreover,multiple dissipative solitons with greater quantities of solitons are observed with pump power increasing.The experimental results agree well with a previous numerical study of multiple dissipative solitons.

  15. Mode-locked Yb-doped fiber laser emitting broadband pulses at ultra-low repetition rates

    Bowen, Patrick; Provo, Richard; Harvey, John D; Broderick, Neil G R

    2016-01-01

    We report on an environmentally stable, Yb-doped, all-normal dispersion, mode-locked fibre laser that is capable of creating broadband pulses with ultra-low repetition rates. Specifically, through careful positioning of fibre sections in an all-PM-fibre cavity mode-locked with a nonlinear amplifying loop mirror, we achieve stable pulse trains with repetition rates as low as 506 kHz. The pulses have several nanojules of energy and are compressible down to ultrashort (< 500 fs) durations.

  16. High-gain amplification in Yb:CaF2 crystals pumped by a high-brightness Yb-doped 976 nm fiber laser

    We report on high single-pass gain in Yb:CaF2 crystal longitudinally pumped with a 40 W high-brightness fiber laser source based on an ytterbium-doped ultra-large core photonic crystal rod-type fiber operating at 976 nm. A single-pass small-signal gain of 3.2 has been achieved in a 6 % Yb-doped 10-mm-long CaF2 crystal at room temperature, outperforming any CW-diode-pumped scheme and paving the way towards very promising innovative lasers and amplifiers schemes merging the Yb-doped solid state and fiber technologies. (authors)

  17. Characterization of the lasing properties of a 5%Yb doped Lu.sub.2./sub.SiO.sub.5./sub. crystal along its three optical axes

    Toci, G.; Pirri, A.; Beitlerová, Alena; Shoji, Y.; Yoshikawa, A.; Hybler, Jiří; Nikl, Martin; Vannini, M.

    2015-01-01

    Roč. 23, č. 10 (2015), s. 13210-13221. ISSN 1094-4087 Institutional support: RVO:68378271 Keywords : Lu 2 SiO 5 * Yb-doped * laser Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.488, year: 2014

  18. Optimization and control of the sweeping range in an Yb-doped self-sweeping fiber laser

    Lobach, I. A.; Tkachenko, A. Yu; Kablukov, S. I.

    2016-04-01

    Influence of the laser cavity parameters (an active fiber length and output coupling losses) and the temperature of elements (active fiber and pump laser diode) on the sweeping range in an Yb-doped self-sweeping laser is investigated. The obtained results show that the sweeping spectral region is shifted to shorter wavelengths for shorter active fibers and with increasing absorbed power. This allows one to obtain self-sweeping operation in a broad range within a ytterbium gain bandwidth from 1028 to 1080 nm. At the same time, there are optimal cavity parameters at which the sweeping span is the broadest (>20 nm). Good agreement between the experimental sweeping range and the calculated maximum gain wavelength is demonstrated.

  19. Pulsed laser deposition and thermoelectric properties of In-and Yb-doped CoSb3 skutterudite thin films

    Sarath Kumar, S. R.

    2011-07-29

    In-and Yb-doped CoSb3 thin films were prepared by pulsed laser deposition. Process optimization studies revealed that a very narrow process window exists for the growth of single-phase skutterudite films. The electrical conductivity and Seebeck coefficient measured in the temperature range 300-700 K revealed an irreversible change on the first heating cycle in argon ambient, which is attributed to the enhanced surface roughness of the films or trace secondary phases. A power factor of 0.68 W m-1 K-1 was obtained at ∼700 K, which is nearly six times lower than that of bulk samples. This difference is attributed to grain boundary scattering that causes a drop in film conductivity. Copyright © Materials Research Society 2011.

  20. Pump-induced carrier envelope offset frequency dynamics and stabilization of an Yb-doped fiber frequency comb

    In this paper, we demonstrate a carrier envelope phase-stabilized Yb-doped fiber frequency comb seeding by a nonlinear-polarization-evolution (NPE) mode-locked laser at a repetition rate of 60 MHz with a pulse duration of 191 fs. The pump-induced carrier envelope offset frequency (f0) nonlinear tuning is discussed and further explained by the spectrum shift of the laser pulse. Through the environmental noise suppression, the drift of the free-running f0 is reduced down to less than 3 MHz within an hour. By feedback control on the pump power with a self-made phase-lock loop (PLL) electronics the carrier envelope offset frequency is well phase-locked with a frequency jitter of 85 mHz within an hour. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  1. High order harmonic mode-locking in an all-normal-dispersion Yb-doped fiber laser with a graphene oxide saturable absorber

    Huang, S. S.; Wang, Y. G.; Yan, P. G.; Zhang, G. L.; Zhao, J. Q.; Li, H. Q.; Lin, R. Y.

    2014-01-01

    A high order passive harmonic mode-locking (HML) Yb-doped all-normal-dispersion fiber laser based on a graphene oxide saturable absorber has been experimentally demonstrated. For two different pump powers and different polarization states of the laser cavity, lower order and higher order HML have been achieved. The highest 30th-order harmonic (31.86 MHz) was achieved with subnanosecond pulse duration; this is transitional from a bunched multipulse state.

  2. High order harmonic mode-locking in an all-normal-dispersion Yb-doped fiber laser with a graphene oxide saturable absorber

    A high order passive harmonic mode-locking (HML) Yb-doped all-normal-dispersion fiber laser based on a graphene oxide saturable absorber has been experimentally demonstrated. For two different pump powers and different polarization states of the laser cavity, lower order and higher order HML have been achieved. The highest 30th-order harmonic (31.86 MHz) was achieved with subnanosecond pulse duration; this is transitional from a bunched multipulse state. (paper)

  3. Terahertz radiation using log-spiral-based low-temperature-grown InGaAs photoconductive antenna pumped by mode-locked Yb-doped fiber laser.

    Kong, Moon Sik; Kim, Ji Su; Han, Sang Pil; Kim, Namje; Moon, Kiwon; Park, Kyung Hyun; Jeon, Min Yong

    2016-04-01

    We demonstrate a terahertz (THz) radiation using log-spiral-based low-temperature-grown (LTG) InGaAs photoconductive antenna (PCA) modules and a passively mode-locked 1030 nm Yb-doped fiber laser. The passively mode-locked Yb-doped fiber laser is easily implemented with nonlinear polarization rotation in the normal dispersion using a 10-nm spectral filter. The laser generates over 250 mW of the average output power with positively chirped 1.58 ps pulses, which are dechirped to 127 fs pulses using a pulse compressor outside the laser cavity. In order to obtain THz radiation, a home-made emitter and receiver constructed from log-spiral-based LTG InGaAs PCA modules were used to generate and detect THz signals, respectively. We successfully achieved absorption lines over 1.5 THz for water vapor in free space. Therefore, we confirm that a mode-locked Yb-doped fiber laser has the potential to be used as an optical source to generate THZ waves. PMID:27136997

  4. Ferromagnetic half-metallic characteristic and phase transition in rare-earth Yb doped SiC: A GGA+U study

    The electronic, magnetic and structural properties of rare earth Yb doped on SiC are investigated theoretically based on the density functional theory (DFT). Both zincblende (ZB) and rocksalt (RS) structures of SiC have been calculated. We found that Si3YbC4 with ZB exhibits a complete half-metallic characteristic with a wide gap more than 1.8 eV using GGA and GGA+U methods. However, the half-metallicity is destroyed with RS. The sensitivity of magnetic moments of Si3YbC4 as a function of pressure is also discussed, there are two magnetic phase transition points with increased pressure. The exchange interaction between local Yb-4f electrons and conduction electrons plays an important role in their heavy fermion characters. The exchange splitting of the conduction band is confirmed to be much larger than that of the valence band in Si3YbC4, which makes the holes-mediated ferromagnetism in this material. - Highlights: • Yb-doped SiC with zincblende are predicted half-metallic materials. • Two phase transition points, one is magnetic transition and the other is structure transition with increased pressure. • The calculated band gap using the GGA+U approach is larger than the GGA values. • The study of the exchange splitting shows that Yb-doped SiC makes the holes-mediated ferromagnetism

  5. Flexibly controllable multi-pulse mode-locked MOPA Yb-doped fiber laser in all normal dispersion regime

    Bu, Chenxi; Wang, Chinhua

    2013-09-01

    A Controllable, high energy, all normal dispersion (ANDi), passively mode-locked Yb-doped fiber laser is demonstrated with a Master Oscillator Power-Amplifier (MOPA) structure. The mode-locking is achieved by nonlinear polarization evolution (NPE). different types of laser pulse are achieved from fundamental mode-locked (FML) single pulse to twin pulse and then to harmonically mode-locked (HML) pulses (the maximum order is 7 times) by adjusting quarter-wave plates (QWPS) and a half-wave plate (HWP) in our system. Using a cascaded long-period fiber grating as the spectral filter, the center wavelength of our laser is fixed at 1034nm.The repetition frequency rate of the FML pulse is 1.53MHz with a pulse width of 817ps. The maximum average energy is 450 mW and the maximum pulse energy of FML single pulse is 294 nJ. Besides, the 517nm green laser output is also achieved by using a LiB3O5 (LBO) crystal as the frequency doubling crystal. The maximum average of the green pulse is 4.71mW.

  6. A controllable noise-like operation regime in a Yb-doped dispersion-mapped fiber ring laser

    Zaytsev, A. K.; Lin, C. H.; You, Y. J.; Tsai, F. H.; Wang, C. L.; Pan, C. L.

    2013-04-01

    We report the generation of tunable high-energy noise-like pulses with a super-broadband spectrum from a Yb-doped dispersion-mapped fiber ring laser. Self-starting noise-like operation can be maintained over a relatively large range of pumping powers (4-13 W). The corresponding output power varies from 0.1 to 1.45 W. The maximum 3 dB spectral bandwidth of the noise-like pulses is about 48.2 nm while the output energy is as high as 47 nJ, limited by optical damage of the components. The central wavelength of the noise-like pulses can be tuned easily over ˜12 nm. The bandwidth and duration of the generated wave packets can also be controlled. The use of a negative dispersion-delay line and spectral filter are found to be important for generating such high-power noise-like operation. Experimental results are in good agreement with theoretical simulations.

  7. Electrically tunable fiber-integrated Yb-doped laser covering 74 nm based on a fiber Bragg grating array

    Tiess, T.; Rothhardt, M.; Chojetzki, C.; Jäger, M.; Bartelt, H.

    2015-03-01

    Fiber lasers provide the foundation to combine an excellent beam quality in single mode operation with a robust and highly efficient design. Based on fiber-integrated configurations, they are employed in many different applications ranging from industry over research to medical technology. However, there is lots of potential to approach even new fields of applications e.g. in spectroscopy based on tunable systems with an adjustable emission wavelength. We present a novel tuning concept for pulsed fiber-integrated laser systems using an array of fiber Bragg gratings (FBGs) as discrete spectral filter. Based on stacking many standard FBGs, the bandwidth and filter properties are easy to scale by increasing the number of gratings allowing huge tuning ranges as well as tailored tuning characteristics. In this work, we demonstrate the potential of this electrically controlled tuning concept. Using an Ytterbium (Yb)-doped fiber laser, we investigate the general tuning characteristics. With variable pulse durations in the nanosecond regime, we demonstrate high signal contrast (~45 dB), excellent wavelength stability and narrow linewidth (knowledge, is the largest bandwidth reported based on a monolithic filter design.

  8. Lattice dynamics and substrate-dependent transport properties of (In, Yb)-doped CoSb3 skutterudite thin films

    Sarath Kumar, S. R.

    2011-10-24

    Lattice dynamics, low-temperature electrical transport, and high-temperature thermoelectric properties of (In, Yb)-doped CoSb3thin films on different substrates are reported. Pulsed laser deposition under optimized conditions yielded single-phase polycrystalline skutterudite films. Raman spectroscopy studies suggested that In and Yb dopants occupy the cage sites in the skutterudite lattice. Low-temperature electrical transport studies revealed the n-type semiconducting nature of the films with extrinsic and intrinsic conduction mechanisms, in sharp contrast to the degenerate nature reported for identical bulk samples. Calculations yielded a direct bandgap close to 50 meV with no evidence of an indirect gap. The carrier concentration of the films was identical to that reported for the bulk and increased with temperature beyond 250 K. The higher resistivity exhibited is attributed to the enhanced grain boundary scattering in films with a high concentration of grains. The maximum power factor of ∼0.68 W m−1 K−1 obtained at 660 K for the film on glass is found to be nearly four times smaller compared to that reported for the bulk. The observed difference in the power factors of the films on different substrates is explained on the basis of the diffusion of oxygen from the substrates and the formation of highly conducting CoSb2 phase upon the oxidation of CoSb3.

  9. Luminescent properties of Yb-doped LaSc3(BO3)4 under VUV excitation

    Ytterbium doped borate crystals are promising laser media, e.g. in LaSc3(BO3)4 (LSB) matrices large distance between ytterbium ions results in reduced concentration quenching of the ytterbium f-f luminescence [Petermann, K., Fagundes-Peters, D., Johansen, O., Mond, M., Peters, V., Romero, J.J., Kutovoi, S., Speiser, J., Giesen, A., 2005. Highly Yb-doped oxides for thin-disc lasers. J. Crystal Growth 275, 135-140]. Yb3+ ions in complex oxides in addition to the 4f → 4f transitions often manifest fast charge transfer luminescence (CTL) in the UV-visible range. In some borates it was not observed at all, like in orthoborates of Sc, Y and La [Van Pieterson, L., Heeroma, M., de Heer, E., Meijerink, A., 2000. Charge transfer luminescence of Yb3+. J. Lumin. 91, 177-193]; in haloborates Sr2B5O9X, where X = Cl, Br, the UV/visible luminescence was attributed to ytterbium CTL though it looked substantially different from other matrices [Dotsenko, V.P., Berezovskaya, I.V., Pyrogenko, P.V., Efryushina, N.P., Rodniy, P.A., Eijk van, C.W.E., Sidorenko, A.V., 2002. Valence states and luminescence properties of ytterbium ions in strontium haloborates. J. Solid State Chem. 166, 271-276]; while in oxyborate Li2Lu5O4(BO3)3 'classical' CTL was observed [Jubera, V., Garcia, A., Chaminade, J.P., Guillen, F., Sablayrolles, Jean, Fouassier, C., 2007. Yb3+ and Yb3+-Eu3+ luminescent properties of the Li2Lu5O4(BO3)3 phase. J. Lumin. 124(1), 10-14]. In this work the luminescence properties of another borate, namely LSB doped by Yb are presented

  10. High-power mode-locked operation of Yb-doped NaY(WO4)2 end-pumped by laser diodes

    Passively cw mode-locked laser operation of Yb-doped NaY(WO4)2 (Yb:NaYW) crystal was demonstrated with an average power of 400 mW. This is the highest power achieved from the mode-locked Yb:NaYW laser to our knowledge. The laser was end-pumped by a high power fiber pigtailed laser diode bar and the mode-locking was enabled by a semiconductor saturable absorber mirror (SESAM). The laser pulse duration was 1.1 ps, centered at the wavelength of 1019.7 nm with a bandwidth of 1.6 nm, and nearly transform-limited

  11. Characteristics of Soliton Evolution in the Wave-Breaking-Free Regime in a Passively Mode-Locked Yb-Doped Fiber Laser

    WU Ge; TIAN Xiao-Jian; GAO Bo; SHAN Jiang-Dong; RU Yu-Xing

    2011-01-01

    @@ We focus on several aspects concerning the numerical simulation of a passively mode-locked Yb-doped fiber laser by a non-distributed model.The characteristics of soliton evolution in a wave-breaking-free regime are numerically investigated with the split-step Fourier method.Based on the model,a parabolic-shaped soliton with a nearlylinear chirp and bound soliton pairs are obtained by controlling the intra-cavity average dispersion of the fiber laser.A phenomenon is observed that by keeping the system parameters unchanged,linearly chirped parabolic soliton and bound soliton pairs are attainable under different initial conditions in the transient region between these two kinds of solitons.%We focus on several aspects concerning the numerical simulation of a passively mode-locked Yb-doped fiber laser by a non-distributed model. The characteristics of soliton evolution in a wave-breaking-free regime are numerically investigated with the split-step Fourier method. Based on the model, a parabolic-shaped soliton with a nearly linear chirp and bound soliton pairs are obtained by controlling the intra-cavity average dispersion of the fiber laser. A phenomenon is observed that by keeping the system parameters unchanged, linearly chirped parabolic soliton and bound soliton pairs are attainable under different initial conditions in the transient region between these two kinds of solitons.

  12. Density-functional study on the robust ferromagnetism in rare-earth element Yb-doped SnO{sub 2}

    Zhang, Kai-Cheng, E-mail: kczhang@yeah.net [College of Mathematics and Physics, Bohai University, Jinzhou 121013 (China); Li, Yong-Feng [Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal ResourcesInner Mongolia University of Science and Technology, Baotou 014010 (China); School of Mathematics, Physics and Biological Engineering, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Liu, Yong [State Key Laboratory of Metastable Materials Science and Technology and College of Science, Yanshan University, Qinhuangdao, Hebei 066004 (China); Chi, Feng [College of Engineering, Bohai University, Jinzhou 121013 (China)

    2014-06-01

    So far, little has been known about the ferromagnetism induced by p–f hybridization. We investigate the magnetic properties of Yb-doped SnO{sub 2} by first-principles calculations. We find that the doped system favors the ferromagnetic state and a room-temperature ferromagnetism can be expected in it. The origin of ferromagnetism can be attributed to the p–f hybridization between Yb impurity and its surrounding oxygen atoms. The formation energy of defect complex is calculated and the magnetic mediation of intrinsic vacancies is studied. Our results reveal that the formation energy of the defect complex with Sn vacancy is about 7.3 eV lower in energy than that with oxygen vacancy. This means Sn vacancy is much easier to form than oxygen vacancy in the presence of Yb substitution. The ferromagnetism of the doped system is greatly enhanced in the presence of Sn vacancies. - Highlights: • Room-temperature ferromagnetism can be expected in Yb-doped SnO{sub 2}. • The origin of ferromagnetism can be attributed to the p–f hybridization between Yb and O atoms. • Oxygen vacancies are much hard to form and contribute little to the ferromagnetism. • Sn vacancies are easy to form under oxygen-rich condition and stabilize the ferromagnetism effectively.

  13. Luminescent properties of Yb-doped LaSc{sub 3}(BO{sub 3}){sub 4} under VUV excitation

    Guerassimova, N.; Kamenskikh, I. [Physics Department, M.V. Lomonosov Moscow State University, Leninskie gory, 119992 Moscow (Russian Federation); Krasikov, D. [Physics Department, M.V. Lomonosov Moscow State University, Leninskie gory, 119992 Moscow (Russian Federation)], E-mail: kdn@nm.ru; Mikhailin, V. [Physics Department, M.V. Lomonosov Moscow State University, Leninskie gory, 119992 Moscow (Russian Federation); Zagumennyi, A.; Koutovoi, S.; Zavartsev, Yu. [Laser Crystals Department, General Physics Institute of RAS, Vavilova str. 38, 119991 Moscow (Russian Federation); Pedrini, C. [Laboratoire de Physico-Chimie des Materiaux Luminescents, Universite Claude Bernard Lyon-1, UMR 5620 CNRS, 69622 Villeurbanne (France)

    2007-04-15

    Ytterbium doped borate crystals are promising laser media, e.g. in LaSc{sub 3}(BO{sub 3}){sub 4} (LSB) matrices large distance between ytterbium ions results in reduced concentration quenching of the ytterbium f-f luminescence [Petermann, K., Fagundes-Peters, D., Johansen, O., Mond, M., Peters, V., Romero, J.J., Kutovoi, S., Speiser, J., Giesen, A., 2005. Highly Yb-doped oxides for thin-disc lasers. J. Crystal Growth 275, 135-140]. Yb{sup 3+} ions in complex oxides in addition to the 4f {yields} 4f transitions often manifest fast charge transfer luminescence (CTL) in the UV-visible range. In some borates it was not observed at all, like in orthoborates of Sc, Y and La [Van Pieterson, L., Heeroma, M., de Heer, E., Meijerink, A., 2000. Charge transfer luminescence of Yb{sup 3+}. J. Lumin. 91, 177-193]; in haloborates Sr{sub 2}B{sub 5}O{sub 9}X, where X = Cl, Br, the UV/visible luminescence was attributed to ytterbium CTL though it looked substantially different from other matrices [Dotsenko, V.P., Berezovskaya, I.V., Pyrogenko, P.V., Efryushina, N.P., Rodniy, P.A., Eijk van, C.W.E., Sidorenko, A.V., 2002. Valence states and luminescence properties of ytterbium ions in strontium haloborates. J. Solid State Chem. 166, 271-276]; while in oxyborate Li{sub 2}Lu{sub 5}O{sub 4}(BO{sub 3}){sub 3} 'classical' CTL was observed [Jubera, V., Garcia, A., Chaminade, J.P., Guillen, F., Sablayrolles, Jean, Fouassier, C., 2007. Yb{sup 3+} and Yb{sup 3+}-Eu{sup 3+} luminescent properties of the Li{sub 2}Lu{sub 5}O{sub 4}(BO{sub 3}){sub 3} phase. J. Lumin. 124(1), 10-14]. In this work the luminescence properties of another borate, namely LSB doped by Yb are presented.

  14. Research progress of chelate precursor doping method to fabricate Yb-doped large-mode-area silica fibers for kW-level laser

    Wang, Zhen; Zhan, Huan; Ni, Li; Peng, Kun; Wang, Xiaolong; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

    2015-11-01

    With continuous efforts and practical managing experiences, the chelate precursor doping method has been justified as an effective way to dope rare-earth ions into silica host materials, a key technique in making large-mode-area silica fibers for high power laser applications. It is characterized by good controllability, stability and repeatability to accomplish different refractive index profiles. Different preforms with a large core, designed refractive index profile, good symmetrical shape and homogeneous elemental distribution were successfully fabricated. The home-made standard 20/400-type double-cladding Yb-doped large-mode-area silica fiber was drawn and presented a 1.6 kW laser output at 1064 nm, the highest power record publically reported with this method. With further optimization, chelate precusor doping method has potential to manufacture high power laser fibers for the next generation.

  15. Characteristics of a low repetition rate passively mode-locked Yb-doped fiber laser in an all-normal dispersion cavity

    The lasing characteristics of a 365 kHz low repetition rate Yb-doped fiber laser operated in an all-normal dispersion cavity and mode-locked by the nonlinear polarization rotation mechanism are investigated in detail. As the pump power increases, the laser exhibits two transition routes when evolved from the continuous-wave (CW) state to the mode-locked (ML) state. In one evolution route the Q-switched mode-locked (QML) state is sandwiched between the CW and ML states, whereas in the other more interesting evolution route the hysteresis transition between the CW and ML states is found for the first time. Under the mode-locking operation, the laser generates sub-nanosecond pulses with linear dependence of pulsewidth on bandwidth under different pump powers, indicating the presence of giant linear chirps on the laser output pulses. (paper)

  16. All-normal-dispersion passively mode-locked Yb-doped fiber ring laser based on a graphene oxide saturable absorber

    We have demonstrated an all-normal-dispersion passively mode-locked Yb-doped fiber laser using a graphene oxide/polyvinyl alcohol (GO–PVA) saturable absorber without surfactant, for the first time to the best of our knowledge. The experimental results show that the pulse duration of the mode-locked lasers varies from 191 ps to 1.68 ns, while the cavity round trip time changes from 24 to 458 ns, through the variation of the cavity length. In addition, the proposed passively mode-locked fiber laser demonstrates a maximum average output power of 539 mW with a laser cavity length of 94 m, and the corresponding single pulse energy reaches 0.429 μJ. The proposed mode-locked fiber lasers with large chirp pulses may find potential applications in fiber chirped pulse amplification systems for micromachining, material processing and diagnostic applications. (letter)

  17. Second Harmonic Generation Using an All-Fiber Q-Switched Yb-Doped Fiber Laser and MgO:c-PPLN

    Yi Gan

    2008-01-01

    Full Text Available We have experimentally demonstrated an efficient all-fiber passively Q-switched Yb-doped fiber laser with Samarium doped fiber as a saturable absorber. Average output power of 3.4 W at a repetition rate of 250 kHz and a pulse width of 1.1 microseconds was obtained at a pump power of 9.0 W. By using this fiber laser system and an MgO-doped congruent periodically poled lithium niobate (MgO:c-PPLN, second harmonic generation (SHG output at 532 nm was achieved at room temperature. The conversion efficiency is around 4.2% which agrees well with the theoretical simulation.

  18. All-fiber 30-μm core diameter Yb-doped pulse-pumped amplifier cascade generating 10 nm-bandwidth 545 kW peak power pulses

    An electric-pulse-driven super-luminescent diode laser generating 1064 nm wavelength with 37 nm-bandwidth, several nanoseconds pulses at 20 Hz repetition rate was used to seed an amplifier cascade featuring a 30 μm core Yb-doped fiber as the final power amplifier. From this amplifier cascade, we obtained pulse energy from 1.0 to 1.5 mJ depending on different pulse durations with beam quality of M2 1.7; the highest peak power in excess of 545 kW and 10 nm-bandwidth centered at 1064 nm, which is the widest bandwidth of pulsed Yb-doped millijoule fiber amplifier to our knowledge. Moreover, this all-fiber structure has application to many fields

  19. 980-nm all-fiber mode-locked Yb-doped phosphate fiber oscillator based on semiconductor saturable absorber mirror and its amplifier

    Li, Ping-Xue; Yao, Yi-Fei; Chi, Jun-Jie; Hu, Hao-Wei; Zhang, Guang-Ju; Liang, Bo-Xing; Zhang, Meng-Meng; Ma, Chun-Mei; Su, Ning

    2016-08-01

    A 980-nm semiconductor saturable absorber mirror (SESAM) mode-locked Yb-doped phosphate fiber laser is demonstrated by using an all-fiber linear cavity configuration. Two different kinds of cavity lengths are introduced into the oscillator to obtain a robust and stable mode-locked seed source. When the cavity length is chosen to be 6 m, the oscillator generates an average output power of 3.5 mW and a pulse width of 76.27 ps with a repetition rate of 17.08 MHz. As the cavity length is optimized to short, 4.4-mW maximum output power and 61.15-ps pulse width are produced at a repetition rate of 20.96 MHz. The output spectrum is centered at 980 nm with a narrow spectral bandwidth of 0.13 nm. In the experiment, no undesired amplified spontaneous emission (ASE) nor harmful oscillation around 1030 nm is observed. Moreover, through a two-stage all-fiber-integrated amplifier, an output power of 740 mW is generated with a pulse width of 200 ps. Project supported by the National Natural Science Foundation of China (Grant No. 61205047).

  20. All-normal dispersion passively mode-locked Yb-doped fiber laser using MoS2-PVA saturable absorber

    Sathiyan, S.; Velmurugan, V.; Senthilnathan, K.; Babu, P. Ramesh; Sivabalan, S.

    2016-05-01

    We demonstrate the generation of a dissipative soliton in an all-normal dispersion ytterbium (Yb)-doped fiber laser using few-layer molybdenum disulfide (MoS2) as a saturable absorber. The saturable absorber is prepared by mixing few-layer MoS2 solution with polyvinyl alcohol (PVA) to form a free-standing composite film. The modulation depth and saturation intensity of the MoS2-PVA film are 11% and 5.86 MW cm-2, respectively. By incorporating the MoS2 saturable absorber in the fiber laser cavity, the mode-locked pulses are generated with a pulse width of 1.55 ns and a 3 dB spectral bandwidth of 0.9 nm centered at 1037.5 nm. The fundamental repetition rate and the average power are measured as 15.43 MHz and 1.5 mW, respectively. These results reveal the feasibility of deploying liquid-phase exfoliated few-layer MoS2 nanosheets for dissipative soliton generation in the near-IR region.

  1. Sintering of transparent Yb-doped Lu{sub 2}O{sub 3} ceramics using nanopowder produced by laser ablation method

    Kijko, V.S. [Ural Federal University named after the first President of Russia B.N. Yeltsin, Mira St. 19, Ekaterinburg 620002 (Russian Federation); Maksimov, R.N., E-mail: romanmaksimov@e1.ru [Ural Federal University named after the first President of Russia B.N. Yeltsin, Mira St. 19, Ekaterinburg 620002 (Russian Federation); Institute of Electrophysics UB RAS, Amundsen St.106, Ekaterinburg 620016 (Russian Federation); Shitov, V.A. [Institute of Electrophysics UB RAS, Amundsen St.106, Ekaterinburg 620016 (Russian Federation); Demakov, S.L.; Yurovskikh, A.S. [Ural Federal University named after the first President of Russia B.N. Yeltsin, Mira St. 19, Ekaterinburg 620002 (Russian Federation)

    2015-09-15

    Highlights: • Yb:Lu{sub 2}O{sub 3} nanoparticles synthesized by laser ablation method were investigated. • Transparent Yb:Lu{sub 2}O{sub 3} ceramics were fabricated via vacuum and spark plasma sintering. • Highest transmittance was 79.3% at 1080 nm for vacuum sintered Yb:Lu{sub 2}O{sub 3} sample. - Abstract: Transparent Yb-doped Lu{sub 2}O{sub 3} ceramic samples were fabricated via conventional vacuum and spark plasma sintering. Nanoparticles synthesized by laser ablation method were used as starting material. The morphology and phase evolution of the nanopowder were studied by transmission electron microscopy, simultaneous thermal analysis and X-ray diffraction. The obtained nanoparticles exhibited the monoclinic phase and were fully converted into the main cubic phase after calcination at 1100 °C for 1 h. Conventional vacuum sintering of Yb:Lu{sub 2}O{sub 3} powder compact at 1780 °C for 20 h resulted in a fully-dense ceramics with an average grain size of 1.6 μm and optical transmittance of 79.3% at 1080 nm. Spark plasma sintering of the calcined Yb:Lu{sub 2}O{sub 3} nanoparticles at 1450 °C and 15 kN for 40 min led to a 0.2 μm-grained ceramics exhibiting an optical transmittance of 75.6% at 1080 nm.

  2. 超长腔碳纳米管锁模多波长掺镱光纤激光器∗%Ultra-long cavity multi-wavelength Yb-doped fiber laser mode-locked by carbon nanotubes

    王玉宝; 齐晓辉; 沈阳; 姚繄蕾; 徐志敬; 潘玉寨

    2015-01-01

    We demonstrate an ultra-long cavity multi-wavelength Yb-doped fiber laser mode-locked by carbon nanotubes. The total length of the fiber laser is 1021.2 m. The different regimes of noise-like soliton and soliton rain mode-locking with the multi-wavelength operation are experimentally obtained with a repetition rate of 199.8 kHz. The higher output power and pulse energy from the soliton rain are measured to be 40.3 mW and 201.5 nJ, respectively, with a pulse width of about 102.5 ns.

  3. 30 W Cr:LiSrAlF 6 flashlamp-pumped pulsed laser.

    Samad, Ricardo Elgul; Baldochi, Sonia Licia; Calvo Nogueira, Gesse Eduardo; Vieira, Nilson Dias

    2007-01-01

    We report the performance of a flashlamp-pumped Cr:LiSrAlF(6) (Cr:LiSAF) laser developed and built by us. The pumping cavity incorporates filters that select the flashlamps' emission spectrum to match the absorption bands of the gain medium, allowing control of the amount of nonradiactive decay heat contribution of the optical cycle, minimizing thermal effects on the laser operation. The laser generated 2 J pulses at 15 Hz, resulting in 30 W of average power, the highest power extracted from a Cr:LiSAF rod laser to our knowledge. We were able to conclude that the laser efficiency is affected by resonator configuration changes due to thermal lens effects, and not to thermal quenching of the Cr:LiSAF luminescence. PMID:17167580

  4. High power, picosecond green laser based on a frequency-doubled, all-fiber, narrow-bandwidth, linearly polarized, Yb-doped fiber laser

    Tian, Wenyan; Isyanova, Yelena; Stegeman, Robert; Huang, Ye; Chieffo, Logan R.; Moulton, Peter F.

    2016-03-01

    We report on the development of an all-fiber, 68-kW-peak-power, 16-ps-pulse-width, narrow-bandwidth, linearly polarized, 1064-nm fiber laser suitable for high-power, picosecond-pulse-width, green-light generation. Our 1064-nm fiber laser delivered an average power of up to 110 W at a repetition of 100- MHz in a narrow bandwidth, with minimal nonlinear distortion. We developed a high-power, picosecond green source at 532 nm through use of single-pass frequency-doubling of our 1064-nm fiber laser in lithium triborate (LBO). Using a 15-mm long LBO crystal, we have generated 30 W of average power in the second harmonic with 73-W of fundamental average power, for a conversion efficiency of 41%.

  5. Experimental investigation on laser milling of aluminium oxide using a 30 W Q-switched Yb:YAG fiber laser

    Leone, C.; Genna, S.; Tagliaferri, F.; Palumbo, B.; Dix, M.

    2016-01-01

    In the present study, laser milling tests were carried out on aluminium oxide (Al2O3) plate, 3 mm in thickness, using a Q-Switched 30 W Yb:YAG fiber laser. A systematic approach based on Design of Experiment (DoE) has been successfully adopted with the aim to detect which and how the process parameters affect the laser beam-material interaction, and to explain the effect of the process parameters on the material removal rate and surface quality. The examined process parameters were the laser beam scan speed, the pulse frequency, the total energy released for surface unit, the distance between two consecutive scan lines and the scanning strategy. A full factorial design and ANalysis Of VAriance (ANOVA) were applied for the results analysis. Finally, the various effects of the process parameters on the material removal rate and surface roughness have been analysed and discussed.

  6. Effect of Sintering Temperature on Microstructure, Chemical Stability and Electrical Properties of Transition Metal or Yb-Doped BaZr0.1Ce0.7Y0.1M0.1O3-δ (M = Fe, Ni, Co and Yb

    Behzad eMirfakhraei

    2014-03-01

    Full Text Available Perovskite-type BaZr0.1Ce0.7Y0.1M0.1O3-δ (M = Fe, Ni, Co and Yb (BZCY-M oxides were synthesized using the conventional solid-state reaction method at 1350-1550 oC in air in order to investigate the effect of dopants on sintering, crystal structure, chemical stability under CO2 and H2S, and electrical transport properties. The formation of the single-phase perovskite-type structure with an orthorhombic space group Imam was confirmed by Rietveld refinement using powder X-ray diffraction (PXRD for the Fe, Co, Ni and Yb-doped samples. The BZCY-Co and BZCY-Ni oxides show a total electrical conductivity of 0.01 and 8 × 10-3 Scm-1 at 600 oC in wet H2 with an activation energy of 0.36 and 0.41 eV, respectively. Scanning electron microscopy (SEM and energy-dispersive X-ray analysis (EDX revealed Ba and Co rich secondary phase at the grain-boundaries, which may explain the enhancement in the total conductivity of the BZCY-Co. However, ex-solution of Ni at higher sintering temperatures, especially at 1550 oC, decreases the total conductivity of the BZCY-Ni material. The Co and Ni dopants act as a sintering aid and form dense pellets at a lower sintering temperature of 1250 oC. The Fe, Co and Ni-doped BZCY-M samples synthesized at 1350 oC show stability in 30 ppm H2S/H2 at 800 oC, and increasing the firing temperature to 1550 oC, enhanced the chemical stability in CO2 / N2 (1: 2 at 25-900 oC. The BZCY-Co and Ni compounds with high conductivity in wet H2 could be considered as possible anodes for intermediate temperature solid oxide fuel cells (IT-SOFCs.

  7. High power radially-polarized Yb-doped fiber laser

    Lin, Di; Daniel, J. M. O.; Gecevičius, M.; Beresna, M; Kazansky, P. G.; Clarkson, W. A.

    2014-01-01

    A simple technique for directly generating a radially-polarized output beam from an ytterbium-doped fiber laser using an intracavity spatially-variant waveplate is reported. The laser yielded 32W of output with a corresponding slope efficiency of 65.8% in a radially-polarised beam with beam propagation factor ~2.1 and polarization purity >95%

  8. Yb-doped glass microcavity laser operation in water

    Ostby, Eric P.; Vahala, Kerry J.

    2009-01-01

    A ytterbium-doped silica microcavity laser demonstrates stable laser emission while completely submerged in water. To our knowledge, it is the first solid-state laser whose cavity mode interacts with water. The device generates more than 2 μW of output power. The laser performance is presented, and low-concentration biosensing is discussed as a potential application.

  9. Scintillation properties of Yb-doped yttrium-aluminum garnets

    Relative light yield (LY) dependence on temperature for Yb:YAG crystals containing 10% to 100% of Yb dopant is studied for γ and α excitation. The maximum LY is achieved at 120 K3 Ph/MeV at T=140 K for (Yb 25%) YAG. Linearity of the light output is checked. α/γ ratio is found to be 0.42±0.02. Pulse shapes induced by γ and α particles and cosmic rays are investigated by analysing a set of single events recorded. γ events are fast (τ<4 ns), while other kinds of radiation give rise to more complicated and longer profiles, allowing particle discrimination. Dependence of scintillation properties on concentration of Yb and purity is discussed

  10. Preparation and Characterization of Yb - doped YAG Ceramics

    Hostasa, Jan; Esposito, Laura; Alderighi, Daniele; Pirri, Angela

    2011-01-01

    Rare-earth doped yttrium aluminum garnet (YAG) ceramics are among the most widely produced transparent ceramics for laser applications. Yb:YAG ceramics are an interesting IR laser material [1], which allows significantly higher doping compared to the generally more used Nd:YAG [2,3]. This work presents the preparation of polycrystalline Yb:YAG ceramics with dopant concentration from 0 up to 20 at.% via solid state reactive sintering. Samples were prepared via cold isostatic pressing of spray ...

  11. Preparation and characterization of Yb-doped YAG ceramics

    Hostaša, Jan; Esposito, Laura; Alderighi, Daniele; Pirri, Angela

    2013-02-01

    This work presents the results of the preparation of polycrystalline Yb:YAG ceramics for laser sources with dopant concentration from 0 up to 20 at.% via solid state reactive sintering. Samples were prepared via cold isostatic pressing of spray dried mixture of pure oxide powders with TEOS as a sintering aid. Sintering was conducted under high vacuum and clean atmosphere. Various sintering cycles were tested, so that optimum conditions could be selected in dependence on Yb concentration. Samples with optical transmittance higher than 80% were prepared and their laser performance was examined. Slope efficiency as high as 73% and a maximum output power of 6 W were obtained for the sample doped with 10% Yb. Final microstructure of prepared samples was analyzed via optical microscopy, scanning and transmission electron microscopy, and EDS.

  12. An optimization of Raman effects in tandem-pumped Yb-doped kilowatt fiber amplifiers

    Zhang, Tianzi; Ding, Yingchun; Liu, Zhongxuan; Gong, Wupeng

    2015-07-01

    Kilowatt Ytterbium-doped fiber laser is found widespread application in medical technology, industry and military areas. At present, most of the multi-kilowatt single-mode fiber lasers are achieved by tandem-pumped master oscillator power-amplifier (MOPA) system. When the laser output power reaches kilowatt, the output will be strongly affected by nonlinear effects in the amplifier. The Stimulated Raman Scattering effects is known as the major restrictions to the increase of output signal power. Up to now, Raman effects in conventional diode-pumped amplifier have been well studied while the Raman effects in tandem-pumped has not yet been thoroughly analyzed. In this paper, a theoretical analysis of Raman effects using numerical solution of steady-state rate equations in kilowatts tandem-pumped ytterbium-doped fiber amplifiers is presented. The numerical simulation describing output power characteristics and laser distribution along the fiber is carried under the co-directional end-pumping. Furthermore, an optimization of Raman effects is discussed, which provides a solid foundation for achieving a higher fiber laser output.

  13. Gain-switched, Yb-doped, all-fiber laser with narrow bandwidth

    Larsen, Casper; Giesberts, Martin; Nyga, Sebastian; Fitzau, Oliver; Hoffmann, Hans Dieter; Bang, Ole

    2013-01-01

    We demonstrate that an all-fiber, narrow bandwidth, high pulse energy pulsed laser can be constructed from commercially available components by applying gain-switching. After single-stage amplification the pulses are frequency doubled in ppSLT with high efficiency....

  14. Lasing properties of new Yb-doped borate compounds with varying gadolinium and yttrium concentration

    Manek-Hönninger, Inka; Chavoutier, Marie; Jubera, Véronique; Descamps, Dominique; Veber, Philippe; Velazquez, Matias; Garcia, A.; Canioni, L.

    2011-02-01

    We show spectroscopic and lasing properties of new ytterbium-doped borate compounds with the structure Li6(Gd(1- x)Yx)0.75Yb0.25(BO3)3 with x = 0, 0.25, 0.5, 0.75 and 1, respectively. All compounds show large emission spectra suitable for femtosecond pulse generation. We studied the laser performances in a diode-pumped linear laser cavity on about 1- mm-thick crystal samples having an ytterbium doping concentration of 22 %. The compounds show all cw lasing at wavelengths around 1040 to 1060 nm with a slope efficiency of 32 %. The maximum observed output power was 460 mW at an incident pump power of 1.6 W at 972 nm.

  15. Properties of Er and Yb Doped Gallium nitride layers fabricated by magnetron sputtering

    Prajzler, V.; Burian, Z.; Hüttel, I.; Špirková, J.; Hamáček, J.; Oswald, J.; Zavadil, Jiří; Peřina, Vratislav

    2006-01-01

    Roč. 46, č. 6 (2006), s. 49-55. ISSN 1210-2709 R&D Projects: GA ČR(CZ) GA102/06/0424 Institutional research plan: CEZ:AV0Z20670512; CEZ:AV0Z10480505 Keywords : fluorescence * gallium * rare earth compounds Subject RIV: BM - Solid Matter Physics ; Magnetism

  16. Tm-Yb Doped Optical Fiber Performance with Variation of Host-Glass Composition

    Anirban Dhar

    2014-01-01

    Full Text Available The fabrication process of Thulium-Ytterbium doped optical fiber comprising different host glass through the Modified Chemical Vapor Deposition (MCVD coupled with solution doping technique is presented. The material and optical performance of different fibers are compared with special emphasis on their lasing efficiency for 2 µm application.

  17. Demonstration of a homogeneous Yb-doped core fully aperiodic large-pitch fiber laser.

    Dauliat, Romain; Benoît, Aurélien; Darwich, Dia; Jamier, Raphaël; Kobelke, Jens; Grimm, Stephan; Schuster, Kay; Roy, Philippe

    2016-08-10

    The first demonstration of a 40 μm core homogeneously ytterbium-doped fully aperiodic large-pitch fiber laser, to the best of our knowledge, is reported here. In this concept, the amplification of unwanted high-order modes is prevented by means of an aperiodic inner-cladding structure, while the core and inner-cladding material has a higher refractive index than pure silica. In a laser configuration, up to 252 W of extracted power, together with an optical-to-optical efficiency of 63% with respect to the incident pump power, have been achieved. While an average M2 of 1.4 was measured, the emitted power becomes temporally unstable when exceeding 95 W, owing to the occurrence of modal instabilities. PMID:27534463

  18. Ce and Yb doped InP layers grown for radiation detection

    Zavadil, Jiří; Procházková, Olga; Žďánský, Karel; Gladkov, Petar

    2007-01-01

    Roč. 4, č. 4 (2007), s. 1444-1447. ISSN 1610-1634. [EXMATEC 2006 - International Workshop on Expert Evaluation & Control of Compound Semiconductor Materials & Technologies /8./. Cádiz, 14.05.2006-17.05.2006] R&D Projects: GA ČR GA102/06/0153 Institutional research plan: CEZ:AV0Z20670512 Keywords : semiconductors * photoluminescence * galvanomagnetic effects Subject RIV: CA - Inorganic Chemistry

  19. Linearly polarized intracavity passive Q-switched Yb-doped photonic crystal fibre laser

    Usha Chakravarty; Antony Kuruvilla; Rajpal Singh; B N Upadhyay; K S Bindra; S M Oak

    2014-02-01

    In this paper we report linearly polarized high average power passive Q-switched ytterbium-doped photonic crystal fibre laser with a Cr4+:YAG crystal as a saturable absorber. An average output power of 9.4 W with pulse duration of 64 ns and pulse repetition rate of 57.4 kHz with a slope efficiency of 52% was achieved. Measured polarization extinction ratio (PER) of the Q-switched laser output was 10.5 dB.

  20. How do traces of thulium explain photodarkening in Yb doped fibers?

    Peretti, R; Jurdyc, A-M; Jacquier, B; Gonnet, Cédric; Pastouret, Alain; Burov, Ekaterina; Cavani, Olivier

    2010-09-13

    Ytterbium doped fiber lasers are known to be impacted by the creation of color centers during lasing so called photodarkening. This defect creation was investigated in a spectroscopic point of view, showing the presence of thulium traces (ppb) in the ytterbium doped fiber. Moreover, this contamination exhibit luminescence in the UV range under 976 nm excitation of the ytterbium-doped fiber. In adding more thulium to an ytterbium-doped fiber it was shown that thulium strongly impact the defects creation process, involved in photodarkening. PMID:20940938

  1. Tm-Yb Doped Optical Fiber Performance with Variation of Host-Glass Composition

    Anirban Dhar; Atasi Pal; Shyamal Das; Ranjan Sen

    2014-01-01

    The fabrication process of Thulium-Ytterbium doped optical fiber comprising different host glass through the Modified Chemical Vapor Deposition (MCVD) coupled with solution doping technique is presented. The material and optical performance of different fibers are compared with special emphasis on their lasing efficiency for 2 µm application.

  2. Monolithic Highly Stable Yb-Doped Femtosecond Fiber Lasers for Applications in Practical Biophotonics

    Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

    2012-01-01

    Operational and environmental stability of ultrafast laser systems is critical for their applications in practical biophotonics. Mode-locked fiber lasers show great promise in applications such as supercontinuum sources or multiphoton microscopy systems. Recently, substantial progress has been made...... in the development of all-fiber nonlinear-optical laser control schemes, which resulted in the demonstration of highly stable monolithic, i.e., not containing any free-space elements, lasers with direct fiber-end delivery of femtosecond pulses. This paper provides an overview of the progress in the...... development of such all-fiber mode-locked lasers based on Yb-fiber as gain medium, operating at the wavelength around 1 $\\mu$m, and delivering femtosecond pulses reaching tens of nanojoules of energy....

  3. Yb-doped silica glass and photonic crystal fiber based on laser sintering technology

    Zhang, Wei; Wu, Jiale; Zhou, Guiyao; Xia, Changming; Liu, Jiantao; Tian, Hongchun; Liang, Wanting; Hou, Zhiyun

    2016-03-01

    We demonstrate the fabricating method for Yb3+-doped silica glass and double-cladding large mode area photonic crystal fiber (LMA PCF) based on laser sintering technology combined with a liquid phase doping method. The doped material prepared shows the amorphous property and the hydroxyl content is approximately 40 ppm. The attenuation of the fabricated LMA PCF is 14.2 dB m-1 at 976 nm, and the lowest value is 0.25 dB m-1 at 1200 nm. The laser slope efficiency is up to 70.2%.

  4. 3.5-GHz intra-burst repetition rate ultrafast Yb-doped fiber laser

    Kerse, Can; Kalaycıoğlu, Hamit; Elahi, Parviz; Akçaalan, Önder; Ilday, F. Ömer

    2016-05-01

    We report on an all-fiber Yb laser amplifier system with an intra-burst repetition rate of 3.5 GHz. The system is able to produce minimum of 15-ns long bursts containing approximately 50 pulses with a total energy of 215 μJ at a burst repetition rate of 1 kHz. The individual pulses are compressed down to the subpicosecond level. The seed signal from a 108 MHz fiber oscillator is converted to approximately 3.5 GHz by a multiplier consisting of six cascaded 50/50 couplers, and then amplified in ten stages. The highly cascaded amplification suppresses amplified spontaneous emission at low repetition rates. Nonlinear interactions between overlapping pulses within a burst is also discussed.

  5. Power-scalable long-wavelength Yb-doped photonic bandgap fiber sources

    Olausson, Christina Bjarnal Thulin; Shirakawa, Akira; Maurayama, Hiroki; Ken-ichi, Ueda; Lyngsøe, Jens Kristian; Broeng, Jes

    2010-01-01

    Ytterbium-doped photonic-bandgap fiber sources operationg at the long-wavelength edge of the ytterbium gain band are being investigated for high power amplification. Artificial shaping of the gain spectrum by the characteristic distributed filtering effect of the photonic bandgap enables spontane...

  6. Graphene incorporated Q-switching of a polarization-maintaining Yb-doped fiber laser

    Environmentally-stable, all-polarization-maintaining Q-switching ytterbium-doped fiber laser was demonstrated using graphene as saturable absorber. By optically driving deposition of graphene onto the fiber connector, the saturable absorber is fabricated and inserted into the laser cavity to construct the Q-switching fiber laser. The maximum average output power of 15.6 mW at a repetition rate of 110 kHz, which corresponds to a single pulse energy of 141.8 nJ, was achieved. They are the maximum average output power and the highest single pulse energy reported so far for graphene Q-switched fiber lasers

  7. Electrical and microstructural properties of Yb-doped CeO2

    B. Matović

    2014-06-01

    Full Text Available Nanopowdered Ce1−xYbxO2−δ solid solutions (0 ≤ x ≤ 0.2 were synthesized by a self-propagating room temperature synthesis. XRD and SEM were used to study the properties of these materials as well as the Yb solubility in CeO2 lattice. Results showed that all the obtained powders were solid solutions with a fluorite-type crystal structure and with nanometric particle size. The average size of Ce1−xYbxO2−δ particles was approximately 3 nm. Electrochemical impedance spectroscopy for the sintered pellets depicted that it was possible to separate Rbulk and Rgb in the temperature interval of 550–800 °C. The activation energy for the bulk conduction was 1.03 eV and for grain boundary conduction was 1.14 eV. Grain boundary resistivity dominates over the other resistivities. These measurements confirmed that Yb3+-doped CeO2 material had a potential as electrolyte for intermediate-temperature solid oxide fuel cell applications.

  8. Thermal Properties of Transparent Yb-Doped YAG Ceramics at Elevated Temperatures

    Hostaša, J.; Matějíček, Jiří; Nait-Ali, B.; Smith, D.S.; Pabst, W.; Esposito, L.

    2014-01-01

    Roč. 97, č. 8 (2014), s. 2602-2606. ISSN 0002-7820 Institutional support: RVO:61389021 Keywords : yttrium aluminium garnet * Yb: YAG * thermal diffusivity Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.610, year: 2014 http://onlinelibrary.wiley.com/doi/10.1111/jace.13015/abstract

  9. Single-mode amplification in Yb-doped rod-type photonic crystal fibers for high brilliance lasers

    Poli, F.; Lægsgaard, Jesper; Passaro, D.;

    2009-01-01

    higher-order mode (HOM), stressing the difference between their spatial distributions, with respect to the uniform refractive index core. In the present analysis a rod-type PCF with a 19-missing air-hole core, whose radius is 30 mum, has been considered. Initially, a PCF step-index model has been applied...... a forward-pumped configuration....

  10. Thermo-Optical Tuning of Whispering Gallery Modes in Er:Yb Doped Glass Microspheres to Arbitrary Probe Wavelengths

    Watkins, Amy; Chormaic, Síle Nic

    2012-01-01

    We present experimental results on an all-optical, thermally-assisted technique for broad range tuning of microsphere cavity resonance modes to arbitrary probe wavelengths. An Er:Yb co-doped phosphate glass (Schott IOG-2) microsphere is pumped at 978 nm via the supporting stem and the heat generated by absorption of the pump light expands the cavity and changes the refractive index. This is a robust tuning method that decouples the pump from the probe and allows fine tuning of the microsphere's whispering gallery modes. Pump/probe experiments were performed to demonstrate thermo-optical tuning to specific probe wavelengths, including the 5S1/2 F = 3 to 5P3/2 F' = 4 laser cooling transition of 85Rb. This is of particular interest for cavity QED-type experiments, while the broad tuning range achievable is useful for integrated photonic devices, including sensors and modulators.

  11. Theory of noise in a kilo-Hz cascaded high-energy Yb-doped nanosecond pulsed fiber amplifier

    A theoretical analysis of noise in a high-power cascaded fiber amplifier is presented. Unlike the noise theory in low power communication, the noise of a high power system is redefined as the leaked output energy between pulses with coherent beat noise uncounted. This definition is more appropriate for high power usage in which the pulse energy receives more attention than the pulse shape integrity. Then the low power pre-amplifying stages are considered as linear amplification and analyzed by linear theory. In the high-power amplification stages, the inversion is assumed to recover linearly in the time interval between pulses. The time shape of the output pulse is different from that of the input signal because of different gains at the front and back ends of the pulse. Then, a criterion is provided to distinguish the nonlinear and linear amplifications based on the signal-to-noise ratio (SNR) analysis. Then, an experiment that shows that the output SNR actually drops off in nonlinear amplification is performed. The change in the noise factor can be well evaluated by pulse shape distortion. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  12. Efficient intracavity frequency doubling of an Yb-doped fiber laser using an internal resonant enhancement cavity

    Cieslak, R.; Sahu, J.K.; Clarkson, W. A.

    2010-01-01

    We describe a simple approach for efficient generation of visible light in high-power continuous-wave fiber lasers via second harmonic generation in an internal resonant cavity. Preliminary results for a cladding-pumped Yb fiber laser are presented.

  13. Spatially selective Er/Yb-doped CaF2 crystal formation by CO2 laser exposure

    Highlights: • Oxyfluoride glass–ceramics containing CaF2 nanocrystals doped with Er3+ and Yb3+ ions were formed on the glass surface by CO2 laser and a heat gun exposure. • Most of Er and Yb ions were distributed inside CaF2 nanocrystals and fluorine loss was observed in the EDS element maps. • IR-to-VIS upconversion emission efficiency of laser annealed glass ceramics was much increased and compared with that of the furnace-annealed glass ceramics. • Distributed volume of the glass ceramics were estimated by a confocal fluorescence microscope imaging. - Abstract: We report the glass–ceramic precipitation on the oxyfluoride glass surface by spatially selective annealing with a CO2 laser and a heat gun exposure. X-ray diffraction analysis showed the formation of major CaF2 and miner Ca2SiO4 nanoparticles. We observed ∼100 nm nanoparticle aggregation by tunneling electron microscopy and element distribution in glass and crystal phases. Spatial distribution of glass ceramics near the glass surface was probed by confocal fluorescence microscope by using much enhanced emission from the Er ions in the laser-treated area. Strong emissions at 365 nm excitation and visible up-conversion emissions at 980 nm excitation also indicated well incorporation of Er and Yb ions into a crystalline environment

  14. High-peak-power second-harmonic generation of single-stage Yb-doped fiber amplifiers

    Horiuchi, Ryusuke; Saiki, Koichi; Adachi, Koji; Tei, Kazuyoku; Yamaguchi, Shigeru

    2008-05-01

    A high-peak-power and high-repetition-rate fiber laser architecture is successfully demonstrated using a single-stage fiber amplifier. Nonlinear optical effects in a fiber amplifier degrade the monochromaticity of amplified laser pulses. In general, it is difficult for a non-monochromatic laser pulse to realize high-order harmonic generation with bulk nonlinear optical crystals. To overcome this problem, a single-stage amplifier architecture and a gain fiber with a high cladding absorption coefficient are employed. Furthermore, single-stage amplification enables the use of a multi-longitudinal mode electro-optically (EO) Q-switched micro seed laser. This architecture can generate a peak power of 100 kW at 50 kHz and an average power of 10 W. A second-harmonic conversion efficiency of 51% is obtained using this architecture and a LiB3O5 (LBO) crystal.

  15. Mode-locked femtosecond all-normal all-PM Yb-doped fiber laser at 1060 nm

    Bowen, Patrick; Singh, Harman; Runge, Antoine; Provo, Richard; Broderick, Neil G. R.

    2016-04-01

    We report an all-normal-dispersion, all-fibre, all-PM, laser operating at a central wavelength of 1060 nm. The laser is mode-locked using a nonlinear amplifying loop mirror and generates linearly polarised pulses that can be compressed to 360 fs. The laser is based on our earlier scheme operating at 1030 nm [1] and we discuss the similarities and differences between the two configurations. We also present amplification up to an output power of 1 W using a commercially built amplifier and show through numerical methods that this pulse may be recompressible to 1.65 ps.

  16. Mode-locked Yb-doped all-fiber laser based on in-fiber acoustooptic modulation

    We show what we believe is the first demonstration of an ytterbium-doped strictly all-fiber active mode-locking laser. The active control of the laser is based on in-fiber amplitude modulation at 11 MHz, which is achieved by using an all-fiber acoustooptic superlattice modulator driven by standing acoustic waves. In our experiments, the laser was operated at 1091.3 nm and had two stable regimes producing either a train of mode-locked single pulses or a train of pulse pairs. Best results for the mode-locked train of single pulses were 740 ps of time width and 26 mW of average power, at a pump power of 480 mW

  17. Thermal effect-resilient design of large mode area double-cladding Yb-doped photonic crystal fibers

    Coscelli, Enrico; Poli, Federica; Johansen, Mette Marie;

    2013-01-01

    on the finite-element method has been used to calculate the guided modes of the fibers operating at high power levels. The results demonstrate that resonant structures added to the fiber cross-section can be exploited to provide efficient suppression of high-order modes with a good resilience to...

  18. Thermal effect-resilient design of large mode area double-cladding Yb-doped photonic crystal fibers

    Coscelli, Enrico; Poli, Federica; Johansen, Mette Marie; Alkeskjold, Thomas Tanggaard; Leick, Lasse; Broeng, Jes; Sozzi, Michele; Candiani, Alessandro; Cucinotta, Annamaria; Selleri, Stefano

    2013-01-01

    The effects of thermally-induced refractive index change on the guiding properties of different large mode area fibers have been numerically analyzed. A simple but accurate model has been applied to obtain the refractive index change in the fiber cross-section, and a full-vector modal solver based...... on the finite-element method has been used to calculate the guided modes of the fibers operating at high power levels. The results demonstrate that resonant structures added to the fiber cross-section can be exploited to provide efficient suppression of high-order modes with a good resilience to...... thermal effects....

  19. Superconductivity at 31.3 K in Yb-doped La(O/F)FeAs superconductors

    J Prakash; S J Singh; S Patnaik; A K Ganguli

    2010-01-01

    The effect of ytterbium substitution at the lanthanum site on the superconducting properties of La1-YbO0.8F0.2FeAs ( = 0.10, 0.20 and 0.30) oxypnictides has been investigated. Powder X-ray diffraction studies show the presence of Yb2O3 and LaOF as secondary phases. The superconducting transition temperature (c) of 31.3 (± 0.05) K has been observed in = 0.1 composition which is the maximum c so far in the La(O/F)FeAs superconductor family at ambient pressure. Further increase in leads to suppression and broadening of superconducting transition. The resistive transition curves under different magnetic fields were investigated, leading to determination of upper critical field c2 () of this new superconductor. The value of c2 at zero temperature is estimated to be about 46 T corresponding to coherence length ∼ 27 Å.

  20. Luminance Conversion Property of Er and Yb Doped KZnF3 Nanocrystal Synthesized by Hydrothermal Method

    Weidong Lai

    2015-01-01

    Full Text Available In order to make full use of exposure energy, one feasible way is to modify the luminance of crystal by rare earth doping technique. KZnF3:Er3+ and KZnF3:Er3+/Yb3+ nanocrystals of uniform cuboid perovskite type morphology, with average diameter of 130 nm, has been synthesized by hydrothermal method. When Yb3+ ions were codoped with Er3+, absorption peak at 970 nm has been heightened and widened, and the photon absorption cross section increased. The common xenon lamp exposure cannot initiate obvious nonlinear phenomenon of the doped Er3+ and Yb3+, and exposing at 245 nm only excites the fluorescence around 395 nm. Contrarily, under high power IR exposure at 980 nm, obvious upconversion photoluminescence (PL has been observed due to the two-photon process. The PL mechanism of the doped Er3+ ion in KZnF3:Er3+/Yb3+ nanocrystals is confirmed. Furthermore, Yb3+ codoped as sensitizer has modified the PL intensity of Er3+ from green light range to red range, and the primary channel is changed from 4S3/2(Er3+ → 4I15/2(Er3+ of only Er3+ doped KZnF3 nanocrystal to 4F9/2(Er3+ → 4I15/2(Er3+ of Er3+/Yb3+ codoped sample. With exposure energy increasing, such primary transition channel after two-photon excitation is unchanged.

  1. Tapered large-core 976 nm Yb-doped fiber laser with 10 W output power

    We report on a tapered large-core Yb fiber laser operating at 976 nm emission wavelength. It was realized using a high-numerical aperture large-core fiber with 126 μm core diameter, which was fabricated by powder-sinter technology and shows a very homogeneous step-index profile. The end of the fiber is tapered down to match a single-mode fiber containing a fiber Bragg grating. Using the benefits of core-pumping and the feedback of the spliced fiber Bragg grating, we achieved efficient pump light absorption and wavelength stable 976 nm lasing with single-mode performance. We could demonstrate 10 W laser power out of a 10 μm fiber core with a slope efficiency of 31% with respect to the launched pump power. The presented device is well-suited for fiber-coupled pumping of amplifiers for high peak power. (letter)

  2. Generation of 130 W narrow-linewidth high-peak-power picosecond pulses directly from a compact Yb-doped single-stage fiber amplifier

    Qi, Yaoyao; Yu, Haijuan; Zhang, Jingyuan; Wang, Lei; Zhang, Ling; Lin, Xuechun

    2015-09-01

    We report a compact, 130-W single-stage master oscillator power amplifier with a high peak power of 51.3 kW and a narrow spectral linewidth of 0.1 nm. The seed source is a single-mode, passively mode-locked solid-state laser at 1064 nm with an average power of 2 W. At a repetition rate of 73.5 MHz, the pulse duration is 30 ps. After amplification, it stretches to 34.5 ps. The experiment enables the optical-to-optical conversion efficiency to reach 75%. To the best of our knowledge, this is the first report of such a high-power, narrow spectral linewidth, high peak power picosecond-pulse fiber amplifier based on a continuous-wave, mode-locked solid-state seeding laser. No amplified spontaneous emission and stimulated Raman scattering were observed when the pump was increased.

  3. Metal-to-metal charge transfer between dopant and host ions: Photoconductivity of Yb-doped CaF{sub 2} and SrF{sub 2} crystals

    Barandiarán, Zoila, E-mail: zoila.barandiaran@uam.es; Seijo, Luis [Departamento de Química, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Instituto Universitario de Ciencia de Materiales Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid (Spain)

    2015-10-14

    Dopant-to-host electron transfer is calculated using ab initio wavefunction-based embedded cluster methods for Yb/Ca pairs in CaF{sub 2} and Yb/Sr pairs in SrF{sub 2} crystals to investigate the mechanism of photoconductivity. The results show that, in these crystals, dopant-to-host electron transfer is a two-photon process mediated by the 4f{sup N−1}5d excited states of Y b{sup 2+}: these are reached by the first photon excitation; then, they absorb the second photon, which provokes the Y b{sup 2+} + Ca{sup 2+} (Sr{sup 2+}) → Y b{sup 3+} + Ca{sup +} (Sr{sup +}) electron phototransfer. This mechanism applies to all the observed Y b{sup 2+} 4f–5d absorption bands with the exception of the first one: Electron transfer cannot occur at the first band wavelengths in CaF{sub 2}:Y b{sup 2+} because the Y b{sup 3+}–Ca{sup +} states are not reached by the two-photon absorption. In contrast, Yb-to-host electron transfer is possible in SrF{sub 2}:Y b{sup 2+} at the wavelengths of the first 4f–5d absorption band, but the mechanism is different from that described above: first, the two-photon excitation process occurs within the Y b{sup 2+} active center, then, non-radiative Yb-to-Sr electron transfer can occur. All of these features allow to interpret consistently available photoconductivity experiments in these materials, including the modulation of the photoconductivity by the absorption spectrum, the differences in photoconductivity thresholds observed in both hosts, and the peculiar photosensitivity observed in the SrF{sub 2} host, associated with the lowest 4f–5d band.

  4. Stimulated Brillouin Scattering Enhancement Factor Improvement in a 11.6-GHz-Linewidth 1.5-kW Yb-Doped Fiber Amplifier

    Guang-Bo, Liu; Yi-Feng, Yang; Jian-Hua, Wang; Ye, Zheng; Xiao-Long, Chen; Kai, Liu; Chun, Zhao; Yun-Feng, Qi; Bing, He; Jun, Zhou

    2016-07-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos U1330134, 61308024 and 11174305, the National High-Technology Research and Development Program of China under Grant No 2014AA041901, and the Shanghai Natural Science Foundation under Grant No 11ZR1441400.

  5. Polarized spectra calculation and continuous wave laser operation of Yb-doped disordered Ca3La2(BO3)4 crystal

    Wang, Yeqing; Chen, Aixi; You, Zhenyu; Tu, Chaoyang

    2015-12-01

    A notable disorder crystal Yb:Ca3La2(BO3)4 crystal with Yb3+ ion doping concentration of 10 at.% was grown by the Czochralski method. The polarized absorption, polarized emission, and polarized gain cross sections were systematically calculated. The laser operations were investigated with Yb:Ca3La2(BO3)4 crystals cut along the a, b, and c crystallographic axes. The highest output power of 3.88 W was obtained by using the b-cut Yb:Ca3La2(BO3)4 crystal, with a slope efficiency of 62%. Additionally, it was confirmed that the output laser spectra were largely dependent on the output coupler.

  6. Optical properties of laser created LiNbO3 and Er,Yb doped LiNbO3 layers

    Jelínek, Miroslav; Oswald, Jiří; Kocourek, Tomáš; Rubešová, K.; Havránek, V.; Studnička, Václav

    Strasbourg: European Materials Research Society, 2012 - (Dusastre, V.) [E- MRS 2012 Spring Meeting. 14.05.2012-18.05.2012, Strasbourg] R&D Projects: GA ČR(CZ) GAP106/10/1477 Institutional research plan: CEZ:AV0Z10100522 Keywords : PLD * LiNbO3 * planar waveguides Subject RIV: BM - Solid Matter Physics ; Magnetism

  7. Investigation on repetition rate and pulse duration influences on ablation efficiency of metals using a high average power Yb-doped ultrafast laser

    Lopez J.

    2013-11-01

    Full Text Available Ultrafast lasers provide an outstanding processing quality but their main drawback is the low removal rate per pulse compared to longer pulses. This limitation could be overcome by increasing both average power and repetition rate. In this paper, we report on the influence of high repetition rate and pulse duration on both ablation efficiency and processing quality on metals. All trials have been performed with a single tunable ultrafast laser (350 fs to 10ps.

  8. Optical properties of laser-prepared Er-and Er,Yb-doped LiNbO.sub.3./sub. waveguidinglayers

    Jelínek, Miroslav; Oswald, Jiří; Kocourek, Tomáš; Rubešová, K.; Nekvindová, P.; Chvostová, Dagmar; Dejneka, Alexandr; Železný, Vladimír; Studnička, Václav; Jurek, Karel

    2013-01-01

    Roč. 23, č. 10 (2013), "105819-1"-"105819-5". ISSN 1054-660X R&D Projects: GA ČR(CZ) GAP106/10/1477; GA ČR(CZ) GAP204/11/1011 Institutional support: RVO:68378271 Keywords : doped LiNbO 3 * deposition conditions * optical properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.025, year: 2013

  9. Mode-locked Yb-doped large-mode-area photonic crystal fiber laser operating in the vicinity of zero cavity dispersion

    A passively mode-locked ytterbium-doped large-mode-area photonic crystal fiber oscillator operating in the vicinity of zero cavity dispersion is demonstrated. The self-starting mode-locking operation is achieved by a high contrast saturable absorber mirror. Two mode-locking regimes with opposite signs of net cavity dispersion are investigated. At a net cavity dispersion of –0.0035 ps2, the fiber laser directly generates 10-nJ laser pulses with an average power of 630 mW at 65.3 MHz repetition rate. The pulses can be dechirped to 78 fs by extracavity dispersion compensation. The pulse energy is scaled up to 18 nJ, yielding an average power of 1.2 W, when the cavity dispersion is set at 0.0035 ps2. In this regime, the laser output can be extracavity-dechirped to 120 fs. Dynamics of pulse evolution in the fiber laser is illustrated by numerical simulation, which agrees well with experimental results

  10. High-power near-infrared linearly-polarized supercontinuum generation in a polarization-maintaining Yb-doped fiber amplifier.

    Zhang, Bin; Jin, Aijun; Ma, Pengfei; Chen, Shengping; Hou, Jing

    2015-11-01

    We report an all-fiber linearly-polarized (LP) supercontinuum (SC) source with high average power generated in a polarization-maintaining (PM) master-oscillation power-amplifier (MOPA). The experimental configuration comprises an LP picosecond pulsed laser and three PM Yd-doped fiber amplifiers (YDFA). The output has the average power of 124.8 W with the spectrum covering from 850 to 1900 nm. The measured polarization extinction ratio (PER) of the whole SC source is about 85% which verifies the SC an LP source. This work is, to our best knowledge, the highest output average power of an LP SC source that ever reported. The influence of PM fiber splicing method on the LP SC property is investigated by splicing the PM fibers with slow axis parallel or perpendicularly aligned, and also an LP SC with low output power is demonstrated. PMID:26561136

  11. Over three-octave spanning supercontinuum generated in a fluoride fiber pumped by Er & Er:Yb-doped and Tm-doped fiber amplifiers

    Swiderski, Jacek; Michalska, Maria

    2013-11-01

    We demonstrate broadband 0.9-3.6 μm supercontinuum (SC) generation with 0.66 W of output power, using a single-mode fluoride (ZBLAN) fiber pumped by 1.55 μm nanosecond pulses amplified in a cascade of fiber amplifiers. Expanding the pump source by adding an additional amplification section based on thulium-doped fibers, the long-wavelength edge of the spectrum was shifted to ~4 μm and was limited by intrinsic losses of the used nonlinear fiber. For this cases, the average SC power as high as 288 mW was recorded, of which 266 mW (92%), 167 mW (58%) and 60 mW (21%) corresponds to wavelengths longer than 2 μm, 3 μm and 3.6 μm. The performance of the SC sources is described.

  12. Thermal lens measurements in Yb-doped YAG, LuAG, Lu2O3, Sc2O3 ceramic lasers

    we report the last experimental results obtained measuring the thermal lens effect in Yb(1at.%):Lu2O3, Yb(1at.%):Sc3O3, Yb(10at.%):LuAG and Yb(10at.%):YAG ceramics. The experimental set-up apparatus using a Shack-Hartmann wavefront sensor allows the comparison of the thermal lens obtained under lasing and non lasing conditions, in order to highlight differences in the thermal loading.

  13. Multi-mJ mid-infrared kHz OPCPA and Yb-doped pump lasers for tabletop coherent soft x-ray generation

    We present our recent progress on the development of a mid-infrared (mid-IR), multi-mJ, kHz optical parametric chirped-pulse amplification (OPCPA) system, pumped by a homebuilt picosecond cryogenic Yb:YAG chirped-pulse amplifier, and its application to soft x-ray high-order harmonic generation. The cryogenic Yb:YAG laser operating at 1 kHz repetition rate delivers 42 mJ, 17 ps, 1.03 μm pulses to pump the OPCPA system. Efficient second and fourth harmonic generations from the Yb:YAG system are demonstrated, which provide the pumping capability for OPCPA at various wavelengths. The mid-IR OPCPA system produces 2.6 mJ, 39 fs, 2.1 μm pulses with good beam quality (M 2 = ∼1.5) at 1 kHz repetition rate. The output pulses of the OPCPA are used to generate high-order harmonics in both gas cell and hollow-core fiber targets. A photon flux of ∼2 × 108 photon/s/1% bandwidth at 160 eV in Ar is measured while the cutoff is 190 eV. The direct measurements of the photon flux from x-ray photodiodes have confirmed the generation of water-window soft x-ray photons with a flux ∼106 photon/s/1% bandwidth at 330 eV in Ne. The demonstrated OPCPA and Yb:YAG pump laser technologies provide an excellent platform of energy and power scalable few-cycle mid-IR sources that are suitable for high-flux tabletop coherent soft x-ray generation. (paper)

  14. Metal-to-metal charge transfer between dopant and host ions: Photoconductivity of Yb-doped CaF2 and SrF2 crystals

    Dopant-to-host electron transfer is calculated using ab initio wavefunction-based embedded cluster methods for Yb/Ca pairs in CaF2 and Yb/Sr pairs in SrF2 crystals to investigate the mechanism of photoconductivity. The results show that, in these crystals, dopant-to-host electron transfer is a two-photon process mediated by the 4fN−15d excited states of Y b2+: these are reached by the first photon excitation; then, they absorb the second photon, which provokes the Y b2+ + Ca2+ (Sr2+) → Y b3+ + Ca+ (Sr+) electron phototransfer. This mechanism applies to all the observed Y b2+ 4f–5d absorption bands with the exception of the first one: Electron transfer cannot occur at the first band wavelengths in CaF2:Y b2+ because the Y b3+–Ca+ states are not reached by the two-photon absorption. In contrast, Yb-to-host electron transfer is possible in SrF2:Y b2+ at the wavelengths of the first 4f–5d absorption band, but the mechanism is different from that described above: first, the two-photon excitation process occurs within the Y b2+ active center, then, non-radiative Yb-to-Sr electron transfer can occur. All of these features allow to interpret consistently available photoconductivity experiments in these materials, including the modulation of the photoconductivity by the absorption spectrum, the differences in photoconductivity thresholds observed in both hosts, and the peculiar photosensitivity observed in the SrF2 host, associated with the lowest 4f–5d band

  15. Evaluation of temperature dependence of the emission cross-section of Yb-doped ceramic materials from 298K to 393K for high average power operation

    The temperature dependence of the emission cross-sections of ceramic materials doped with Yb have been investigated in the temperature range from 298K to 393K. The materials such as YAG, Y2O3 and Lu2O3 have been adopted as host ceramic materials. The emission spectra have been found to decrease with a rise in temperature. The cross sections at the wavelength giving the peaks in the emission spectra have shown a gradual decrease against temperature. (author)

  16. Multi-mJ mid-infrared kHz OPCPA and Yb-doped pump lasers for tabletop coherent soft x-ray generation

    Lai, Chien-Jen; Hong, Kyung-Han; Siqueira, Jonathas P.; Krogen, Peter; Chang, Chun-Lin; Stein, Gregory J.; Liang, Houkun; Keathley, Phillip D.; Laurent, Guillaume; Moses, Jeffrey; Zapata, Luis E.; Kärtner, Franz X.

    2015-09-01

    We present our recent progress on the development of a mid-infrared (mid-IR), multi-mJ, kHz optical parametric chirped-pulse amplification (OPCPA) system, pumped by a homebuilt picosecond cryogenic Yb:YAG chirped-pulse amplifier, and its application to soft x-ray high-order harmonic generation. The cryogenic Yb:YAG laser operating at 1 kHz repetition rate delivers 42 mJ, 17 ps, 1.03 μm pulses to pump the OPCPA system. Efficient second and fourth harmonic generations from the Yb:YAG system are demonstrated, which provide the pumping capability for OPCPA at various wavelengths. The mid-IR OPCPA system produces 2.6 mJ, 39 fs, 2.1 μm pulses with good beam quality (M 2 = ∼1.5) at 1 kHz repetition rate. The output pulses of the OPCPA are used to generate high-order harmonics in both gas cell and hollow-core fiber targets. A photon flux of ∼2 × 108 photon/s/1% bandwidth at 160 eV in Ar is measured while the cutoff is 190 eV. The direct measurements of the photon flux from x-ray photodiodes have confirmed the generation of water-window soft x-ray photons with a flux ∼106 photon/s/1% bandwidth at 330 eV in Ne. The demonstrated OPCPA and Yb:YAG pump laser technologies provide an excellent platform of energy and power scalable few-cycle mid-IR sources that are suitable for high-flux tabletop coherent soft x-ray generation.

  17. Studies on preparation of Mo-30W alloy by co-precipitation followed by co-reduction

    This paper deals with the thermogravimetric studies conducted to study the reduction process of mixed oxide of MoO3 and WO3 prepared by co-precipitation route. The results show that the reduction takes place at multiple stages. The temperatures of formation of intermediate sub-oxides during reduction of mixed oxide were found to be similar with the individual sub-oxides formed during reduction of individual MoO3 and WO3. The reduced powder was analyzed by XRD and EDS for phase and composition. The variations of morphologies of the powder reduced at different temperature were studied using SEM. (author)

  18. Polarization-maintaining amplifier based on 3C fiber structures

    Enokidani, Jun; Ito, Rumi; Sakurai, Tsutomu; Shin, Sumida; Tei, Kazuyoku

    2015-03-01

    Chirally-Coupled-Core (3C) fiber structure can preserve a single mode quality and even a linear polarization for a large core size. A principal advantage of fiber laser is its compatibility with monolithic integration and robust system. But so far, devices such as a combiner using the 3C fibers have not been reported. Here we report the first demonstration of such monolithic amplifier structure which contains an active fiber and a combiner based on 3C fibers. A single-stage amplifier is seeded by an EO Q-switched micro-laser and pumped by two high power fiber pigtailed 976-nm laser diodes via an in-house fabricated (2 + 1) × 1 pump signal combiner. The active fiber is based on a 3-m-long, 3C Yb-doped fiber (33 μm/250 μm core/cladding diameter with 0.06/0.46 NA). The amplifier demonstrates scaling up to 30W average power and 150 kW peak power in 0.3mJ, 2ns pulses. The beam profiles and beam qualities were characterized as its output power was varied up to 30W. The beam profile was maintained at a high beam quality of around M2=1.2. The spectral properties of the 3C fiber were also characterized as its output peak power was varied.

  19. 可调谐Yb光纤激光器LBO倍频特性理论研究%Theoretical analysis of frequency doubling of wavelength-tunable Yb-doped fiber lasers with LBO crystal

    戴明; 柳强; 闫平; 巩马理

    2006-01-01

    针对大信号高斯光束聚焦情况,对平面波耦合波方程进行了改进;利用改进后的耦合波方程,分析了LBO晶体对掺Yb光纤激光整个发射光谱的腔外倍频特性.结果显示,利用温度调谐,LBO晶体可以在掺Yb光纤的整个发射光谱内达到非临界相位匹配;随着基频光波长的增加,倍频效率会有小幅度下降,可接收角有小幅度增长,可接收温度宽度和可接收线宽有较大幅度加宽.结果表明,采取非临界相位匹配,并选用较长的基频光波,易于得到理想的倍频效果.

  20. Crystal growth and luminescence properties of Yb-doped Gd.sub.3./sub.Al.sub.2./sub.Ga.sub.3./sub.O.sub.12./sub. infra-red scintillator

    Suzuki, A.; Kurosawa, S.; Nagata, S.; Yamamura, T.; Pejchal, Jan; Yamaji, A.; Yokota, Y.; Shirasaki, K.; Homma, Y.; Aoki, D.; Shikama, T.; Yoshikawa, A.

    2014-01-01

    Roč. 36, č. 9 (2014), s. 1484-1487. ISSN 0925-3467 Institutional support: RVO:68378271 Keywords : infra-red scintillator * radiation therapy * Yb:GAGG * bulk crystal Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.981, year: 2014

  1. Highly stable high power fiber laser system for optical trapping of ultracold atoms

    Full text: For our quantum gas experiments we simultaneously confine ultracold Rb and Cs atoms in an optical dipole trap. For that purpose the light of a commercially available, narrow-band, single mode 1064-nm solid-state laser is amplified in a home-built fiber amplifier using a Yb-doped large mode area (LMA) fiber. The fiber is pumped by a high-power 980-nm diode laser and yields an (amplified) narrow-band optical output of more than 30 W for an input seed power of about 1 W at 1064 nm. The performance of this fiber amplifier is presented in terms of slope efficiency, relative intensity noise (RIN), and long term stability. The light of the fiber laser is used for optical trapping of the quantum gas mixture in running wave and standing wave dipole traps. We present our progress towards the realization of a 3D optical lattice for the realization of strongly correlated quantum gas mixtures and for the study of quantum gas mixtures in low-dimensional geometry. (author)

  2. 1.5  kW ytterbium-doped single-transverse-mode, linearly polarized monolithic fiber master oscillator power amplifier.

    Huang, Long; Ma, Pengfei; Tao, Rumao; Shi, Chen; Wang, Xiaolin; Zhou, Pu

    2015-04-01

    A linearly polarized monolithic fiber laser based on a master oscillator power amplifier structure with a master oscillator and a one-stage power amplifier is reported. We design a homemade oscillator based on the theory that, in the coiled gain fiber, the higher modes and the polarized mode of the fundamental mode along the fast axis are suppressed effectively because of their obviously higher bend loss than that of the polarized mode of the fundamental mode along the slow axis. The oscillator operates at 1080 nm, launching a 30 W seed laser with a high polarization extinction ratio of 19 dB into the power amplifier via a mode field adapter. The power amplifier utilizes Yb-doped polarization-maintaining fiber of 20/400  μm, which produces nearly diffraction-limited output power of about 1.5 kW with an optical-optical efficiency of 81.5% and a polarization extinction ratio of 13.8 dB. Both the M(x)² factor and the M(y)² factor of the collimated beam are measured to be about 1.2. The spectral width of the output power is broadened approximately linearly, and the full width at half maximum of the spectrum at the maximum output power is about 5.8 nm. It is known as the highest linearly polarized output power to the best of our knowledge. PMID:25967203

  3. Cathodoluminescence of boron nitride nanotubes doped by ytterbium

    Boron nitride nanotubes (BNNTs) are wide band gap semiconducting material with super thermal and chemical stabilities, which make them an ideal nano-sized host for luminescent ions. In this work, we report an in situ synthesis of Ytterbium (Yb) doped BNNTs using a ball milling and annealing approach. Yb doped BNNTs show more red-light emissions in the cathodoluminescent (CL) spectrum in comparison with pure BNNTs. The light emission is due to the insertion of Yb ions into the nanotube wall as the BNNTs serve as a host and contribute directly to the light emission. The cathodoluminescent image demonstrates strong cathodoluminescent emission of whole Yb doped BNNTs.

  4. Optical channel waveguides in $KY(WO_4)_2:Yb^{3+}$

    Borca, C.N.; Romanyuk, Y.E.; Gardillou, F.; Pollnau, M.; Bernal, M.P.; Moretti, P.

    2006-01-01

    First channel waveguide emission from Yb-doped $KY(WO_4)_2$ has been demonstrated. Two different methods have been used to fabricate micron-size active-guiding structures, namely reactive ion etching and ion implantation.

  5. All-fiber nonlinearity- and dispersion-managed dissipative soliton nanotube mode-locked laser

    We report dissipative soliton generation from an Yb-doped all-fiber nonlinearity- and dispersion-managed nanotube mode-locked laser. A simple all-fiber ring cavity exploits a photonic crystal fiber for both nonlinearity enhancement and dispersion compensation. The laser generates stable dissipative solitons with large linear chirp in the net normal dispersion regime. Pulses that are 8.7 ps long are externally compressed to 118 fs, outperforming current nanotube-based Yb-doped fiber laser designs

  6. All-fiber nonlinearity- and dispersion-managed dissipative soliton nanotube mode-locked laser

    Zhang, Z. [Department of Physics, Bilkent University, 06800 Ankara (Turkey); Nanjing University of Posts and Communications, Nanjing 210003 (China); Popa, D., E-mail: dp387@cam.ac.uk; Wittwer, V. J.; Milana, S.; Hasan, T.; Jiang, Z.; Ferrari, A. C. [Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA (United Kingdom); Ilday, F. Ö. [Department of Physics, Bilkent University, 06800 Ankara (Turkey); Department of Electrical and Electronics Engineering, Bilkent University, 06800 Ankara (Turkey)

    2015-12-14

    We report dissipative soliton generation from an Yb-doped all-fiber nonlinearity- and dispersion-managed nanotube mode-locked laser. A simple all-fiber ring cavity exploits a photonic crystal fiber for both nonlinearity enhancement and dispersion compensation. The laser generates stable dissipative solitons with large linear chirp in the net normal dispersion regime. Pulses that are 8.7 ps long are externally compressed to 118 fs, outperforming current nanotube-based Yb-doped fiber laser designs.

  7. Theoretical analysis of radiation-balanced double clad fiber laser

    CHEN Ji-xin; SUI Zhan; CHEN Fu-shen; LI Ming-zhong; WANG Jian-jun

    2005-01-01

    In this letter,a theoretical model of radiation-balanced double clad fiber laser is presented.The characteristic of the laser with Yb doped double clad fiber is analyzed numerically.It is concluded that high output laser power can be obtained by selecting output coupling mirror with lower reflectivity,improving Yb doped concentration and choosing fiber length. This result can help us to design radiation balanced fiber laser.

  8. X波段30W固态功率放大模块的设计%Design for 30W X-band Solid State Power Amplifier Module

    程光伟; 闫燕勤

    2014-01-01

    Microwave power amplifier is widely used and indispensable in radar,navigation,communications,satellite earth station,electronic warfare equipment .Introduce a x-band solid-state power amplifier module design process.Through the RF simulation software ADS according to the S parameters of microwave solid state power amplifier module design and optimize bias blocking circuit and matching circuit,power amplifier through synthesis of cascade,power allocation,meet the requirements of design index.%微波功率放大器的应用范围广,在雷达、导航、通信、卫星地面收发站、电子对抗仪器设备中不可或缺。介绍一个 X波段固态功率放大器模块的设计过程,通过 ADS射频仿真软件根据 S参数对微波固态功放模块的偏置隔直电路以及匹配电路进行设计优化,功率放大器经过级联、功率分配合成,达到设计的指标要求。

  9. Ultralow-threshold Yb(3+):SiO(2) glass laser fabricated by the solgel process.

    Ostby, Eric P; Yang, Lan; Vahala, Kerry J

    2007-09-15

    A Yb-doped silica microcavity laser on a silicon chip is fabricated from a solgel thin film. The high-Q micro-toroid cavity, which has a finesse of 10,000, is evanescently coupled to an optical fiber taper. We report a threshold of 1.8 microW absorbed power that is, to the best of our knowledge, the lowest published threshold to date for any Yb-doped laser. The effect of Yb(3+) concentration on laser threshold is experimentally quantified. PMID:17873923

  10. 7+1 to 1 pump/signal combiner for air-clad fiber with 15 m MFD PM single-mode signal feed-through

    Noordegraaf, Danny; Nielsen, Martin D.; Skovgaard, Peter M. W.;

    2010-01-01

    A 7+1 to 1 pump/signal combiner with single-mode (SM) polarization maintaining (PM) 15 µm mode-field-diameter (MFD) signal feed-through is demonstrated. The combiner is designed for pulse amplification in an active Yb-doped airclad fiber operated in backward pumped configuration. Signal coupling...

  11. Growth and characterization of highly Yb3+doped KY(WO4)2 thin layers

    Aravazhi, S.; Geskus, D.; Dalfsen, van K.; Günther, D.; Pollnau, M.

    2011-01-01

    Highly Yb-doped, lattice-matched layers of potassium double tungstates with different compositions were grown on undoped KY(WO4)2 substrates. Structural and optical investigations confirmed their high quality. Applications are in high-gain amplifiers and thin-disk lasers.

  12. Thermo-optical effects in high-power Ytterbium-doped fiber amplifiers

    Hansen, Kristian Rymann; Alkeskjold, Thomas Tanggaard; Broeng, Jes;

    2011-01-01

    We investigate the effect of temperature gradients in high-power Yb-doped fiber amplifiers by a numerical beam propagation model, which takes thermal effects into account in a self-consistent way. The thermally induced change in the refractive index of the fiber leads to a thermal lensing effect...

  13. Wavelength-swept fiber laser with frequency shifted feedback

    Yun, S. H.; Richardson, D. J.; Culverhouse, D.O.; Kim, B.Y

    1997-01-01

    We report a frequency-shifted, wavelength-swept Er/Yb-doped fiber laser. By matching the intra-cavity filter sweep rate to the frequency shift per round trip controllable, high power (>100mW), cw modeless output over 38m, with

  14. 100W fully-fiberised Ytterbium doped master oscillator power amplifier incorporating adaptive pulse shaping

    Lin, Dejiao; Alam, Shaif-ul; Chen, Kangkang; Malinowski, Andrew; Norman, Steve; Richardson, David

    2009-01-01

    We report a pulsed, fully-fiberised, Yb-doped MOPA with a maximum average output power of 100W. Adaptive pulse shaping was incorporated to reduce the impact of nonlinearities, delivering 2mJ flat-topped pulses with 20kW peak power.

  15. Efficient room temperature cw Yb:glass laser pumped by a 946nm Nd:YAG laser

    R. Koch; Clarkson, W.A.; Hanna, D.C.; Jiang, S.; Myers, M J; Rhonehouse, D.; Hamlin, S.J.; Griebner, U.; Schönnagel, H.

    1997-01-01

    By pumping with a cw diode-pumped Nd:YAG laser operating at 946nm laser operation of a new Yb-doped phosphate glass with 440mW cw output power and a slope efficiency of 48% with respect to the absorbed pump power was achieved at room temperature

  16. Andesita Cerro Bola: Nueva unidad vinculada al magmatismo mioceno de la Cordillera de Olivares, San Juan, Argentina (30°35´S; 69°30´O Cerro Bola Andesite: New unit linked to the Miocene magmatism of the Olivares Cordillera, San Juan (30°35' S ; 68°30' W

    A.F. Wetten

    2005-03-01

    Full Text Available El área de estudio se halla en la zona de Tocota, inmediatamente al este de la Cordillera de Olivares, en el borde oriental de la Cordillera Frontal, provincia de San Juan. En ella se encuentran unidades ígneas y sedimentarias del ciclo gondwánico, las que fueron intruidas y cubiertas en relación discordante por cuerpos subvolcánicos y volcánicos asignados anteriormente al ciclo ándico en sentido amplio, los cuales constituyen el principal objeto del presente estudio. Estos cuerpos han sido mapeados a fin de poder caracterizarlos adecuadamente, en el contexto estratigráfico de la región. Los afloramientos de interés han sido reconocidos en el cerro Bola y alrededores, donde se observan distribuidos irregularmente, cubriendo un área superior a 5 km². Las rocas, de coloración gris clara y composición andesítica - fenoandesítica, presentan estructuras de domo y colada. Estos afloramientos serían correlacionables con la unidad volcánica Pircas (Mioceno, la que aflora al oeste, y conformarían un evento magmático posterior al de pórfidos de diferente composición situados tanto en el arroyo Chita como en el cerro Divisadero. La extensión del área involucrada, la uniformidad litológica, el bajo grado de alteración y una edad radimétrica obtenida por el método K/Ar, fueron considerados para proponer a estas volcanitas como una unidad litoestratigráfica de edad miocena superior, con la denominación de Andesita Cerro Bola.The study area is located in the region of Tocota Creek, close to the Cordillera Olivares, eastern border of the Frontal Range, San Juan province. In this place, igneous and sedimentary units belonging to the Gondwanic cycle, were recognized. These units were intruded and unconformably covered by subvolcanic and volcanic bodies, which were commonly referred to the Tertiary or Andean cycle. The study of these bodies is the main proposal of this work. These bodies had been mapped in order to characterize them properly in the regional stratigraphic context. The main outcrops were recognized in the Bola Hill and surroundings, where they are irregularly distributed, covering an area greater than 5 km². Dome and lava flow structures are present with the light gray andesite - phenoandesite rock. These outcrops can be correlated with the Pircas volcanic unit (Miocene, to the west, and could be further related to other porphyry bodies of different composition, situated both in Chita Creek and in Divisadero Hill. The extension of the area, lithological uniformity, the low alteration and a K/Ar radiometric age were considered, in order to propose these subvolcanic and volcanic bodies as a new lithostratigraphic unit, Upper Miocene in age, denominated "Cerro Bola Andesite".

  17. Generation of 14  W at 589  nm by frequency doubling of high-power CW linearly polarized Raman fiber laser radiation in MgO:sPPLT crystal.

    Surin, A A; Borisenko, T E; Larin, S V

    2016-06-01

    We introduce an efficient, single-mode, linearly polarized continuous wave (CW) Raman fiber laser (RFL), operating at 1178 nm, with 65 W maximum output power and a narrow linewidth of 0.1 nm. Single-pass second-harmonic generation was demonstrated using a 20 mm long MgO-doped stoichiometric periodically polled lithium tantalate (MgO:sPPLT) crystal pumped by RFL radiation. Output power of 14 W at 589 nm with 22% conversion efficiency was achieved. The possibility of further power scaling is considered, as no crystal degradation was observed at these power levels. PMID:27244435

  18. Diode-pumped actively Q-switched c-cut Nd:YVO4 self-Raman laser

    An efficient compact self-Raman frequency conversion in an end-diode-pumped actively Q-switched c-cut Nd:YVO4 laser has been demonstrated. At an incident pump power of 5.0 W, the self-stimulated Raman laser produces 910 mW of 1178 nm average output power at a pulse repetition frequency of 20 kHz. Diode-to-Raman optical conversion efficiency is more than 18%. A maximum average output power of 1.4 W is achieved at a pulse repetition frequency of 60 kHz and an incident pump power of 9.0 W

  19. A high average power single-stage picosecond double-clad fiber amplifier

    In this paper, we report 38.8 W average power output through a single-stage fiber amplifier, with emission of 1064 nm wavelength with 80 MHz repetition and 35 ps pulse width amplified from a 2.15 W SESAM passively mode-locked Nd:YVO4 laser oscillator. The high power fiber amplification is through a coupled 60.8 W 976 nm backward unidirectional pump power into a 2 m long 30/250 μm Yb-doped inner cladding. No obvious nonlinear effects arise in the high power output. To our knowledge this is the highest average power output with 2 m 30/250 μm Yb-doped double-clad fiber in a single-stage picosecond fiber amplifier. (paper)

  20. Effect of Structural Stress on the Laser Quality of Highly Doped Yb:KY(WO4)2/KY(WO4)2 and Yb:KLu(WO4)2/KLu(WO4)2 Epitaxial Structures

    Carvajal, J.; Raghothamachar, B; Silvestre, O; Chen, H; Pujol, M; Petrov, V; Dudley, M; Aguilo, M; Diaz, F

    2009-01-01

    In this communication we demonstrate how the difference in laser performance of two highly doped (20 at %) epitaxial layers of Yb-doped KY(WO4)2 (KYW) grown on a KYW substrate and Yb-doped KLu(WO4)2 (KLuW) grown on a KLuW substrate, respectively, is related to the presence of structural stress in the epilayers, investigated by synchrotron white beam X-ray topography. From the results obtained, it is clear that the samples that show a larger amount of structural stress, Yb:KYW/KYW epitaxies, lead to lower efficiency in laser operation, giving a direct correlation between the existence and magnitude of such structural stress and the loss in efficiency of laser performance in such epitaxial layers which, from a spectroscopical point of view, are otherwise equivalent.

  1. All-fiber femtosecond Cherenkov radiation source

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe;

    2012-01-01

    An all-fiber femtosecond source of spectrally isolated Cherenkov radiation is reported, to the best of our knowledge, for the first time. Using a monolithic, self-starting femtosecond Yb-doped fiber laser as the pump source and the combination of photonic crystal fibers as the wave-conversion med......An all-fiber femtosecond source of spectrally isolated Cherenkov radiation is reported, to the best of our knowledge, for the first time. Using a monolithic, self-starting femtosecond Yb-doped fiber laser as the pump source and the combination of photonic crystal fibers as the wave......-conversion medium, we demonstrate milliwatt-level, stable, and tunable Cherenkov radiation at visible wavelengths 580–630 nm, with pulse duration of sub-160-fs, and the 3 dB spectral bandwidth not exceeding 36 nm. Such an all-fiber Cherenkov radiation source is promising for practical applications in biophotonics...

  2. 980-nm Q-switched photonic crystal fiber laser by MoS2 saturable absorber

    Li, Pingxue; Liang, Boxing; Su, Meng; Zhang, Yuefei; Zhao, Yan; Zhang, Mengmeng; Ma, Chunmei; Su, Ning

    2016-05-01

    We demonstrate a 980-nm Q-switch Yb-doped photonic crystal fiber laser by a multilayer molybdenum sulfide polymer composite as the broadband saturable absorber which is prepared by the chemical vapor deposition method. We achieve passively Q-switching operations at 978 nm with the pulse width of 2.7 and 0.63 μs, corresponding to the repetition rate of 212 and 221 kHz, respectively. The maximum output power is 127 mW. It is the first time that MoS2 Q-switched Yb-doped photonic crystal fiber laser at 980 nm is demonstrated. The experimental results show that few-layer MoS2 is a promising broadband saturable absorber material.

  3. Effect of ytterbium inclusion in hafnium oxide on the structural and electrical properties of the high-k gate dielectric

    陈帅; 刘正堂; 冯丽萍; 车兴森; 赵小如

    2014-01-01

    The undoped and Yb-doped HfO2 thin films were deposited on p-type single crystal Si(100) substrates using RF magnetron sputtering method. The structure and electrical properties were investigated as a function of doping concentrations. The results showed that the presence of Yb could stabilize HfO2 in cubic phase. The dielectric constant was enhanced after in-troducing Yb3+ ions into the HfO2 host. Compared with undoped HfO2 thin film, the Yb-doped HfO2 thin film exhibited a low leakage current. The silicate reaction between rare earth ions and SiO2 layers was used to eliminate interfacial silica and form a stable interface.

  4. Comparison of Molecular Iodine Spectral Properties at 514.7 and 532 nm Wavelengths

    Hrabina J.

    2014-08-01

    Full Text Available We present results of investigation and comparison of spectral properties of molecular iodine transitions in the spectral region of 514.7 nm that are suitable for laser frequency stabilization and metrology of length. Eight Doppler-broadened transitions that were not studied in detail before were investigated with the help of frequency doubled Yb-doped fiber laser, and three of the most promising lines were studied in detail with prospect of using them in frequency stabilization of new laser standards. The spectral properties of hyperfine components (linewidths, signal-to-noise ratio were compared with transitions that are well known and traditionally used for stabilization of frequency doubled Nd:YAG laser at the 532 nm region with the same molecular iodine absorption. The external frequency doubling arrangement with waveguide crystal and the Yb-doped fiber laser is also briefly described together with the observed effect of laser aging.

  5. Trapping and self-trapping in ytterbium-doped oxides with charge transfer luminescence

    Kamenskikh, I., E-mail: ikamenskikh@bk.r [Department of Physics, M.V. Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Pedrini, C. [LPCML, UMR 5620 CNRS and Universite Lyon 1, 69622 Villeurbanne Cedex (France); Petrosyan, A. [Laboratory of Crystal Growth of Luminescent Materials, Institute for Physical Research, 378410 Ashtarak-2 (Armenia); Vasil' ev, A. [Skobeltsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2009-12-15

    Temperature dependence of the charge transfer luminescence (CTL) of Yb-doped yttrium aluminum garnet Y{sub 3}Al{sub 5}O{sub 12}-Yb (YAG-Yb) and Yb-doped lutetium aluminum perovskite LuAlO{sub 3}-Yb (LuAP-Yb) crystals under X-ray excitation and their thermostimulated luminescence are investigated in the temperature range 30-350 K and compared to those of undoped crystals. Simulation using a set of kinetic equations describing the processes of creation of excitons, electron-hole pairs, their trapping and self-trapping, radiative relaxation and quenching is presented for the systems under investigation to analyze qualitatively two different types of experimentally observed temperature dependences: CTL yield decline with the temperature decrease below 110 K as in case of YAG-Yb and constant yield in the same temperature range as in case of LuAP-Yb.

  6. 52 W kHz-linewidth low-noise linearly-polarized all-fiber single-frequency MOPA laser

    Yang, Changsheng; Xu, Shanhui; Chen, Dan; Zhang, Yuanfei; Zhao, Qilai; Li, Can; Zhou, Kaijun; Feng, Zhouming; Gan, Jiulin; Yang, Zhongmin

    2016-05-01

    An all-fiber Yb-doped kHz-linewidth low-noise linearly polarized single-frequency master-oscillator power-amplifier (MOPA) laser with a stable CW output power of >52 W is demonstrated. By suppressing the intensity noise of the DBR phosphate fiber oscillator, the linewidth of MOPA laser is not noticeably broadened, and an ultra-narrow linewidth of 63 dB are achieved.

  7. BLUE COOPERATIVE UP-CONVERSION LUMINESCENCE OF Yb3+ IONS IN OXYFLUORIDE GLASS EXCITED BY 960 nm LASER

    CHEN XIAO-BO; SONG ZENG-FU; N. SAWANOBORI

    2001-01-01

    Investigates the up-conversion luminescence of Yb-doped oxyfluoride glass excited by a 960nm-diode laser. A new up-conversion cooperative radiation luminescence is found, which is rather strong and positioned at 476.1 nm. It comes from the coupled states of two-Yb3+-ions cluster. It is significant because it is an effective and convenient method of producing blue light.

  8. Thermal properties and cw-laser operation of the ytterbium doped borate Li{sub 6}Y(BO{sub 3}){sub 3}

    Sablayrolles, J. [CNRS, Universite de Bordeaux, ICMCB, 87 av. Dr. A. Schweitzer, Pessac F-33608 (France); Jubera, V., E-mail: jubera@icmcb-bordeaux.cnrs.fr [CNRS, Universite de Bordeaux, ICMCB, 87 av. Dr. A. Schweitzer, Pessac F-33608 (France); Delaigue, M.; Manek-Hoenninger, I. [Universite de Bordeaux, CELIA, 351 cours de la Liberation, Talence F-33405 (France); Chaminade, J.-P. [CNRS, Universite de Bordeaux, ICMCB, 87 av. Dr. A. Schweitzer, Pessac F-33608 (France); Hejtmanek, J. [Institute of Physics, Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic); Decourt, R.; Garcia, A. [CNRS, Universite de Bordeaux, ICMCB, 87 av. Dr. A. Schweitzer, Pessac F-33608 (France)

    2009-06-15

    Single crystals of Yb doped Li{sub 6}Y(BO{sub 3}){sub 3} were obtained by Czochralski method. The first laser tests were encouraging. Different parameters have been investigated to improve cw-laser performances. Thermal properties but also ytterbium content, crystal thickness and pump polarisation are reported. The best crystal configuration was determined and led to high power cw-laser tests equal to 2 W output power.

  9. Thermal properties and cw-laser operation of the ytterbium doped borate Li6Y(BO3)3

    Single crystals of Yb doped Li6Y(BO3)3 were obtained by Czochralski method. The first laser tests were encouraging. Different parameters have been investigated to improve cw-laser performances. Thermal properties but also ytterbium content, crystal thickness and pump polarisation are reported. The best crystal configuration was determined and led to high power cw-laser tests equal to 2 W output power.

  10. Self-induced laser line sweeping and self-pulsing in rare-earth doped fiber lasers

    Navrátil, Petr; Vojtíšek, Petr; Peterka, Pavel; Honzátko, Pavel; Kubeček, V.

    Bellingham : SPIE, 2012. ISBN 978-0-8194-9481-8. [18th Czech-Polish-Slovak Optical Conference on Wave and Quantum Aspects of Contemporary Optics. Ostravice (CZ), 03.09.2012-07.09.2012] R&D Projects: GA MŠk ME10119; GA ČR GAP205/11/1840 Institutional support: RVO:67985882 Keywords : Laser line sweeping * Fiber lasers * Er-doped * Yb-doped Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  11. Power-scalable internal frequency doubling scheme for continuous-wave fiber lasers

    Cieslak, Rafal; Clarkson, W.Andrew

    2011-01-01

    We describe a simple power-scalable concept for efficient second harmonic generation in a cladding-pumped continuous-wave fiber laser. Our approach makes use of an internal resonant enhancement cavity to increase the intracavity power and second harmonic conversion efficiency without the need for active cavity length control and stabilization. This technique has been applied to a cladding-pumped Yb-doped fiber laser yielding 15 W of linearly-polarized continuous-wave green output (at 540 nm) ...

  12. Continuous-wave all-fiber MOPA with SBS phase conjugate mirror

    Kovalev, V.I.; Harrison, R. G.; Sahu, J.K.; Nilsson, J.; Lebedev, P. N.

    2004-01-01

    A CW Nd:YAG master oscillator - fibre power amplifier (MOPFA) with fiber based SBS phase conjugate mirror is reported. A two-pass amplifier configuration is employed to compensate beam distortions in the multi-mode diode pumped Yb-doped fiber amplifier in conjunction with a fibre phase conjugator. The compensation of distortions is observed with ~30% of the total reflected power being of diffraction limited quality. Possibilities for improving the beam quality and power scaling in this system...

  13. Tunable femtosecond Cherenkov fiber laser

    Liu, Xiaomin; Svane, Ask Sebastian; Lægsgaard, Jesper;

    2014-01-01

    We demonstrate electrically-tunable femtosecond Cherenkov fiber laser output at the visible range. Using an all-fiber, self-starting femtosecond Yb-doped fiber laser as the pump source and nonlinear photonic crystal fiber link as the wave-conversion medium, ultrafast, milliwatt-level, tunable...... and spectral isolated Cherenkov radiation at visible wavelengths are reported. Such a femtosecond Cherenkov laser source is promising for practical biophotonics applications....

  14. High power pulsed ytterbium doped fibre lasers and their applications

    Chen, Kang Kang

    2011-01-01

    The aim of my project is to develop pulsed Ytterbium (Yb) doped fibre master oscillator power amplifier (MOPA) systems seeded by semiconductor lasers. I was principally focused on two specific projects aligned to sponsored programs of research within the ORC pulsed fibre laser group: the first project, TSB funded project LAMPS, aimed to develop an important class of next generation laser system capable of average output powers of more than 100 W when operating in both the nanosecond and pico...

  15. Analysis of the modal content into large-mode-area photonic crystal fibers under heat load

    Coscelli, Enrico; Dauliat, Romain; Poli, Federica; Darwich, Dia; Cucinotta, Annamaria; Selleri, Stefano; Schuster, Kay; Benoit, Aurélien; Jamier, Raphaël; Roy, Philippe; Salin, François

    2015-01-01

    Thanks to their capability to provide very large mode area together with effective suppression of high-order modes, while allowing strong pump absorption and efficient conversion, Yb-doped double-cladding photonic crystal fibers are one of the key enabling factors for the development of high power fiber lasers. Thermal effects are currently appointed as the main bottleneck for future power scaling since, beyond a certain average power, they allow guidance of high order modes and energy transf...

  16. Passively mode-locked Yb:LuVO4 oscillator

    Rivier, Simon; Mateos, Xavier; Liu, Junhai; Petrov, Valentin; Griebner, Uwe; Zorn, Martin; Weyers, Markus; Zhang, Huaijin; Wang, Jiyang; Jiang, Minhua

    2006-11-01

    Passive mode locking of the ytterbium doped orthovanadate crystal Yb:LuVO4 is reported for the first time. We demonstrate what we believe to be the shortest pulses directly generated with an Yb-doped crystalline laser using a semiconductor saturable absorber. The pulses at 1036 nm have a duration as short as 58 fs for an average power of 85 mW.

  17. High-power continuous-wave frequency-doubling in KTiOAsO4.

    Zeil, Peter; Zukauskas, Andrius; Tjörnhammar, Staffan; Canalias, Carlota; Pasiskevicius, Valdas; Laurell, Fredrik

    2013-12-16

    High-power continuous-wave generation at 533 nm is demonstrated in bulk periodically poled KTiOAsO(4) (KTA) by single-pass frequency doubling of a VBG-locked Yb-doped fiber laser. Absorption characteristic and second harmonic generation (SHG) performance of different KTA samples are studied and compared. The best performing sample catered for 25%-efficient SHG of 13.6 W green light with high spatial beam quality M(2) <1.2. PMID:24514622

  18. Femtosecond micromachining of symmetric waveguides at 1.5 microm by astigmatic beam focusing.

    Cerullo, G; Osellame, R; Taccheo, S; Marangoni, M; Polli, D; Ramponi, R; Laporta, P; De Silvestri, S

    2002-11-01

    We report on a new spatial beam-shaping approach for fabrication of waveguides with a circular transverse profile by femtosecond laser pulses, using an astigmatic beam and controlling both beam waist and focal position in the tangential and sagittal planes. We apply this technique to write single-mode active waveguides at 1.5microm in Er:Yb-doped glass substrates. The experimental results are well described by a simple nonlinear absorption model. PMID:18033408

  19. Erbium–ytterbium fibre laser emitting more than 13W of power in 1.55 m region

    Srikanth Gurram; Antony Kuruvilla; Rajpal Singh; Blacius Ekka; B N Upadhyay; K S Bindra; S M Oak

    2014-01-01

    We report the work on erbium:ytterbium-doped double clad fibre laser (EYDFL), that is pumped at 976 nm. The maximum output power generated is 13.6Win 1550 nm region with a slope efficiency of about 21%. To the best of our knowledge, this is the highest power reported from an EYDFL, that uses commercially available off-the-shelf large mode area Er:Yb-doped double-clad fibre.

  20. All-fiber normal-dispersion femtosecond laser

    Kieu, K.; Wise, F. W.

    2008-01-01

    Spectral filtering of a chirped pulse can be a strong pulse-shaping mechanism in all-normal-dispersion femtosecond fiber lasers. We report an implementation of such a laser that employs only fiber-format components. The Yb-doped fiber laser includes a fiber filter, and a saturable absorber based on carbon nanotubes. The laser generates 1.5-ps, 3-nJ pulses that can be dechirped to 250 fs duration outside the cavity.

  1. Improved thermal stability and narrowed line width of photoluminescence from InGaN nanorod by ytterbium doping

    Wang, Jingzhou; Wright, Jason; Kaya, S.; Jadwisienczak, W.M. [School of Electrical Engineering and Computer Science, Ohio University, Stocker Center, Athens OH 45701 (United States); Dasari, Kiran; Palai, Ratnakar [Department of Physics, University of Puerto Rico, San Juan, PR 00936 (United States); Cooper, Kevin; Thota, Venkata R.; Ingram, David C.; Stinaff, Eric A. [Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States)

    2015-03-18

    Nanorod of in situ Yb-doped InGaN and undoped InGaN have been grown on (0001) sapphire substrates by plasma assisted molecular beam epitaxy (MBE). Selected regions on Yb-doped InGaN sample show single dominant near band edge emission (NBE) in green, yellow or orange color due to the variation of In content. Temperature dependent PL peak energy of InGaN nanorod shows the characteristic S -shaped behavior indicating the presents of strong exciton localization energy in undoped InGaN nanorod. The exciton localization energy reduced significantly after incorporating Yb into InGaN, giving rise to damping of the S-shape profile amplitude and narrowing of the PL line width from ∝20 meV to ∝12 meV at 11 K. It is proposed that the improved PL thermal stability and the PL line width in Yb-doped InGaN nanorod is affected by the Yb gettering effect. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Charge trapping behavior of rare-earth ion-doped Al2O3 and its application to nonvolatile memories

    We investigated the charge trapping properties of rare-earth(RE)-Yb-doped Al2O3 in view of their potential application to nonvolatile memories. The as-grown, low-temperature annealed Yb-doped Al2O3 film showed a dominant hole trapping behavior, but it changed to mostly electron trapping after high temperature annealing. No correlation was found between the Yb charge state and the reduction of hole traps, excluding the Yb ion itself as the hole trap. As-grown annealed Yb-doped Al2O3 showed a defect-related below-bandgap optical absorption. Since the oxygen vacancy is a charge trap in Al2O3 among all the intrinsic defects, we attribute the observed hole trap to the oxygen vacancy. On the other hand, the energy levels of the Yb3+ ion in Al2O3 make it the most likely electron trap. In addition, the large Yb ion strains the nearby bonds to make it vulnerable to defect formation during an external stress. We found that hot electron injection actually created addition electron traps. Yb ions and/or defect complexes including Yb ions seem to be responsible for the observed electron trapping. Our experimental results show that RE ion doping may be a new method for realizing a nonvolatile memory device.

  3. Multi-kW cw fiber oscillator pumped by wavelength stabilized fiber coupled diode lasers

    Becker, Frank; Neumann, Benjamin; Winkelmann, Lutz; Belke, Steffen; Ruppik, Stefan; Hefter, Ulrich; Köhler, Bernd; Wolf, Paul; Biesenbach, Jens

    2013-02-01

    High power Yb doped fiber laser sources are beside CO2- and disk lasers one of the working horses of industrial laser applications. Due to their inherently given robustness, scalability and high efficiency, fiber laser sources are best suited to fulfill the requirements of modern industrial laser applications in terms of power and beam quality. Pumping Yb doped single-mode fiber lasers at 976nm is very efficient. Thus, high power levels can be realized avoiding limiting nonlinear effects like SRS. However the absorption band of Yb doped glass around 976nm is very narrow. Therefore, one has to consider the wavelength shift of the diode lasers used for pumping. The output spectrum of passively cooled diode lasers is mainly defined by the applied current and by the heat sink temperature. Furthermore the overall emission line width of a high power pump source is dominated by the large number of needed diode laser emitters, each producing an individual spectrum. Even though it is possible to operate multi-kW cw single-mode fiber lasers with free running diode laser pumps, wavelength stabilizing techniques for diode lasers (e.g. volume holographic gratings, VHG) can be utilized in future fiber laser sources to increase the output power level while keeping the energy consumption constant. To clarify the benefits of wavelength stabilized diode lasers with integrated VHG for wavelength locking the performance of a dual side pumped fiber oscillator is discussed in this article. For comparison, different pumping configurations consisting of stabilized and free-running diode lasers are presented.

  4. Lasing of Yb in a mixed YGdVO4 crystal with bistability and polarization switching

    Liu, Junhai; Zhang, Huaijin; Mateos, Xavier; Han, Wenjuan; Petrov, Valentin

    2009-02-01

    The orthovanadate crystals YVO4, GdVO4, and LuVO4 attract much attention as promising host materials for the trivalent Yb-ion since such crystals are characterized by large absorption and emission cross sections, broad absorption and emission bands, and higher thermal conductivities than most of the other Yb-doped materials. More interestingly, their laser operation is characterized by optical bistability, apparently a unique feature of Yb-doped vanadates, not found so far in other Yb-lasers or even in other solid-state lasers. The optically "passive" vanadates, YVO4, GdVO4, and LuVO4, as well as the stoichiometric YbVO4 exhibit the same zircon structure and continuous isostructural solid solutions can be expected. The absorption and emission spectra of Yb0.0054:Y0.3481Gd0.6465VO4, a specific compound in the mixed Ybt:YxGd1-x-tVO4 series, inherit the spectroscopic features of both Yb:YVO4 and Yb:GdVO4. We found that this Yb-doped solid solution also displays optical bistability in continuous-wave (cw) laser operation. The strongly pronounced bistability extends from Pabs=1.9 W to Pabs=3.4 W while the output power amounts to 0.98 W at the upthreshold. Distinct from the previously reported Yb:LuVO4 laser, coexistence and switching of the σ and π polarization states occur along with emission wavelength shift in the bistability region upon decreasing the pump power. Increasing the output coupling reduces the bistability region while expanding the coexistence region for the σ and π polarization states.

  5. Effects of rare-earth doping on femtosecond laser waveguide writing in zinc polyphosphate glass

    We have investigated waveguide writing in Er-Yb doped zinc polyphosphate glass using a femtosecond laser with a repetition rate of 1 KHz. We find that fabrication of good waveguides requires a glass composition with an O/P ratio of 3.25. The dependence on laser writing parameters including laser fluence, focusing conditions, and scan speed is reported. Waveguide properties together with absorption and emission data indicate that these glasses can be used for the fabrication of compact, high gain amplifying devices.

  6. Hybrid master oscillator power amplifier high-power narrow-linewidth nanosecond laser source at 257 nm

    Délen, Xavier; Deyra, Loïc; Benoit, Aurélien; Hanna, Marc; Balembois, François; Cocquelin, Benjamin; Sangla, Damien; Salin, François; Didierjean, Julien; Georges, Patrick

    2013-01-01

    We report on a high-power narrow-linewidth pulsed laser source emitting at a wavelength of 257 nm. The system is based on a master oscillator power amplifier architecture, with Yb-doped fiber preamplifiers, a Yb:YAG single crystal fiber power amplifier used to overcome the Brillouin limitation in glass fiber and nonlinear frequency conversion stages. This particularly versatile architecture allows the generation of Fourier transform-limited 15 ns pulses at 1030 nm with 22 W of average power a...

  7. Progress in high-power single frequency master oscillator power amplifier

    Maran, Jean-Noel; Jeong, Yoonchan; Yoo, Seongwoo; Sahu, Jayanta; Nilsson, Johan

    2008-01-01

    In the recent years some tremendous progresses have been made to scale up the output power of fiber laser to the point where fiber laser technology is becoming a serious competitor to the solid-state lasers in most of the industrial applications. Nowadays single mode Ytterbium (Yb) doped fiber lasers with an output power of 2kW[1] are commercially available and some 5kW systems are a reality in the laboratory environment. Unfortunately the scaling of laser systems up to increasingly higher po...

  8. Enhanced 1.0 μm emission and simultaneously suppressed upconversion emission in Yb:PbF2 laser crystal codoped with NaF

    Zhang, P. X.; Yin, J. G.; Hang, Y.; Yin, J. P.

    2013-04-01

    Na-codoped and only Yb-doped Yb:PbF2 crystals were successfully grown using the vertical Bridgman method. The influence of the ions codoped with Na+ on the distribution coefficients has been studied. Enhanced ˜1.0 μm emission and simultaneously suppressed upconversion emission was observed for Yb:PbF2 crystals codoped with 2 mol% NaF. A time-resolved spectroscopy study showed that the ions codoped with Na+ lengthen the fluorescence lifetime by 6%. Absorption spectra were also studied and showed that the ions codoped with Na+ can effectively suppress the formation of Yb2+ ions.

  9. Tandem-pumped 1120-nm actively Q-switched fiber laser

    王建华; 胡金萌; 张世强; 陈露璐; 房勇; 冯衍

    2015-01-01

    We report on a tandem-pumped actively Q-switched fiber laser system emitting at 1120 nm. Parasitic oscillation is challenging in Yb-doped Q-switched 1120-nm fiber laser, which is suppressed by pumping with a fiber laser at 1018 nm. At least 4 times improvement in output peak power is demonstrated in a single laser setup with 1018-nm fiber laser pumping instead of 976-nm laser diode pumping. This is, to the best of our knowledge, the first demonstration of a tandem-pumped Q-switched fiber laser.

  10. RGB generation by four-wave mixing in small-core holey fibers

    Horak, P.; Dupriez, P.; Poletti, F.; Petrovich, M.N.; Jeong, Y.; Nilsson, J.; Richardson, D J; Payne, D. N.

    2007-01-01

    We report the generation of white light comprising red, green, and blue spectral bands from a frequency-doubled fiber laser by an efficient four-wave mixing process in submicron-sized cores of microstructured holey fibers. A master-oscillator power amplifier (MOPA) source based on Yb-doped fiber is employed to generate 80 ps pulses at 1060 nm wavelength with 32 MHz repetition rate, which are then frequency-doubled in an LBO crystal to generate up to 2 W average power of green light. The green...

  11. Internally-frequency-doubled Yb fiber laser with 15 W CW green output

    Cieslak, Rafal; Clarkson, William Andrew

    2011-01-01

    In this paper we present a high power continuous-wave (CW) green source using a novel approach for frequency doubling of high power CW fiber lasers based on an internal resonant enhancement cavity integrated within the fiber laser resonator. The experimental configuration (shown in Fig. 1) comprised a double-clad fiber with an Yb-doped core in a simple standing-wave resonator. Feedback for lasing was provided by a diffraction grating at one end of the fiber, and by an external cavity containi...

  12. Multi-mJ bursts of green light obtained by frequency doubling the output of a fiber based MOPA

    Rowen, Eitan E.; Shalev, Nir; Tal, Eran; Lasri, Kobi; Inbar, Eran

    2016-03-01

    We demonstrate a fiber laser that generates bursts of 70-300 pulses at a frequency of 2-8 MHz with over 4 mJ of energy per burst at a wavelength of 532 nm. The output of an Yb-doped fiber amplifier chain is doubled in a single pass through an LBO crystal with efficiency of above 65%. A seed-diode generates the pulse train, which is amplified to a peak power that allows efficient SHG. Such a solution may have many industrial and other applications, where fiber-based solutions have many advantages, but suffer a disadvantage of relatively low pulse energy.

  13. Highly Efficient Self-Starting Femtosecond Cr:Forsterite Laser

    ZHOU Bin-Sin; ZHANG Yong-Dong; ZHONG Xin; WEI Zhi-Yi

    2008-01-01

    We report a highly efficient and high power self-starting femtosecond Cr:forsterite laser pumped by a 1064-nm Yb doped fibre laser. Five chirped mirrors are used to compensate for the intra-cavity group-delay dispersion,and the mode-locking is initiated by a semiconductor saturable absorber mirror (SESAM). Under pump power of 7.9 W, stable femtosecond laser pulses with average power of 760mW are obtained, yielding a pump power slope efficiency of 12.3%. The measured pulse duration and spectral bandwidth (FWHM) are 46 fs and 45 nm;the repetition rate is 82 MHz.

  14. Mitigation of mode instabilities by dynamic excitation of fiber modes

    Otto, Hans-Jürgen; Jauregui, Cesar; Stutzki, Fabian; Jansen, Florian; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    By dynamically varying the power content of the excited fiber modes of the main amplifier of a fiber-based MOPA system at high average output power levels, it was possible to mitigate mode instabilities to a large extent. In order to achieve the excitation variation, we used an acousto-optic deflector in front of the Yb-doped rod-type fiber. Therewith, it was possible to significantly increase both the average and the instantaneous minimum power content of the fundamental mode. This, consequently, led to a substantial improvement of the beam quality and pointing stability at power levels well beyond the threshold of mode instabilities.

  15. Ultrahigh-resolution optical coherence tomography at 1.3 μm central wavelength by using a supercontinuum source pumped by noise-like pulses

    You, Yi-Jing; Wang, Chengming; Lin, Yi-Lun; Zaytsev, Alexey; Xue, Ping; Pan, Ci-Ling

    2016-02-01

    We report on the ultrahigh-resolution optical coherence tomography (OCT) with a novel high-power supercontinuum (SC) light source generated by noise-like pulses from an Yb-doped fiber laser. The SC spectrum is flat with a bandwidth of 420 nm centered around ~1.3 μm. The light source is successfully employed in a time-domain OCT (TD-OCT), achieving an axial resolution of 2.3 μm. High resolution fiber-based spectral-domain OCT (SD-OCT) imaging of bio-tissue was also demonstrated.

  16. Raman-scattering-assistant broadband noise-like pulse generation in all-normal-dispersion fiber lasers

    Li, Daojing; Shen, Deyuan; Li, Lei; Chen, Hao; Tang, Dingyuan; Zhao, Luming

    2015-10-01

    We report on the observation of both stable dissipative solitons and noise-like pulses with the presence of strong Raman scattering in a relatively short all-normal-dispersion Yb-doped fiber laser. We show that Raman scattering can be filtered out by intracavity filter. Furthermore, by appropriate intracavity polarization control, the Raman effect can be utilized to generate broadband noise-like pulses (NLPs) with bandwidth up to 61.4 nm. To the best of our knowledge, this is the broadest NLP achieved in all-normal-dispersion fiber lasers

  17. Generation of double-scale femto/pico-second optical lumps in mode-locked fiber lasers.

    Kobtsev, Sergey; Kukarin, Sergey; Smirnov, Sergey; Turitsyn, Sergey; Latkin, Anton

    2009-11-01

    We observed generation of stable picoseconds pulse train and double-scale optical lumps with picosecond envelope and femtosecond noise-like oscillations in the same Yb-doped fiber laser with all-positive-dispersion cavity mode-locked due to the effect of non-linear polarization evolution. In the noise-like pulse generation regime the auto-correlation function has a non-usual double (femto- and picosecond) scale shape. We discuss mechanisms of laser switching between two operation regimes and demonstrate a good qualitative agreement between experimental results and numerical modeling based on modified nonlinear Schrödinger equations. PMID:19997301

  18. Raman-scattering-assistant broadband noise-like pulse generation in all-normal-dispersion fiber lasers

    Li, Daojing; Shen, Deyuan; Li, Lei; Chen, Hao; Tang, Dingyuan; Zhao, Luming

    2015-01-01

    We report on the observation of both stable dissipative solitons and noise-like pulses with the presence of strong Raman scattering in a relatively short all-normal-dispersion Yb-doped fiber laser. We show that Raman scattering can be filtered out by intracavity filter. Furthermore, by appropriate intracavity polarization control, the Raman effect can be utilized to generate broadband noise-like pulses (NLPs) with bandwidth up to 61.4 nm. To the best of our knowledge, this is the broadest NLP...

  19. Multi-pulse operation of a dissipative soliton fibre laser based on nonlinear polarisation rotation

    Yu, H. L.; Wang, X. L.; Zhou, P.; Chen, J. B.

    2016-03-01

    We report an experimental observation of multiple dissipative soliton (DS) operation states in an all-normal-dispersion passively mode-locked Yb-doped fibre laser, including DS bound and oscillating states. In the bound state, multiple DSs up to 11 can coexist in the cavity. In the oscillating state, the DSs' movements are not purely random and three typical states are generalised and illustrated. A single-pulse mode-locked state is established at a high pump power by carefully adjusting the polarisation controllers. The broad spectrum indicates that it may be noise-like pulses, which can serve as a pump to generate a supercontinuum.

  20. Raman-scattering-assistant broadband noise-like pulse generation in all-normal-dispersion fiber lasers

    Li, Daojing; Li, Lei; Chen, Hao; Tang, Dingyuan; Zhao, Luming

    2015-01-01

    We report on the observation of both stable dissipative solitons and noise-like pulses with the presence of strong Raman scattering in a relatively short all-normal-dispersion Yb-doped fiber laser. We show that Raman scattering can be filtered out by intracavity filter. Furthermore, by appropriate intracavity polarization control, the Raman effect can be utilized to generate broadband noise-like pulses (NLPs) with bandwidth up to 61.4 nm. To the best of our knowledge, this is the broadest NLP achieved in all-normal-dispersion fiber lasers

  1. Optimized all-fiber supercontinuum source at 1.3 μm generated in a stepwise dispersion-decreasing-fiber arrangement

    Abrardi, Laura; Martín López, Sonia; Carrasco-Sanz, Ana; Corredera, Pedro; Hernanz, María Luisa; González Herráez, Miguel

    2007-01-01

    In this paper, the generation of a continuous-wave (CW)-pumped supercontinuum (SC) source at 1.3 μm is described. The device makes use of a tunable Yb-doped fiber laser, a cascade of Fiber Bragg Grating mirrors, and a concatenation of standard silica fibers with stepwise decreasing dispersion. It is shown that the dispersion-decreasing-fiber set enhances the width of the generated SC, since it favors the fission of the CW input into high-order solitons. The generated SC spans from 1280 to 151...

  2. Ultra-fast photoacoustic flow cytometry with a 0.5 MHz pulse repetition rate nanosecond laser

    Nedosekin, Dmitry A.; Sarimollaoglu, Mustafa; Shashkov, Evgeny V.; Galanzha, Ekaterina I.; Zharov, Vladimir P.

    2010-01-01

    In vivo photoacoustic (PA) flow cytometry (PAFC) has great potential for detecting disease-associated biomarkers in blood and lymph flow, as well as real-time control of the efficacy of photothermal (PT) and other therapies through the counting of circulating abnormal objects. We report on a high speed PAFC with a Yb-doped fiber laser having a 0.5-MHz pulse repetition rate at a wavelength of 1064 nm, pulse width of 10 ns, and energy up to 100 µJ. This is the first biomedical application of PA...

  3. Electro-optical Bunch Length Monitor for FLUTE: Layout and Simulations

    Borysenko, A.; Hertle, E.; Schuh, M.; Schwarz, M.; Wesolowski, P.; Steffen, Bernd; Hiller, N.; Judin, V.; Kehrer, B.; Marsching, S.; Müller, A. -S.; Nasse, M. J.; Rossmanith, R.; Ruprecht, R.

    2014-01-01

    A new compact linear accelerator FLUTE is currently under construction at Karlsruhe Institute of Technology (KIT) in collaboration with DESY and PSI. It aims at obtaining femtosecond electron bunches (~1fs - 300 fs) with a wide charge range (1 pC - 3 nC) and requires a precise bunch length diagnostic system. Here we present the layout of a bunch length monitor based on the electro-optic technique of spectral decoding using an Yb-doped fiber laser system (central wavelength 1030 nm) and a GaP ...

  4. LLE Review 119 (April-June 2009)

    Edgell, D.H., editor

    2009-10-22

    This issue has the following articles: (1) Shock-Ignition Experiments on OMEGA at NIF-Relevant Intensities; (2) Laser-Driven Magnetic-Flux Compression in High-Energy-Density Plasmas; (3) Lorentz Mapping of Magnetic Fields in Hot, Dense Plasmas; (4) Characterization and Optimization of Yb-Doped Photonic-Crystal Fiber Rod Amplifiers Using Spatially Resolved Spectral Interferometry; (5) Optical Differentiation and Multimillijoule {approx}150-ps Pulse Generation in a Regenerative Amplifier with a Temperature-Tuned Intracavity Volume Bragg Grating; (6) Slow Crack Growth During Radiatiave Cooling of LHG8 and BK7 Plates; and (7) Finite Element Simulation of Metal-Semiconductor-Metal Photoconductor.

  5. Raman-scattering-assistant broadband noise-like pulse generation in all-normal-dispersion fiber lasers.

    Li, Daojing; Shen, Deyuan; Li, Lei; Chen, Hao; Tang, Dingyuan; Zhao, Luming

    2015-10-01

    We report on the observation of both stable dissipative solitons and noise-like pulses with the presence of strong Raman scattering in a relatively short all-normal-dispersion Yb-doped fiber laser. We show that Raman scattering can be filtered out by intracavity filter. Furthermore, by appropriate intracavity polarization control, the Raman effect can be utilized to generate broadband noise-like pulses (NLPs) with bandwidth up to 61.4 nm. To the best of our knowledge, this is the broadest NLP achieved in all-normal-dispersion fiber lasers. PMID:26480103

  6. Efficient magneto-optical trapping of a metastable helium gas

    Pereira Dos Santos, F.; Perales, F.; Léonard, J.; Sinatra, A.; Wang, J.; Pavone, F. S.; Rasel, E.; Unnikrishnan, C. S.; Leduc, M.

    2001-04-01

    This article presents a new experiment aiming at BEC of metastable helium atoms. It describes the design of a high flux discharge source of atoms and a robust laser system using a DBR diode coupled with a high power Yb doped fiber amplifier for manipulating the beam of metastable atoms. The atoms are trapped in a small quartz cell in an extreme high vacuum. The trapping design uses an additional laser (repumper) and allows the capture of a large number of metastable helium atoms (approximately 10^9) in a geometry favorable for loading a tight magnetostatic trap.

  7. Modeling of 1.2-μm phosphorus doped Raman fiber laser

    Li, Yan-lin; Song, Yan-rong; Tian, Jin-rong; Yu, Zhen-hua; Dou, Zhi-yuan; Zhang, Xiao

    2013-09-01

    A model of 1.2μm Phosphorus doped Raman fiber laser is discussed. It is pumped by a 1.035μm high power Yb-doped dual-cladding fiber laser. The coupled equations for forward and backward stokes waves are set up. An approximate solution for the first -order Stocks laser is obtained by using `fsolve' function in MATLAB which is simply for writing and calculates fast. The relationships between energy conversion efficiency and the length of P-doped fiber, the reflectivity of the output FLM are discussed respectively. And the laser system is optimized.

  8. The spectroscopic properties of Yb3+ doped α-BBO crystal

    Yu, Pingsheng; Su, Liangbi; Wu, Feng; Xu, Jun

    2012-05-01

    2.0 mol% (relative to Ba2+) Yb3+ doped α-BaB2O4 (α-BBO) crystal was obtained by the Czochralski method. The doped crystal structure was determined by means of an X-ray diffraction analysis. The absorption, near-infrared (NIR) luminescence spectra and fluorescence decay curve of Yb3+ doped α-BBO crystal were investigated. NIR emission under 940 nm and 980 nm LDs (laser diodes) excitation was observed in the Yb doped α-BBO crystal.

  9. Defects induced in Yb3+/Ce3+ co-doped aluminosilicate fiber glass preforms under UV and γ-ray irradiation

    Chiesa, Mario; Mattsson, Kent Erik; Taccheo, Stefano; Robin, Thierry; Lablonde, Laurent; Mechin, David; Milanese, Daniel

    2014-01-01

    high Yb content samples is observed on as prepared samples regardless of the presence of Ce3+ ions. Si-E′ and Al-OHC centers were identified upon photon irradiation. The results are correlated to the micro-structural origin of the photodarkening process occurring in Ce–Yb doped glass fibers.......A set of Ce-/Yb-co-doped silica optical fiber preform cores, differing in terms of dopant concentrations are studied by Electron Paramagnetic Resonance (EPR) spectroscopy before and after irradiation of the samples with excimer UV laser light and γ-rays. Evidence of Yb3+ clustering in the case of...

  10. Monolithic Yb-fiber femtosecond laser with intracavity all-solid PBG fiber and ex-cavity HC-PCF

    Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

    2010-01-01

    (PM) photonic bandgap fiber (PBG) is used in the cavity of the master oscillator for dispersion compensation and stabilization of modelocking. The final compression of an chirped-pulse-amplified laser signal is performed in a hollow PM PCF, yielding final fiber-delivered pulse energy of around 7 n......We demonstrate an all-fiber femtosecond master oscillator / power amplifier operating at the central wavelength of 1033 nm, based on Yb-doped fiber as gain medium, and two different kinds of photonic crystal fibers for dispersion control and stabilization. An all-solid (AS) polarization maintaining...

  11. Inner cladding influence on large mode area photonic crystal fiber properties under severe heat load

    Coscelli, Enrico; Poli, Federica; Dauliat, Romain; Darwich, Dia; Cucinotta, A.; Selleri, S; Schuster, Kay; Benoit, Aurélien; Jamier, Raphaël; Roy, Philippe; Salin, François

    2016-01-01

    The influence of the size and the air-filling fraction of the inner microstructure on the first HOM confinement in Yb-doped LMA PCFs under different heat load values has been investigated with a full-vector modal solver based on the finite element method, used also to solve the steady-state heat equation. In particular, the air-cladding inner dimension and the air-hole diameter in Symmetry-Free PCFs and Large Pitch Fibers have been modified in order to study which conditions facilitate the co...

  12. Metastable Magnesium fluorescence spectroscopy using a frequency-stabilized 517 nm laser

    He, Ming; Jensen, Brian B; Therkildsen, Kasper T;

    2009-01-01

    We present a laser operating at 517 nm for our Magnesium laser-cooling and atomic clock project. A two-stage Yb-doped fiber amplifier (YDFA) system generates more than 1.5 W of 1034 nm light when seeded with a 15 mW diode laser. Using a periodically poled lithium niobate (PPLN) waveguide, we...... obtained more than 40 mW of 517 nm output power by single pass frequency doubling. In addition, fluorescence spectroscopy of metastable magnesium atoms could be used to stabilize the 517 nm laser to an absolute frequency within 1 MHz....

  13. Tandem-pumped 1120-nm actively Q-switched fiber laser

    We report on a tandem-pumped actively Q-switched fiber laser system emitting at 1120 nm. Parasitic oscillation is challenging in Yb-doped Q-switched 1120-nm fiber laser, which is suppressed by pumping with a fiber laser at 1018 nm. At least four times improvement in output peak power is demonstrated in a single laser setup with 1018-nm fiber laser pumping instead of 976-nm laser diode pumping. This is, to the best of our knowledge, the first demonstration of a tandem-pumped Q-switched fiber laser. (paper)

  14. Strictly all-fiber picosecond Ytterbium fiber laser utilizing chirped-fiber-Bragg-gratings for dispersion control

    KATZ, Ori; Sintov, Yoav

    2008-01-01

    A compact, strictly all-fiber, picosecond pulse source based on ytterbium (Yb) doped fiber is described. Stable solitary mode-locking is obtained in a fiber-oscillator utilizing a carefully designed chirped fiber-Bragg-grating (C-FBG) for both dispersion control and spectral filtering. Self-starting is assured through the use of a fiber-coupled semiconductor-saturable-absorber-mirror (SESAM). The oscillator's 50MHz 3.8ps pulse-train output at 1064nm wavelength is amplified to 1.2W average pow...

  15. Enhanced Visible Light Generation from 1 μm Femtosecond Pulses within High-Δ Photonic Crystal Fibers

    We demonstrate the blue light generated in high-Δ photonic crystal fibers (PCFs). A femtosecond Yb-doped fiber laser, operating at 1039nm, is used to pump a GeO2-doped PCF in the largely anomalous group velocity dispersion (GVD) region. The emitted radiation covers 418.6–544.6nm with 5dB flatness. The calculated result indicates that the cross phase module (XPM) effect induced by higher-mode soliton makes a contribution to the blue component generation. (fundamental areas of phenomenology(including applications))

  16. All-fiber femtosecond Cherenkov radiation source.

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe; Tu, Haohua; Boppart, Stephen A; Turchinovich, Dmitry

    2012-07-01

    An all-fiber femtosecond source of spectrally isolated Cherenkov radiation is reported, to the best of our knowledge, for the first time. Using a monolithic, self-starting femtosecond Yb-doped fiber laser as the pump source and the combination of photonic crystal fibers as the wave-conversion medium, we demonstrate milliwatt-level, stable, and tunable Cherenkov radiation at visible wavelengths 580-630 nm, with pulse duration of sub-160-fs, and the 3 dB spectral bandwidth not exceeding 36 nm. Such an all-fiber Cherenkov radiation source is promising for practical applications in biophotonics such as bioimaging and microscopy. PMID:22743523

  17. All-fiber femtosecond Cherenkov radiation source

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe; Tu, Haohua; Boppart, Stephen A.; Turchinovich, Dmitry

    2012-01-01

    An all-fiber femtosecond source of spectrally isolated Cherenkov radiation is reported, to the best of our knowledge, for the first time. Using a monolithic, self-starting femtosecond Yb-doped fiber laser as the pump source and the combination of photonic crystal fibers as the wave-conversion medium, we demonstrate milliwatt-level, stable, and tunable Cherenkov radiation at visible wavelengths 580–630 nm, with pulse duration of sub-160-fs, and the 3 dB spectral bandwidth not exceeding 36 nm. ...

  18. Influence of mode competition on beam quality of fiber amplifier

    Theoretical and experimental studies of the influence of the mode competition on the output beam quality of fiber amplifiers are presented. Rate equations and modal decomposition method are used in the theoretical model. In the experiment, the output beam-quality factor of a fiber amplifier, which is based on a Yb-doped double-clad large mode area fiber as a function of the seed beam quality and the pump power of the amplifier, is measured. The experimental results are consistent with the theoretical analysis. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  19. Reduction of Photoluminescence Quenching by Deuteration of Ytterbium-Doped Amorphous Carbon-Based Photonic Materials

    Hui-Lin Hsu; Keith R. Leong; I-Ju Teng; Michael Halamicek; Jenh-Yih Juang; Sheng-Rui Jian; Li Qian; Nazir P. Kherani

    2014-01-01

    In situ Yb-doped amorphous carbon thin films were grown on Si substrates at low temperatures (<200 °C) by a simple one-step RF-PEMOCVD system as a potential photonic material for direct integration with Si CMOS back end-of-line processing. Room temperature photoluminescence around 1 µm was observed via direct incorporation of optically active Yb3+ ions from the selected Yb(fod)3 metal-organic compound. The partially fluorinated Yb(fod)3 compound assists the suppression of photoluminescence...

  20. Fiber-comb-stabilized light source at 556 nm for magneto-optical trapping of ytterbium

    Yasuda, Masami; Kohno, Takuya; Inaba, Hajime; Nakajima, Yoshiaki; Hosaka, Kazumoto; Onae, Atsushi; Hong, Feng-Lei

    2010-01-01

    A frequency-stabilized light source emitting at 556 nm is realized by frequency-doubling a 1112-nm laser, which is phase-locked to a fiber-based optical frequency comb. The 1112-nm laser is either an ytterbium (Yb)-doped distributed feedback fiber laser or a master-slave laser system that uses an external cavity diode laser as a master laser. We have achieved the continuous frequency stabilization of the light source over a five-day period. With the light source, we have completed the second-...

  1. A 12 mJ 11 ns spectrally narrow fiber amplifier with a pulsed pump

    We report on the fiber-based amplification of a flash lamp pumped Q-switched Nd:YAG laser. At a repetition rate of 10 Hz and spectrum width of 0.1 nm, an output single pulse energy of up to 12 mJ is generated in a 95 µm core Yb-doped large mode area fiber with a seed pulse energy of 0.75 mJ and pulse duration of 11 ns. No stimulated Brillouin scattering, stimulated Raman scattering or saturation are observed. Furthermore, higher pulse energies will be achieved with higher pump powers

  2. Observation of soliton explosions in a passively mode-locked fiber laser

    Runge, Antoine F. J.; Broderick, Neil G.R.; Erkintalo, Miro

    2014-01-01

    Soliton explosions are among the most exotic dissipative phenomena studied in mode-locked lasers. In this regime, a dissipative soliton circulating in the laser cavity experiences an abrupt structural collapse, but within a few roundtrips returns to its original quasi-stable state. In this work we report on the first observation of such events in a fiber laser. Specifically, we identify clear explosion signatures in measurements of shot-to-shot spectra of an Yb-doped mode-locked fiber laser t...

  3. LLE Review 119 (April-June 2009)

    This issue has the following articles: (1) Shock-Ignition Experiments on OMEGA at NIF-Relevant Intensities; (2) Laser-Driven Magnetic-Flux Compression in High-Energy-Density Plasmas; (3) Lorentz Mapping of Magnetic Fields in Hot, Dense Plasmas; (4) Characterization and Optimization of Yb-Doped Photonic-Crystal Fiber Rod Amplifiers Using Spatially Resolved Spectral Interferometry; (5) Optical Differentiation and Multimillijoule ∼150-ps Pulse Generation in a Regenerative Amplifier with a Temperature-Tuned Intracavity Volume Bragg Grating; (6) Slow Crack Growth During Radiatiave Cooling of LHG8 and BK7 Plates; and (7) Finite Element Simulation of Metal-Semiconductor-Metal Photoconductor.

  4. Yb:YAG Laser Crystals with Controlled Doping Distribution

    Arzakantsyan, Mikayel

    2013-01-01

    Development of high average-power solid state lasers rises up issues never faced before by other laser systems. Amplified Spontaneous Emission (ASE) and Thermal management as well as availability of large size high quality gain media are becoming key limiting factors for further energy increase. Lucia is a high average-power laser chains relying on active mirror concept and trivalent Yb doped YAG crystals/ceramics (Yb:YAG) as a gain medium. As for other similar laser systems, Lucia gain media...

  5. Diode-pumped ultrahigh-peak-power laser

    Laser characteristics of diode-pumped Yb-doped materials have been improved at low temperature dramatically for high power operation. An emission cross section is enlarged and the reduced saturation fluence enables efficient energy extraction of the storage energy even by using commercially obtainable optics. The thermal conductivity of laser crystals is considerably improved. In addition, A laser system in the materials has been changed from quasi-three-level to four-level at low temperature. A Yb:YLF chirped-pulse regenerative amplifier has been developed at low temperature and 36-mJ, 800-fs pulses have been obtained at 20 Hz. (author)

  6. High power linearly polarized Raman fiber laser at 1120 nm

    Jianhua Wang; Lei Zhang; Jun Zhou; Lei Si; Jinbao Chen; Yan Feng

    2012-01-01

    An all-fiber linearly polarized Raman fiber laser at 1 120 nm is demonstrated.With a 1 070-nm linearly polarized Yb-doped fiber laser as pump source,an output of up to 7.7 W at 1 120 nm is obtained with an optical efficiency of 55%.The polarization extinction ratio of the linearly polarized Raman fiber is higher than 18 dB.A numerical simulation model is developed to determine the Raman coefficient of the gain fiber and to evaluate the laser performance.The spectral isolation between the Raman fiber laser and the pump fiber laser is determined to be necessary for further improvements of performance.%An all-fiber linearly polarized Raman fiber laser at 1120 nm is demonstrated. With a 1070-nm linearly polarized Yb-doped fiber laser as pump source, an output of up to 7.7 W at 1120 nm is obtained with an optical efficiency of 55%. The polarization extinction ratio of the linearly polarized Raman fiber is higher than 18 dB. A numerical simulation model is developed to determine the Raman coefficient of the gain fiber and to evaluate the laser performance. The spectral isolation between the Raman fiber laser and the pump fiber laser is determined to be necessary for further improvements of performance.

  7. Fiber fuse behavior in kW-level continuous-wave double-clad field laser

    Jun-Yi, Sun; Qi-Rong, Xiao; Dan, Li; Xue-Jiao, Wang; Hai-Tao, Zhang; Ma-Li, Gong; Ping, Yan

    2016-01-01

    In this study, original experimental data for fiber fuse in kW-level continuous-wave (CW) high power double-clad fiber (DCF) laser are reported. The propagating velocity of the fuse is 9.68 m/s in a 3.1-kW Yb-doped DCF laser. Three other cases in Yb-doped DCF are also observed. We think that the ignition of fiber fuse is caused by thermal mechanism, and the formation of bullet-shaped tracks is attributed to the optical discharge and temperature gradient. The inducements of initial fuse and formation of bullet-shaped voids are analyzed. This investigation of fiber fuse helps better understand the fiber fuse behavior, in order to avoid the catastrophic destruction caused by fiber fuse in high power fiber laser. Project supported by the Key Laboratory of Science and Technology on High Energy Laser and China Academy of Engineering Physics (Grant No. 2014HEL02) and the National Natural Science Foundation of China (Grant No. 61307057).

  8. Thermoluminescence responses of the Yb- and Yb–Tb-doped SiO2 optical fibers to 6-MV photons

    Characteristics of the thermoluminescence (TL) responses of Yb- and Yb–Tb-doped optical fibers irradiated with 6 MV photons are reported. The concentration of Yb in the Yb-doped optical fiber was 0.26 mol%; the concentrations of Yb and Tb in the Yb–Tb-doped optical fiber were 0.62 and 0.2 mol%, respectively. The TL dose responses are linear in the dose range 0.5–4 Gy. The radiation sensitivity of the Yb–Tb material is almost two orders of magnitude higher than the sensitivity of the material doped with Yb alone. - Highlights: • SiO2 fibers doped with Yb and Yb+Tb can be used as thermoluminescence dosimeters. • The TL response to the dose is linear in the range 0.5–4.0 Gy. • The radiation sensitivity of the Yb–Tb-doped material is much higher than the sensitivity of the Yb-doped one. • Minimal detectable doses with the fibers doped with Yb and Yb+Tb are 333 and 19 mGy, respectively

  9. Diode radial pumped composite microchip Yb:YAG laser: output performances and thermal effects

    Dascalu, Traian; Pavel, Nicolaie A.; Taira, Takunori

    2004-10-01

    A diode radial pumped microchip Yb:YAG laser that consists of a Yb-doped core surrounded by undoped YAG of slab shape is presented. Quasi-continuous wave pumping of an 800-μm thick 10-at.% Yb doped core of 2 x 2 mm2 square shape with pulses of 5-Hz repetition rate and 2.5% duty cycle delivers 66-W output peak power at 220-W input pump power with 49% slope efficiency. 112-W peak power with 63% slope efficiency and 38% optical-to-optical efficiency, were obtained from a of 1.2 x 1.2 mm2 square 15-at.% Yb:YAG core of 800-μm thickness. Continuous-wave operation with up to 90 W were obtained from a 400-μm thick Yb:YAG/YAG structure with a 10-at.% Yb:YAG square core of 2x2-mm2 area; the slope efficiency and optical-to-optical efficiency with respect to the pump power were 40% and 28%, respectively. Measurements of the optical phase distortions induced by pumping gives focus shift bellow 0.05 m and shows the absence of astigmatic effects, indicating the axial heat flow in this pumping configuration.

  10. Influence of Yb2O3 on electrical and microstructural characteristics of CaCu3Ti4O12 ceramics

    Graphical abstract: Some Yb atoms entered in the lattice of CCTO substituted the Ca sites, the rest of Yb atoms concentrated at grain boundaries decreased the grain size. The dielectric constant was decreased by Yb doping. The dielectric loss of the CCTO could be greatly reduced at low frequency. - Highlights: • Yb atoms may take the place of Ca sites and concentrate at grain boundaries. • Tiny second phase corresponding to Yb may decrease the grain size. • Decrease of the grain size leads to the decrease of dielectric constant. • Yb doping could decrease the dielectric loss of CCTO. - Abstract: This paper focuses on the remarkable effects of Yb2O3 doping on the microstructure and dielectric characteristics of CaCu3Ti4O12 (CCTO). Samples were prepared by the solid phase reaction method and sintered in air at 1030 °C for 12 h. X-ray diffraction and X-ray photoelectron spectroscopy studies confirm that the primary phase is CCTO. Some Yb3+ ions may substitute into the Ca site at the center or zenith sites of the CCTO lattice hexahedron, while the rest of the Yb atoms may concentrate at grain boundaries. The grain size of Yb2O3-doped CCTO ceramics were examined by scanning electron microscopy and demonstrate sharp grain size reduction with Yb2O3 doping. From dielectric property measurements, the Yb2O3 doping reduces the dielectric constant of CCTO, and the dielectric loss is also reduced

  11. Synthesis–property relationship in thermoelectric Sr 1− x Yb x TiO 3− δ ceramics

    Bhattacharya, S

    2014-08-22

    The electronic transport properties of a series of Sr1-xYbxTiO3-delta (x = 0.05, 0.1) ceramics are investigated as a function of solid-state reaction (SSR) parameters, specifically calcination steps. It was found that the electrical conductivity (sigma) increases almost by a factor of 6, through the optimization of SSR parameters. The enhancement in the electrical conductivity leads to an enhancement in the thermoelectric power factor by a factor of 3. In addition, the lattice thermal conductivity (k(L)) of the Sr1-xYbxTiO3-delta ceramics is suppressed with increasing Yb-doping, supposedly due to heavier atomic mass of Yb substituted at the Sr site and a smaller ionic radii of Yb+3 with respect to Sr+2 ions. However, our model calculations indicate that strain-field effect, which occurs due to the difference in ionic radii, is the more prominent phonon scattering mechanism in the Yb-doped SrTiO3. This work is an extension of our previous study on the underlying phonon scattering mechanisms in the Y-doped SrTiO3, which would provide new insight into thermal transport in doped SrTiO3 and could be used as a guideline for more effective material synthesis.

  12. Visible photoluminescence and room temperature ferromagnetism in high In-content InGaN:Yb nanorods grown by molecular beam epitaxy

    Dasari, K.; Palai, R., E-mail: r.palai@upr.edu [Department of Physics, University of Puerto Rico, San Juan, Puerto Rico 00936 (United States); Wang, J.; Jadwisienczak, W. M. [School of Electrical Engineering and Computer Science, Ohio University, Athens, Ohio 45701-2979 (United States); Guinel, M. J.-F. [Department of Physics, University of Puerto Rico, San Juan, Puerto Rico 00936 (United States); Department of Chemistry, University of Puerto Rico, San Juan, Puerto Rico 00936 (United States); Huhtinen, H. [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, Turku FI-20014 (Finland); Mundle, R.; Pradhan, A. K. [Department of Engineering, Norfolk State University, 700 Park Avenue, Norfolk, Virginia 23504 (United States)

    2015-09-28

    We report the growth of high indium content InGaN:Yb nanorods grown on c-plane sapphire (0001) substrates using plasma assisted molecular beam epitaxy. The in situ reflection high energy electron diffraction patterns recorded during and after the growth revealed crystalline nature of the nanorods. The nanorods were examined using electron microscopy and atomic force microscopy. The photoluminescence studies of the nanorods showed the visible emissions. The In composition was calculated from x-ray diffraction, x-ray photoelectron spectroscopy, and the photoluminescence spectroscopy. The In-concentration was obtained from photoluminescence using modified Vegard's law and found to be around 37% for InGaN and 38% for Yb (5 ± 1%)-doped InGaN with a bowing parameter b = 1.01 eV. The Yb-doped InGaN showed significant enhancement in photoluminescence properties compared to the undoped InGaN. The Yb-doped InGaN nanorods demonstrated the shifting of the photoluminescence band at room temperature, reducing luminescence amplitude temperature dependent fluctuation, and significant narrowing of excitonic emission band as compared to the undoped InGaN. The magnetic properties measured by superconducting quantum interference devices reveals room temperature ferromagnetism, which can be explained by the double exchange mechanism and magnetostriction.

  13. Comparative study the effect of Yb concentrations on laser characteristics of Yb:YAG ceramics and crystals

    Laser performance of Yb:YAG ceramics and single-crystals doped with different Yb concentrations was investigated using two-pass pumping miniature laser configuration. Highly efficient laser performance was obtained for both Yb:YAG ceramics and single-crystals. For the low doping concentration, the laser performance of ceramics is lower than those of their single-crystal counterpart. However, better laser performance was observed for heavy-doped Yb:YAG ceramic than single-crystal (CYb = 20 at.%). The maximum optical-to-optical efficiency decreases with Yb doping concentration for both Yb:YAG ceramics and crystals. However, the decrease of maximum optical-to-optical efficiency is faster for Yb:YAG crystals than that for Yb:YAG ceramics with Yb doping concentration. The effects of Yb concentration and the transmission of the output couplers on the laser performance and output laser wavelength of Yb:YAG ceramics and crystals were addressed by taking account into the intracavity laser intensity and reabsorption

  14. Components for monolithic fiber chirped pulse amplification laser systems

    Swan, Michael Craig

    The first portion of this work develops techniques for generating femtosecond-pulses from conventional fabry-perot laser diodes using nonlinear-spectral-broadening techniques in Yb-doped positive dispersion fiber ampliers. The approach employed an injection-locked fabry-perot laser diode followed by two stages of nonlinear-spectral-broadening to generate sub-200fs pulses. This thesis demonstrated that a 60ps gain-switched fabry-perot laser-diode can be injection-locked to generate a single-longitudinal-mode pulse and compressed by nonlinear spectral broadening to 4ps. Two problems have been identified that must be resolved before moving forward with this approach. First, gain-switched pulses from a standard diode-laser have a number of characteristics not well suited for producing clean self-phase-modulation-broadened pulses, such as an asymmetric temporal shape, which has a long pulse tail. Second, though parabolic pulse formation occurs for any arbitrary temporal input pulse profile, deviation from the optimum parabolic input results in extensively spectrally modulated self-phase-modulation-broadened pulses. In conclusion, the approach of generating self-phase-modulation-broadened pulses from pulsed laser diodes has to be modified from the initial approach explored in this thesis. The first Yb-doped chirally-coupled-core ber based systems are demonstrated and characterized in the second portion of this work. Robust single-mode performance independent of excitation or any other external mode management techniques have been demonstrated in Yb-doped chirally-coupled-core fibers. Gain and power efficiency characteristics are not compromised in any way in this novel fiber structure up to the 87W maximum power achieved. Both the small signal gain at 1064nm of 30.3dB, and the wavelength dependence of the small signal gain were comparable to currently deployed large-mode-area-fiber technology. The efficiencies of the laser and amplifier were measured to be 75% and 54

  15. High average power picoseconds fiber amplifier with 20 μm core YDF

    In this letter we report a simple single-stage amplifier realized as high as 62 W average power output at 1064 nm wavelength, 40 picoseconds pulse width and 80 MHz repetition from 0.7 W seed laser based on backward pumped master-oscillator fiber power amplifier (MOPA) system. It is can stable operation in 57.6 W output for hours. We applied a semiconductor saturable absorber mirror (SESAM) passive mode-lock Nd:YVO4 oscillator as seed source and 6m long 20 μm core double-cladding Yb-doped fiber (YDF) as gain medium. To the best of our knowledge, 62 W average power is the highest output of single-stage ps-pulse amplifier with 20 μm-core fiber. None amplified spontaneous emission (ASE) and stimulated Raman scattering (SRS) nonlinear phenomenon was observed in 57.6 W high average power output

  16. Optimal design of a high-power picosecond laser system using a dual-stage ytterbium-doped fibre amplifier

    You, Yi-Jing; Lin, Chih-Hsuan; Zaytsev, Alexey; Tsai, Feng-Hua; Wang, Chi-Luen; Pan, Ci-Ling

    2013-07-01

    An average power as high as 60 W with 73 W of pumping was achieved for an ytterbium-doped fibre-based dual-stage amplifier (MOFA) system seeded by a diode-pumped solid-state (DPSS) laser. The corresponding optical conversion efficiency is 80%. The laser system generates a steady pulse train with a pulse width of 11 ps at a repetition rate of 250 MHz or a peak power of 21.8 kW. Moreover, the output beam quality M2 ≈ 1.6. The length and pumping power for the Yb-doped fibres were optimized to suppress stimulated Raman scattering (SRS) and amplified spontaneous emission (ASE) while maintaining desirable output characteristics.

  17. Developments of new laser crystals doped with Yb ions

    In the development of laser crystal suitable for the ultra high peak power CPA (Chirped Pulse Amplification) laser system with a compact size, fluoride YLF laser crystals doped with Yb3+ rare earth ion have been grown by a vertical Bridgman method. To prevent opaque crystal growth, one of growth materials, YF3 and PbF2 as a scavenger were mixed and heated twice in the vacuum furnace to get rid of YOF. We also adjusted the temperature gradient at the crystal growth surface and a mixing rate of the initial materials of LiF and YF3. As a result, Yb doped YLF crystal was successfully grown with the optimum temperature gradient of 30 - 40degC/cm, and the rate of 60:40 for LiF:YF3 in mol-%. (author)

  18. 11 mJ all-fiber-based actively Q-switched fiber master oscillator power amplifier

    We report a high energy all fiber format nanosecond pulsed laser source at ∼1064 nm in master oscillator power amplifier (MOPA) configuration. The seed source is an acousto-optic Q-switched fiber laser with a varied pulse duration and repetition rate. The output average power of the oscillator is ∼30 mW and two pre-amplifiers were developed to boost the average power to ∼3 W. Pulse energy of >11 mJ for ∼660 ns pulses at 3 kHz was achieved in the final power amplifier using a commercial 50/400 μm (core/cladding diameter) double cladding Yb-doped fiber (DCYF). (letter)

  19. High-energy square pulses and burst-mode pulses in an all-normal dispersion double-clad mode-locked fiber laser

    Qiao, Zhi; Wang, Xiaochao; Wang, Chao; Jing, Yuanyuan; Fan, Wei; Lin, Zunqi

    2016-05-01

    A double-clad Yb-doped mode-locked fiber laser that can operate in burst-mode and square-pulse states is experimentally investigated. In the burst-mode state, a burst train with 55 pulses of 500 ps duration is obtained. In the square-pulse state, which is similar to noiselike pulses, the maximum pulse energy is 820 nJ and the duration can be tuned from 15.8 to 546 ns. The square pulses have a narrow and multipeak spectrum, which is quite different from that of normal noiselike pulses. The fiber laser promises an alternative formation mechanism for burst-mode and square-pulse mode-locked fiber lasers.

  20. High power L-band mode-locked fiber laser based on topological insulator saturable absorber.

    Meng, Yichang; Semaan, Georges; Salhi, Mohamed; Niang, Alioune; Guesmi, Khmaies; Luo, Zhi-Chao; Sanchez, Francois

    2015-09-01

    We demonstrate a passive mode-locked Er:Yb doped double-clad fiber laser using a microfiber-based topological insulator (Bi(2)Se(3)) saturable absorber (TISA). By optimizing the cavity loss and output coupling ratio, the mode-locked fiber laser can operate in L-band with high average output power. With the highest pump power of 5 W, 91st harmonic mode locking of soliton bunches with average output power of 308 mW was obtained. This is the first report that the TISA based erbium-doped fiber laser operating above 1.6 μm and is also the highest output power yet reported in TISA based passive mode-locked fiber laser. PMID:26368409

  1. Observation of soliton explosions in a passively mode-locked fiber laser

    Runge, Antoine F J; Erkintalo, Miro

    2014-01-01

    Soliton explosions are among the most exotic dissipative phenomena studied in mode-locked lasers. In this regime, a dissipative soliton circulating in the laser cavity experiences an abrupt structural collapse, but within a few roundtrips returns to its original quasi-stable state. In this work we report on the first observation of such events in a fiber laser. Specifically, we identify clear explosion signatures in measurements of shot-to-shot spectra of an Yb-doped mode-locked fiber laser that is operating in a transition regime between stable and noise-like emission. The comparatively long, all-normal-dispersion cavity used in our experiments also permits direct time-domain measurements, and we show that the explosions manifest themselves as abrupt temporal shifts in the output pulse train. Our experimental results are in good agreement with realistic numerical simulations based on an iterative cavity map.

  2. Effect of Stoichiometric Composition and Different Metal Salts on the Phase Formation of Cerate-Zirconate Ceramics

    The effects of compositions and different metal salts on the phase of Ba(Ce,Zr)O3 perovskite ceramics derived from the solid state-reaction, sol-gel and Pechini methods are studied. X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to study the phase formation of the compound. It was found that the purity of Yb-doped Ba(Ce,Zr)O3 strongly depends on the stoichiometric compositions and metal salts of the raw materials. A high purity compound at relatively low temperature was obtained only when the powder of Ba(Ce0.8Zr0.2)0.95Yb0.05O2.975 was prepared from metal nitrate salts. Result of FTIR also confirmed that there was no carbonate species present in the sample prepared by Pechini method after it was sintered at 1400 degree Celsius. (author)

  3. 110  W all-fiber picosecond master oscillator power amplifier based on large-core-diameter ytterbium-doped fiber.

    Yu, Zhenhua; Shi, Wei; Dong, Xinzheng; Li, Jinhui; Zhao, Yizhu; Liu, Huixian

    2016-05-20

    We demonstrate an all-fiber picosecond fiber laser in a master oscillator power amplifier configuration. The seed source is a soliton-type passively mode-locked Yb-doped fiber laser by a semiconductor saturable absorber mirror and chirped fiber Bragg grating. The pulse width of the seed laser is 4.5 ps with a repetition rate of 15 MHz. A highly doped active fiber with a large core diameter (50 μm) is employed to boost the average power of the seed pulses to 117 W with 11 ps pulse width and 709 kW peak power. The corresponding output beam quality factor at maximum output power is 3.7. The all-fiber construction of the whole laser system enables compact size and robust operation. PMID:27411140

  4. High power burst-mode operated sub-nanosecond fiber laser based on 20/125 μm highly doped Yb fiber

    Wei, Kaihua; Wu, Pinghui; Wen, Ruhua; Song, Jiangxin; Guo, Yan; Lai, Xiaomin

    2016-02-01

    A master oscillator power amplification (MOPA) structured high power sub-nanosecond fiber laser with pulse bunch output is experimentally demonstrated. The seed was a figure-of-eight structured mode-locked fiber laser with a pulse duration of 700 ps and a repetition rate of 2.67 MHz. The seed pulse via two cascaded fiber couplers was multiplied to a pulse bunch, which was composed of 6 sub-pulses. The multiplied pulses were pre-amplified to an average power of 1.5 W through a cladding-pumping fiber amplifier. The pre-amplified laser was further amplified using a 20/125 μm large mode area (LMA) Yb-doped fiber. The laser emitted from the power-amplifier had an average power of 36 W, and a slope efficiency of 72%.

  5. An Ultra-Stable Referenced Interrogation System in the Deep Ultraviolet for a Mercury Optical Lattice Clock

    Dawkins, S T; Petersen, M; Millo, J; Magalhães, D V; Mandache, C; Coq, Y Le; Bize, S

    2010-01-01

    We have developed an ultra-stable source in the deep ultraviolet, suitable to fulfill the interrogation requirements of a future fully-operational lattice clock based on neutral mercury. At the core of the system is a Fabry-P\\'erot cavity which is highly impervious to temperature and vibrational perturbations. The mirror substrate is made of fused silica in order to exploit the comparatively low thermal noise limits associated with this material. By stabilizing the frequency of a 1062.6 nm Yb-doped fiber laser to the cavity, and including an additional link to LNE-SYRTE's fountain primary frequency standards via an optical frequency comb, we produce a signal which is both stable at the 1E-15 level in fractional terms and referenced to primary frequency standards. The signal is subsequently amplified and frequency-doubled twice to produce several milliwatts of interrogation signal at 265.6 nm in the deep ultraviolet.

  6. A High Efficiency Architecture for Cascaded Raman Fiber Lasers

    Supradeepa, V R; Headley, Clifford E; Yan, Man F; Palsdottir, Bera; Jakobsen, Dan

    2013-01-01

    We demonstrate a new high efficiency architecture for cascaded Raman fiber lasers based on a single pass cascaded amplifier configuration. Conversion is seeded at all intermediate Stokes wavelengths using a multi-wavelength seed source. A lower power Raman laser based on the conventional cascaded Raman resonator architecture provides a convenient seed source providing all the necessary wavelengths simultaneously. In this work we demonstrate a 1480nm laser pumped by an 1117nm Yb-doped fiber laser with maximum output power of 204W and conversion efficiency of 65% (quantum-limited efficiency is ~75%). We believe both the output power and conversion efficiency (relative to quantum-limited efficiency) are the highest reported for Raman fiber lasers.

  7. Spectrally tailored supercontinuum generation from single-mode-fiber amplifiers

    Spectral filtering of an all-normal-dispersion Yb-doped fiber laser was demonstrated effective for broadband supercontinuum generation in the picosecond time region. The picosecond pump pulses were tailored in spectrum with 1 nm band-pass filter installed between two single-mode fiber amplifiers. By tuning the spectral filter around 1028 nm, four-wave mixing was initiated in a photonic crystal fiber spliced with single-mode fiber, as manifested by the simultaneous generation of Stokes wave at 1076 nm and anti-Stokes wave at 984 nm. Four-wave mixing took place in cascade with the influence of stimulated Raman scattering and eventually extended the output spectrum more than 900 nm of 10 dB bandwidth. This technique allows smooth octave supercontinuum generation by using simple single-mode fiber amplifiers rather than complicated multistage large-mode-area fiber amplifiers.

  8. Point defect stability in gamma irradiated aluminoborosilicate glasses: Influence of Yb{sup 3+} doping ions

    Ollier, N., E-mail: nadege.ollier@polytechnique.edu [CEA, IRAMIS, Laboratoire des Solides Irradies, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Pukhkaya, V. [CEA, IRAMIS, Laboratoire des Solides Irradies, Ecole Polytechnique, CNRS, 91128 Palaiseau (France)

    2012-04-15

    Yb-doped aluminoborosilicate were irradiated with gamma rays at 10{sup 4}, 10{sup 5}, 10{sup 6} and 10{sup 7} Gy. The thermal stability as well as the recovery at room temperature of paramagnetic point defects such as Boron Oxygen Hole Center (BOHC), peroxy radicals and E Prime center were studied. At first, doping with Yb induced a saturation of the E Prime defect production and more importantly, the E Prime center recovering temperature was decreased by 50 Degree-Sign C. E Prime and BOHC defects both showed a limited stability at room temperature. By doping with Yb the glasses, the fading time of defects and in particular the BOHC defect recovery was modified. The BOHC defect showed moreover a larger sensitivity to photobleaching compared to the E Prime centers.

  9. A 23.75-GHz frequency comb with two low-finesse filtering cavities in series for high resolution spectroscopy

    侯磊; 韩海年; 王薇; 张龙; 庞利辉; 李德华; 魏志义

    2015-01-01

    A laser frequency comb with several tens GHz level is demonstrated, based on an Yb-doped femtosecond fiber laser and two low-finesse Fabry–P´erot cavities (FPCs) in series. The original 250-MHz mode-line-spacing of the source comb is filtered to 4.75 GHz and 23.75 GHz, respectively. According to the multi-beam interferences theory of FPC, the side-mode suppression rate of FPC schemes is in good agreement with our own theoretical results from 27 dB of a single FPC to 43 dB of paired FPCs. To maintain long-term stable operation and determine the absolute frequency mode number in the 23.75-GHz comb, the Pound–Drever–Hall (PDH) locking technology is utilized. Such stable tens GHz frequency combs have important applications in calibrating astronomical spectrographs with high resolution.

  10. Fifty-ps Raman fiber laser with hybrid active-passive mode locking.

    Kuznetsov, A G; Kharenko, D S; Podivilov, E V; Babin, S A

    2016-07-25

    Actively mode locked Raman lasing in a ring PM-fiber cavity pumped by a linearly polarized Yb-doped fiber laser is studied. At co-propagating pumping, a stochastic pulse with duration defined by the AOM switching time (~15 ns) is generated with the round-trip period. At counter-propagating pumping, one or several sub-ns pulses (within the AOM switching envelope) are formed. It has been found that the formation of such stable multi-pulse structure is defined by the single-pulse energy limit (~20 nJ) set by the second-order Raman generation. Adding a NPE-based saturable absorber in the actively mode locked cavity, results in sufficient shortening of the generated pulses both in single- and multi-pulse regimes (down to 50 ps). A model is developed adequately describing the regimes. PMID:27464081

  11. Performance evaluation of Laser Induced Breakdown Spectroscopy (LIBS) for quantitative analysis of rare earth elements in phosphate glasses

    Devangad, Praveen; Unnikrishnan, V. K.; Nayak, Rajesh; Tamboli, M. M.; Muhammed Shameem, K. M.; Santhosh, C.; Kumar, G. A.; Sardar, D. K.

    2016-02-01

    In the current study, we have determined the elemental compositions of synthesized rare earth doped phosphate glasses using a laboratory Laser-Induced Breakdown Spectroscopy (LIBS) system. LIBS spectra of this rare earth (samarium (Sm), thulium (Tm) and ytterbium (Yb)) doped glass samples with known composition are recorded using a highly sensitive detector. Major atomic emission lines of Sm, Tm and Yb found in LIBS spectra are reported. By considering the atomic emission line of phosphorous as an internal standard, calibration curves were constructed for all the rare earth concentrations. Very good linear regression coefficient (R2) values were obtained using this technique. Analytical predictive skill of LIBS was studied further using leave-one-out method. Low values of the reported correlation uncertainty between measured LIBS concentration ratio and certified concentration ratio confirms that LIBS technique has great potential for quantitative analysis of rare earth elements in glass matrix.

  12. Rare earth 4f hybridization with the GaN valence band

    The placement of the Gd, Er and Yb 4f states within the GaN valence band has been explored by both experiment and theory. The 4d–4f photoemission resonances for various rare-earth(RE)-doped GaN thin films (RE = Gd, Er, Yb) provide an accurate depiction of the occupied 4f state placement within the GaN. The resonant photoemission show that the major Er and Gd RE 4f weight is at about 5–6 eV below the valence band maximum, similar to the 4f weights in the valence band of many other RE-doped semiconductors. For Yb, there is a very little resonant enhancement of the valence band of Yb-doped GaN, consistent with a large 4f14-δ occupancy. The placement of the RE 4f levels is in qualitative agreement with theoretical expectations. (paper)

  13. Experimental study on the all-fiberized continuous-wave ytterbium-doped laser operating near 980 nm.

    Wang, Ruixing; Liu, Ying; Cao, Jianqiu; Guo, Shaofeng; Si, Lei; Chen, Jinbao

    2013-08-20

    All-fiberized continuous-wave Yb-doped fiber lasers operating near 980 nm are fabricated, and 1.73 W, 980 nm lasing is obtained. Moreover, the output properties of the 980 nm fiber laser are studied by experiment. It is demonstrated, for the first time to the best of our knowledge, that the output power curve versus the active fiber length experiences double-peak values, which are caused by the red shift of the lasing wavelength induced by the longitudinal-mode competition. It is also demonstrated that the pump threshold increases exponentially with the active fiber length. The relationship between the pump threshold and the optimum active fiber length is examined. PMID:24084992

  14. The Improved Power of the Central Lobe in the Beam Combination and High Power Output

    In order to increase the power fraction of the central lobe in the coherent beam combination of lasers in an array, the effects of the distance factor of near-field distribution on far-field interference patterns are calculated and demonstrated experimentally. An improved beam array of interwoven distribution is demonstrated to enable the power in the central lobe to reach 41%. An optimized mirror array is carefully designed to obtain a high duty ratio, which is up to 53.3% at a high power level. By using these optimized methods and designs, the passive phase locking of eight Yb-doped fiber amplifiers with ring cavities are obtained, and a pleasing interference pattern with 87% visibility is observed. The maximum coherent output power of the system is up to 1066 W. (fundamental areas of phenomenology(including applications))

  15. Hybrid-pumped, gain-switching operation of a Tm-doped fiber laser with linear-polarized output

    We report an all-fiber laser with a linear-polarized, pulsed 2 μm output up to 4.6 W by applying a hybrid-pump gain-switched scheme. In this method, a 790 nm laser diode serves as the main supplier of inverse population while a 1 μm pulsed Yb-doped fiber laser triggers the 2 μm pulsed lasing, to realize the gain-switching operation. We construct a resonant cavity with a polarization-maintaining Tm-doped fiber and a fiber Bragg grating to achieve a polarized laser. The laser output is centered at 2021 nm and has a polarization extinction ratio of 13.7 dB; the maximum pulse energy is 230 μJ at a repetition rate of 20 kHz. (letter)

  16. Compression of chirp pulses from a femtosecond fiber based amplifier

    Ito, Rumi; Takiuchi, Ken-ichi; Tei, Kazuyoku; Yamaguchi, Shigeru; Enokidani, Jyun; Sumida, Shin

    2015-03-01

    We demonstrate a single mode fiber based master oscillator power amplifier (MOPA) with a single polarization and a fully monolithic design. We have built a passive mode-locked polarization maintaining Yb doped fiber as the master oscillator contains a semiconductor saturable absorber mirror and a chirped fiber Bragg grating for the dispersion management. The net intracavity dispersion was managed to be slightly anomalous. The oscillator generates the 150 fs (sech2) pulses at the center wavelength of 1065 nm, and the repetition rate of 42 MHz. The oscillator output was amplified to 1.4 W from 80 mW in the single stage fiber amplifier which results in pulse shape distortion. The pulse shaping with a band pass filter and a compressor was applied to the amplified pulses. The shaping pulses have the pulse width of 90 fs and the pulse energy of 16 nJ.

  17. Nonlinear polarization rotation-induced pulse shaping in a stretched-pulse ytterbium-doped fiber laser

    Bai, Dong-Bi; Li, Wen-Xue; Yang, Kang-Wen; Shen, Xu-Ling; Chen, Xiu-Liang; Zeng, He-Ping

    2014-10-01

    We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intensity profile from Lorentz to Gaussian and then to sech2 shapes by adjusting the intra-cavity polarization through a quarter-wave plate inside the fiber laser cavity. The laser pulses with different pulse shapes exhibit pulse-to-pulse amplitude fluctuation of ~ 1.02%, while the sech2-shaped pulse train is provided with a more stable free-running repetition rate as a result of the stronger self-phase modulation in the fiber laser cavity than Lorentz- and Gaussian-shaped pulse trains.

  18. Yb hybrid laser system of DAW RF gun for SuperKEKB

    SuperKEKB is a planned upgrade to the KEKB accelerator with higher luminosity. Corresponding to the reduction of dynamic aperture and beam life, the photocathode DAW-type RF gun for high-current, low-emittance beams will be employed in the injector linac. The electron beams with a charge of 5 nC and a normalized emittance of 10 μm are expected to be generated in the RF gun by using the laser source at A-1 unit. Introducing the Ytterbium (Yb) hybrid laser system that includes Yb-doped fiber and Yb:YAG solid system, generates mJ pulses with a center wavelength of 258 nm and a pulse width of 30 ps. 1.0 nC beam generation from the RF gun was achieved. (author)

  19. Depolarization effect in rare-earth doped Y{sub 2}O{sub 3} films in blue and UV spectral range

    Gasimov, Naghi; Mammadov, Eldar; Babayev, Sardar; Mamedova, Irada; Mamedov, Nazim [Department of Ellipsometry, Institute of Physics, Azerbaijan National Academy of Sciences, H. Javid ave. 33, Baku-1143 (Azerbaijan); Joudrier, Anne L.; Andriamiadamanana, Christian; Naghavi, Negar; Guillemoles, Jean F. [Institute for Research and Development of Photovoltaic Energy, 6 Quai Watier, 78401 Chatou, Paris (France)

    2015-06-15

    The 200 to 300 nm thick, Er and Er,Yb doped Y{sub 2}O{sub 3} films deposited onto silicon substrate by spin coating have been studied by spectroscopic ellipsometry over the 192-1680 nm spectral range at room temperature. All samples have been found to be strongly depolarizing in the blue and UV part of the spectrum. Complimentary examination of the sample surfaces, using confocal photoluminescence microscopy has disclosed the non-uniform distribution of the rare-earth dopants. The depolarization effects have then been modeled and found to be best reproduced by taking the thickness non-uniformity as the main source of depolarization. The optical constants of the studied films have been determined after four-step modeling with sequential decrease of the mean square error. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Spectrally tailored supercontinuum generation from single-mode-fiber amplifiers

    Hao, Qiang; Guo, Zhengru; Zhang, Qingshan [Shanghai Key Laboratory of Modern Optical System, Engineering Research Center of Optical Instrument and System (Ministry of Education), School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093 (China); Liu, Yang; Li, Wenxue [State Key Laboratory of Precision Spectroscopy, East China Normal University, 3663 Zhongshan North Road, Shanghai 200062 (China); Zeng, Heping, E-mail: hpzeng@phy.ecnu.edu.cn [Shanghai Key Laboratory of Modern Optical System, Engineering Research Center of Optical Instrument and System (Ministry of Education), School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093 (China); State Key Laboratory of Precision Spectroscopy, East China Normal University, 3663 Zhongshan North Road, Shanghai 200062 (China)

    2014-05-19

    Spectral filtering of an all-normal-dispersion Yb-doped fiber laser was demonstrated effective for broadband supercontinuum generation in the picosecond time region. The picosecond pump pulses were tailored in spectrum with 1 nm band-pass filter installed between two single-mode fiber amplifiers. By tuning the spectral filter around 1028 nm, four-wave mixing was initiated in a photonic crystal fiber spliced with single-mode fiber, as manifested by the simultaneous generation of Stokes wave at 1076 nm and anti-Stokes wave at 984 nm. Four-wave mixing took place in cascade with the influence of stimulated Raman scattering and eventually extended the output spectrum more than 900 nm of 10 dB bandwidth. This technique allows smooth octave supercontinuum generation by using simple single-mode fiber amplifiers rather than complicated multistage large-mode-area fiber amplifiers.

  1. Optimal design of a high-power picosecond laser system using a dual-stage ytterbium-doped fibre amplifier

    An average power as high as 60 W with 73 W of pumping was achieved for an ytterbium-doped fibre-based dual-stage amplifier (MOFA) system seeded by a diode-pumped solid-state (DPSS) laser. The corresponding optical conversion efficiency is 80%. The laser system generates a steady pulse train with a pulse width of 11 ps at a repetition rate of 250 MHz or a peak power of 21.8 kW. Moreover, the output beam quality M2 ≈ 1.6. The length and pumping power for the Yb-doped fibres were optimized to suppress stimulated Raman scattering (SRS) and amplified spontaneous emission (ASE) while maintaining desirable output characteristics. (paper)

  2. Generation of 30-fs pulses from a diode-pumped graphene mode-locked Yb:CaYAlO4 laser

    Ma, Jie; Ning, Kaijie; Xu, Xiaodong; Xie, Guoqiang; Qian, Liejia; Loh, Kian Ping; Tang, Dingyuan

    2015-01-01

    Stable 30 fs pulses centered at 1068 nm (less than 10 optical cycles) are demonstrated in a diode pumped Yb:CaYAlO4 laser by using high-quality chemical vapor deposited monolayer graphene as the saturable absorber. The mode locked 8.43 optical-cycle pulses have a spectral bandwidth of ~ 50 nm and a pulse repetition frequency of ~ 113.5 MHz. To our knowledge, this is the shortest pulse ever reported for graphene mode-locked lasers and mode-locked Yb-doped bulk lasers. Our experimental results demonstrate that graphene mode locking is a very promising practical technique to generate few-cycle optical pulses directly from a laser oscillator.

  3. Hybrid master oscillator power amplifier system providing 10 mJ, 32 W, and 50 MW pulses for optical parametric chirped-pulse amplification pumping

    We present a high-energy, high-average-power picosecond laser system based on a hybrid chain in a master oscillator power amplifier configuration. The chain is seeded by a Ti:sapphire oscillator, followed by a Yb doped fiber preamplifier, a Nd:YAG-based regenerate amplifier, and a Nd:YVO4-based single-pass amplifier. The final diode-pumped, solid-state amplifier is detailed and produces pulses with more than 10 mJ energy at 32 W average power with 207 ps duration, corresponding to 50 MW peak power. The picosecond pulse output is seeded and optically synchronized with the sub-5-fs oscillator for optical parametric chirped-pulse amplification pumping. (authors)

  4. Anisotropic magnetic susceptibility of erbium and ytterbium in zircon, ZrSiO4

    Thorpe, A.N.; Briggs, Charles; Tsang, T.; Senftle, F.; Alexander, Corrine

    1977-01-01

    Magnetic susceptibility measurements have been made for both Er- and Yb-doped (1̃03ppm) zircon single crystals with the magnetic field perpendicular and parallel to the [001] axis. Large susceptibility anisotropies were found in both cases. Our observed anisotropies of ZrSiO4: Yb indicate small populations (1̃9%) of Yb ions at the axial (tetragonal) sites, as the susceptibility of ZrSiO4: Yb would be nearly isotropic if the Yb ions only occupied the orthorhombic sites. For Er3+ in orthorhombic sites of zircon, our data indicate that the first excited state is paramagnetic with gx = 9 and gy 5̃ at 20 cm-1 above the ground state (gx 0̃, gy 1̃5). The first excited state is quite similar to the ground states observed for Er3+ in many host lattices. ?? 1977.

  5. Dynamic population gratings in rare-earth-doped optical fibres

    Stepanov, Serguei [Optics Department, CICESE, km.107 carr. Tijuana-Ensenada, Ensenada, 22860, BC (Mexico)], E-mail: steps@cicese.mx

    2008-11-21

    Dynamic Bragg gratings can be recorded in rare-earth (e.g. Er, Yb) doped optical fibres by two counter-propagating mutually coherent laser waves via local saturation of the fibre optical absorption or gain (in optically pumped fibres). Typical recording cw light power needed for efficient grating formation is of sub-mW-mW scale which results in characteristic recording/erasure times of 10-0.1 ms. This review paper discusses fundamental aspects of the population grating formation, their basic properties, relating wave-mixing processes and also considers different applications of these dynamic gratings in single-frequency fibre lasers, tunable filters, optical fibre sensors and adaptive interferometry.

  6. 6-GHz, Kerr-lens mode-locked Yb:Lu2O3 ceramic laser for comb-resolved broadband spectroscopy.

    Endo, Mamoru; Ozawa, Akira; Kobayashi, Yohei

    2013-11-01

    A laser diode (LD)-pumped, 6-GHz repetition rate, ytterbium (Yb)-doped Lu2O3 ceramic Kerr-lens mode-locked laser is described. A bow-tie ring cavity enabled the generation of femtosecond pulses centered at a wavelength of 1076 nm with an average power of 10 mW. The pulse duration after an amplifier was 161 fs whereas the transform-limited pulse duration directly from the oscillator was 148 fs. The repetition frequency was sufficiently high for each longitudinal mode to be spectrally resolved by a commercially available optical spectrum analyzer. The developed laser was successfully applied to the absorption spectroscopy of metastable helium4 and demonstrated the suitability of the system as a source for comb-resolved broadband spectroscopy. PMID:24177130

  7. Structural, morphological and optical studies of YAG and Yb:YAG nanopowder by co-precipitation method

    Nanocrystalline Yttrium aluminum garnet (YAG) and Rare earth (Yb) doped YAG was prepared by co-precipitation method using ammonium hydrogen carbonate as precipitant. The phase formation of undoped YAG and Yb:YAG were characterized by X-ray diffraction (XRD). The cubic phase of YAG was found by varying the calcination temperatures from 700℃ to 1300℃. The impact of intermediate phases during the formation of YAG was determined through XRD. The morphology of YAG and Yb:YAG nanopowders calcined at various temperature were also investigated by Field Emission Scanning Electron Microscope (FESEM) and High Resolution Transmission Electron Microscope (HRTEM). The optical absorption spectrum of Yb:YAG nanopowder undergoes spatial distribution between Yb3+ in Y3Al5O12 in terms of absorption centers was also studied. (author)

  8. CW frequency doubling of 1029 nm radiation Using single pass bulk and waveguide PPLN crystals

    Chiodo, Nicola; Hrabina, Jan; Candela, Yves; Wallerand, Jean-Pierre; Acef, Ouali

    2013-01-01

    Following various works on second harmonic process using periodically poled Lithium Niobate crystals (PPLN), we report on the performances comparison between commercial bulk and waveguide crystals at 1029 nm. We use a continuous wave (CW) amplified Yb doped single fibre laser delivering up to 500mW in single mode regime. In case of bulk crystal we generate 4 mW using 400 mW IR power. The use of waveguide crystal leads to an increase of the harmonic power up to 33mW with input IR power limited to 200mW. Nevertheless, this impressive efficiency was affected by the long term degradation of the non-linear waveguide crystal.

  9. Broadband collimated generation in YAG:Yb crystal and ytterbium glass under LiF:F2+ color center laser pumping

    Nanosecond pulses of broadband collimated generation in the wavelength region of 1.0–1.06 μm were observed at focusing the pump radiation from LiF:F2+ color center laser onto the plates from YAG:Yb crystal or Yb-doped phosphate glass. Spectra of the widths up to 200 Å for YAG:Yb and up to 500Å for glass were registered. The angular divergence (10-3–10-4 rad) of broadband radiation from the emitting area of 100–200 μm in diameter was by 1–2 orders of magnitude smaller than the diffraction limit corresponding to this area. Physical mechanism responsible for the occurrence of highly collimated broadband lasing under stimulated Brillouin scattering (SBS) of the pump radiation in the active medium is discussed

  10. A 23.75-GHz frequency comb with two low-finesse filtering cavities in series for high resolution spectroscopy

    A laser frequency comb with several tens GHz level is demonstrated, based on a Yb-doped femtosecond fiber laser and two low-finesse Fabry–Pérot cavities (FPCs) in series. The original 250-MHz mode-line-spacing of the source comb is filtered to 4.75 GHz and 23.75 GHz, respectively. According to the multi-beam interferences theory of FPC, the side-mode suppression rate of FPC schemes is in good agreement with our own theoretical results from 27 dB of a single FPC to 43 dB of paired FPCs. To maintain long-term stable operation and determine the absolute frequency mode number in the 23.75-GHz comb, the Pound–Drever–Hall (PDH) locking technology is utilized. Such stable tens GHz frequency combs have important applications in calibrating astronomical spectrographs with high resolution. (paper)

  11. Pump-limited, 203 W, single-frequency monolithic fiber amplifier based on laser gain competition.

    Zeringue, Clint; Vergien, Christopher; Dajani, Iyad

    2011-03-01

    We present high power results of a Yb-doped fiber amplifier seeded with a combination of broad and single-frequency laser signals. This two-tone concept was used in conjunction with externally applied or intrinsically formed thermal gradients to demonstrate combined stimulated Brillouin scattering suppression in a copumped monolithic, polarization-maintaining (PM) fiber. Depending on the input parameters and the thermal gradient, the output power of the single-frequency signal ranged from 80 to 203 W with slope efficiencies from 70% to 80%. The 203 W amplifier was pump limited and is, to the best of our knowledge, the highest reported in the literature for monolithic, PM single-frequency fiber amplifiers. PMID:21368926

  12. New insights on P-related paramagnetic point defects in irradiated phosphate glasses: Impact of glass network type and irradiation dose

    P-related paramagnetic point defects were studied in irradiated Yb-doped phosphate glasses by electron paramagnetic resonance spectroscopy (X and Q-bands). A strong impact of the glass network type on the defect nature is shown. In all glasses, r-POHC defects formation is in strong correlation with Q2 tetrahedra amount supporting the structure of r-POHC. Ultra-phosphate glasses contain the larger defect type: Peroxy radicals, P1, P2, and P4 defects whose formation is linked to Q3 tetrahedra presence. In meta-phosphate and poly-phosphate glasses, peroxy radicals appear with r-POHC thermal recovery. In meta-phosphate glasses, a combination of P1 and P3 defects was evidenced for the first time, whereas in poly-phosphate glasses, only P3 defects were identified. Dose effect as well as defect recovery were analyzed.

  13. Amplification of laser radiation in disk Yb:YAG crystals cooled down to the liquid nitrogen temperature

    The parameters of a diode-pumped Yb:YAG amplifier are calculated. The derived expressions allow one to determine the optimal doping of the YAG crystal with Yb ions, which is ∼10% for a 600-μm-thick crystal. The calculations take into account the absorption line profile and the characteristics of the pump spectrum (the shape, width, central wavelength). When the 10% Yb-doped YAG crystal is cooled down from 296 K to 80 K, the shift of the gain profile centre (∼0.3 nm) and the increase in the stimulated emission cross section (by four times) as well as the depletion of the lower working level are observed. The small-signal gain (the maximum value is 1.7, which corresponds to the gain 4.4 cm-1) is measured as a function of the absorbed pump power and well agrees with the results of theoretical calculations. (lasers)

  14. Hybrid master oscillator power amplifier high-power narrow-linewidth nanosecond laser source at 257 nm.

    Délen, Xavier; Deyra, Loïc; Benoit, Aurélien; Hanna, Marc; Balembois, François; Cocquelin, Benjamin; Sangla, Damien; Salin, François; Didierjean, Julien; Georges, Patrick

    2013-03-15

    We report on a high-power narrow-linewidth pulsed laser source emitting at a wavelength of 257 nm. The system is based on a master oscillator power amplifier architecture, with Yb-doped fiber preamplifiers, a Yb:YAG single crystal fiber power amplifier used to overcome the Brillouin limitation in glass fiber and nonlinear frequency conversion stages. This particularly versatile architecture allows the generation of Fourier transform-limited 15 ns pulses at 1030 nm with 22 W of average power and a diffraction-limited beam (M(2)<1.1). At a repetition rate of 30 kHz, 106 μJ UV pulses are generated corresponding to an average power of 3.2 W. PMID:23503285

  15. Therapeutic effect of intravesical administration of paclitaxel solubilized with poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) in an orthotopic bladder cancer model

    To evaluate the effects of intravesical administration of paclitaxel (PTX-30W), which was prepared by solubilization with a water-soluble amphiphilic polymer composed of PMB30W, a copolymer of 2-methacryloyloxyethyl phosphorylcholine and n-butyl methacrylate, in an orthotopic bladder cancer model. The cytotoxicities of PMB30W were examined in MBT-2 cell cultures and the results were compared with those of the conventional paclitaxel solubilizer Cremophor. In an orthotopic MBT-2 bladder cancer model, the effect of intravesical administration of PTX-30W was compared with that of paclitaxel solubilized with Cremophor (PTX-CrEL). The paclitaxel concentration in bladder tumors after the intravesical treatment was also evaluated using liquid chromatography tandem mass spectrometry (LC-MS/MS) system. In vitro, Cremophor exhibited dose-dependent cytotoxicity towards MBT-2 cells, whereas no cytotoxicity was observed with PMB30W. In the orthotopic bladder cancer model, intravesical administration of PTX-30W resulted in a significant reduction of bladder wet weight compared with that of PTX-CrEL. The paclitaxel concentration in bladder tumors after the intravesical treatment was significantly higher in PTX-30W treated mice than in PTX-CrEL treated mice. Intravesically administered PTX-30W can elicit stronger antitumor effects on bladder tumors than conventional paclitaxel formulated in Cremophor, presumably because of its better penetration into tumor cells. PTX-30W might be a promising antitumor agent for intravesical treatment of non-muscle invasive bladder cancer

  16. Effect of sintering temperature on the morphology and mechanical properties of PTFE membranes as a base substrate for proton exchange membrane

    Nor Aida Zubir

    2002-11-01

    Full Text Available This paper reports the development of PTFE membranes as the base substrates for producing proton exchange membrane by using radiation-grafting technique. An aqueous dispersion of PTFE, which includes sodium benzoate, is cast in order to form suitable membranes. The casting was done by usinga pneumatically controlled flat sheet membrane-casting machine. The membrane is then sintered to fuse the polymer particles and cooled. After cooling process, the salt crystals are leached from the membrane by dissolution in hot bath to leave a microporous structure, which is suitable for such uses as a filtration membrane or as a base substrate for radiation grafted membrane in PEMFC. The effects of sintering temperature on the membrane morphology and tensile strength were investigated at 350oC and 385oC by using scanning electron microscopy (SEM and EX 20, respectively. The pore size and total void space are significantly smaller at higher sintering temperature employed with an average pore diameter of 11.78 nm. The tensile strength and tensile strain of sintered PTFE membrane at 385oC are approximately 19.02 + 1.46 MPa and 351.04 + 23.13 %, respectively. These results were indicated at 385oC, which represents significant improvements in tensile strength and tensile strain, which are nearly twice those at 350oC.

  17. Structural characteristics and spectral properties of novel transparent lithium aluminosilicate glass-ceramics containing (Er,Yb)NbO4 nanocrystals

    Transparent lithium aluminosilicate glass-ceramics based on nanosized crystals of β-quartz solid solutions and Er,Yb orthoniobates are prepared for the first time, to our knowledge. According to X-ray diffraction analysis, parent Er,Yb-codoped glass contains (Er,Yb)NbO4 nanocrystals with the defected fluorite structure while the single Yb-doped glass is X-ray amorphous. The Er,Yb orthoniobates with the tetragonal structure crystallize under heat-treatments at 800–900 °C; and at 1000 °C the transformation to a monoclinic form begins. β-quartz solid solutions are the main crystalline phase of glass-ceramics prepared in the temperature range of 800–1000 °C. These structural transformations are confirmed by Raman spectroscopy. The structure evolution is illustrated by the TEM study of the Yb-doped glass and glass-ceramics. The spectral-luminescent properties of glass-ceramics are directly linked to their structure; an appearance of the monoclinic phase has a crucial effect on these properties. Glass-ceramics with tetragonal (Er,Yb)NbO4 nanophase are characterized by the high efficiency of Yb3+→Er3+ energy transfer (85%), strong absorption in the vicinity of 0.98 μm and shorter lifetime of 4I13/2 state (as compared with the parent glass), so they look promising for laser operation in the eye-safe region around 1.53 μm. - Highlights: • Transparent glass-ceramics based on β-quartz ss and (Er,Yb)NbO4 nanocrystals were prepared. • Fluorite-to-tetragonal-to-monoclinic phase transition for (Er,Yb)NbO4 was observed. • The spectral-luminescent properties of materials are directly linked to their structure. • High efficiency of Yb3+→Er3+ energy transfer (85%). • Glass-ceramics with tetragonal (Er,Yb)NbO4 are promising for laser operation at 1.53 μm

  18. Intense cooperative upconversion emission in Yb/Er: TeO{sub 2}–Li{sub 2}O–WO{sub 3} oxyfluoride glass ceramics

    Ansari, Ghizal F.; Mahajan, S.K., E-mail: sachin_k_mahajan@rediffmail.com

    2014-12-15

    Novel oxyfluoride glass ceramics based on Yb{sup 3+}-doped TeO{sub 2}–Li{sub 2}O–WO{sub 3}–ErF{sub 3} (TWLE) were prepared using the two-stage heat-treatment method. The structural characterisation of these materials with X-ray diffraction indicated that crystalline phases of LiYbErF{sub 4} nanocrystals grew in the glass ceramics. Upon excitation with a 980 nm laser diode the Yb{sup 3+} doped (2 mol%) TWLE glass-ceramic produced intense blue emission at 487 nm, weak green emission at 525 nm and 550 nm, and red emission at 650 nm at room temperature. The mechanism of the blue emission, which is attributed to cooperative upconversion from pairs of excited Yb{sup 3+} ions to ground-state Er{sup 3+} ions, and the weak red and green emissions, which are attributed to energy transfer from Yb{sup 3+} to Er{sup 3+} ions, were investigated. The results of a pump-power dependence measurement suggested that the blue cooperative emission is a two-photon process. A rate equation was used to describe the cooperative energy-transfer process among the donor and acceptor ions. The observed results were compared to the behavior of another glass materials that exhibits blue cooperative emission, revealing the considerable advantage of TWLE:2Yb glass ceramics for optical devices. - Highlights: • The transparent glass-ceamics based on Yb doped TeO{sub 2}–Li{sub 2}O–WO{sub 3}–ErF{sub 3} (TWLE) have been prepared. • XRD confirm crystalline phase of LiYbErF{sub 4} nanocrystals are grown in glass ceramics. • Under 980 nm LD excitation of TWLE:2Yb produced intense blue emission due to cooperative upconversion process exists. • Pump power excitation confirms cooperative upconvesion is two-photon process. • The quadratic dependence of pump intensity determined by mean of the rate equations. • Comparative studies of blue cooperative for TWLE:2Yb with other Yb doped materials described.

  19. Factorial study on influence of gas generating agent and diluent on drug release kinetics of clopidogrel bisulfate floating tablets

    K R Koteswara Rao; K Rajya Lakshmi; T. E. G. K. Murthy; A Sivarama Prasad

    2013-01-01

    The purpose of present work was to formulate and characterize a floating drug delivery system for Clopidogrel bisulphate to improve bioavailability and to minimize the side-effects of the drug such as gastric bleeding and drug resistance development. Clopidogrel floating tablets were prepared by direct compression technique by the use of xanthan gum at different concentrations (20%, 25% and 30% w/w). Sodium bicarbonate (15% w/w) and microcrystalline cellulose (MCC) (30% w/w) were used as gas ...

  20. (6+1) x1 fiber combiner based on thermally expanded core technique for high power amplifiers

    Zhao, Ke; Chen, Zilun; Zhou, Xuanfeng; Wang, Zefeng; Jiang, Houman

    2015-07-01

    A high-efficiency pump-signal combiner for high power fiber amplifiers based on thermally expanded core (TEC) technique is reported in this paper. TEC technique is used to fabricate mode-field adapter which allows optimization of signal fibers in a monolithic (6+1) ×1 fiber combiner. The combiner is fabricated by connecting a tapered fiber bundle (TFB) to a passive 25/250 (NA=0.06/0.46) double-clad fiber (DCF). By this method, the coupling efficiency of SMF-28 signal fiber at 1064nm improves from 54% to 92.7%. The average pump coupling efficiencies of six 105/125 (NA=0.15) fibers are measured to be 96.7% at 976nm. Furthermore, the average signal transmission efficiency is around 93.3%. The fabricated fiber combiner is spliced to an Yb-doped DCF for use as an all-fiber amplifier. The slope efficiency is measured to be 71.6%.

  1. High peak power picosecond hybrid fiber and solid-state amplifier system

    We report the high peak power picosecond hybrid fiber and solid-state laser amplifier system. The passively mode-locked solid-state seed source produced an average power of 1.8 W with pulse width of 14 ps and repetition rate of 86 MHz. It was directly coupled into the first Yb-doped polarized photonic crystal fiber amplifier stage. To avoid the nonlinear effects in fiber, the output power from the first stage was merely amplified to 24 W with the narrow spectra broadening of 0.21 nm. For the improvement of the peak power, the dual-end pumped composite Nd:YVO4 amplifier system has been chosen at the second stage. To reduce the serious thermal effect, the thermally bonded composite YVO4 – Nd:YVO4 – YVO4 rod crystal was used as the gain medium. The 53 W TEM00 mode with the peak power of 40 kW, beam quality of M2 < 1.15, corresponding to the optical-optical efficiency of 42.4% was obtained at the hybrid amplifier laser system. The system allows using a low power seed source and demonstrates an increase in the peak power beyond a fiber master oscillator power amplifier's (MOPA's) limit

  2. Synthesis and down-conversion luminescence properties of Er3+/Yb3+ co-doped AlF3-PbF2-CaF2 powders

    Liu, Fangchao; Han, Qun; Liu, Tiegen; Chen, Yaofei; Du, Yang; Yao, Yunzhi

    2015-08-01

    Er3+/Yb3+ co-doped oxy-fluoride powders with varying Er/Yb concentration were prepared by a melt quenching method at various sintering temperature. The effect of the Er/Yb doped concentration and sintering temperature were analyzed by using optical absorption and emission techniques. The Judd-Ofelt theory has been used to evaluate the three intensity parameters (Ωλ, where λ = 2, 4 and 6) and calculate the oscillator strengths (fc). Ultraviolet-to-visible emissions were observed under the excitation of a 325 nm CW laser. It was found that the down-conversion fluorescence intensity changes with the sintering temperature and Er/Yb content ratio, the results were explained with the level transitions in Er3+/Yb3+ co-doped systems. The intensity ratios (intensity of 437 nm as reference) of the luminescence spectra that the samples sintered at various temperature are relevant to Ω6 parameter which indicates the vibration amplitude of the Er-O distance. The sintering temperature also has an influence on the intensity ratios via affecting the thermalization of the excited 4I15/2 level.

  3. Structure and distortion of lead fluoride nanocrystals in rare earth doped oxyfluoride glass ceramics.

    Ge, Jin; Zhao, Lijuan; Guo, Hui; Lan, Zijian; Chang, Lifen; Li, Yiming; Yu, Hua

    2013-10-28

    A series of rare earth (RE) doped oxyfluoride glasses with the composition of (45-x) SiO2-5Al2O3-40PbF2-10CdF2-xRe2O3 (x = 1, 5, 10, 15) (mol%) were prepared by a traditional melt-quenching method. Glass ceramics (GCs) were obtained after thermal treatment and characterized by X-ray diffraction (XRD) to investigate the nanocrystal structure and distortion. Both the dopant type and the doping level play an important role in the distortion of the PbF2-RE lattice. It is found that a cubic Pb3REF9 phase forms in low doping GCs, a tetragonal PbREF5 phase forms in middle doping GCs and cubic PbRE3F11 forms in high doping GCs. Accordingly, the site symmetry of RE(3+) dopants in β-PbF2 nanocrystal undergoes a transition of Oh···D4h···Oh with the increase of doping level. The change in the ligands coordinating the RE(3+) ions was further illustrated by the optical changes in Yb-doped GCs. This paper provides insights on the nanocrystal structure of RE at the atomic level and tries to make a complete description of the nanocrystal structure and distortion in these glass-ceramic materials, which will benefit the optimization of optical properties. PMID:24019159

  4. Optimization of noncollinear optical parametric amplification

    Schimpf, D. N.; Rothardt, J.; Limpert, J.; Tünnermann, A.

    2007-02-01

    Noncollinearly phase-matched optical parametric amplifiers (NOPAs) - pumped with the green light of a frequency doubled Yb-doped fiber-amplifier system 1, 2 - permit convenient generation of ultrashort pulses in the visible (VIS) and near infrared (NIR) 3. The broad bandwidth of the parametric gain via the noncollinear pump configuration allows amplification of few-cycle optical pulses when seeded with a spectrally flat, re-compressible signal. The short pulses tunable over a wide region in the visible permit transcend of frontiers in physics and lifescience. For instance, the resulting high temporal resolution is of significance for many spectroscopic techniques. Furthermore, the high magnitudes of the peak-powers of the produced pulses allow research in high-field physics. To understand the demands of noncollinear optical parametric amplification using a fiber pump source, it is important to investigate this configuration in detail 4. An analysis provides not only insight into the parametric process but also determines an optimal choice of experimental parameters for the objective. Here, the intention is to design a configuration which yields the shortest possible temporal pulse. As a consequence of this analysis, the experimental setup could be optimized. A number of aspects of optical parametric amplifier performance have been treated analytically and computationally 5, but these do not fully cover the situation under consideration here.

  5. Optical properties of highly crystalline Y2O3:Er,Yb nanoparticles prepared by laser ablation in water

    Y2O3:Er,Yb nanoparticles were prepared by laser ablation in water. We investigated crystallinity, distribution of dopant, and optical properties of the prepared nanoparticles. The full-width half-maximum (FWHD) of the crystalline peak of nanoparticles measured by an x-ray diffractometer (XRD) barely changed. Further, using scanning transmission electron microscopy–energy dispersive x-ray spectroscopy (STEM–EDX), we confirmed the peaks of Y, Er, Yb, and O. Moreover, on the basis of the optical properties of the nanoparticles, the emission of red (2F9/2 → 4I15/2) and green (2H11/2, 4S3/2 → 4I15/2) was confirmed. We also investigated the emission intensity as a function of the excitation power of 980 nm LD in the prepared nanoparticles. The photon avalanche effect was observed at the excitation power of 100 mW. These results confirmed that uniformly Er-Yb-doped Y2O3 nanoparticles were successfully prepared by laser ablation in water. (paper)

  6. Glass-on-Glass Fabrication of Bottle-Shaped Tunable Micro-Lasers and Their Applications

    Ward, Jonathan M; Chormaic, Sile Nic

    2016-01-01

    We describe a novel method for making microbottle-shaped lasers by using a CO$_2$ laser to melt Er:Yb glass onto silica microcapillaries or fibres. This is realised by the fact that the two glasses have different melting points. The CO$_2$ laser power is controlled to flow the doped glass around the silica cylinder. In the case of a capillary, the resulting geometry is a hollow, microbottle-shaped resonator. This is a simple method for fabricating a number of glass WGM lasers with a wide range of sizes on a single, micron-scale structure. The Er:Yb doped glass outer layer is pumped at 980 nm via a tapered optical fibre and whispering gallery mode (WGM) lasing is recorded around 1535 nm. This structure facilitates a new way to thermo-optically tune the microlaser modes by passing gas through the capillary. The cooling effect of the gas flow shifts the WGMs towards shorter wavelengths, thus thermal tuning of the lasing modes over 70 GHz is achieved. Results are fitted using the theory of hot wire anemometry, al...

  7. Glass-on-Glass Fabrication of Bottle-Shaped Tunable Microlasers and their Applications

    Ward, Jonathan M.; Yang, Yong; Nic Chormaic, Síle

    2016-04-01

    We describe a novel method for making microbottle-shaped lasers by using a CO2 laser to melt Er:Yb glass onto silica microcapillaries or fibres. This is realised by the fact that the two glasses have different melting points. The CO2 laser power is controlled to flow the doped glass around the silica cylinder. In the case of a capillary, the resulting geometry is a hollow, microbottle-shaped resonator. This is a simple method for fabricating a number of glass whispering gallery mode (WGM) lasers with a wide range of sizes on a single, micron-scale structure. The Er:Yb doped glass outer layer is pumped at 980 nm via a tapered optical fibre and WGM lasing is recorded around 1535 nm. This structure facilitates a new way to thermo-optically tune the microlaser modes by passing gas through the capillary. The cooling effect of the gas flow shifts the WGMs towards shorter wavelengths and thermal tuning of the lasing modes over 70 GHz is achieved. Results are fitted using the theory of hot wire anemometry, allowing the flow rate to be calibrated with a flow sensitivity as high as 72 GHz/sccm. Strain tuning of the microlaser modes by up to 60 GHz is also demonstrated.

  8. Gigahertz Self-referenceable Frequency Comb from a Semiconductor Disk Laser

    Zaugg, Christian A; Mangold, Mario; Mayer, Aline S; Link, Sandro M; Emaury, Florian; Golling, Matthias; Gini, Emilio; Saraceno, Clara J; Tilma, Bauke W; Keller, Ursula

    2014-01-01

    We present a 1.75-GHz self-referenceable frequency comb from a vertical external-cavity surface-emitting laser (VECSEL) passively modelocked with a semiconductor saturable absorber mirror (SESAM). The VECSEL delivers 231-fs pulses with an average power of 100 mW and is optimized for stable and reliable operation. The optical spectrum was centered around 1038 nm and nearly transform-limited with a full width half maximum (FWHM) bandwidth of 5.5 nm. The pulses were first amplified to an average power of 5.5 W using a backward-pumped Yb-doped double-clad large mode area (LMA) fiber and then compressed to 85 fs with 2.2 W of average power with a passive LMA fiber and transmission gratings. Subsequently, we launched the pulses into a highly nonlinear photonic crystal fiber (PCF) and generated a coherent octave-spanning supercontinuum (SC). We then detected the carrier-envelope offset (CEO) frequency (fCEO) beat note using a standard f-to-2f-interferometer. The fCEO exhibits a signal-to-noise ratio of 17 dB in a 10...

  9. Electron Bunch Shape Measurements Using Electro-optical Spectral Decoding

    Borysenko, A.; Hiller, N.; Müller, A.-S.; Steffen, B.; Peier, P.; Ivanisenko, Y.; Ischebeck, R.; Schlott, V.

    Longitudinal diagnostics of the electron bunch shapes play a crucial role in the operation of linac-based light sources. Electro-optical techniques allow us to measure the longitudinal electron bunch profiles non-destructively on a shot-by-shot basis. Here we present results from measurements of electron bunches with a length of 200-900 fs rms at the Swiss FEL Injector Test Facility. All the measurements were done using an Yb-doped fibre laser system (with a central wavelength of a 1050 nm) and a GaP crystal. The technique of electro-optical spectral decoding (EOSD) was applied and showed great capabilities to measure bunch shapes down to around 370 fs rms. Measurements were performed for different electron energies to study the expected distortions of the measured bunch profile due to the energy-dependent widening of the electric field, which plays a role for low beam energies below and around 40 MeV. The studies provide valuable input for the design of the EOSD monitors for the compact linear accelerator FLUTE that is currently under commissioning at the Karslruhe Institute of Technology (KIT).

  10. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO2 fiber

    Visible light thermal radiation from SiO2 glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO2 fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO2 fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO2 fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO2 fibers are smaller than those from SiO2 fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO2 are potentially applicable for the fiber-optic thermometry above 900 K

  11. Optical, luminescent and laser properties of highly transparent ytterbium doped yttrium lanthanum oxide ceramics

    Ivanov, M.; Kopylov, Yu.; Kravchenko, V.; Li, Jiang; Pan, Yubai; Kynast, U.; Leznina, M.; Strek, W.; Marciniak, Lukasz; Palashov, O.; Snetkov, I.; Mukhin, I.; Spassky, D.

    2015-12-01

    This paper describes the fabrication and investigation of highly transparent Yb-doped yttrium lanthanum oxide ceramics. For sintering of the ceramics we used a technology, which consists of several consecutive steps: (a) synthesis of weakly agglomerated nanopowder by laser ablation, (b) compacting of the green body with cold isostatic pressing (CIP), and (c) sintering in vacuum. After calcinations of the synthesized nanopowder at 1200 °C, a pure single-phase solid solution Yb3+:(LaxY1-x)2O3 was formed. The lanthanum ions proved to be a good aid to sinter yttria ceramics doped with Yb3+ at comparatively moderate temperatures of about 1650 °C. The ceramics have a relative density higher than 99.99% and grain sizes around 40 μm. The absorption coefficient of 3.2 mm thick Yb0.12La0.27Y1.61O3 ceramics is 0.01 cm-1 at 1150 nm. Laser oscillation at a wavelength of 1033 nm is demonstrated.

  12. Tunable pulse width and multi-megawatt peak-power pulses from a nonlinearly compressed monolithic fiber MOPA system

    Yamashita, Ryutarou; Maeda, Kazuo; Watanabe, Goro; Tei, Kazuyoku; Yamaguchi, Shigeru; Enokidani, Jun; Sumida, Shin

    2016-03-01

    We report on tunable pulse width and high peak power pulse generation from a nonlinearly compressed monolithic fiber MOPA system. The master seed source employs a Mach-Zehnder intensity modulator (MZIM). This seed source has operational flexibility with respect to pulse width, 90 ps to 2 ns and repetition rate, 200 kHz to 2 MHz. The seed pulses are amplified by a monolithic three-stage amplifier system based on polarization maintain Yb-doped fibers. The maximum output power was 32 W at the shortest pulse condition, the pulse width of 90 ps and the repetition rate of 750 kHz. A spectral width after amplification was broadened to 0.73 nm at RMS width. Both of ASE and SRS are not observed in the spectrum. After amplification, we also demonstrated pulse compression with a small piece of chirped volume Bragg-grating (CVBG) which has the dispersion rate of 81 ps/nm. As a result of pulse compression, the shortest pulse width was reduced from 90 ps to 3.5 ps, which brought an increase of the peak power up to 3.2 MW. The compressed pulses are clean with little structure in their wings. We can expand the operation range of the monolithic fiber MOPA system in pulse width, 3.5 ps to 2 ns.

  13. Multi-mJ, kHz, ps deep-ultraviolet source.

    Chang, Chun-Lin; Krogen, Peter; Liang, Houkun; Stein, Gregory J; Moses, Jeffrey; Lai, Chien-Jen; Siqueira, Jonathas P; Zapata, Luis E; Kärtner, Franz X; Hong, Kyung-Han

    2015-02-15

    We demonstrate a 0.56-GW, 1-kHz, 4.2-ps, 2.74-mJ deep-ultraviolet (DUV) laser at ∼257.7  nm with a beam propagation factor (M2) of ∼2.54 from a frequency-quadrupled cryogenic multi-stage Yb-doped chirped-pulse amplifier. The frequency quadrupling is achieved using LiB3O5 and β-BaB2O4 crystals for near-infrared (NIR)-to-green and green-to-DUV conversion, respectively. An overall NIR-to-DUV efficiency of ∼10% has been achieved, which is currently limited by the thermal-induced phase mismatching and the DUV-induced degradation of transmittance. To the best of our knowledge, this is the highest peak-power picosecond DUV source from a diode-pumped solid-state laser operating at kHz repetition rates. PMID:25680176

  14. Fiber laser pumped burst-mode operated picosecond mid-infrared laser

    魏凯华; 姜培培; 吴波; 陈滔; 沈永行

    2015-01-01

    We demonstrate a compact periodically poled MgO-doped lithium niobate (MgO:PPLN)-based optical parametric oscillator (OPO) quasi-synchronously pumped by a fiber laser system with burst-mode operation. The pump source is a peak-power-selectable pulse-multiplied picosecond Yb fiber laser. The chirped pulses from a figure of eight-cavity mode-locked fiber laser seed are narrowed to a duration of less than 50 ps using an FBG refl ector and a circulator. The narrowed pulses are directed to pass through a pulse multiplier and to form pulse bunches, each of which is composed of 13 sub-pulses. The obtained pulse bunches are amplified by two-stage fiber pre-amplifiers:one-stage is core-pumped and the other is cladding-pumped. A fiberized acousto–optic modulator is inserted to control the pulse repetition rate (PRR) of the pulse bunches before they are power-amplified in the final amplifier stage with a large mode area (LMA) PM Yb-doped fiber. The maximum average powers from the final amplifier are 85 W, 60 W, and 45 W respectively, corresponding to the PRR of 2.72 MHz, 1.36 MHz, and 0.68 MHz. The amplified pulses are directed to pump an MgO:PPLN-based optical parametric oscillator (OPO). A maximum peak power at 3.45 µm is obtained approximately to be 8.4 kW. Detailed performance characteristics are presented.

  15. Structural, morphological and spectroscopic properties of Eu3+-doped rare earth fluorides synthesized by the hydrothermalmethod

    Rare earth fluorides (REF3, RE=Y, La, Gd or Yb) doped with 5% of Eu3+ ions were synthesized via the hydrothermal method and their physicochemical properties were compared. The synthesis was carried out in an aqueous medium at elevated pressure and temperature. The reaction was performed in situ, with use of NaBF4 as a source of fluoride ions. Structural and morphological properties of obtained nanophosphors were characterized with the use of powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. Synthesized products were nanocrystalline with hexagonal or orthorhombic crystal structures. They showed different morphology, from nanoplates to nanorings, depending on the used REF3 fluoride as the host for the Eu3+ ions. The elemental composition was confirmed by the energy-dispersive X-ray spectroscopy (EDX) results. Spectroscopic properties were investigated by measuring the excitation and emission spectra. Also luminescence lifetimes were determined. The synthesized materials showed bright red luminescence, due to the presence of Eu3+ ions in their structure. - Graphical abstract: Luminescence spectra of the REF3:Eu3+ (RE=Y, La, Gd and Yb) fluorides and their TEM images as background. Highlights: ► Nanocrystalline fluorides were synthesized using modified hydrothermal method. ► Structural and morphological properties of in situ prepared nanomaterials were studied. ► Luminescence properties of REF3:Eu3+ (RE=Y, La, Gd, Yb) were compared and investigated

  16. Study of ytterbium doping effects on structural, mechanical and opto-thermal properties of sprayed ZnO thin films using the Boubaker Polynomials Expansion Scheme (BPES)

    Amlouk, A. [Unite de physique des dispositifs a semi-conducteurs, Faculte des sciences de Tunis, Universite de Tunis El Manar, 2092 Tunis (Tunisia); Boubaker, K., E-mail: mmbb11112000@yahoo.f [Unite de physique des dispositifs a semi-conducteurs, Faculte des sciences de Tunis, Universite de Tunis El Manar, 2092 Tunis (Tunisia); Amlouk, M. [Unite de physique des dispositifs a semi-conducteurs, Faculte des sciences de Tunis, Universite de Tunis El Manar, 2092 Tunis (Tunisia); Bouhafs, M. [Unite de Recherche MA2I, Ecole Nationale d' Ingenieurs de Tunis, B.P. 37 Le Belvedere, 1002 Tunis (Tunisia)

    2009-10-19

    In this work, ZnO thin films have been grown on glass substrates by using a solution of propanol (C{sub 3}H{sub 8}O), water (H{sub 2}O) and zinc acetate (Z{sub n}(CH{sub 3}CO{sub 2}){sub 2}) in acidified medium (pH 5). The obtained films were n doped with ytterbium (Yb) at the rates of 100, 200 and 300 ppm. The structural features of the doped films were investigated using XRD, atomic force microscopy and scanning electronic microscopy techniques. XRD analysis shows a strong (0 0 2) X-ray diffraction line for increasing Yb-doping amounts. This c-axis preferential orientation of ZnO crystallites is naturally required to use this oxide as transparent conductor in optoelectronic applications. Atomic force microscopy (AFM) analysis shows an enhancement in the surface roughness of the doped ZnO:Yb thin films. Optical measurements were performed in 300-1800 nm domain via transmittance T(lambda) and reflectance R(lambda) spectra. Conjoint optical and thermal properties were deduced from the optical measurements in reference to the Amlouk-Boubaker opto-thermal expansivity psi{sub AB}. Optically relevant ytterbium doping effects have been discussed. Finally, mechanical measurements have been carried out using Vickers standard disposal. The results confirmed the structural and functional changes that several recent studies attributed to ytterbium doping.

  17. High pulse energy femtosecond large-mode-area photonic crystal fiber laser

    SONG YouJian; HU MingLie; ZHANG Chi; CHAI Lu; WANG ChingYue

    2008-01-01

    A high pulse energy femtosecond fiber laser based on a large-mode-area photonic crystal fiber is demonstrated. A segment of Yb-doped single-polarization large-mode-area photonic crystal fiber with extremely low nonlinearity is explored as gain media of this fiber laser, resulting in intrinsically environmentally stability. The fiber laser is based on a linear cavity with dispersion compensation free configuration, and the stable mode-locking is obtained by a semiconductor saturable absorber mirror (SESAM). The fiber laser directly generates 2.5 W of average power at a repetition rate of 51.4 MHz,corresponding to a single pulse energy of 50 nJ. The output pulse duration is 4.2 ps, which is dechirped to 410 fs after extracavity dispersion compensation. The nonlinear absorption of SESAM determines the pulse shaping at low output power, while the mode-locking mechanism is under the balance between spectrum broadening from self-phase-modulation and gain filtering at the high output power.

  18. Laser induced deflection (LID) method for absolute absorption measurements of optical materials and thin films

    Mühlig, Christian; Bublitz, Simon; Paa, Wolfgang

    2011-05-01

    We use optimized concepts to measure directly low absorption in optical materials and thin films at various laser wavelengths by the laser induced deflection (LID) technique. An independent absolute calibration, using electrical heaters, is applied to obtain absolute absorption data without the actual knowledge of the photo-thermal material properties. Verification of the absolute calibration is obtained by measuring different silicon samples at 633 nm where all laser light, apart from the measured reflection/scattering, is absorbed. Various experimental results for bulk materials and thin films are presented including measurements of fused silica and CaF2 at 193 nm, nonlinear crystals (LBO) for frequency conversion and AR coated fused silica for high power material processing at 1030 nm and Yb-doped silica raw materials for high power fiber lasers at 1550 nm. In particular for LBO the need of an independent calibration is demonstrated since thermal lens generation is dominated by stress-induced refractive index change which is in contrast to most of the common optical materials. The measured results are proven by numerical simulations and their influence on the measurement strategy and the obtained accuracy are shown.

  19. Water-window soft x-ray high-harmonic generation up to the nitrogen K-edge driven by a kHz, 2.1 μm OPCPA source

    Stein, Gregory J.; Keathley, Phillip D.; Krogen, Peter; Liang, Houkun; Siqueira, Jonathas P.; Chang, Chun-Lin; Lai, Chien-Jen; Hong, Kyung-Han; Laurent, Guillaume M.; Kärtner, Franz X.

    2016-08-01

    We report the generation of coherent water-window soft x-ray harmonics in a neon-filled semi-infinite gas cell driven by a femtosecond multi-mJ mid-infrared optical parametric chirped-pulse amplification (OPCPA) system at a 1 kHz repetition rate. The cutoff energy was extended to ∼450 eV with a 2.1 μm driver wavelength and a photon flux of ∼ 1.5× {10}6 photons/s/1% bandwidth was obtained at 350 eV. A comparable photon flux of ∼ 1.0× {10}6 photons/s/1% bandwidth was observed at the nitrogen K-edge of 410 eV. This is the first demonstration of water-window harmonic generation up to the nitrogen K-edge from a kHz OPCPA system. Finally, this system is suitable for time-resolved soft x-ray near-edge absorption spectroscopy. Further scaling of the driving pulse's energy and repetition rate is feasible due to the availability of high-power picosecond Yb-doped pump laser technologies, thereby enabling ultrafast, tabletop water-window x-ray imaging.

  20. The ASE noise of a Yb3+-doped phosphate fiber single-frequency laser at 1083 nm

    A thorough investigation of the effect of amplified spontaneous emission (ASE) on the noise characteristics of a heavily Yb-doped phosphate fiber single-frequency laser at 1083 nm was made. Both the intensity noise and the frequency noise were measured and analyzed by introducing a band pass filter (BPF) into the fiber laser. For the intensity noise, it was found that the ASE noise is present at frequencies beyond the resonant relaxation oscillation (RRO) and until 6 MHz at low pump intensity, while it is diminished in the high power regime. Under a pump power of 42 mW, a maximum reduction of over 3 dB of the relative intensity noise (RIN) was observed with the help of the BPF. As for the frequency noise, a transition of the dominating noise sources from ASE noise in the low pump intensity condition to pump noise in the high pump intensity condition was observed. In the low power condition, more than 7 dB of the ASE noise was found to add to the frequency noise spectrum. It is believed that the obtained results will be helpful in understanding and optimizing the noise characteristics of this type of fiber laser. (letter)

  1. Growth, structural and spectroscopic properties of Yb{sup 3+}-doped Li{sub 0.75}Gd{sub 0.75}Ba{sub 0.5}(MoO{sub 4}){sub 2} crystals

    Garcia-Cortes, A. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, c/ Sor Juana Ines de la Cruz, 3, Cantoblanco, 28049 Madrid (Spain); Cascales, C. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, c/ Sor Juana Ines de la Cruz, 3, Cantoblanco, 28049 Madrid (Spain)], E-mail: ccascales@icmm.csic.es; Zaldo, C. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, c/ Sor Juana Ines de la Cruz, 3, Cantoblanco, 28049 Madrid (Spain)], E-mail: cezaldo@icmm.csic.es

    2008-01-15

    Yb-doped Li{sub 0.75}Gd{sub 0.75}Ba{sub 0.5}(MoO{sub 4}){sub 2} crystals were grown in air by the Top Seeded Solution Growth slow cooling method in a Li{sub 2}Mo{sub 2}O{sub 7} flux. The single crystal X-ray diffraction analysis indicates the symmetry of monoclinic space group C2/c (No. 15), with lattice parameters a = 5.2355(3) A, b = 12.7396(8) A, c = 19.1626(11) A, {beta} = 91.170(1) deg., V = 1277.84(13) A{sup 3}, and Z = 8, with one 8f site shared (0.725:0.06:0.215) by Gd{sup 3+}, Yb{sup 3+} and Li{sup +} ions, respectively. The optical absorption and photoluminescence properties are described consistently with the anisotropic character of the monoclinic phase. The relative energies of the Yb{sup 3+} Stark levels have been determined, and in order to make a preliminary evaluation of its laser properties, values of the 300 K absorption and emission cross-sections have been derived.

  2. Structure dependence of near-infrared stimulated blue emission in polycrystalline Ln2(WO4)3 (Ln=Gd and Lu) doped with Tm and Yb

    Tm- and Yb-doped gadolinium tungstate, (GdxTmyYb1-x-y)2(WO4)3 (x=0.7-0.9; y=0.001-0.01), have been prepared by the polymerized complex method to achieve a homogeneous dispersion of dopants and to stabilize the host structure. Decomposition (900 deg. C 5 h) of the precursors with x=0.8-0.9 yielded a pure monoclinic phase, while that of x=0.7 resulted in formation of an orthorhombic impurity. The monoclinic phase exhibits bright up-converted blue emission due to the 1G4→3H6 transition of Tm3+ (472 nm) upon excitation into the Yb3+:2F7/2→2F5/2 absorption band as a result of energy transfer from Yb to Tm. The orthorhombic impurity acts as a strong quencher of emission, and the quenching mechanism has been discussed on the basis of structural and spectroscopic properties of orthorhombic Lu2(WO4)3:Tm,Yb prepared by the same method.

  3. High efficiency fourth-harmonic generation from nanosecond fiber master oscillator power amplifier

    Mu, Xiaodong; Steinvurzel, Paul; Rose, Todd S.; Lotshaw, William T.; Beck, Steven M.; Clemmons, James H.

    2016-03-01

    We demonstrate high power, deep ultraviolet (DUV) conversion to 266 nm through frequency quadrupling of a nanosecond pulse width 1064 nm fiber master oscillator power amplifier (MOPA). The MOPA system uses an Yb-doped double-clad polarization-maintaining large mode area tapered fiber as the final gain stage to generate 0.5-mJ, 10 W, 1.7- ns single mode pulses at a repetition rate of 20 kHz with measured spectral bandwidth of 10.6 GHz (40 pm), and beam qualities of Mx 2=1.07 and My 2=1.03, respectively. Using LBO and BBO crystals for the second-harmonic generation (SHG) and fourth-harmonic generation (FHG), we have achieved 375 μJ (7.5 W) and 92.5 μJ (1.85 W) at wavelengths of 532 nm and 266 nm, respectively. To the best of our knowledge these are the highest narrowband infrared, green and UV pulse energies obtained to date from a fully spliced fiber amplifier. We also demonstrate high efficiency SHG and FHG with walk-off compensated (WOC) crystal pairs and tightly focused pump beam. An SHG efficiency of 75%, FHG efficiency of 47%, and an overall efficiency of 35% from 1064 nm to 266 nm are obtained.

  4. Multi-mJ, kHz picosecond deep UV source based on a frequency-quadrupled cryogenic Yb:YAG laser

    Hong, Kyung-Han; Chang, Chun-Lin; Krogen, Peter; Liang, Houkun; Stein, Gregory J.; Moses, Jeffrey; Lai, Chien-Jen; Kärtner, Franz X.

    2015-05-01

    We report on the development of a 2.74-mJ, ~4.2 ps, ~258 nm deep-ultraviolet (DUV) source at 1 kHz based on frequency quadrupling of ~32 mJ, 8.4 ps, ~1030 nm near-infrared (NIR) laser pulses with an excellent beam profile, generated from a diode-pumped, ultrafast hybrid Yb-doped chirped-pulse amplification laser system. We have used a two-stage second harmonic generation scheme at LBO (NIR-to-green) and BBO crystals (green-to-DUV), respectively, to achieve the fourth-harmonic generation (FHG). The NIR-to-DUV conversion efficiency of ~10% in the FHG is obtained. The peak power of the produced DUV laser pulses is as high as 0.56 GW. The beam profiles at near-field and far-field are found to be excellent and the M2 value is measured as ~2.6. We also present the systematic parameter study on the optimization of DUV generation. To our best knowledge, this is the most energetic DUV generation from a diodepumped solid-state laser at kHz repetition rates.

  5. Bidirectional pumped high power Raman fiber laser.

    Xiao, Q; Yan, P; Li, D; Sun, J; Wang, X; Huang, Y; Gong, M

    2016-03-21

    This paper presents a 3.89 kW 1123 nm Raman all-fiber laser with an overall optical-to-optical efficiency of 70.9%. The system consists of a single-wavelength (1070nm) seed and one-stage bidirectional 976 nm non-wavelength-stabilized laser diodes (LDs) pumped Yb-doped fiber amplifier. The unique part of this system is the application of non-wavelength-stabilized LDs in high power bidirectional pumping configuration fiber amplifier via refractive index valley fiber combiners. This approach not only increases the pump power, but also shortens the length of fiber by avoiding the usage of multi-stage amplifier. Through both theoretical research and experiment, the bidirectional pumping configuration presented in this paper proves to be able to convert 976 nm pump laser to 1070 nm laser via Yb3+ transfer, which is then converted into 1123 nm Raman laser via the first-order Raman effect without the appearance of any higher-order Raman laser. PMID:27136862

  6. Mode-locked ytterbium fiber lasers using a large modulation depth carbon nanotube saturable absorber without an additional spectral filter

    We demonstrate an all-normal-dispersion ytterbium (Yb)-doped fiber laser mode-locked by a higher modulation depth carbon nanotube saturable absorber (CNT-SA) based on an evanescent field interaction scheme. The laser cavity consists of pure normal dispersion fibers without dispersion compensation and an additional spectral filter. It is exhibited that the higher modulation depth CNT-SA could contribute to stabilize the mode-locking operation within a limited range of pump power and generate the highly chirped pulses with a high-energy level in the cavity with large normal dispersion and strong nonlinearity. Stable mode-locked pulses with a maximal energy of 29 nJ with a 5.59 MHz repetition rate at the operating wavelength around 1085 nm have been obtained. The maximal time-bandwidth product is 262.4. The temporal and spectral characteristics of pulses versus pump power are demonstrated. The experimental results suggest that the CNT-SA provides a sufficient nonlinear loss to compensate high nonlinearity and catch up the gain at a different pump power and thus leads to the stable mode locking. (letter)

  7. Ultra-compact Watt-level flat supercontinuum source pumped by noise-like pulse from an all-fiber oscillator.

    Chen, He; Zhou, Xuanfeng; Chen, Sheng-Ping; Jiang, Zong-Fu; Hou, Jing

    2015-12-28

    We demonstrate Watt-level flat visible supercontinuum (SC) generation in photonic crystal fibers, which is directly pumped by broadband noise-like pulses from an Yb-doped all-fiber oscillator. The novel SC generator is featured with elegant all-fiber-integrated architecture, high spectral flatness and high efficiency. Wide optical spectrum spanning from 500 nm to 2300 nm with 1.02 W optical power is obtained under the pump of 1.4 W noise-like pulse. The flatness of the spectrum in the range of 700 nm~1600 nm is less than 5 dB (including the pump residue). The exceptional simplicity, economical efficiency and the comparable performances make the noise-like pulse oscillator a competitive candidate to the widely used cascade amplified coherent pulse as the pump source of broadband SC. To the best of our knowledge, this is the first demonstration of SC generation which is directly pumped by an all-fiber noise-like pulse oscillator. PMID:26831958

  8. High-Nonlinearity Dispersion-Shifted Lead-Silicate Holey Fibers for Efficient 1-µm Pumped Supercontinuum Generation

    Leong, J. Y. Y.; Petropoulos, P.; Price, J. H. V.; Ebendorff-Heidepriem, Heike; Asimakis, S.; Moore, R. C.; Frampton, K. E.; Finazzi, V.; Feng, X.; Monro, T. M.; Richardson, D. J.

    2006-01-01

    This paper reports on the recent progress in the design and fabrication of high-nonlinearity lead-silicate holey fibers (HFs). First, the fabrication of a fiber designed to offer close to the maximum possible nonlinearity per unit length in this glass type is described. A value of gamma = 1860 W-1 · km-1 at a wavelength of 1.55 µm is achieved, which is believed to be a record for any fiber at this wavelength. Second, the design and fabrication of a fiber with a slightly reduced nonlinearity but with dispersion-shifted characteristics tailored to enhance broadband supercontinuum (SC) generation when pumped at a wavelength of 1.06 µm-a wavelength readily generated using Yb-doped fiber lasers-are described. SC generation spanning more than 1000 nm is observed for modest pulse energies of sim 100 pJ using a short length of this fiber. Finally, the results of numerical simulations of the SC process in the proposed fibers are presented, which are in good agreement with the experimental observations and highlight the importance of accurate control of the zero-dispersion wavelength (ZDW) when optimizing such fibers for SC performance.

  9. Effects of ytterbium on electrical and optical properties of BCP/Ag/WO3 transparent electrode based organic photovoltaic cells

    Oh, Il Soo; Ji, Chan Hyuk; Oh, Se Young

    2016-01-01

    This study introduces dielectric/metal/dielectric multilayers based on a WO3/Ag/WO3 (WAW) anode and Yb/BCP/Ag/WO3 (Yb/BAW) cathode for use in organic photovoltaic cells (OPVs). Here, the Yb/BCP hybrid multilayer provides an effective electron transport layer (ETL), while the Yb doping ensures that voltage loss due to interfacial band bending is effectively suppressed. Transparent OPVs produced with a structure of WAW/P3HT:PCBM/Yb/BAW are shown to exhibit a power conversion efficiency (PCE) of up to 2.42%, achieving a 65.4% fill factor (FF) under one sun irradiation. These results indicate that the use of Yb in transparent OPVs is vastly superior to other ETLs, as it improves the majority of critical parameters such as short circuit current (Jsc), fill factor (FF) and PCE. This is attributed to a decrease in the series resistance and increase in the shunt resistance, while an increase in electron mobility also helps to ensure faster sweep out. [Figure not available: see fulltext.

  10. A frequency-locked and frequency-doubled, hybrid Q-switched Yb:KYW laser at 515 nm with a widely adjustable repetition rate

    Tjörnhammar, S.; Zukauskas, A.; Canalias, C.; Pasiskevicius, V.; Laurell, F.

    2015-09-01

    We demonstrate a compact wavelength-stabilized, frequency-doubled Yb-doped double-tungstate laser with widely tunable repetition rate, spanning from 35 Hz to 3 kHz obtained by hybrid Q-switching. The Q-switching unit consisted of a combination of a passive Cr:YAG crystal and an opto-mechanical active intensity modulator. The fundamental wavelength was locked at 1029 nm with a volume Bragg grating, and the pulse length and energy were 42 ns and 250 µJ, respectively. As the laser was stabilized with the VBG and the opto-mechanical modulator, the frequency instability was reduced six times from free running down to 0.29 %. Frequency doubling was done extra-cavity in PPKTP, and a repetition rate-independent conversion efficiency of 63 % was obtained. The controllable repetition rate together with stable temporal and spatial characteristics makes this laser a suitable candidate in many biology-related experiments, as a pump source for in vivo excitation of fluorophores, e.g., pumping of "living lasers" and matrix-assisted laser desorption/ionization mass spectroscopy.

  11. High repetition rate femtosecond laser forming sub-10 µm diameter interconnection vias

    Tan, B; Panchatsharam, S; Venkatakrishnan, K

    2009-03-01

    Laser ablative microvia formation has been widely accepted as an effective manufacturing method for interconnect via formation. Current conventional nanosecond laser microvia formation has reached its limit in terms of minimum via diameter and machining quality. Femtosecond laser has been investigated intensively for its superior machining quality and capability of producing much smaller features. However, the traditional femtosecond laser has very low power and is thus unable to meet the throughput requirement. In this paper we report ablative microvia formation using femtosecond lasers at megahertz repetition rates. Laser ablation was demonstrated for the first time for sub-10 µm interconnection via drilling at a throughput of 10 000 vias per second. A systematic study of the influence of a high repetition rate in femtosecond laser micromachining of silicon was carried out. The experiments were performed using an Yb-doped fibre amplified/oscillator laser with 1030 nm wavelength in an air environment. The effects of a high repetition rate on microvia formation were observed at ~300 fs for silicon substrates. Laser parameters along with threshold energy, via diameter, ablation depth, ablation rate and via quality were studied in detail to accentuate the need of femtosecond lasers for forming sub-10 µm diameter microvias. The experimental results show that femtosecond laser pulses with high repetition rates show unequivocally the advantages of short-pulse laser ablation for high-precision applications in micrometre-scale dimensions.

  12. High repetition rate femtosecond laser forming sub-10 μm diameter interconnection vias

    Laser ablative microvia formation has been widely accepted as an effective manufacturing method for interconnect via formation. Current conventional nanosecond laser microvia formation has reached its limit in terms of minimum via diameter and machining quality. Femtosecond laser has been investigated intensively for its superior machining quality and capability of producing much smaller features. However, the traditional femtosecond laser has very low power and is thus unable to meet the throughput requirement. In this paper we report ablative microvia formation using femtosecond lasers at megahertz repetition rates. Laser ablation was demonstrated for the first time for sub-10 μm interconnection via drilling at a throughput of 10 000 vias per second. A systematic study of the influence of a high repetition rate in femtosecond laser micromachining of silicon was carried out. The experiments were performed using an Yb-doped fibre amplified/oscillator laser with 1030 nm wavelength in an air environment. The effects of a high repetition rate on microvia formation were observed at ∼300 fs for silicon substrates. Laser parameters along with threshold energy, via diameter, ablation depth, ablation rate and via quality were studied in detail to accentuate the need of femtosecond lasers for forming sub-10 μm diameter microvias. The experimental results show that femtosecond laser pulses with high repetition rates show unequivocally the advantages of short-pulse laser ablation for high-precision applications in micrometre-scale dimensions.

  13. SBS mitigation with 'two-tone' amplification: a theoretical model

    Bronder, T. J.; Shay, T. M.; Dajani, I.; Gavrielides, A.; Robin, C. A.; Lu, C. A.

    2008-02-01

    A new technique for mitigating stimulated Brillouin scattering (SBS) effects in narrow-linewidth Yb-doped fiber amplifiers is demonstrated with a model that reduces to solving an 8×8 system of coupled nonlinear equations with the gain, SBS, and four-wave mixing (FMW) incorporated into the model. This technique uses two seed signals, or 'two-tones', with each tone reaching its SBS threshold almost independently and thus increasing the overall threshold for SBS in the fiber amplifier. The wavelength separation of these signals is also selected to avoid FWM, which in this case possesses the next lowest nonlinear effects threshold. This model predicts an output power increase of 86% (at SBS threshold with no signs of FWM) for a 'two-tone' amplifier with seed signals at 1064nm and 1068nm, compared to a conventional fiber amplifier with a single 1064nm seed. The model is also used to simulate an SBS-suppressing fiber amplifier to test the regime where FWM is the limiting factor. In this case, an optimum wavelength separation of 3nm to 10nm prevents FWM from reaching threshold. The optimum ratio of the input power for the two seed signals in 'two-tone' amplification is also tested. Future experimental verification of this 'two-tone' technique is discussed.

  14. Kinetic parameters of γ-irradiated Y2O3 phosphors: Effect of doping/codoping and heating rate

    This paper reports the thermoluminescence characteristics of Yb doped and Yb/RE3+ (RE=Eu, Tb) codoped Y2O3 phosphors under γ-irradiations. The phosphors were prepared by combustion synthesis method and characterized by X-ray diffraction (XRD) and Thermoluminescence (TL) techniques. XRD studies confirm the body-centered cubic structure of the phosphors. TL glow curves of doped and codoped phosphors exhibit single broad peak. Codoping with rare earth ions influences the glow peak temperature and intensity drastically. Intensity of the glow peak increases linearly in the studied γ-dose range. Kinetic parameters such as order of kinetics, trap depth and frequency factor associated with the glow peak were calculated by various glow curve methods. - Highlights: • In this paper, the effects of doping/codoping and heating rates are reported. • Codoping with Eu3+ ions is more effective compared to Tb3+ ions for TL sensitivity. • Modification/rearrangement of trap levels after codoping were observed. • Increase in trap depth/frequency factor after codoping was observed

  15. SESAM-modelocked Yb:CaF2 thin-disk-laser generating 285 fs pulses with 1.78 μJ of pulse energy

    Dannecker, Benjamin; Abdou Ahmed, Marwan; Graf, Thomas

    2016-05-01

    We report on a SESAM-modelocked Yb:CaF2 thin-disk oscillator designed to generate more than 1 μJ of pulse energy at a moderate pulse repetition rate. The goal of our experiment was to explore the potential of Yb:CaF2 in a thin-disk laser (TDL) architecture for high power at pulse durations shorter than 300 fs as compared to other Yb-doped crystals exhibiting broad gain bandwidth. At a repetition rate of 10 MHz the laser produced an average output power of up to 17.8 W (1.78 μJ of pulse energy) with a beam quality factor M 2 below 1.2. The pulse duration was measured to be 285 fs, which results in a peak power of 5.5 MW. To the best of our knowledge, this is the highest pulse energy and peak power demonstrated to date with sub-300 fs pulses generated by SESAM-modelocked oscillators, leading to the conclusion that Yb:CaF2 is a very promising crystal for TDL technology.

  16. Fermi-surface topology of the Ce1-xYbxCoIn5

    The heavy-fermion (HF) metals are very susceptible to chemical substitution. In these compounds the Kondo coupling between a lattice of local moments and the conduction band creates quasiparticle excitations with large effective masses and the dopants disrupt the coherent Kondo coupling. We study the effect of Yb doping on the Pauli-limited, HF superconductor, CeCoIn5 via de Haas-van Alphen (dHvA) measurements. Yb acts as a non-magnetic divalent substitution for Ce, equivalent to hole doping on the rare-earth site. Our main goal consists in the systematic investigation of the dHvA oscillations on Ce1-xYbxCoIn5 in order to elucidate the evolution of the Fermi surface as a function of Yb. The dHvA data were obtained on high-quality single crystals with different concentrations of Yb atoms. The experiment was performed in a top-loading dilution refrigerator by use of a capacitive torque cantilever technique at temperatures down to 20 mK in magnetic fields up to 18 T.

  17. Kilowatt high-efficiency narrow-linewidth monolithic fiber amplifier operating at 1034 nm

    Naderi, Nader A.; Flores, Angel; Anderson, Brian M.; Rowland, Ken; Dajani, Iyad

    2016-03-01

    Power scaling investigation of a narrow-linewidth, Ytterbium-doped all-fiber amplifier operating at 1034 nm is presented. Nonlinear stimulated Brillouin scattering (SBS) effects were suppressed through the utilization of an external phase modulation technique. Here, the power amplifier was seeded with a spectrally broadened master oscillator and the results were compared using both pseudo-random bit sequence (PRBS) and white noise source (WNS) phase modulation formats. By utilizing an optical band pass filter as well as optimizing the length of fiber used in the pre-amplifier stages, we were able to appreciably suppress unwanted amplified spontaneous emission (ASE). Notably, through PRBS phase modulation, greater than two-fold enhancement in threshold power was achieved when compared to the WNS modulated case. Consequently, by further optimizing both the power amplifier length and PRBS pattern at a clock rate of 3.5 GHz, we demonstrated 1 kilowatt of power with a slope efficiency of 81% and an overall ASE content of less than 1%. Beam quality measurements at 1 kilowatt provided near diffraction-limited operation (M2 knowledge, the power scaling results achieved in this work represent the highest power reported for a spectrally narrow all-fiber amplifier operating at < 1040 nm in Yb-doped silica-based fiber.

  18. Effect of rare earth substitution in cobalt ferrite bulk materials

    Bulai, G.; Diamandescu, L.; Dumitru, I.; Gurlui, S.; Feder, M.; Caltun, O. F.

    2015-09-01

    The study was focused on the influence of small amounts of rare earth (RE=La, Ce, Sm, Gd, Dy, Ho, Er, Yb) addition on the microstructure, phase content and magnetic properties of cobalt ferrite bulk materials. The X-Ray diffraction measurements confirmed the formation of the spinel structure but also the presence of secondary phases of RE oxides or orthoferrite in small percentages (up to 3%). Density measurements obtained by Archimedes method revealed a ~1 g cm-3 decrease for the RE doped cobalt ferrite samples compared with stoichiometric one. Both the Mössbauer and Fourier Transform Infrared Spectrocopy analysis results confirmed the formation of the spinel phase. The saturation magnetization and coercive field values of the doped samples obtained by Vibrating Sample Magnetometry were close to those of the pure cobalt ferrite. For magnetostrictive property studies the samples were analyzed using the strain gauge method. Higher maximum magnetostriction coefficients were found for the Ho, Ce, Sm and Yb doped cobalt ferrite bulk materials as related to the stoichiometric CoFe2O4 sample. Moreover, improved strain derivative was observed for these samples but at higher magnetic fields due to the low increase of the coercive field values for doped samples.

  19. Effect of rare earth substitution in cobalt ferrite bulk materials

    The study was focused on the influence of small amounts of rare earth (RE=La, Ce, Sm, Gd, Dy, Ho, Er, Yb) addition on the microstructure, phase content and magnetic properties of cobalt ferrite bulk materials. The X-Ray diffraction measurements confirmed the formation of the spinel structure but also the presence of secondary phases of RE oxides or orthoferrite in small percentages (up to 3%). Density measurements obtained by Archimedes method revealed a ~1 g cm−3 decrease for the RE doped cobalt ferrite samples compared with stoichiometric one. Both the Mössbauer and Fourier Transform Infrared Spectrocopy analysis results confirmed the formation of the spinel phase. The saturation magnetization and coercive field values of the doped samples obtained by Vibrating Sample Magnetometry were close to those of the pure cobalt ferrite. For magnetostrictive property studies the samples were analyzed using the strain gauge method. Higher maximum magnetostriction coefficients were found for the Ho, Ce, Sm and Yb doped cobalt ferrite bulk materials as related to the stoichiometric CoFe2O4 sample. Moreover, improved strain derivative was observed for these samples but at higher magnetic fields due to the low increase of the coercive field values for doped samples. - Highlights: • Substitution by a large number of rare earth elements was investigated. • First reported results on magnetostriction measurements of RE doped cobalt ferrite. • The doped samples presented an increased porosity and a decreased grain size. • Increased magnetostrctive response was observed for several doped samples

  20. Fiber-comb-stabilized light source at 556 nm for magneto-optical trapping of ytterbium

    Yasuda, Masami; Inaba, Hajime; Nakajima, Yoshiaki; Hosaka, Kazumoto; Onae, Atsushi; Hong, Feng-Lei

    2010-01-01

    A frequency-stabilized light source emitting at 556 nm is realized by frequency-doubling a 1112-nm laser, which is phase-locked to a fiber-based optical frequency comb. The 1112-nm laser is either an ytterbium (Yb)-doped distributed feedback fiber laser or a master-slave laser system that uses an external cavity diode laser as a master laser. We have achieved the continuous frequency stabilization of the light source over a five-day period. With the light source, we have completed the second-stage magneto-optical trapping (MOT) of Yb atoms using the 1S0 - 3P1 intercombination transition. The temperature of the ultracold atoms in the MOT was 40 uK when measured using the time-of-flight method, and this is sufficient for loading the atoms into an optical lattice. The fiber-based frequency comb is shown to be a useful tool for controlling the laser frequency in cold-atom experiments.

  1. Glass-on-Glass Fabrication of Bottle-Shaped Tunable Microlasers and their Applications.

    Ward, Jonathan M; Yang, Yong; Nic Chormaic, Síle

    2016-01-01

    We describe a novel method for making microbottle-shaped lasers by using a CO2 laser to melt Er:Yb glass onto silica microcapillaries or fibres. This is realised by the fact that the two glasses have different melting points. The CO2 laser power is controlled to flow the doped glass around the silica cylinder. In the case of a capillary, the resulting geometry is a hollow, microbottle-shaped resonator. This is a simple method for fabricating a number of glass whispering gallery mode (WGM) lasers with a wide range of sizes on a single, micron-scale structure. The Er:Yb doped glass outer layer is pumped at 980 nm via a tapered optical fibre and WGM lasing is recorded around 1535 nm. This structure facilitates a new way to thermo-optically tune the microlaser modes by passing gas through the capillary. The cooling effect of the gas flow shifts the WGMs towards shorter wavelengths and thermal tuning of the lasing modes over 70 GHz is achieved. Results are fitted using the theory of hot wire anemometry, allowing the flow rate to be calibrated with a flow sensitivity as high as 72 GHz/sccm. Strain tuning of the microlaser modes by up to 60 GHz is also demonstrated. PMID:27121151

  2. High quantum efficiency YbAG-crystals

    Fagundes-Peters, D. [Universitaet Hamburg, Institut fuer Laser-Physik, Luruper Chaussee 149, 22761, Hamburg (Germany); Martynyuk, N. [Universitaet Hamburg, Institut fuer Laser-Physik, Luruper Chaussee 149, 22761, Hamburg (Germany); Luenstedt, K. [Universitaet Hamburg, Institut fuer Laser-Physik, Luruper Chaussee 149, 22761, Hamburg (Germany); Peters, V. [Universitaet Hamburg, Institut fuer Laser-Physik, Luruper Chaussee 149, 22761, Hamburg (Germany); Petermann, K. [Universitaet Hamburg, Institut fuer Laser-Physik, Luruper Chaussee 149, 22761, Hamburg (Germany)]. E-mail: klaus.petermann@physnet.uni-hamburg.de; Huber, G. [Universitaet Hamburg, Institut fuer Laser-Physik, Luruper Chaussee 149, 22761, Hamburg (Germany); Basun, S. [Joffe Physical-Technical Institute, St. Petersburg (Russian Federation); Laguta, V. [Institute for Problems of Material Sciences, Ukrainian Academy of Sciences, Krjijanovskogo 3, 03142 Kiev (Ukraine); Hofstaetter, A. [I. Physikalisches Institut, Heinrich-Buff-Ring 16, Justus-Liebig-Universitaet Giessen, D-35392 Giessen (Germany)

    2007-07-15

    In this work, the growing process of Yb-doped YAG crystals is modified to achieve stoichiometric YbAG samples with a minimum quenching of the Yb{sup 3+}-fluorescence. The best samples were grown by the Czochralski technique from rhenium-crucibles under reducing atmosphere (H{sub 2}+N{sub 2}). The as-grown YbAG crystals are of light blue color due to Yb{sup 2+}-centers. The fluorescence lifetime of Yb{sup 3+} after annealing the YbAG crystals under oxidizing atmosphere is 862+/-15{mu}s. The non-annealed samples show strong quenching of the Yb{sup 3+}-fluorescence with a lifetime of only a few tens of microseconds depending on the actual growth conditions. This strong quenching is partially attributed to the Yb{sup 2+}-centers giving rise to a cooperative energy transfer process among two excited Yb{sup 3+}-ions and one non-excited Yb{sup 2+}-ion. Typical quenching centers in Yb:YAG crystals grown from Ir-crucibles are Fe- and Ni-impurities. Another effective quenching center in non-annealed crystals is a complex center consisting of a Si{sup 2+}-ion and a charge compensating oxygen vacancy with one trapped electron (F{sup +}color center). This type of center was identified by ESR- and ENDOR-measurements.

  3. Ion diffusion at the bonding interface of undoped YAG/Yb:YAG composite ceramics

    Fujioka, Kana; Sugiyama, Akira; Fujimoto, Yasushi; Kawanaka, Junji; Miyanaga, Noriaki

    2015-08-01

    Cation diffusion across a boundary between ytterbium (Yb)-doped and undoped yttrium aluminum garnet (YAG) ceramics was examined by electron microprobe analysis (EPMA). Polished Yb:YAG and undoped YAG ceramics were bonded by surface treatment with argon fast atom beam, and then heat-treated at 1400 or 1600 °C for 50 h or at 1400 °C for 10 h under vacuum. We obtained EPMA mapping images of the bonded samples that clearly showed the bulk and grain-boundary diffusion of Y and Yb ions. The number density profiles showed that the total diffusion distances of Yb and Y ions were almost equal and approximately 2 and 15 μm at 1400 and 1600 °C, respectively, and the dependence of diffusion distance on heating time was weak. The diffusion curves were well modeled by Harrison type B kinetics including bulk and grain-boundary diffusion. In addition, it was found that Si ions added to the samples as a sintering aid might be segregated at the grain boundary by heat treatment, and diffused only along grain boundaries.

  4. Power scaling analysis of fiber lasers and amplifiers based on non-silica materials

    Dawson, J W; Messerly, M J; Heebner, J E; Pax, P H; Sridharan, A K; Bullington, A L; Beach, R J; Siders, C W; Barty, C P; Dubinskii, M

    2010-03-30

    A developed formalism for analyzing the power scaling of diffraction limited fiber lasers and amplifiers is applied to a wider range of materials. Limits considered include thermal rupture, thermal lensing, melting of the core, stimulated Raman scattering, stimulated Brillouin scattering, optical damage, bend induced limits on core diameter and limits to coupling of pump diode light into the fiber. For conventional fiber lasers based upon silica, the single aperture, diffraction limited power limit was found to be 36.6kW. This is a hard upper limit that results from an interaction of the stimulated Raman scattering with thermal lensing. This result is dependent only upon physical constants of the material and is independent of the core diameter or fiber length. Other materials will have different results both in terms of ultimate power out and which of the many limits is the determining factor in the results. Materials considered include silica doped with Tm and Er, YAG and YAG based ceramics and Yb doped phosphate glass. Pros and cons of the various materials and their current state of development will be assessed. In particular the impact of excess background loss on laser efficiency is discussed.

  5. Influence of ytterbium concentration on the emissive properties of Yb:YAG and Yb:Y2O3

    The Paul Scherrer Institut has initiated a project to develop a thermophotovoltaic (TPV) converter for residential heating applications. By economic reasons we have decided to design a thermophotovoltaic generator based on Si-cells and, accordingly, to make use of the selective emission properties of ytterbium containing emitter materials. In this contribution, we focus on the emitter materials and present results of an experimental study on the influence of ytterbium concentration on the emissive properties of ytterbium doped yttrium aluminum garnet (YAG) and yttria. The emitter materials were prepared by decomposition of nitrates and by co-precipitation methods with subsequent calcination at elevated temperatures. The polycrystalline materials are characterized by X-Ray diffraction (XRD), particle size distribution (PSD) measurements and Raman and fluorescence microscopy. The emissive properties of the Yb-doped materials have been measured at about 1400 K. Additionally, current-voltage (I endash V) curves of the Si-cells used in a prototype TPV generator have been recorded for selected emitter materials. copyright 1997 American Institute of Physics

  6. Multi-kW high brightness Yb:YAG thin disk laser

    Peng, Y. H.; Lim, Y. X.; Cheng, James; Tan, Y. B.; Lau, Ernest; Lai, K. S.

    2013-03-01

    Simple stable laser resonators with a single Yb:YAG thin disk module have been designed and demonstrated to produce up to 5 kW CW laser output at 1030 nm with M2 factor of 7. Pumped with 940 nm diodes, the optical-to-optical efficiencies were >50 % at full power. Simple I and V-shaped resonators consisting of only two and three optical elements were implemented, including the 16 mm diameter Yb doped thin disk acting as an active mirror. No additional adaptive optics for aberration or mode control was used; instead the results were achieved with laser cavity designs that take into account the changing radius of curvature of the pumped thin disk. The designs ensured the laser always operated well within the stable cavity zone and with an optimised and relatively large fundamental laser mode size on the thin disk. The low optical aberrations and effective thermal management of the thin disk, mounted on a diamond cooled heat sink, together with the above cavity design approach, enabled the realization of such high power and good beam quality thin disk laser in a simple single disk laser oscillator.

  7. Evaluation of inclusion level of wheat distillers dried grains with solubles with and without protease or β-mannanase on performance and water intake of turkey hens.

    Opoku, E Y; Classen, H L; Scott, T A

    2015-07-01

    It is becoming a common practice to use higher levels of wheat distillers dried grains with solubles (wDDGS) in poultry diets. The objective of this study was to determine the effects of level of inclusion of wDDGS with or without enzyme (E-, i.e., wDDGSE-) supplementation on performance and water consumption of turkey hens (0 to 72 d). Two diets (0 or 30% wDDGS) were formulated to meet the nutrient requirements of Hybrid Converter turkeys. Diets (0 or 30% wDDGS; starter, grower, and finisher) were then blended to obtain a different level of inclusion (15%) of wDDGS. The 30% wDDGS diet was divided into 3 fractions and 2 fractions supplemented with either protease (P+, i.e., wDDGSP+; 0.126 g/kg) or β-mannanase (M+, i.e., wDDGSM+; 0.05 g/kg). All 5 diets were fed ad libitum as mash. The 700 0-d turkey hens were randomly allocated into groups of 35 birds per replicate with 4 replicate floor pens per treatment, in a completely randomized design. Water consumption per pen was recorded beginning at 7 d. There was no effect of dietary treatment on feed intake. BW of turkey hens (52 d; grower) was significantly higher for 30% wDDGSP+ as compared to 0% wDDGSE- or 15% wDDGSE- diets; but was not different from 30% wDDGSE- or 30% wDDGSM+ diets. FCR (P < 0.01; 28 to 52 d), and total FCR (P < 0.05; 0 to 72 d) was significantly improved for birds fed 15 or 30% wDDGS regardless of enzyme treatment compared to 0% wDDGSE-. Water intake (WI, in mL per bird per day) tended to be higher (P = 0.08) between 7 and 28 d for 30% wDDGSP+ diets compared to other treatments. Similarly, WI of birds fed 30% wDDGSP+ was higher (P < 0.05; 28 to 52 and 52 to 72 d) and total WI (P = 0.07; 7 to 72 d) tended to be higher than other treatments. This study is the first to report the impact of wDDGS on WI. As high as 30% wDDGS can be substituted in turkey hen diets. No effect of P+ or M+ at the inclusion level tested was found on performance. PMID:25971948

  8. 11-W CW 100-μm fiber-coupled 971-nm Al-free active region pump source

    Larat, Christian; Auzanneau, Sophie-Charlotte; Calligaro, Michel; Parillaud, Olivier; Krakowski, Michel; Boulant, Benoit; Laugustin, Arnaud; Fillardet, Thierry

    2004-05-01

    Laser diodes at 980 nm have important applications in medicine (surgery, dentistry) and Telecoms for WDM, high bit rate networks (Er or Er/Yb doped fibre amplifiers). These applications need a high coupling efficiency of the source into a fibre. High brightness mini-bars with an emissive length of 2.7 mm have been recently developed. These devices consist of an array of aluminium free active region index guided tapered laser diodes with standard AR/HR coatings. We have improved the performances as a result of a new epitaxial layer and a new mini-bar design. We measure an optical output power of 25W at 40A under CW operation at 15°C. At 25°C and 33A, we obtain 20W CW and the far field along the slow axis has a Gaussian shape, with a low FWHM value of 3.5°. Along the fast axis, the far-field also has a Gaussian shape and a FWHM of 31,5°. To couple this tapered diode laser mini-bar into a 100μm diameter fibre (0.26 numerical aperture), we use a patented collective beam shaping technique for optical coupling. We obtain a coupled power of 11.2W under CW operation at 971 nm, 21°C with an emitted power from the mini-bar of 21.7W, resulting in a coupling efficiency of 52%. The conductively cooled mini-bar, all the optics and the optical fibre connector are assembled into a 82x62x23mm package. To our knowledge this is the highest reported power coupled into 100μm optical fibre from a single laser diode chip using a collective coupling scheme without any array of micro-optics.

  9. Compact fixed wavelength femtosecond oscillators as an add-on for tunable Ti:sapphire lasers extend the range of applications towards multimodal imaging and optogenetics

    Hakulinen, T.; Klein, J.

    2016-03-01

    Two-photon (2P) microscopy based on tunable Ti:sapphire lasers has become a widespread tool for 3D imaging with sub-cellular resolution in living tissues. In recent years multi-photon microscopy with simpler fixed-wavelength femtosecond oscillators using Yb-doped tungstenates as gain material has raised increasing interest in life-sciences, because these lasers offer one order of magnitude more average power than Ti:sapphire lasers in the wavelength range around 1040 nm: Two-photon (2P) excitation of mainly red or yellow fluorescent dyes and proteins (e.g. YFP, mFruit series) simultaneously has been proven with a single IR laser wavelength. A new approach is to extend the usability of existing tunable Titanium sapphire lasers by adding a fixed IR wavelength with an Yb femtosecond oscillator. By that means a multitude of applications for multimodal imaging and optogenetics can be supported. Furthermore fs Yb-lasers are available with a repetition rate of typically 10 MHz and an average power of typically 5 W resulting in pulse energy of typically 500 nJ, which is comparably high for fs-oscillators. This makes them an ideal tool for two-photon spinning disk laser scanning microscopy and holographic patterning for simultaneous photoactivation of large cell populations. With this work we demonstrate that economical, small-footprint Yb fixed-wavelength lasers can present an interesting add-on to tunable lasers that are commonly used in multiphoton microscopy. The Yb fs-lasers hereby offer higher power for imaging of red fluorescent dyes and proteins, are ideally enhancing existing Ti:sapphire lasers with more power in the IR, and are supporting pulse energy and power hungry applications such as spinning disk microscopy and holographic patterning.

  10. Lattice mismatch and crystal growth of monoclinic KY{sub 1-x}Yb{sub x}(WO{sub 4}){sub 2}/KY (WO{sub 4}){sub 2} layers by liquid phase epitaxy

    Silvestre, O; Aznar, A; Sole, R; Pujol, M C; Diaz, F; Aguilo, M [Fisica i Cristallografia de Materials (FiCMA), Universitat Rovira i Virgili (URV), Campus Sescelades c/Marcel-Ii Domingo, s/n, E-43007-Tarragona (Spain)], E-mail: magdalena.aguilo@urv.cat

    2008-06-04

    Monoclinic layers of KY{sub 1-x}Yb{sub x}(WO{sub 4}){sub 2} with a thickness of up to 330 {mu}m were grown on KY (WO{sub 4}){sub 2} substrates by liquid phase epitaxy (LPE) using K{sub 2}W{sub 2}O{sub 7} solvent. The layers grown from solutions of up to 7.5 at.% substitution of Y by Yb generally had flat surfaces on {l_brace}010{r_brace} and {l_brace}110{r_brace} crystal faces with no macroscopic defects at the layer/substrate interface. Already at 10 at.% of Yb substituting Y, some defects at the interface tend to appear and increase for higher concentrations. The layers grown on {l_brace}310{r_brace} and {l_brace}111{r_brace} faces show more growth instabilities even at low Yb concentrations. The thermal evolutions of the lattice mismatches between the epilayer and the substrate for {l_brace}110{r_brace}, {l_brace}110{r_brace}, {l_brace}310{r_brace} and {l_brace}111{r_brace} faces were calculated to range from 0.55% at 1273 K to -0.31% at 298 K. The optical spectroscopic studies carried out with these samples agree well with Yb-doped KYW bulk crystals, the measured absorption and calculated (by the reciprocity method) emission cross-sections at 981 nm with E II N{sub m} being {sigma}{sub abs} = 12.5 x 10{sup -20} cm{sup 2} and {sigma}{sub em} = 15.8 x 10{sup -20} cm{sup 2}, respectively.

  11. Sub-300-femtosecond operation from a MIXSEL.

    Mangold, Mario; Golling, Matthias; Gini, Emilio; Tilma, Bauke W; Keller, Ursula

    2015-08-24

    Peak power scaling of semiconductor disk lasers is important for many applications, but their complex pulse formation mechanism requires a rigorous pulse characterization to confirm stable fundamental modelocking. Here we fully confirm sub-300-fs operation of Modelocked Integrated eXternal-cavity Surface Emitting Lasers (MIXSELs) with record high peak power at gigahertz pulse repetition rates. A strain-compensated InGaAs quantum well gain section enables an emission wavelength in the range of Yb-doped amplifiers at ≈1030 nm. We demonstrate the shortest pulses from a MIXSEL with a duration of 253 fs with 240 W of peak power, the highest peak power generated from any MIXSEL to date. This peak power performance is comparable to conventional SESAM-modelocked VECSELs for the first time. At a 10-GHz pulse repetition rate we still obtained 279-fs pulses with 310 mW of average output power, which is currently the highest output power of any femtosecond MIXSEL. Continuous tuning of the pulse repetition rate has been demonstrated with sub-400-fs pulse durations and >225 mW of average output power between 2.9 and 3.4 GHz. The strain-compensated MIXSEL chip allowed for more detailed parameter studies with regards to different heat sink temperatures, pump power, and epitaxial homogeneity of the MIXSEL chip for the first time. We discuss in detail, how the critical temperature balance between quantum well gain and quantum well absorber, the partially saturated absorber and a limited epitaxial growth quality influence the overall device efficiency. PMID:26368179

  12. Cost of electricity difference for direct and indirect drive targets for inertial fusion energy using a diode pumped solid state laser driver

    A detailed systems analysis code has been used to compare the projected cost of electricity (COE) for inertial fusion energy for direct drive (DD) and indirect drive (ID) target scenarios, based on a diode pumped solid state laser driver with Yb:S-FAP (Yb doped Sr5(PO4)3F) gain media. Previously published target gain curves which resulted in a target gain at the optimal DD operating point that is 30% higher than that for the ID scenario have been used. This gain advantage for DD is offset by a requirement for improved beam smoothing, which was obtained via smoothing by spectral dispersion (SSD) with a 1 THz bandwidth at 349 nm. Such a large SSD bandwidth has a number of effects on laser performance, including greater risk of optics damage from non-linear effects, lowered harmonic conversion efficiency, altered extraction parameters and higher front-end costs. The non-linear effects, which contribute to optical component damage by amplification of intensity non-uniformities, were parameterized through a constraint on the maximum allowable B integral (i.e. the total average phase retardation due to the non-linear indices of all materials traversed by the beam). If we constrain B to be no larger than 1.8 rad, which is the presently accepted safe value based on observations in single shot glass laser facilities, the COEs for DD and ID are predicted to be the same within the uncertainties. If technology permits the B limit to be raised, the optimized COE for DD is predicted to decrease relative to that for ID. (author)

  13. Fiber laser pumped burst-mode operated picosecond mid-infrared laser

    Wei, Kai-Hua; Jiang, Pei-Pei; Wu, Bo; Chen, Tao; Shen, Yong-Hang

    2015-02-01

    We demonstrate a compact periodically poled MgO-doped lithium niobate (MgO:PPLN)-based optical parametric oscillator (OPO) quasi-synchronously pumped by a fiber laser system with burst-mode operation. The pump source is a peak-power-selectable pulse-multiplied picosecond Yb fiber laser. The chirped pulses from a figure of eight-cavity mode-locked fiber laser seed are narrowed to a duration of less than 50 ps using an FBG reflector and a circulator. The narrowed pulses are directed to pass through a pulse multiplier and to form pulse bunches, each of which is composed of 13 sub-pulses. The obtained pulse bunches are amplified by two-stage fiber pre-amplifiers: one-stage is core-pumped and the other is cladding-pumped. A fiberized acousto-optic modulator is inserted to control the pulse repetition rate (PRR) of the pulse bunches before they are power-amplified in the final amplifier stage with a large mode area (LMA) PM Yb-doped fiber. The maximum average powers from the final amplifier are 85 W, 60 W, and 45 W, respectively, corresponding to the PRR of 2.72 MHz, 1.36 MHz, and 0.68 MHz. The amplified pulses are directed to pump an MgO:PPLN-based optical parametric oscillator (OPO). A maximum peak power at 3.45 μm is obtained approximately to be 8.4 kW. Detailed performance characteristics are presented. Project supported by the National Natural Science Foundation of China (Grant No. 61078015) and the National Basic Research Program of China (Grant No. 2011CB311803).

  14. Structural, morphological and spectroscopic properties of Eu{sup 3+}-doped rare earth fluorides synthesized by the hydrothermalmethod

    Grzyb, Tomasz, E-mail: tgrzyb@amu.edu.pl [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Poznań 60-780 (Poland); Runowski, Marcin [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Poznań 60-780 (Poland); Szczeszak, Agata [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, Poznań 60-179 (Poland); Lis, Stefan [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Poznań 60-780 (Poland)

    2013-04-15

    Rare earth fluorides (REF{sub 3}, RE=Y, La, Gd or Yb) doped with 5% of Eu{sup 3+} ions were synthesized via the hydrothermal method and their physicochemical properties were compared. The synthesis was carried out in an aqueous medium at elevated pressure and temperature. The reaction was performed in situ, with use of NaBF{sub 4} as a source of fluoride ions. Structural and morphological properties of obtained nanophosphors were characterized with the use of powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. Synthesized products were nanocrystalline with hexagonal or orthorhombic crystal structures. They showed different morphology, from nanoplates to nanorings, depending on the used REF{sub 3} fluoride as the host for the Eu{sup 3+} ions. The elemental composition was confirmed by the energy-dispersive X-ray spectroscopy (EDX) results. Spectroscopic properties were investigated by measuring the excitation and emission spectra. Also luminescence lifetimes were determined. The synthesized materials showed bright red luminescence, due to the presence of Eu{sup 3+} ions in their structure. - Graphical abstract: Luminescence spectra of the REF{sub 3}:Eu{sup 3+} (RE=Y, La, Gd and Yb) fluorides and their TEM images as background. Highlights: ► Nanocrystalline fluorides were synthesized using modified hydrothermal method. ► Structural and morphological properties of in situ prepared nanomaterials were studied. ► Luminescence properties of REF{sub 3}:Eu{sup 3+} (RE=Y, La, Gd, Yb) were compared and investigated.

  15. Preparation and electrochemical properties of SrCe0.4Zr0.4Yb0.2O2.9 electrolyte

    Juan Li; Ruisong Guo; Hong Jiang

    2012-11-01

    The perovskite Yb-doped strontium cerate–zirconate material, SrCe0.4Zr0.4Yb0.2O2.9, was prepared by solid-state reaction and the structure was characterized by X-ray diffraction. The calcination process of the powder was investigated by thermogravimetric/differential thermal analysis (TG–DTA). The high temperature conductivities were measured by d.c. four-probe technique in the temperature range from 500 to 950°C in wet hydrogen and effect of temperature on conductivity was investigated. The conductivity increased with the elevation of temperature from 500 to 950°C. The highest conductivity of 4.4 × 10-2 S.cm-1 was observed for SrCe0.4Zr0.4Yb0.2O2.9 at 950°C. The current–voltage (–) and current–power (–) characteristics of the single cell (H2, Pt/SrCe0.4Zr0.4Yb0.2O2.9/Pt, O2) at temperature range from 600 to 850°C were tested. With the temperature increasing from 600 to 850°C, the open circuit voltage (OCV) decreased from 1.164 to 1.073 V and the ionic transfer number decreased from 0.996 to 0.946. At 850°C, the maximum power density of 25.2 mW.cm-2 was observed.

  16. Layered Yb:YAG ceramics produced by two different methods: processing, characterization and comparison

    Hostaša, Jan; Esposito, Laura; Biasini, Valentina; Piancastelli, Andreana; Vannini, Matteo; Toci, Guido

    2016-03-01

    The use of Yb:YAG ceramic gain media in solid state lasers has been of growing interest for high repetition rate and high power lasers. Probably the most important advantage of ceramic production technology in comparison with that of single crystals is the flexibility of shaping methods that allow the production of near-net-shape components with a welldefined internal structure. In the case of Yb:YAG with dopant distribution designed accordingly to the pumping and cooling geometry the efficiency of the laser device can be enhanced by mitigating thermal lensing effects. The presented work reports on Yb:YAG transparent ceramics composed of layers with different Yb doping produced by two different shaping methods: dry pressing of spray-dried powders and tape casting, all sintered under high vacuum. The selected geometry of materials was based on numerical simulations. Microstructure of the produced materials was characterized by SEM and EDX with a particular attention to the dopant content across the layers. The optical quality of produced ceramics was characterized and discussed in connection with the microstructure and laser emission results. Output power of nearly 7 W and slope efficiency 58.1 % were obtained in QCW regime from bilayered 0-10 %Yb:YAG. In the case of multilayered materials higher scattering losses were observed. The comparison between the two processing methods highlighted that the tape-cast materials provided higher optical uniformity and the diffusion zone between the single layers with different dopant content was about 150 nm compared to about 250 nm in samples produced by pressing of powders.

  17. Effect of rare earth substitution in cobalt ferrite bulk materials

    Bulai, G., E-mail: georgiana.bulai@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bd. Carol I, nr. 11, 700506 Iasi (Romania); Diamandescu, L. [National Institute of Material Physics, P.O. Box MG-7, 07125 Bucharest (Romania); Dumitru, I.; Gurlui, S. [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bd. Carol I, nr. 11, 700506 Iasi (Romania); Feder, M. [National Institute of Material Physics, P.O. Box MG-7, 07125 Bucharest (Romania); Caltun, O.F. [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bd. Carol I, nr. 11, 700506 Iasi (Romania)

    2015-09-15

    The study was focused on the influence of small amounts of rare earth (RE=La, Ce, Sm, Gd, Dy, Ho, Er, Yb) addition on the microstructure, phase content and magnetic properties of cobalt ferrite bulk materials. The X-Ray diffraction measurements confirmed the formation of the spinel structure but also the presence of secondary phases of RE oxides or orthoferrite in small percentages (up to 3%). Density measurements obtained by Archimedes method revealed a ~1 g cm{sup −3} decrease for the RE doped cobalt ferrite samples compared with stoichiometric one. Both the Mössbauer and Fourier Transform Infrared Spectrocopy analysis results confirmed the formation of the spinel phase. The saturation magnetization and coercive field values of the doped samples obtained by Vibrating Sample Magnetometry were close to those of the pure cobalt ferrite. For magnetostrictive property studies the samples were analyzed using the strain gauge method. Higher maximum magnetostriction coefficients were found for the Ho, Ce, Sm and Yb doped cobalt ferrite bulk materials as related to the stoichiometric CoFe{sub 2}O{sub 4} sample. Moreover, improved strain derivative was observed for these samples but at higher magnetic fields due to the low increase of the coercive field values for doped samples. - Highlights: • Substitution by a large number of rare earth elements was investigated. • First reported results on magnetostriction measurements of RE doped cobalt ferrite. • The doped samples presented an increased porosity and a decreased grain size. • Increased magnetostrctive response was observed for several doped samples.

  18. A novel fiber laser development for photoacoustic microscopy

    Yavas, Seydi; Aytac-Kipergil, Esra; Arabul, Mustafa U.; Erkol, Hakan; Akcaalan, Onder; Eldeniz, Y. Burak; Ilday, F. Omer; Unlu, Mehmet B.

    2013-03-01

    Photoacoustic microscopy, as an imaging modality, has shown promising results in imaging angiogenesis and cutaneous malignancies like melanoma, revealing systemic diseases including diabetes, hypertension, tracing drug efficiency and assessment of therapy, monitoring healing processes such as wound cicatrization, brain imaging and mapping. Clinically, photoacoustic microscopy is emerging as a capable diagnostic tool. Parameters of lasers used in photoacoustic microscopy, particularly, pulse duration, energy, pulse repetition frequency, and pulse-to-pulse stability affect signal amplitude and quality, data acquisition speed and indirectly, spatial resolution. Lasers used in photoacoustic microscopy are typically Q-switched lasers, low-power laser diodes, and recently, fiber lasers. Significantly, the key parameters cannot be adjusted independently of each other, whereas microvasculature and cellular imaging, e.g., have different requirements. Here, we report an integrated fiber laser system producing nanosecond pulses, covering the spectrum from 600 nm to 1100 nm, developed specifically for photoacoustic excitation. The system comprises of Yb-doped fiber oscillator and amplifier, an acousto-optic modulator and a photonic-crystal fiber to generate supercontinuum. Complete control over the pulse train, including generation of non-uniform pulse trains, is achieved via the AOM through custom-developed field-programmable gate-array electronics. The system is unique in that all the important parameters are adjustable: pulse duration in the range of 1-3 ns, pulse energy up to 10 μJ, repetition rate from 50 kHz to 3 MHz. Different photocoustic imaging probes can be excited with the ultrabroad spectrum. The entire system is fiber-integrated; guided-beam-propagation rendersit misalignment free and largely immune to mechanical perturbations. The laser is robust, low-cost and built using readily available components.

  19. Fiber laser pumped burst-mode operated picosecond mid-infrared laser

    We demonstrate a compact periodically poled MgO-doped lithium niobate (MgO:PPLN)-based optical parametric oscillator (OPO) quasi-synchronously pumped by a fiber laser system with burst-mode operation. The pump source is a peak-power-selectable pulse-multiplied picosecond Yb fiber laser. The chirped pulses from a figure of eight-cavity mode-locked fiber laser seed are narrowed to a duration of less than 50 ps using an FBG reflector and a circulator. The narrowed pulses are directed to pass through a pulse multiplier and to form pulse bunches, each of which is composed of 13 sub-pulses. The obtained pulse bunches are amplified by two-stage fiber pre-amplifiers: one-stage is core-pumped and the other is cladding-pumped. A fiberized acousto–optic modulator is inserted to control the pulse repetition rate (PRR) of the pulse bunches before they are power-amplified in the final amplifier stage with a large mode area (LMA) PM Yb-doped fiber. The maximum average powers from the final amplifier are 85 W, 60 W, and 45 W, respectively, corresponding to the PRR of 2.72 MHz, 1.36 MHz, and 0.68 MHz. The amplified pulses are directed to pump an MgO:PPLN-based optical parametric oscillator (OPO). A maximum peak power at 3.45 μm is obtained approximately to be 8.4 kW. Detailed performance characteristics are presented. (paper)

  20. Reduction of Photoluminescence Quenching by Deuteration of Ytterbium-Doped Amorphous Carbon-Based Photonic Materials

    Hui-Lin Hsu

    2014-08-01

    Full Text Available In situ Yb-doped amorphous carbon thin films were grown on Si substrates at low temperatures (<200 °C by a simple one-step RF-PEMOCVD system as a potential photonic material for direct integration with Si CMOS back end-of-line processing. Room temperature photoluminescence around 1 µm was observed via direct incorporation of optically active Yb3+ ions from the selected Yb(fod3 metal-organic compound. The partially fluorinated Yb(fod3 compound assists the suppression of photoluminescence quenching by substitution of C–H with C–F bonds. A four-fold enhancement of Yb photoluminescence was demonstrated via deuteration of the a-C host. The substrate temperature greatly influences the relative deposition rate of the plasma dissociated metal-organic species, and hence the concentration of the various elements. Yb and F incorporation are promoted at lower substrate temperatures, and suppressed at higher substrate temperatures. O concentration is slightly elevated at higher substrate temperatures. Photoluminescence was limited by the concentration of Yb within the film, the concentration of Yb ions in the +3 state, and the relative amount of quenching due to the various de-excitation pathways associated with the vibrational modes of the host a-C network. The observed wide full-width-at-half-maximum photoluminescence signal is a result of the variety of local bonding environments due to the a-C matrix, and the bonding of the Yb3+ ions to O and/or F ions as observed in the X-ray photoelectron spectroscopy analyses.

  1. Preparation and electrochemical properties of SrCe0.4Zr0.4Yb0.2O2.9 electrolyte

    The perovskite Yb-doped strontium cerate-zirconate material, SrCe0.4Zr0.4Yb0.2O2.9, was prepared by solid-state reaction and the structure was characterized by X-ray diffraction. The calcination process of the powder was investigated by thermogravimetric/differential thermal analysis (TG-DTA). The high temperature conductivities were measured by d.c. four-probe technique in the temperature range from 500 to 950 deg C in wet hydrogen and effect of temperature on conductivity was investigated. The conductivity increased with the elevation of temperature from 500 to 950 deg C. The highest conductivity of 4.4 x 10-2 S.cm-1 was observed for SrCe0.4Zr0.4Yb0.2O2.9 at 950 deg C. The current-voltage (I-V) and current-power (I-P) characteristics of the single cell (H2, Pt/SrCe0.4Zr0.4Yb0.2O2.9/Pt, O2) at temperature range from 600 to 850 deg C were tested. With the temperature increasing from 600 to 850 deg C, the open circuit voltage (OCV) decreased from 1.164 to 1.073 V and the ionic transfer number decreased from 0.996 to 0.946. At 850 deg C, the maximum power density of 25.2 mW.cm-2 was observed. (author)

  2. Graded Yb:YAG ceramic structures: design, fabrication and characterization of the laser performances

    Toci, Guido; Lapucci, Antonio; Ciofini, Marco; Esposito, Laura; Hostaša, Jan; Piancastelli, Andreana; Gizzi, Leonida A.; Labate, Luca; Ferrara, Paolo; Pirri, Angela; Vannini, Matteo

    2015-05-01

    Significant improvements in efficiency in high power, high repetition rate laser systems should come from the use of ceramic laser active elements suitably designed to mitigate the thermal and thermo-mechanical effects (TEs and TMEs) deriving from the laser pumping process. Laser active media exhibiting a controlled and gradual distribution of the active element(s) could therefore find useful applications in the laser-driven inertial confinement fusion systems, which are considered among the most promising energy source of the future (ultraintense laser pulses), and in medical applications (ultrashort laser pulses) The present work explores the flexibility of the ceramic process for the construction of YAG (Y3Al5O12) ceramic laser elements with a controlled distribution of the Yb doping, in view of the realization of structures modelled to respond to specific application. Two processing techniques are presented to prepare layered structures with a tailored modulation of the doping level, with the goal of reducing the peak temperature, the temperature gradients and also the thermally-induced deformation of the laser material, thus mitigating the overall thermal effects. Tape casting in combination with thermal compression of ceramic tapes with a varying doping level is one of the presented techniques. To make this process as more adaptable as possible, commercial micrometric ceramic powders have been used. The results are compared with those obtained using nanometric powders and a shaping process based on the subsequent pressing of spray dried powders with a different doping level. Laser performance has been characterized in a longitudinally diode pumped laser cavity. The laser efficiency under high thermal load conditions has been compared to those obtained from samples with uniform doping, and for samples obtained with press shaping and tape casting, under the same conditions.

  3. 76 FR 47566 - Nationwide Categorical Waivers Under Section 1605 (Buy American) of the American Recovery and...

    2011-08-05

    ... counters; (3) 28W, 30W, and 60W 360 degree LED bulbs for retrofits of HPS streetlights; (4) bathroom... degree LED bulbs for retrofits of HPS streetlights; (4) bathroom ventilation fans with a built in... these bulbs, none are yet manufacturing domestically. (4) Bathroom Ventilation Fans With Built...

  4. Measurement of Thermal Lens Focal Length and Its Effect on Laser Output Characteristics in LD End-pumped Nd∶YVO4 Lasers

    WAN Chunming(万春明); WANG Hui(王慧)

    2002-01-01

    According to the resonator transform circle theory, the focal length of thermal lens of laser media in laser diode end-pumped solid-state lasers is analyzed and measured with a simple method. A 30W 808nm LD pumped YVO4 laser is developed and characterized.

  5. Tensile properties of cellulose fiber reinforced hydroxypropylcellulose films

    Borges, J.P.; Godinho, M.H.; Martins, A.F.; Stamatialis, D.F.; De Pinho, M.N.; Belgacem, M.N.

    2004-01-01

    The tensile properties of cross-linked and uncross-linked composite films (thickness 20-35 m) prepared from Hydroxypropylcellulose (HPC) with incorporation of microcrystalline cellulose fibers (Avicel) were studied. The concentration of fibers in the composites ranged from 0 to 30 w/w% and cross-lin

  6. Sensorless Position Measurement Based on PWM Eddy Current Variation for Switched Reluctance Motor

    Laurent, Philippe; Multon, Bernard; Hoang, Emmanuel; Gabsi, Mohamed

    1995-01-01

    This paper proposes a new method for indirect sensing of the rotor position in a switched reluctance motor. The method operates with the rotor eddy current losses produced by the PWM converter switching, regardless of magnetic saturation. Experimental results concerning sensivity and performances are schown in a 6/4 30W 3000rpm SRM.

  7. Influence of water availability on the enzymatic hydrolysis of proteins

    Butré, C.I.; Wierenga, P.A.; Gruppen, H.

    2014-01-01

    The overall rate of enzymatic protein hydrolysis decreases with increasing protein concentration (0.1–30% (w/v)) at constant enzyme/substrate ratio. To understand the role of water, the amount of available water was expressed as the ratio between free and bound water and experimentally determined fr

  8. Effects of Ionic Strength on the Enzymatic Hydrolysis of Diluted and Concentrated Whey Protein Isolate

    Butré, C.I.; Wierenga, P.A.; Gruppen, H.

    2012-01-01

    To identify the parameters that affect enzymatic hydrolysis at high substrate concentrations, whey protein isolate (1–30% w/v) was hydrolyzed by Alcalase and Neutrase at constant enzyme-to-substrate ratio. No changes were observed in the solubility and the aggregation state of the proteins. With inc

  9. 76 FR 78938 - Carpinteria Offshore Field Redevelopment Project-Developmental Drilling Into the Carpinteria...

    2011-12-20

    ..., in 154 feet of water (Latitude 34 20'16'' N; Longitude 119 32'30'' W) to develop resources in... Drilling Into the Carpinteria Offshore Field Oil and Gas Reserves, California State Waters, From Federal... includes Federal and state leases. As many as 25 new production or injection wells would be drilled...

  10. Impact of lignins isolated from pretreated lignocelluloses on enzymatic cellulose saccharification

    Barsberg, Søren Talbro; Selig, Michael Joseph; Felby, Claus

    2013-01-01

    % (w/w) and ash was from 5.8 to 30 % (w/w). ATR-IR analyses indicated significant and similar levels of calcium in all lignin isolates. Commercial cellulase adsorption studies showed that the presence of these lignins had no significant impact on the total amount of adsorbed enzyme in cellulose and...

  11. Recrystallization of amylopectin in concentrated starch gels

    Keetels, CJAM; Oostergetel, GT; vanVliet, T

    1996-01-01

    The relation between the recrystallization of amylopectin and the increase in stiffness of starch gels during storage was studied by various techniques. From transmission electron microscopy it was concluded that the size of the crystalline domains in retrograded 30% w/w potato starch gels was about

  12. Biological responses to current UV-B radiation in Arctic regions

    Albert, Kristian; N. Mikkelsen, Teis; Ro-Poulsen, Helge

    Depletion of the ozone layer and the consequent increase in solar ultraviolet-B radiation (UV-B) may impact living conditions for arctic plants significantly. In order to evaluate how the prevailing UV-B fluxes affect the heath ecosystem at Zackenberg (74°30'N, 20°30'W) and other high...

  13. Monitoring lipase-catalyzed interesterification for bulky fats modification with FT-IR/NIR spectroscopy

    Chang, Tinghong; Lai, Xuxin; Zhang, Hong;

    2005-01-01

    This work demonstrates the application of FT-IR and FT-NIR spectroscopy to monitor the enzymatic interesterification process for bulky fat modification. The reaction was conducted between palm stearin and coconut oil (70/30, w/w) with the catalysis of Lipozyme TL IM at 70°C in a batch reactor...

  14. CORN GLUTEN MEAL AS A THERMOPLASTIC RESIN: EFFECT OF PLASTICIZERS AND WATER CONTENT

    Corn gluten meal (CGM) was studied to investigate the effect plasticizers and water have on its melt processing, and how this melting affects its mechanical properties. CGM containing varying amounts of water were mixed with 30%(w/w) plasticizers; (glycerol, triethylene glycol (TEG), dibutyl tartra...

  15. The effects of extrusion of wheat distillers dried grains with solubles with or without an enzyme cocktail on performance of turkey hen poults.

    Opoku, E Y; Classen, H L; Scott, T A

    2015-02-01

    Two experiments were conducted to determine if extrusion (EX) or enzymes (E) could overcome the restrictions (e.g., high fiber) of feeding wheat distillers dried grain with solubles (wDDGS) and improve its nutritional value for feeding turkeys. Two starter diets with either 0 or 30% wDDGS were formulated to meet or exceed the nutrient requirements of the Hybrid Converter female turkeys. The 30% wDDGS diet was substituted with either non-extruded (EX-) or extruded (EX+) wDDGS to produce three basal diets [0% wDDGS (EX-) or 30% wDDGS (EX-/EX+)]. Diets were blended to obtain 15% wDDGS. In the respective treatments, only wDDGS was extruded (temperature; 118°C, retention; 15 sec, total moisture; 25% and pressure 33 bar). The respective experimental diets were supplemented with/without an enzyme cocktail (E; 0.5 g/kg). Test diets were fed from 7-21 d in a completely randomized design. In Experiment 1, a total of 210 turkey hen poults were fed diets containing 0, 15, or 30% wDDGS (EX-) with or without enzyme (E+/E-). Body weight (BW) and feed intake (FI) were significantly higher for 0% wDDGSE-. Nitrogen retention (NR) and apparent metabolizable energy (AME) for the 30% wDDGSE- was significantly higher than other treatments at 21 d. The results indicated significant main effects of E and an interaction between wDDGS level and E. In Experiment 2, 280 turkey hen poults were fed 8 diets [15/30% wDDGS (E+/E-), (EX-/EX+)]. The level of wDDGS had a significant effect on BW, FI and gain:feed; 15% inclusion was superior to 30%. There were significant 2- and 3-way interactions for AME and NR at 21 d due to differences in enzyme response with 15 or 30% wDDGS inclusion and/or extrusion of wDDGS. As high as 15% wDDGS can be incorporated in turkey hen diets. There were no beneficial effects of EX or E on poult performance. PMID:25595482

  16. 迷迭香(Rosmarinus officinalis)提取残渣栽培糙皮侧耳%Use of Rosemary (Rosmarinus officinalis) Processing Waste for Pleurotus ostreatus Cultivation

    Andrej GREGORI; Bojan PAHOR; Franc POHLEVEN

    2008-01-01

    食品工业中用迷迭香提取抗氧化物质后的残渣(rosemary processing waste RPW)拌入粉碎的玉米粒可以用作栽培糙皮侧耳的培养料.提取抗氧化剂后的迷迭香残渣RPW-1中所含提取残留的丙酮对栽培有害,RPW-1直接栽培糙皮侧耳所获子实体产量比用RPW-2(废料充分通气,去除残存的丙酮)平均低49%.试验中获得最高生物效率(67%)的培养料配比为RPW-2中加入30%(w/w)粉碎的玉米粒(crushed corn seeds CCS)和2%CaCO3.增加培养料中的麸皮(wheat bran WB)比例(降低C/N比)可加快菌丝生长速度,但通常导致子实体产量降低.试验中菌丝生长最快(23 d生长9.9 cm)的培养料配比为RPW-2中添加30%(w/w) CCS 和30% (w/w) WB,/N比为24.%Rosemary processing waste (RPW) generated after extraction of antioxidant components for the food industry, in combination with crushed corn seeds, represented a suitable growth substrate for the cultivation of Pleurotus ostreatus . On average, fruit body yields were 49% lower on substrate mixtures containing RPW1, containing residual acetone from the antioxidant extraction process, compared to substrates incorporating RPW2 which had been allowed to stand in wellaerated conditions in order to remove residual solvent. The highest Biological Efficiency value (67%) were recorded with a substrate mixture containing 30% (w/w) crushed corn seeds (CCS) mixed with RPW2 and 2% CaCO3. Increasing proportions of wheat bran (WB) in the mixtures decreased the C/N ratio, had a positive effect on mycelial growth rates, but generally resulted in lower fruit body yields. The highest vegetative growth rate (9.9 cm in 23 days) was recorded on substrate mixtures with a C/N ratio of 24 and containing RPW2 supplemented with 30% (w/w) CCS and 30% (w/w) WB.

  17. Laser system for cooling of relativistic C{sup 3+}-ion beams in storage rings; Lasersystem zur Kuehlung relativistischer C{sup 3+}-Ionenstrahlen in Speicherringen

    Beck, Tobias

    2015-02-15

    Cold ion beams are essential for many precision experiments at storage rings. While spectroscopic experiments gain from the high energy resolution, collision experiments benefit from the increased luminosity. Furthermore, sympathetic cooling of exotic species is conceivable with the aid of cold ion beams. Besides the long established electron cooling, alternative cooling methods are gaining in importance, especially for high energy particles. In the past, experiments to cool ions with lasers were performed. Because of the matching wavelength and output power, frequency doubled Argon-ion lasers at 257 nm were used during these experiments. Due to the strongly limited scanning potential of these systems, it was not possible to cool the full inertia spread of the ion beams. A new laser system was developed in this thesis because of the lack of commercial alternatives. After the characterization of the system, it was tested during a beamtime at the Experimentierspeicherring (ESR) at the Gesellschaft fuer Schwerionenforschung (GSI). The completely solid state based system delivers up to 180 mW of output power at 257 nm and is modehop free tunable up to 16 GHz in 10 ms at this wavelength. By using efficient diode lasers, the new system consumes considerably less power than comparable Argon-ion lasers. The fundamental wavelength of 1028 nm is amplified up to 16 W with an Yb-doped fiber amplifier. Subsequently, the target wavelength of 257 nm is realized in two consecutive build-up cavities. Another diode laser, stabilized to a wavelength meter, serves as a frequency reference. This new laser system first came to operation during beamtime in August 2012, when relativistic C{sup 3+} ions with β=0.47 were cooled successfully. For the first time it was possible to access the whole inertia spread of a bunched ion beam without electron precooling. In contrast to prior experiments, only the laser frequency was scanned and not the bunching frequency of the ion beam. The results

  18. Efficient sub-Doppler transverse laser cooling of an indium atomic beam

    Kim, Jae-Ihn

    2009-07-23

    Laser cooled atomic gases and atomic beams are widely studied samples in experimental research in atomic and optical physics. For the application of ultra cold gases as model systems for e.g. quantum many particle systems, the atomic species is not very important. Thus this field is dominated by alkaline, earthalkaline elements which are easily accessible with conventional laser sources and have convenient closed cooling transition. On the other hand, laser cooled atoms may also be interesting for technological applications, for instance for the creation of novel materials by atomic nanofabrication (ANF). There it will be important to use technologically relevant materials. As an example, using group III atoms of the periodical table in ANF may open a route to generate fully 3D structured composite materials. The minimal requirement in such an ANF experiment is the collimation of an atomic beam which is accessible by one dimensional laser cooling. In this dissertation, I describe transverse laser cooling of an Indium atomic beam. For efficient laser cooling on a cycling transition, I have built a tunable, continuous-wave coherent ultraviolet source at 326 nm based on frequency tripling. For this purpose, two independent high power Yb-doped fiber amplifiers for the generation of the fundamental radiation at {lambda}{sub {omega}} = 977 nm have been constructed. I have observed sub-Doppler transverse laser cooling of an Indium atomic beam on a cycling transition of In by introducing a polarization gradient in the linear-perpendicular-linear configuration. The transverse velocity spread of a laser-cooled In atomic beam at full width at half maximum was achieved to be 13.5{+-}3.8 cm/s yielding a full divergence of only 0.48 {+-} 0.13 mrad. In addition, nonlinear spectroscopy of a 3-level, {lambda}-type level system driven by a pump and a probe beam has been investigated in order to understand the absorption line shapes used as a frequency reference in a previous two

  19. Bulk damage and absorption in fused silica due to high-power laser applications

    Nürnberg, F.; Kühn, B.; Langner, A.; Altwein, M.; Schötz, G.; Takke, R.; Thomas, S.; Vydra, J.

    2015-11-01

    Laser fusion projects are heading for IR optics with high broadband transmission, high shock and temperature resistance, long laser durability, and best purity. For this application, fused silica is an excellent choice. The energy density threshold on IR laser optics is mainly influenced by the purity and homogeneity of the fused silica. The absorption behavior regarding the hydroxyl content was studied for various synthetic fused silica grades. The main absorption influenced by OH vibrational excitation leads to different IR attenuations for OH-rich and low-OH fused silica. Industrial laser systems aim for the maximum energy extraction possible. Heraeus Quarzglas developed an Yb-doped fused silica fiber to support this growing market. But the performance of laser welding and cutting systems is fundamentally limited by beam quality and stability of focus. Since absorption in the optical components of optical systems has a detrimental effect on the laser focus shift, the beam energy loss and the resulting heating has to be minimized both in the bulk materials and at the coated surfaces. In collaboration with a laser research institute, an optical finisher and end users, photo thermal absorption measurements on coated samples of different fused silica grades were performed to investigate the influence of basic material properties on the absorption level. High purity, synthetic fused silica is as well the material of choice for optical components designed for DUV applications (wavelength range 160 nm - 260 nm). For higher light intensities, e.g. provided by Excimer lasers, UV photons may generate defect centers that effect the optical properties during usage, resulting in an aging of the optical components (UV radiation damage). Powerful Excimer lasers require optical materials that can withstand photon energy close to the band gap and the high intensity of the short pulse length. The UV transmission loss is restricted to the DUV wavelength range below 300 nm and

  20. Diode-pumped solid-state laser driver experiments for inertial fusion energy applications

    Although solid-state lasers have been the primary means by which the physics of inertial confinement fusion (ICF) have been investigated, it was previously thought that solid-state laser technology could not offer adequate efficiencies for an inertial fusion energy (IFE) power plant. Orth and co-workers have recently designed a conceptual IFE power plant, however, with a high efficiency diode-pumped solid-state laser (DPSSL) driver that utilized several recent innovations in laser technology. It was concluded that DPSSLs could offer adequate performance for IFE with reasonable assumptions. This system was based on a novel diode pumped Yb-doped Sr5(PO4)3F (Yb:S-FAP) amplifier. Because this is a relatively new gain medium, a project was established to experimentally validate the diode-pumping and extraction dynamics of this system at the smallest reasonable scale. This paper reports on the initial experimental results of this study. We found the pumping dynamics and extraction cross-sections of Yb:S-FAP crystals to be similar to those previously inferred by purely spectroscopic techniques. The saturation fluence for pumping was measured to be 2.2 J/cm2 using three different methods based on either the spatial, temporal, or energy transmission properties of a Yb:S-FAP rod. The small signal gain implies an emission cross section of 6.0x10-20 cm2. Up to 1.7 J/cm3 of stored energy density was achieved in a 6x6x44 mm3 Yb:S-FAP amplifier rod. In a free running configuration diode-pumped slope efficiencies up to 43% were observed with output energies up to ∼0.5 J per 1 ms pulse from a 3x3x30 mm3 rod. When the rod was mounted in a copper block for cooling, 13 W of average power was produced with power supply limited operation at 70 Hz with 500 μs pulses

  1. Exp erimental studies of multiple pulses in a passively ytterbium-dop ed fib er laser based on graphene-oxide saturable absorb er%氧化石墨烯被动锁模掺镱光纤激光器多脉冲现象的实验研究

    黄诗盛; 王勇刚; 李会权; 林荣勇; 闫培光

    2014-01-01

    The different multiple pulse phenomena are experimentally studied in a passively mode-locked ytterbium-doped fiber laser based on graphene-oxide saturable absorber (GOSA) with net normal dispersion cavity. At the same pump power with different polarization orientations, we observe the multiple pulse phenomena, including harmonic mode-locking of rectangular pulses, dissipative solitons, quasi-harmonic mode-locking, periodical peak modulation, multipulse bunches, multipulse cluster, and chaotic multipulse. The inserted 2 nm narrow bandwidth filter is important for limiting the gain bandwidth and shaping pulses. Adjusting the polarization controller is equivalent to changing the gain in the laser cavity, which is the main reason for the formation of different multiple pulses states. This is the first time that different multiple pulses states have been observed in an-normal-dispersion Yb-doped fiber laser with graphene-oxide saturable absorber. These results could extend the understanding of multiple pulse dynamics in GOSA mode-locked fiber lasers.%利用氧化石墨烯作为可饱和吸收体,在被动锁模全正常色散掺镱光纤激光器中研究了多脉冲的现象。在同一抽运功率不同偏振态下,实验获得了矩形脉冲谐波锁模、耗散孤子谐波锁模、准谐波锁模,脉冲峰值周期性调制,脉冲簇、脉冲束、混沌多重脉冲的多脉冲现象。插入激光腔内的2 nm窄带滤波器具有限制增益带宽、对脉冲塑形、诱导多脉冲产生的作用。调节偏振控制器相当于改变腔内增益,是实现不同类型多脉冲现象的主要原因。本实验研究有利于加深对多脉冲动力学行为在正常色散区域氧化石墨烯锁模掺镱光纤激光器中的理解。

  2. Efficient sub-Doppler transverse laser cooling of an indium atomic beam

    Laser cooled atomic gases and atomic beams are widely studied samples in experimental research in atomic and optical physics. For the application of ultra cold gases as model systems for e.g. quantum many particle systems, the atomic species is not very important. Thus this field is dominated by alkaline, earthalkaline elements which are easily accessible with conventional laser sources and have convenient closed cooling transition. On the other hand, laser cooled atoms may also be interesting for technological applications, for instance for the creation of novel materials by atomic nanofabrication (ANF). There it will be important to use technologically relevant materials. As an example, using group III atoms of the periodical table in ANF may open a route to generate fully 3D structured composite materials. The minimal requirement in such an ANF experiment is the collimation of an atomic beam which is accessible by one dimensional laser cooling. In this dissertation, I describe transverse laser cooling of an Indium atomic beam. For efficient laser cooling on a cycling transition, I have built a tunable, continuous-wave coherent ultraviolet source at 326 nm based on frequency tripling. For this purpose, two independent high power Yb-doped fiber amplifiers for the generation of the fundamental radiation at λω = 977 nm have been constructed. I have observed sub-Doppler transverse laser cooling of an Indium atomic beam on a cycling transition of In by introducing a polarization gradient in the linear-perpendicular-linear configuration. The transverse velocity spread of a laser-cooled In atomic beam at full width at half maximum was achieved to be 13.5±3.8 cm/s yielding a full divergence of only 0.48 ± 0.13 mrad. In addition, nonlinear spectroscopy of a 3-level, Λ-type level system driven by a pump and a probe beam has been investigated in order to understand the absorption line shapes used as a frequency reference in a previous two-color spectroscopy experiment

  3. Towards a greater understanding of hydrothermally grown garnets and sesquioxide crystals for laser applications

    Moore, Cheryl Ann

    The hydrothermal method of crystal growth offers many benefits over traditional melt-based techniques such as lower temperature requirements relieving detrimental high temperature effects such as stress fracturing and a closed-environment, which limits impurities. The continued study of this type of growth including hydrothermal epitaxy is crucial in our world of constant miniaturization. Presented in this thesis is the hydrothermal growth of crystals of LuAG and Lu2O3 doped with a variety of dopants. Their room-temperature and cryogenic absorption spectra are also presented. Much like Nature uses heat, pressure, water and a nutrient-rich feedstock we have used this hydrothermal technique to produce synthetic crystals of grossular, Ca3Al2(SiO4)3, a naturally occurring garnet as well as other aluminosilicates related to grossular, including a new type of vesuvianite. Other garnets important to the laser industry have also been grown using the hydrothermal technique, such as yttrium aluminum garnet (YAG), lutetium aluminum garnet (LuAG) and the related sesquioxide Lu2O3, (lutetia). The growth and characteristics of Yb-doped lutetia and LuAG, Nd-doped lutetia, and Dy-doped lutetia and YAG are presented herein. These laser crystals have been analyzed by high-resolution absorption spectroscopy at room temperature as well as 250K, 200K, 150K and 80K and absorption coefficients are presented. A coprecipitation technique common in the ceramics field has been adapted for use creating precursors for hydrothermal crystal growth, including phase-pure polycrystalline anorthite and phase-pure gehlenite. Coprecipitation has also been utilized to gain greater control of dopants to create pre-doped feedstocks used for the growth of laser crystal. The versatility of the hydrothermal growth method is also highlighted in a novel epitaxial technique, core growth, which coats the internal surfaces of a seed crystal as well as external surfaces. This can result in multifunctional

  4. Laser system for cooling of relativistic C3+-ion beams in storage rings

    Cold ion beams are essential for many precision experiments at storage rings. While spectroscopic experiments gain from the high energy resolution, collision experiments benefit from the increased luminosity. Furthermore, sympathetic cooling of exotic species is conceivable with the aid of cold ion beams. Besides the long established electron cooling, alternative cooling methods are gaining in importance, especially for high energy particles. In the past, experiments to cool ions with lasers were performed. Because of the matching wavelength and output power, frequency doubled Argon-ion lasers at 257 nm were used during these experiments. Due to the strongly limited scanning potential of these systems, it was not possible to cool the full inertia spread of the ion beams. A new laser system was developed in this thesis because of the lack of commercial alternatives. After the characterization of the system, it was tested during a beamtime at the Experimentierspeicherring (ESR) at the Gesellschaft fuer Schwerionenforschung (GSI). The completely solid state based system delivers up to 180 mW of output power at 257 nm and is modehop free tunable up to 16 GHz in 10 ms at this wavelength. By using efficient diode lasers, the new system consumes considerably less power than comparable Argon-ion lasers. The fundamental wavelength of 1028 nm is amplified up to 16 W with an Yb-doped fiber amplifier. Subsequently, the target wavelength of 257 nm is realized in two consecutive build-up cavities. Another diode laser, stabilized to a wavelength meter, serves as a frequency reference. This new laser system first came to operation during beamtime in August 2012, when relativistic C3+ ions with β=0.47 were cooled successfully. For the first time it was possible to access the whole inertia spread of a bunched ion beam without electron precooling. In contrast to prior experiments, only the laser frequency was scanned and not the bunching frequency of the ion beam. The results for

  5. High power and high repetition solid state laser for EUV lithography

    We have been developing a high repetition (5 kHz) and high power (5kW) Nd:YAG laser system for EUV lithography. Key subjects are (1) reliable front-end, (2) uniform and high density pumping of main amplifier rods, and (3) compensation of thermal effects. A stable and reliable front-end based on fiber lasers has been developed. As a cw oscillator using Yb-doped silica fiber operates single longitudinal mode at 1030 nm to 1080nm, various laser materials (Yb:YAG, Nd:YLF, Nd:YAG, Nd:YAP, etc) can be used as main laser medium. A fast LN EO modulator switches out arbitrary pulse shape with response time of 100 ps. Laser pulses from the modulator are amplified by 3 stage fiber amplifiers up to 1 J. We will focus our efforts to attain 1 mJ output from the fiber front-end. Output pulses from the front-end are amplified to 100 mJ level by two 4-mm rod amplifiers (Nd:YAG) and two 6-mm rod amplifiers. Main amplifier chain consists of eight 12-mm rod amplifiers pumped by cw laser diodes. Total output power of the laser diodes is 28.8 kW. Double pass geometry is required to get enough gain and to compensate thermal effects. Spatial filters are installed to adjust thermal lens in the amplifiers and to send an image into just the center of the amplifiers. Ninty degree rotators and faraday rotators are installed in order to compensate thermal birefringence. A test amplifier module was made for investigation on uniform pumping, thermal effects, gain properties, and so on. Six laser diode modules with 4.5 kW total output power are installed in symmetric configuration. Active medium is Nd:YAG rod with 0.6% doping. Diameter and length of the rod are 12 mm and 150 mm, respectively. Peak gain of 1.67 was obtained at 4.2 kW pumping power and 200s pumping duration. Pumping uniformity was measured by both gain distribution and spontaneous emission from the laser rod. Fairly good uniformity was achieved by adjusting pumping geometry. Detail system analysis suggests that 8 amplifier modules

  6. High power and high repetition solid state laser for EUV lithography

    Fujita, H.; Mitra, A.; Wang, T. and the others [Osaka Univ., Osaka (Japan)

    2004-07-01

    We have been developing a high repetition (5 kHz) and high power (5kW) Nd:YAG laser system for EUV lithography. Key subjects are (1) reliable front-end, (2) uniform and high density pumping of main amplifier rods, and (3) compensation of thermal effects. A stable and reliable front-end based on fiber lasers has been developed. As a cw oscillator using Yb-doped silica fiber operates single longitudinal mode at 1030 nm to 1080nm, various laser materials (Yb:YAG, Nd:YLF, Nd:YAG, Nd:YAP, etc) can be used as main laser medium. A fast LN EO modulator switches out arbitrary pulse shape with response time of 100 ps. Laser pulses from the modulator are amplified by 3 stage fiber amplifiers up to 1 J. We will focus our efforts to attain 1 mJ output from the fiber front-end. Output pulses from the front-end are amplified to 100 mJ level by two 4-mm rod amplifiers (Nd:YAG) and two 6-mm rod amplifiers. Main amplifier chain consists of eight 12-mm rod amplifiers pumped by cw laser diodes. Total output power of the laser diodes is 28.8 kW. Double pass geometry is required to get enough gain and to compensate thermal effects. Spatial filters are installed to adjust thermal lens in the amplifiers and to send an image into just the center of the amplifiers. Ninty degree rotators and faraday rotators are installed in order to compensate thermal birefringence. A test amplifier module was made for investigation on uniform pumping, thermal effects, gain properties, and so on. Six laser diode modules with 4.5 kW total output power are installed in symmetric configuration. Active medium is Nd:YAG rod with 0.6% doping. Diameter and length of the rod are 12 mm and 150 mm, respectively. Peak gain of 1.67 was obtained at 4.2 kW pumping power and 200s pumping duration. Pumping uniformity was measured by both gain distribution and spontaneous emission from the laser rod. Fairly good uniformity was achieved by adjusting pumping geometry. Detail system analysis suggests that 8 amplifier modules

  7. Effect of peppermint and citronella essential oils on properties of fish skin gelatin edible films

    Yanwong, S.; Threepopnatkul, P.

    2015-07-01

    Fish skin gelatin films incorporated with peppermint and citronella essential oils at difference concentrations (10, 20 and 30% w/w) were prepared by solution casting. Addition of peppermint oil contributed to a significant decrease of tensile strength and Young's modulus, while the percent elongation at break showed an obvious increase except at 30% w/w. On the other hand, addition of citronella oils promoted a great increase of tensile strength and young's modulus, but an intense decrease of the percent elongation at break. At the predetermined content, the film incorporated with citronella oils outperformed the one with peppermint oils in term of water vapor transmission and solubility in water. Thermal properties of gelatin films with citronella oils exhibited an enhancement in heat stability, while the one with peppermint oils showed slight decrease in heat stability. The additions with both of essential oils exhibited excellent antibacterial properties against both Staphylococcus aureus and Escherichia coli.

  8. Addition of Purified Tannin Sources and Polyethylene Glycol Treatment on Methane Emission and Rumen Fermentation in Vitro

    A. Jayanegara; H. P. S. Makkar; Becker, K

    2015-01-01

    The objectives of this experiment were (1) to observe the effects of purified tannins and polyethy-lene glycol (PEG) on in vitro rumen fermentation and methanogenesis, and (2) to assess the accuracy of volatile fatty acid (VFA) profiles in predicting methane emission. Hydrolysable and condensed tannins were extracted and purified from chestnut, sumach, mimosa and quebracho. Hay and concentrate mixture (70:30 w/w, 380 mg) was incubated in Hohenheim glass syringe containing 10 mL rumen liquor +...

  9. High-energy passively Q-switched laser operation of Yb:Ca3La2(BO3)4 disordered crystal.

    Wang, Lisha; Han, Wenjuan; Pan, Zhongben; Xu, Honghao; Chen, Xiaowen; Liu, Junhai; Yu, Haohai; Zhang, Huaijin

    2016-05-01

    Efficient high-energy passively Q-switched laser operation was demonstrated with Yb:Ca3La2(BO3)4 disordered crystal, producing an average output power of 3.0 W at 1018.7 nm, at a pulse repetition frequency of 5.0 kHz; the resulting pulse energy, duration, and peak power were 600 μJ, 5.3 ns, and 113.2 kW, respectively. PMID:27140354

  10. Стимуляция репаративной регенерации несрастающихся переломов и ложных суставов костей конечностей путем чрескожной лазерной остеоперфорации

    ШУМИЛИН И.И.; Привалов, В. А.

    2006-01-01

    Method of using transcutaneous laser os-teoperforations as well as nearest and remote results of treatment of 51 patients with nonunion fractures and false bone joints have been described in the paper. High-energetic infrared diode laser with the power 30 W and wave length 970 nm was used for osteoperforations. Energy supply to the damaged bone was performed by means of monofiber quartz light pipe with 400 mcm diameter. The results obtained demonstrate low invasiveness and stimulating effect ...

  11. Formation of silicide based oxidation resistant coating over Mo-30 wt. % W alloy

    Silicide based oxidation resistant coatings were developed over Mo-30 W alloy using halide activated pack cementation process. Coated samples were characterized by SEM, optical microscopy, EDX and hardness measurements. Isothermal oxidation tests of coated alloy performed at 1000 deg C for 25h revealed a smaller weight gain at the initial stage of oxidation followed by no weight change indicating the protective nature of the coating. (author)

  12. Comparison of Ankle Proprioception Between Pregnant and Non Pregnant Women

    Preetha R; John Solomon M

    2011-01-01

    Pregnant women report falls especially during their third trimester. Physiological changes along with ligament laxity can affect the joint proprioception in this population. This study was conducted to compare the ankle proprioception between pregnant and non pregnant women. Thirty pregnant and 30 non pregnant women were included in the study and the position of ankles were recorded by a digital camera placed 60 cms away from the feet of the subject. UTHSCSA Image tool software version 3.0. w...

  13. Role of plant growth promoting rhizobacteria on antioxidant enzyme activities and tropane alkaloid production of Hyoscyamus niger under water deficit stress

    GHORBANPOUR, Mansour; HATAMI, Mehrnaz; Kazem KHAVAZI

    2013-01-01

    This study examined the effects of inoculation with 2 rhizobacteria strains, Pseudomonas putida (PP) and Pseudomonas fluorescens (PF), on growth parameters, chlorophyll, proline, leaf relative water content (RWC), antioxidant enzyme activities (including superoxide dismutase (SOD), peroxidase (POX), and catalase (CAT)), tropane alkaloids (such as hyoscyamine (HYO) and scopolamine (SCO)), and production of Hyoscyamus niger under 3 water deficit stress (WDS) levels, i.e. 30% (W1), 60% (W2), and...

  14. Adulticidal activity against Stegomyia aegypti (Diptera: Culicidae) of three Piper spp. Atividade de três Piper spp. contra adultos de Stegomyia aegypti (Diptera: Culicidae)

    Wej Choochote; Udom Chaithong; Kittichai Kamsuk; Eumporn Rattanachanpichai; Atchariya Jitpakdi; Pongsri Tippawangkosol; Dana Chaiyasit; Daruna Champakaew; Benjawan Tuetun; Benjawan Pitasawat

    2006-01-01

    Three Piper species, Piper longum, P. ribesoides and P. sarmentosum, were selected for investigation of adulticidal potential against Stegomyia aegypti, a main vector of dengue and dengue haemorrhagic fever. Successive extraction by maceration with 95% ethanol showed percentage yields of ethanolic extracts, which derived from P. longum, P. ribesoides and P. sarmentosum, of 8.89, 3.21 and 5.30% (w/w), respectively. All Piper extracts illustrated an impressive adulticidal activity when tested a...

  15. Adulticidal activity against Stegomyia aegypti (Diptera: Culicidae) of three Piper spp.

    Choochote Wej; Chaithong Udom; Kamsuk Kittichai; Rattanachanpichai Eumporn; Jitpakdi Atchariya; Tippawangkosol Pongsri; Chaiyasit Dana; Champakaew Daruna; Tuetun Benjawan; Pitasawat Benjawan

    2006-01-01

    Three Piper species, Piper longum, P. ribesoides and P. sarmentosum, were selected for investigation of adulticidal potential against Stegomyia aegypti, a main vector of dengue and dengue haemorrhagic fever. Successive extraction by maceration with 95% ethanol showed percentage yields of ethanolic extracts, which derived from P. longum, P. ribesoides and P. sarmentosum, of 8.89, 3.21 and 5.30% (w/w), respectively. All Piper extracts illustrated an impressive adulticidal activity when tested a...

  16. Lymphocyte Redox Imbalance and Reduced Proliferation after a Single Session of High Intensity Interval Exercise

    Tossige-Gomes, Rosalina; Costa, Karine Beatriz; Ottone, Vinícius de Oliveira; Magalhães, Flávio de Castro; Amorim, Fabiano Trigueiro; Rocha-Vieira, Etel

    2016-01-01

    This study investigated whether an acute session of high-intensity interval training (HIIT) is sufficient to alter lymphocyte function and redox status. Sixteen young healthy men underwent a HIIT session on a cycloergometer, consisting of eight bouts of 1 min at 90–100% of peak power, with 75 seconds of active recovery at 30 W between bouts. Venous blood was collected before, immediately after, and 30 minutes after the HIIT session. In response to Staphylococcus aureus superantigen B (SEB) st...

  17. The metacognition levels of students: a research school of physical education and sports at Anadolu University

    Yaliz, Dilek Solmaz

    2014-01-01

    The aim of this research was to find out the perceived metacognition level of Physical Education and Sports School students at Anadolu University and to identify whether metacognition levels display significant differences in terms of various variables. The subject population sample was 416 Anadolu University Physical Education and Sports School students. "The Meta-Cognitions Questionnaire (MCQ-30)" developed by Cartwright-Hatton and Wells and later developed the 30-item short form (MCQ-30) w...

  18. Eudragit® Microparticles for the Release of Budesonide: A Comparative Study

    Rita Cortesi; Laura Ravani; Enea Menegatti; Elisabetta Esposito; Ronconi, F.

    2012-01-01

    This study compares the behaviour of budesonide-containing microparticles made of Eudragit® RS or Eudragit® RS/Eudragit® RL 70:30 (w/w) prepared either by solvent evaporation or spray-drying technique. The loading efficiency of budesonide within microparticles was about 72% for microparticles prepared by solvent evaporation and around 78% for spray-dried microparticles. Thermal analyses were assessed to collect information about the structural stability of budesonide within the polymeric micr...

  19. Effect of Ultrasound on the Compaction of Ibuprofen/Isomalt Systems

    Fini, Adamo; Cavallari, Cristina; Ospitali, Francesca

    2009-01-01

    Six mixtures, containing 10, 20 and 30% w/w ibuprofen and isomalt, were compacted by a traditional or ultrasound-assisted machine and analysed by means of thermal (DSC and TGA) and micro-spectrometry (Raman and FT-IR) techniques. Ultrasound discharge causes melting of ibuprofen powder, transforming into a paste that could not assume the shape of a tablet; when in mixture with isomalt, thermal events, occurring during ultrasound compaction, change the appearance of the particles formed by mill...

  20. Hybrid seed production in detergent induced male sterile Helianthus annuus L.

    Tripathi S.M.; Singh K.P.

    2008-01-01

    Efficacy of a synthetic detergent 'Surf Excel' as a potential male gametocide in Helianthus annuus was evaluated. Foliar applications of three concentrations of 'Surf Excel' solution (1.0, 2.0 and 3.0% w/v) at different plant development stages caused reduction in plant height, pollen fertility, total yield/ plant, 100-seed weight and brought about early flowering in comparison with control plants. All treatments with 'Surf Exce...

  1. Characteristics of a Teflon rod antenna for millimeter and submillimeter wave irradiation on living bodies

    TATSUKAWA, Toshiaki; Doi, Akitaka; TERANAKA, Masato; Takashima, Hitoshi; Goda, Fuminori; Idehara, Toshitaka; Ogawa, Isamu; KANEMAKI, Tomohiro; NISHIZAWA, Seiji; NAMBA, Tunetoyo

    2003-01-01

    The development of a millimeter and submillimeter wave catheter for irradiation on living bodies using a Teflon rod dielectric antenna is described. The power sources of electromagnetic wave are an Impatt oscillator (90 GHz, 0.3 W) and gyrotron (302 GHz, 30 W). Irradiation tests using various Teflon rod dielectric antennas were performed on beef livers. Irradiation results were considered by microwave theory and ray optics.

  2. Physical properties of pre-crystallized mixtures of cocoa butter and cupuassu fat

    Quast, L. B.; Luccas, V.; T. G. Kieckbusch

    2011-01-01

    The physical characteristics of pre-crystallized binary mixtures of cocoa butter (Bahia + Indonesian blend) and 5, 10, 15, 20, 25 and 30% (w/w) cupuassu fat were determined. Precrystallization was carried out using a lab-scale agitated jacket vessel reactor (700 mL). Samples were submitted to differential scanning calorimetry and X-Ray diffraction. The solid fat content and rupture force were also quantified. The snap values of the crystallized mixture decreased with an increase in the amount...

  3. The influence of starch molecular mass on the properties of extruded thermoplastic starch

    Vliegenthart, J. F. G.; van Soest, J.J.G.; Benes, K.; de Wit, D

    1996-01-01

    The mechanical properties of a low and a high molecular mass thermoplastic starch (TPS) were monitored at water contents in the range of 5–30% (w/w). The granular starches were plasticized by extrusion processing with glycerol and water. The low molecular mass starch was prepared by partial acid hydrolysis of potato starch. The extruded TPS materials were stored at 60% relative humidity for 12 months to level out differences in starch structure due to retrogradation. The water content was the...

  4. FORMULATION AND IN VITRO EVALUATION OF ARAUCARIA BIDWILLI GUM-BASED SUSTAIN RELEASE MATRIX TABLETS OF DICLOFENAE SODIUM

    J. ASHOK KUMAR, M.RAJESH, S.MYTHIESH KUMAR,T. GIRIRAJ KULKARNI, V.GOPAL

    2013-10-01

    Full Text Available A gel forming Polysaccharide gum obtained form the bark of Araucaria bidwilli was employed as a matrix sustained release tablet formulation of Diclofenac sodium (a non steroidal anti inflammatory agent. The effect of Araucaria bidwilli gum (Natural and Synthetic polymer Hydroxypropyl methyl cellulose (HPMC K4 M on the release of Diclofenac sodium was studied. The FT-IR spectroscopic studies of drug, gum and mixture indicated no chemical interaction. Six formulations were prepared by wet granulation method containing Araucaria bidwilli gum powder concentration 10% 20% & 30% w\\w and 10% 20% &30% w\\w of HPMC K4 M with sufficient volume of granulating agent Polyvinyl pyrrolene (PVP K 30, Avicel pH101 as diluents, Magnesium stearate and Aerosil is used lubricant and glidant respectively.This study was carried out to find out the difference between synthetic and natural gum and whether synthetic gum can be replaced by natural gums. Physical and technological studies of granules and tablets were compliance with Pharmacopoial standards.The drug release increased with Araucaria bidwilli gum when compared to synthetics polymer concentration .The value of release exponent were found to be almost straight line and regression coefficient value between 0.938 and 0.998.This implies that the release mechanism is diffusion. Formulation F3 ( contained 30% w\\w Araucaria bidwilli gum met the desired requirements for a sustained release dosage form.

  5. 全光纤结构超短脉冲超连续谱的产生及其特性研究%All- fiber ultra- short super- continuum generation and characters

    于峰; 孙畅; 高静; 匡鸿深; 张晶; 高鹏坤; 葛廷武; 王智勇

    2014-01-01

    Super﹣continuum (SC) is widely used in coherent photography technology, optical spectroscopy analysis, interferometry, etc because of its flat and broad spectrum, high spatial coherence and high power. Super﹣continuum generation could be realized on theory by ultra﹣short pulse laser getting through the high nonlinear medium, accompany with self﹣phase modulation (SPM), stimulated Raman scattering (SRS), four﹣wave mixing (FWM). With the development of fiber technology, Yb- doped ultra﹣short pulse fiber laser, which has high peak power, high optic﹣to﹣optic efficiency, compact structure and small volume was elected as the pump source, and high nonlinear photonic crystal fiber (PCF) as the nonlinear medium for SC. In this paper, a self﹣made amplified mode﹣locked pulse was coupled into a 10m PCF, with 1 040 nm zero dispersion point, to generate 8.13W super﹣continuum by fusing method, during which the key parameters like discharge time, discharge interval, splice loss are seriously optimized to keep the fusing quality well.%超连续光谱以其光谱范围宽、平坦度好、空间相干度高和可实现的较高功率,被广泛应用于相干成像技术、光谱分析、干涉测量等诸多领域。理论上超连续光谱可由超短脉冲通过高非线性介质来实现,期间伴随着自相位调制(SPM)、受激拉曼散射(SRS)、四波混频效应(FWM)。随着光纤技术的发展,利用峰值功率高、光光转换效率高、体积小、结构紧凑的掺Yb超短脉冲光纤激光器作为泵浦源,高非线性的光子晶体光纤作为非线性介质来产生超连续光谱。采用主振荡功率放大结构(MOPA),自行搭建了全光纤锁模脉冲放大器,并通过熔接的方式将其耦合进入长为10 m、零色散点为1040 nm的光子晶体光纤,在对熔接过程中放电时间、放电间隔、熔接损耗等参数进行优化后,获得了8.14 W的超连续光谱。

  6. 4f and 5d energy levels of the divalent and trivalent lanthanide ions in M{sub 2}Si{sub 5}N{sub 8} (M=Ca, Sr, Ba)

    Kate, O.M. ten, E-mail: o.m.tenkate@tudelft.nl [Luminescent Materials Research Group, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands); Energy Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Den Dolech 2, 5600MB Eindhoven (Netherlands); Zhang, Z. [Energy Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Den Dolech 2, 5600MB Eindhoven (Netherlands); Dorenbos, P. [Luminescent Materials Research Group, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands); Hintzen, H.T. [Energy Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Den Dolech 2, 5600MB Eindhoven (Netherlands); Kolk, E. van der [Luminescent Materials Research Group, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands)

    2013-01-15

    Optical data of Sm, Tb and Yb doped Ca{sub 2}Si{sub 5}N{sub 8} and Sr{sub 2}Si{sub 5}N{sub 8} phosphors that have been prepared by solid-state synthesis, are presented. Together with luminescence data from literature on Ce{sup 3+} and Eu{sup 2+} doping in the M{sub 2}Si{sub 5}N{sub 8} (M=Ca, Sr, Ba) hosts, energy level schemes were constructed showing the energy of the 4f and 5d levels of all divalent and trivalent lanthanide ions relative to the valence and conduction band. The schemes were of great help in interpreting the optical data of the lanthanide doped phosphors and allow commenting on the valence stability of the ions, as well as the stability against thermal quenching of the Eu{sup 2+}d-f emission. Tb{sup 3+} substitutes on both a high energy and a low energy site in Ca{sub 2}Si{sub 5}N{sub 8}, due to which excitation at 4.77 eV led to emission from both the {sup 5}D{sub 3} and {sup 5}D{sub 4} levels, while excitation at 4.34 eV gave rise to mainly {sup 5}D{sub 4} emission. Doping with Sm resulted in typical Sm{sup 3+}f-f line absorption, as well as an absorption band around 4.1 eV in Ca{sub 2}Si{sub 5}N{sub 8} and 3.6 eV in Sr{sub 2}Si{sub 5}N{sub 8} that could be identified as the Sm{sup 3+} charge transfer band. Yb on the other hand was incorporated in both the divalent and the trivalent state in Ca{sub 2}Si{sub 5}N{sub 8}. - Graphical abstract: Energy level schemes showing the 4f ground states of the trivalent ( Black-Down-Pointing-Small-Triangle ) and divalent ( Black-Up-Pointing-Small-Triangle ) lanthanide ions and lowest energy 5d states of the trivalent ({nabla}) and divalent ({Delta}) ions with respect to the valence and conduction bands of Ca{sub 2}Si{sub 5}N{sub 8} (left) and Sr{sub 2}Si{sub 5}N{sub 8} (right). Highlights: Black-Right-Pointing-Pointer Construction of energy level schemes of all lanthanides within the M{sub 2}Si{sub 5}N{sub 8} hosts. Black-Right-Pointing-Pointer Construction was done by analyzing existing as well as new

  7. THE INVESTIGATION OF THE PRODUCT OF GUAIACOL ENZYMATIC OXIDATION IN WATER – DMSO BINARY SOLVENTS

    Сергей Александрович Покрышкин; Константин Григорьевич Боголицын

    2014-01-01

    The investigation on the reaction of enzymatic oxidation of guaiacol as lignin model compound with hydrogen peroxide in the presence of horseradish peroxidase  in water – DMSO binary solvents was done. Using the method of gas chromatography – mass spectrometry the five dimeric products of guaiacol oxidative coupling are identified. The possibility of the using of peroxidase in the mixtures of water with DMSO in the range of solvent compositions up to 30% (w/w) DMSO is shown. For the solvent c...

  8. Parameterized Analysis of Zero Voltage Switching in Resonant Converters for Optimal Electrode Layout of Piezoelectric Transformers

    Meyer, Kaspar Sinding; Andersen, Michael Andreas E.; Jensen, Flemming

    2008-01-01

    Ring shaped PTs (Piezoelectric Transformers) are an attractive alternative to magnetics in power converters. The achievable energy efficiency is 98% and the power density is up to 30W/cm3. Additionally power supplies based on PTs display low levels of conducted and radiated EMI due to power...... conversion based on the piezoelectric effect. Rooted in the physics of this effect, both the in- and output terminal of a PT has a noticeable parasitic capacitance. In a common half-bridge power stage without any supporting magnetic components, the input parasitic capacitance can lead to hard switching...

  9. High power amplification of a tailored-pulse fiber laser

    Saby, Julien; Sangla, Damien; Caplette, Stéphane; Boula-Picard, Reynald; Drolet, Mathieu; Reid, Benoit; Salin, François

    2013-02-01

    We demonstrate the amplification of a 1064nm pulse-programmable fiber laser with Large Pitch Rod-Type Fibers of various Mode field diameters from 50 to 70 μm. We have developed a high power fiber amplifier at 1064nm delivering up to 100W/1mJ at 15ns pulses and 30W/300μJ at 2ns with linearly polarized and diffraction limited output beam (M²LBO crystals leading to 50W at 532nm and 25W at 355nm with a diffraction limited output. Similar experiments performed at 1032nm are also reported.

  10. High power, continuous-wave, single frequency fiber amplifier at 1091 nm and frequency doubling to 545.5 nm

    Stappel, M.; Steinborn, R.; Kolbe, D.; Walz, J

    2012-01-01

    We present a high power single-frequency ytterbium fiber amplifier system with an output power of 30 W at 1091 nm. The amplifier system consists of two stages, a preamplifier stage in which amplified spontaneous emission is efficiently suppressed (>40 dB) and a high power amplifier with an efficiency of 52 %. Two different approaches of frequency doubling are compared. We achieve 8.6 W at 545.5 nm by single-pass frequency doubling in a MgO-doped periodically poled stoichiometric LiTaO3 and up...

  11. Spin Density Matrix Elements in exclusive production of ω mesons at Hermes

    Marianski B.

    2014-03-01

    Full Text Available Spin density matrix elements have been determined for exclusive ω meson production on hydrogen and deuterium targets, in the kinematic region of 1.0 < Q2 < 10.0 GeV2, 3.0 < W < 6.3 GeV and –t' < 0.2 GeV2. The data, from which SDMEs are determined, were accumulated with the HERMES forward spectrometer during the running period of 1996 to 2007 using the 27.6 GeV electron or positron beam of HERA. A sizable contribution of unnatural parity exchange amplitudes is found for exclusive ω meson production.

  12. Spin Density Matrix Elements in exclusive production of ω mesons at Hermes

    Marianski, B.; Terkulov, A.

    2014-03-01

    Spin density matrix elements have been determined for exclusive ω meson production on hydrogen and deuterium targets, in the kinematic region of 1.0 < Q2 < 10.0 GeV2, 3.0 < W < 6.3 GeV and -t' < 0.2 GeV2. The data, from which SDMEs are determined, were accumulated with the HERMES forward spectrometer during the running period of 1996 to 2007 using the 27.6 GeV electron or positron beam of HERA. A sizable contribution of unnatural parity exchange amplitudes is found for exclusive ω meson production.

  13. Atmospheric Boundary Layer Height Evolution with Lidar in Buenos Aires from 2008 to 2011

    Pawelko, Ezequiel Eduardo; Salvador, Jacobo Omar; Ristori, Pablo Roberto; Pallotta, Juan Vicente; Otero, Lidia Ana; Quel, Eduardo Jaime

    2016-06-01

    The analysis of the atmospheric boundary layer top height evolution is obtained from 2008 to 2011 in Buenos Aires using the multiwavelength lidar located at CEILAP (CITEDEF-CONICET) (34°33' S; 58°30' W; 17 m asl). Algorithms recognition based on covariance wavelet transform are applied to obtain seasonal statistics. This method is being evaluated for use in the Lidar Network in Argentina and it is being deployed in Patagonia region currently. The technique operates in real time in both low and high aerosol loads and with almost no human supervision.

  14. Enhanced Coagulation Efficiency of Moringa Oleifera Seeds Through Selective Oil Extraction

    2012-01-01

    In this laboratory based study, varying quantities of oil, corresponding to 20 % w/w, 25 % w/w and 30 % w/w kernel weight extracted from Moringa oleifera seeds ( S1, S2, S3) respectively  were applied in the coagulation of model turbid water (kaolin suspension) and turbid river water samples from River Batang Kali and River Selangor in Malaysia to determine the percentage oil removed which gave the best coagulation efficiency. For model turbid water (kaolin suspension) coagulation of low...

  15. Low cryogen inventory, forced flow Ne cooling system with room temperature compression stage and heat recuperation

    Shornikov, A; Wolf, A

    2014-01-01

    We present design and commissioning results of a forced flow cooling system utilizing neon at 30 K. The cryogen is pumped through the system by a room-temperature compression stage. To decouple the cold zone from the compression stage a recuperating counterflow tube-in-tube heat exchanger is used. Commissioning demonstrated successful condensation of neon and transfer of up to 30 W cooling power to the load at 30 K using only 30 g of the cryogen circulating in the system at pressures below 170 kPa.

  16. Cruise report: regional assessment of ecosystem condition and stressor impacts along the northwestern Gulf of Mexico Shelf. NOAA Ship 'Nancy Foster' NF-11-07-RACOW (August 8-16, 2011)

    Cooksey, Cynthia; Hyland, Jeff; Fulton, Mike

    2011-01-01

    This cruise report is a summary of a field survey conducted along a portion of the U.S. continental shelf in northwestern Gulf of Mexico (GOM), at navigable depths along the coastline seaward to the shelf break (~100m) from about 89°30' W to 95°28' W longitude, August 8 – 16, 2011 on NOAA Ship Nancy Foster Cruise NF-11-07-RACOW. Synoptic sampling of multiple ecological indicators was conducted at each of 34 stations throughout these waters using a random probabilistic sampling design. The ori...

  17. Optimization of Fluorine Plasma Treatment for Interface Improvement on HfO2/In0.53Ga0.47As MOSFETs

    Yen-Ting Chen; Yanzhen Wang; Fei Xue; Fei Zhou; Jack C. Lee

    2012-01-01

    This paper reports significant improvements in the electrical performance of In0.53Ga0.47As metal-oxide-semiconductor field-effect transistors (MOSFET) by a post-gate CF4/O2 plasma treatment. The optimum condition of CF4/O2 plasma treatment has been systematically studied and found to be 30 W for 3–5 min. Approximately 5× reduction in interface trap density from 2.8 × 1012 to 4.9 × 1011 cm−2eV−1 has been demonstrated with fluorine (F) incorporation. Subthreshold swing has been improved from 1...

  18. EVALUACIÓN DE LA CAPACIDAD PROBIÓTICA “IN VITRO” DE UNA CEPA NATIVA DE Saccharomyces cerevisiae

    Ángela Ortiz; Joanna Reuto; Erika Fajardo; Sandra Sarmiento; Andrea Aguirre; Gustavo Arbeláez; David Gómez; Balkys Quevedo-Hidalgo

    2008-01-01

    The in vitro probiotic capacity of a native strain of Saccharomyces cerevisiae (A) was evaluated and comparedwith a commercial strain (B) used as a probiotic. The effect of the concentration of sugarcane molasses (10, 20and 30% (w/v)) on the biomass production was investigated and kinetic parameters were determined. The bestmolasses concentration was 20% (w/v) and differences in biomass production on molasses medium betweenstrain A (28 g/L) and control strain B (3 g/L) were observed. In vitro...

  19. High power, diode pumped Er:YAG for dentistry

    Hagen, C.; Heinrich, A.; Nussbaumer, B.

    2011-03-01

    Pantec Medical Laser presents a diode pumped Er:YAG laser for dental and hard tissue applications. The diode pumped laser is practically maintenance free and ensures reliable operation over several thousand hours. The high repetition rate with up to 15 W average output power, allows treatments otherwise not feasible with low repetition rate, lamp pumped Er:YAG systems. The variable pulse duration of 10 to 200 μs combined with the good beam quality ensures precise and fast treatment. First results on enamel ablation as well as the power scalability of the technology to 200 mJ and 30 W average power are also shown.

  20. Growth acceleration and photosynthesis of the scenedesmus algae and cocconeis algae in deuterium water

    In order to find new way to treat the radioactive tritium waste water, scenedesmus algae and cocconeis algae are cultured in medium which contains 30% (w) deuterium water. During different time, activities of photosymthesis, absorption spectrum, growth rate and low-temperature fluorescence spectrum are measured. Accelerated growth is found in the deuterium water compared to the normal water. Activities of photosynthesis show the similar result (Fv/Fm) to the growth data. It is also concluded from low-temperature fluorescence spectra that algae activities in the deuterium water, which are expressed by PS I/PS II, are more sensitive than those in the normal water

  1. Laser treatment of carbon fibre reinforced thermoplastic matrix for adhesive bonding

    Genna, S.; Leone, C.; Ucciardello, N.; Giuliani, M.

    2016-05-01

    In the present study, laser surface treatment of CFRP made of PPS thermoplastic matrix by means of a 30 W Q-Switched Yb:YAG fiber laser, is investigated with the aim to improve adhesive bonding. The process parameters pulse power, scanning speed, hatch distance and scanning strategy, were varied to the aim to study the influence of the process condition on the first top resin layer removal and fibre damage. The operating window was experimentally determined. The effectiveness of laser treatment was verified by single lap shear test.

  2. Laser cutting technology using water jet waveguide

    Laser with water jet is examined to cut in-vessel structure. However, it is necessary to increase the break-up length of water jet to cut a thick plate. Therefore, the effects of the water jet parameter (water pressure, assist gas, laser power) on break-up length were investigated. It was found from observation results of water jet that the longest break-up length is about 135mm under condition of water pressure 40 MPa, laser power 30W and helium assist gas 1L/min. (author)

  3. A high-solids steam injection process for the manufacture of powdered infant milk formula

    Murphy, Eoin; Tobin, John; Roos, Yrjo; Fenelon, Mark

    2013-01-01

    Introduction of more energy efficient processing practices, such as increasing the initial solids content from which powder is manufactured, is of interest to the infant formula industry. This study evaluated the use of an inline rotor-stator mixer followed by direct steam injection to disperse and heat-treat (110 °C, 3 s) high-solids (60% w/w) formulations, for the production of powdered infant milk formula. As a control, 30% w/w infant milk formulations were subjected to a typical process, ...

  4. Distribution and relative abundance of large whales in a former whaling ground off eastern South America

    Artur Andriolo; Jesuina M. da Rocha; Zerbini, Alexandre N.; Paulo C. Simões-Lopes; Moreno, Ignacio B.; Alineide Lucena; Daniel Danilewicz; Manuela Bassoi

    2010-01-01

    Ship-based sighting surveys for cetaceans were conducted in the former whaling ground off the northeastern coast of Brazil. The cruises took place in winter and spring of 1998-2001 with the objectives of investigating current distribution and abundance of cetaceans, particularly large whale species taken during whaling. In 1998 the survey were conducted between the parallels 5°30'W and 9°S and the 200 m isobath and the meridian 033°W. A total of about 3,100 nm were surveyed between 1998 and 2...

  5. The bryophytes of Trindade Island, South Atlantic, Brazil As briófitas da Ilha da Trindade, Atlântico Sul, Brasil

    Allan Laid Alkimim Faria; Micheline Carvalho-Silva; Denise Pinheiro da Costa; Paulo Eduardo Aguiar Saraiva Câmara

    2012-01-01

    Trindade is a Brazilian oceanic island located about 1,200 Km east of the Brazilian coast (between 20º 31' 30" S, 29º 19' 30'' W). The island originated from the abissal zone about 3 million years ago, has a maximum altitude of 620 meters and an area of 9.28 Km². Even though the fanerogamic flora is known, there were virtually no data on the bryophyte flora. Four expeditions to the island were carried out during two years and approximately 431 specimens collected. This work presents the Bryof...

  6. PRODUCTION OF LIPASES IN SOLID-STATE FERMENTATION BY Aspergillus niger F7-02 WITH AGRICULTURAL RESIDUES

    Olayinka Quadri Adio; Sarafdeen Olateju Kareem; Michael Bamitale Osho; Adebukola Mobolaji Omemu

    2015-01-01

    In this study mould strains screened and molecularly identified as Aspergillus niger F7-02 was used to produced extracellular lipase in Solid State Fermentation (SSF) process. Different agricultural residues were combined in different ratios as carbon, nitrogen and elemental sources in the solid culture medium. The optimization of the culture medium was carried out for such parameters as incubation time (24 h - 96 h), inoculum concentration (0.5 – 3.0%, w/v), initial moisture content (40 – 70...

  7. Two-Stage Power Conversion Architecture Suitable for Wide Range Input Voltage

    Lim, Seungbum; Ranson, John David; Otten, David M.; Perreault, David J.

    2014-01-01

    This paper presents a merged-two-stage circuit topology suitable for either wide-range dc input voltage or ac line voltage at low-to-moderate power levels (e.g., up to 30 W). This two-stage topology is based on a soft-charged switched-capacitor preregulator/transformation stage and a high-frequency magnetic regulator stage. Soft charging of the switched capacitor circuit, zero voltage switching of the high-frequency regulator circuit, and time-based indirect current control are used to mainta...

  8. INVESTIGATION OF ULTRASOUND WAVES ON PRETREATMENT OF OSMOTIC DEHYDRATION OF CARROT SLICES

    Tahmasebi, Soheila; Mirzaee, Somaye; Kaviyani, Mehdi; Tabrizi, Mahsa; Shariati, Mohammad

    2014-01-01

    In this study, carrot slices were put in glucose osmotic 50% at 1, 2 and 3 hr. Ultrasound waves, frequency 40 kH power 30 w/l, passed through container of osmotic solution and carrot slices. The results revealed that significant increasing of dry matter of sample by using ultrasound waves.pre osmotic time had a significant on dry material by increasing from 1to 3 hr.sample treated by ultrasound waves lost water faster and their final dry solid was significantly more than control (without ultr...

  9. Effect of Microwave Heating on Potato and Tapioca Starches in Water Suspension

    Nurul Nadiah binti Ismail; Uthumporn Utra @ Sapina Abdullah; Syahariza Zainul Abidin

    2015-01-01

    The effects of microwave heating on properties of starch were studied on potato and tapioca starches in water suspension at different temperature (50°C and 60°C). Potato and tapioca starches were adjusted to 30% (w/v) and heat-moisture treated in a microwave oven and conventional heating.Conventional heating was carried out by direct heating the moisture heated sample at 50oC and 60oC while the microwave heating was carried out by microwave oven and the temperature was controlled approximatel...

  10. Effect of Microwave Heating on Potato and Tapioca Starches in Water Suspension

    Nurul Nadiah Ismail; U. Uthumporn; Z. A. Syahariza

    2016-01-01

    Abstract— The effects of microwave heating on properties of starch were studied on potato and tapioca starches in water suspension at different temperature (50°C and 60°C). Potato and tapioca starches were adjusted to 30% (w/v) and heat-moisture treated in a microwave oven and conventional heating.Conventional heating was carried out by direct heating the moisture heated sample at 50ºC and 60ºC while the microwave heating was carried out by microwave oven and the temperature was controlled ap...

  11. Biochemical and Bioimaging Evidence of Cholesterol in Acquired Cholesteatoma

    Thorsted, Bjarne; Bloksgaard, Maria; Groza, Alexandra;

    2016-01-01

    results show that the total lipid content of the cholesteatoma matrix is similar to that of stratum corneum from skin and that the cholesteatoma matrix unquestionably contains cholesterol. The cholesterol content in the cholesteatoma matrix is increased by over 30% (w/w dry weight) compared to the control....... The cholesterol sulfate content is below 1% of the total lipids in both the cholesteatoma and the control. Cholesterol ester was reduced by over 30% when compared to the control. CONCLUSIONS: The content of cholesterol in the cholesteatoma matrix is significantly different from that in stratum corneum...

  12. Performance of the Oxford miniature Stirling cycle refrigerator

    Bradshaw, T. W.; Delderfield, J.; Werrett, S. T.; Davey, G.

    The 'Oxford Cryocooler' miniature Stirling cycle cooler, a 5-kg mass split-cycle refrigerator developed for use aboard spacecraft, had as its design performance goal the production of 0.5 W of cooling power at 80 K for 30 W of electrical input power. The goal has actually been exceeded, prompting the present discussion of the compressor power budget and displacer losses. Attention is given to graphs of the cold-end temperature vs. compressor input power and cooling power. The cooler is to be used on the Improved Stratospheric and Mesospheric Sounder experiment of the Upper Atmosphere Research Satellite.

  13. Measured versus calculated thermal conductivity of high-grade metamorphic rocks – inferences on the thermal properties of the lower crust at ambient and in-situ conditions

    Ray, Labani; Förster, Hans-Jürgen; Förster, Andrea;

    The bulk thermal conductivity (TC) of 26 rock samples representing felsic, intermediate and mafic granulites, from the Southern Granulite Province, India, is measured at dry and saturated conditions with the optical-scanning method. Thermal conductivity is also calculated from modal mineralogy...... (determined by XRD and EPMA), applying mixing models commonly used in thermal studies. Most rocks are fine- to medium -grained equigranular in texture. All samples are isotropic to weakly anisotropic and possess low porosities (< 2%). Measured TC values range between 2.5 and 3.0 W/(mK) for felsic granulites...

  14. Primeiro registro de Myriastra purpurea (Ridley, 1884 para a costa brasileira (Porifera, Demospongiae

    Beatriz Mothes de Moraes

    1984-01-01

    Full Text Available The first record of occurrence of Myriastra purpurea (Ridley, 1884 for the South Atlantic Ocean at shallow areas of the Brazilian coast (State of Rio de Janeiro, Sepetiba Bay: 23º04'53"/44º00'34"W and State of Santa Catarina, Porto Belo: 27º09'12"S/48º29'30"W widely enlarges the distribution of the species, known only from the Indo-Pacific region. Detailed descriptions and ilustrations of the specimens are offered. A table of micrometric measurements and camera lucida drawings of spicules is also offered.

  15. Dielectric study of the glass transition of PET/PEN blends

    Sellares, J.; Diego, J A; Canadas, J. C.; Mudarra, M.; Belana, J.; Colomer, P.; Roman, F.; Y. Calventus

    2012-01-01

    An analysis of the glass transition of four materials with similar chemical structures is performed: PET, PEN and two PET/PEN blends (90/10 and 70/30 w/w). During the melt processing of the blends transesterification reactions yield block and random PET/PEN copolymers that act as compatibilizers. The blends obtained in this way have been characterized by 1H-NMR and DSC. A degree of randomness of 0.38 and 0.26 has been found for the 90/10 and 70/30 copolymers. It is shown by DSC that this copo...

  16. Photonic crystal fibers for supercontinuum generation pumped by a gain-switched CW fiber laser

    Larsen, Casper; Noordegraaf, Danny; Hansen, Kim P.;

    2012-01-01

    Supercontinuum generation in photonics crystal fibers (PCFs) pumped by CW lasers yields high spectral power density and average power. However, such systems require very high pump power and long nonlinear fibers. By on/off modulating the pump diodes of the fiber laser, the relaxation oscillations...... of the laser can be exploited to enhance the broadening process. The physics behind the supercontinuum generation is investigated by sweeping the fiber length, the zero dispersion wavelength, and the fiber nonlinearity. We show that by applying gain-switching a high average output power of up to 30 W...

  17. Drilling and cutting of thin metal plates in water with radiation of a repetitively pulsed Nd : YAG laser

    Glova, A. F.; Lysikov, A. Yu

    2011-10-01

    The conditions of drilling and cutting of 0.15-mm-thick titanium and stainless steel plates in water with the radiation of a repetitively pulsed Nd : YAG laser having the mean power up to 30 W are studied experimentally in the absence of water and gas jets. Dependences of the maximal cutting speed in water on the radiation power are obtained, the cutting efficiency is determined, and the comparison with the conditions of drilling and cutting of plates in air is carried out.

  18. Drilling and cutting of thin metal plates in water with radiation of a repetitively pulsed Nd : YAG laser

    The conditions of drilling and cutting of 0.15-mm-thick titanium and stainless steel plates in water with the radiation of a repetitively pulsed Nd : YAG laser having the mean power up to 30 W are studied experimentally in the absence of water and gas jets. Dependences of the maximal cutting speed in water on the radiation power are obtained, the cutting efficiency is determined, and the comparison with the conditions of drilling and cutting of plates in air is carried out.

  19. Application of Green Chemistry Principle in Synthesis of Phenytoin and Its Biogical Evaluation as Anticonvulsant Agents

    Abhijit Kadam; Sampada Jangam; Rajesh Oswal

    2011-01-01

    Phenytoin (5,5'-dipenylimidazolidine-2,4-dione) is the prime example of anticonvulsant agent. According to reported procedure, it is synthesized by condensation of benzil and urea in presence of base (30% w/v NaOH) using ethanol as solvent which itself acts as CNS stimulant. Removal of solvent after synthesis is most difficult and non-assured process. In case of phenytoin transformation in polymorphism plays an important role when solvent other than water is used. About 30% extra cost is calc...

  20. Nano-Welding of Multi-Walled Carbon Nanotubes on Silicon and Silica Surface by Laser Irradiation

    Yanping Yuan; Jimin Chen

    2016-01-01

    In this study, a continuous fiber laser (1064 nm wavelength, 30 W/cm2) is used to irradiate multi-walled carbon nanotubes (MWCNTs) on different substrate surfaces. Effects of substrates on nano-welding of MWCNTs are investigated by scanning electron microscope (SEM). For MWCNTs on silica, after 3 s irradiation, nanoscale welding with good quality can be achieved due to breaking C–C bonds and formation of new graphene layers. While welding junctions can be formed until 10 s for the MWCNTs on s...

  1. RHEOLOGICAL PROPERTIES AND THE ENERGETIC VALUE OF WHEAT FLOUR SUBSTITUTED BY DIFFERENT SHARES OF WHITE AND BROWN RICE FLOUR

    Nada Nikolić; Jelena Dodić; Mirjana Mitrović; Miodrag Lazić

    2011-01-01

    In order to produce dough with a lower gluten content, more enriched with rice components and satisfactory rheological properties, the rheological properties, energetic value and cake baking properties of wheat and white or brown rice flour in shares from 3 to 30% (w/w) were investigated in this paper. The water absorption in wheat-rice flour mixtures was lower and decreased to 53.5% and 54.0% along with the increase of the white and the brown rice flour share, respectively, than in wheat fl...

  2. Selective grazing from protist over enteric bacteria in an aquatic system

    Its very clear that the grazing from protozoan can be an important source of mortality for the suspended bacteria, both in marine and freshwater environments. Considering that the presence of fecal contamination its a frequent phenomenon in this environments, and that Escherichia coli and members of Enterococcus genera are indicators of microbiology water quality, we analyze the effect of grazing from protozoan over E. coli and Enterococcus faecalis in de Los Padres Lagoon waters (Buenos Aires, Argentina) 37 degree centigrade 56'30'' S, 57 degree centigrade 44'30'' W). (Author)

  3. MRI-Based Thermometry for Tumor Thermal Ablation: A Comparison of Different MR Sequences

    Vogl, T.J.; W. Maentele; Vogel, V.; Larson, M.C.; F. Huebner; Babak Bazrafshan

    2010-01-01

    Background/Objective: To evaluate T1 and PRF thermometry methods utilizing fast MR sequences and fluoroptic thermometer."nMaterials and Methods: The MR-guided LITT (Laser-Induced Interstitial Thermotherapy) with a laser wavelength/power of 1064nm/30W was applied to pig liver and a gel phantom. During the ablation process, the temperature was measured using a fluoroptic thermometer and MR imaging was performed applying a 1.5-Tesla tomograph with an EPI (Echo Planar Imaging) sequence for P...

  4. Facile synthesis of water-soluble carbon nano-onions under alkaline conditions

    Ahmed, Gaber Hashem Gaber; Laíño, Rosana Badía; Calzón, Josefa Angela García; García, Marta Elena Díaz

    2016-01-01

    Carbonization of tomatoes at 240 °C using 30% (w/v) NaOH as catalyst produced carbon onions (C-onions), while solely carbon dots (C-dots) were obtained at the same temperature in the absence of the catalyst. Other natural materials, such as carrots and tree leaves (acer saccharum), under the same temperature and alkaline conditions did not produce carbon onions. XRD, FTIR, HRTEM, UV–vis spectroscopy, and photoluminescence analyses were performed to characterize the as-synthesized carbon nanom...

  5. Yb:YAG single crystal fiber power amplifier for femtosecond sources.

    Délen, Xavier; Zaouter, Yoann; Martial, Igor; Aubry, Nicolas; Didierjean, Julien; Hönninger, Clemens; Mottay, Eric; Balembois, François; Georges, Patrick

    2013-01-15

    We demonstrate a versatile femtosecond power amplifier using a Yb:YAG single crystal fiber operating from 10 kHz to 10 MHz. For a total pump power of 75 W, up to 30 W is generated from the double-pass power amplifier. At a repetition rate of 10 kHz, an output energy of 1 mJ is obtained after recompression. In this configuration, the pulse duration is 380 fs, corresponding to a peak power of 2.2 GW. The M2 beam quality factor is better than 1.1 for investigated parameters. PMID:23454931

  6. Yb:YAG single crystal fiber power amplifier for femtosecond sources

    Délen, Xavier; Zaouter, Yoann; Martial, Igor; Aubry, Nicolas; Didierjean, Julien; Hönninger, Clemens; Mottay, Eric; Balembois, François; Georges, Patrick

    2013-01-01

    We demonstrate a versatile femtosecond power amplifier using a Yb:YAG single crystal fiber operating from 10 kHz to 10 MHz. For a total pump power of 75 W, up to 30 W is generated from the double-pass power amplifier. At a repetition rate of 10 kHz, an output energy of 1 mJ is obtained after recompression. In this configuration, the pulse duration is 380 fs, corresponding to a peak power of 2.2 GW. The M2 beam quality factor is better than 1.1 for investigated parameters.

  7. 电纺丝技术制备组织工程食管仿生支架%Preparation of tissue-engineered esophageal scaffolds using electrospinning technology

    於学婵; 沈秋霞; 卢珍珍; 张陈; 邓玲; 胡品; 竺亚斌

    2014-01-01

    BACKGROUND:We have found that oriented fibers can guide the alignment of smooth muscle cells in our previous experiments. Thus, we designed the experiment to prepare wel aligned polymeric fibers using electrospinning technology, aiming at guiding the growth of esophageal smooth muscle cells to maintain cellmorphology and biological function. OBJECTIVE:Using electrospinning technology, to fabricate isotropic and directed nano-fibrous scaffolds made of polycaprolacton, gelatin and silk fibroin. METHODS:Polycaprolacton/silk fibroin fibers at a ratio of 4:1 were prepared with proper parameters, including solution concentration, voltage and injection speed, under the self-made spinning system. The polycaprolacton/gelatin sheets with mass ratio of 2:1, 1:1 and 1:2, respectively, were also fabricated under suitable process parameters. Using the rol er col ector instead of the metal plate, polycaprolacton/gelatin nano-fibrous scaffold with good alignment of fibers was manufactured. RESULTS AND CONCLUSION:The isotropic polycaprolacton/silk fibroin scaffold with fiber diameter of (535.9±126.7) nm was prepared under conditions of solution concentration (0.08 g/mL), injection speed (1.6 mL/h) and voltage (22.5 kV), and these fibers were uniform with no beads. The isotropic polycaprolacton/gelatin scaffold with fiber diameter of (257.9±117.8) nm was prepared under conditions of solution concentration (0.10 g/mL), injection speed (0.8 mL/h) and voltage (22.5 kV). Using the rol er col ector instead of the previous metal plate, polycaprolacton/gelatin (w:w, 1:2) nano-fibrous scaffold with good alignment of fibers was manufactured. The process parameters were 3 000 r/min of rol ing speed, 0.8 mL/h of injection speed and 15 kV of voltage.%背景:前期实验中曾发现纤维的取向可以引导平滑肌细胞的取向生长,因此,设想通过制备取向排列的电纺丝纤维支架,以引导食管平滑肌细胞的有序生长,从而有利于维持肌细胞的形貌及生物功能。目的:以可降解聚己内酯、明胶、丝素蛋白为基材,采用自制的电纺丝系统制备无规和有序的纳米级多孔纤维。方法:将聚己内酯与丝素蛋白以4∶1质量比混合,通过调整溶液浓度、电压、喷射速度等参数,采用自制的电纺丝系统制备聚己内酯/丝素蛋白电纺丝纤维。将聚己内酯与明胶分别以2∶1、1∶1、1∶2质量比混合,在金属平板接收器下,通过调整溶液浓度、电压、喷射速度等参数,采用自制的电纺丝系统制备聚己内酯/明胶无规电纺丝纤维;同时改用滚轴接收装置,通过调整滚轴转数、电压、喷射速度等参数,制备聚己内酯/明胶有序电纺丝纤维。结果与结论:在溶液质量浓度为0.08 g/mL、纺丝液流速1.6 mL/h和电压22.5 kV的条件下,制得了均匀、无串珠、纤维直径为(535.9±126.7) nm的聚己内酯/丝素蛋白多孔纳米纤维膜。在溶液质量浓度为0.10 g/mL、纺丝液流速0.8 mL/h和电压22.5 kV的条件下,制得了无明显串珠、纤维直径为(257.9±117.8) nm的聚己内酯/明胶多孔纳米纤维膜;并且在1∶2质量比时更易成纤维,纤维尺寸更均匀。在滚轴转速3000 r/min。溶液流速0.8 mL/h。电压15 kV的条件下,制得的聚己内酯/明胶有序电纺丝纤维排序更理想,纤维也更均匀。

  8. Laser-induced thermotherapy (LITT) - evaluation of a miniaturised applicator and implementation in a 1.0-T high-field open MRI applying a porcine liver model

    Streitparth, Florian; Knobloch, Gesine; Rump, J.; Wonneberger, Uta; Hamm, Bernd; Teichgraeber, Ulf [Charite, Humboldt-Universitaet zu Berlin, Department of Radiology, Berlin (Germany); Balmert, Dirk [Somatex Medical Technologies GmbH, Teltow (Germany); Chopra, Sascha [Charite, Humboldt-University, Department of General, Visceral, and Transplantation Surgery, Berlin (Germany); Philipp, Carsten [Elisabeth Klinik, Department of Laser Medicine, Berlin (Germany)

    2010-11-15

    To evaluate the feasibility and safety of a novel LITT applicator for thermal ablation of liver malignancies in 1.0-T high-field open MRI. A miniaturised 6-F double-tubed protective catheter with a closed cooling circuit was used with a flexible laser fibre, connected to a 1,064-nm Nd:YAG laser and evaluated in non-perfused porcine livers (18-30 W for 10-20 min, 2-W and 2-min increments; n = 210/applicator) in reference to an established 9-F system. As a proof of concept, MR-guided LITT was performed in two healthy domestic pigs in high-field open MRI. Ex-vivo, the coagulation volumes induced by the 6-F system with maximum applicable power of 24 W for 20 min (33.0 {+-} 4.4 cm{sup 3}) did not differ significantly from those set with the 9-F system at 30 W for 20 min (35.8 {+-} 4.9 cm{sup 3}) (p = 0.73). A flow-rate of 15 ml/min of the cooling saline solution was sufficient. MR navigation and thermometry were feasible. The miniaturised 6-F applicator can create comparable coagulation sizes to those of the 9-F system. Applicator guidance and online-thermometry in high-field open MRI are feasible. (orig.)

  9. Thermosensitive polymers: synthesis, characterization, and delivery of proteins.

    Singh, Somnath; Webster, Dean C; Singh, Jagdish

    2007-08-16

    Three triblock copolymers based on the poly(lactide) or poly(lactide-co-glycolide) and poly(ethylene glycol) or poly(ethylene oxide) blocks were synthesized and characterized. The weight average molecular weight and number average molecular weight were determined by gel permeation chromatography and proton nuclear magnetic resonance spectroscopy, respectively. Fourier transform infrared spectroscopy was used to determine the completion of synthesis of polymers. Thermoreversible sol-gel transition temperature and concentration were determined by an inverted tube method. Two formulations each of three synthesized polymers containing 5% (w/v) of lysozyme or bromelain but differing in polymer concentrations (20-30%, w/v) were prepared and studied for in vitro release of the incorporated protein. In vitro biocompatibility of the delivery systems was studied by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay. Biological activities of lysozyme and bromelain were determined by enzyme activity assays. Critical gelling concentrations were found in the range of 20-30% (w/v). In vitro biocompatibility study showed that all the formulations were biocompatible. Increasing the polymer concentration led to a decrease in burst release and extended the in vitro release of proteins. Furthermore, biological activities of lysozyme and bromelain in released samples were found to be significantly (ppolymers were able to deliver proteins in biologically active forms at a controlled rate for 2-8 weeks. PMID:17513075

  10. Application of Polyethylene Glycol to Promote Cellular Biocompatibility of Polyhydroxybutyrate Films

    Rodman T. H. Chan

    2011-01-01

    Full Text Available Polyhydroxybutyrate (PHB is a biomaterial with potential for applications in biomedical and tissue engineering; however, its brittle nature and high crystallinity limit its potential. Blending PHB with a variety of PEGs produced natural-synthetic composite films composed of FDA-approved polymers with significant reductions in crystallinity, from 70.1% for PHB films to 41.5% for its composite with a 30% (w/w loading of PEG2000. Blending also enabled manipulation of the material properties, increasing film flexibility with an extension to break of 2.49±1.01% for PHB films and 8.32±1.06% for films containing 30% (w/w PEG106. Significant changes in the film surface properties, as measured by porosity, contact angles, and water uptake, were also determined as a consequence of the blending process, and these supported greater adhesion and proliferation of neural-associated olfactory ensheathing cells (OECs. A growth rate of 7.2×105 cells per day for PHB films with 30% (w/w PEG2000 loading compared to 2.5×105 for PHB films was observed. Furthermore, while cytotoxicity of the films as measured by lactate dehydrogenase release was unaffected, biocompatibility, as measured by mitochondrial activity, was found to increase. It is anticipated that fine control of PEG composition in PHB-based composite biomaterials can be utilised to support their applications in medicinal and tissue engineering applications.

  11. Enhancement of hydrophobicity and tensile strength of muga silk fiber by radiofrequency Ar plasma discharge

    The hydrophobicity and tensile strength of muga silk fiber are investigated using radiofrequency (RF) Ar plasma treatment at various RF powers (10-30 W) and treatment times (5-20 min). The Ar plasma is characterized using self-compensated Langmuir and emissive probe. The ion energy is observed to play an important role in determining the tensile strength and hydrophobicity of the plasma treated fibers. The chemical compositions of the fibers are observed to be affected by the increase in RF power rather than treatment time. XPS study reveals that the ions that are impinging on the substrates are mainly responsible for the cleavage of peptide bond and side chain of amino acid groups at the surface of the fibers. The observed properties (tensile strength and hydrophobicity) of the treated fibers are found to be dependent on their variation in atomic concentration and functional composition at the surfaces. All the treated muga fibers exhibit almost similar thermal behavior as compared to the virgin one. At RF power of 10 W and treatment time range of 5-20 min, the treated fibers exhibit properties similar to that of the virgin one. Higher RF power (30 W) and the increase in treatment time deteriorate the properties of the fibers due to incorporation of more surface roughness caused by sufficiently high energetic ion bombardment. The properties of the plasma treated fibers are attempted to correlate with the XPS analysis and their surface morphologies.

  12. Influence of Extraction Methods on the Yield of Steviol Glycosides and Antioxidants in Stevia rebaudiana Extracts.

    Periche, Angela; Castelló, Maria Luisa; Heredia, Ana; Escriche, Isabel

    2015-06-01

    This study evaluated the application of ultrasound techniques and microwave energy, compared to conventional extraction methods (high temperatures at atmospheric pressure), for the solid-liquid extraction of steviol glycosides (sweeteners) and antioxidants (total phenols, flavonoids and antioxidant capacity) from dehydrated Stevia leaves. Different temperatures (from 50 to 100 °C), times (from 1 to 40 min) and microwave powers (1.98 and 3.30 W/g extract) were used. There was a great difference in the resulting yields according to the treatments applied. Steviol glycosides and antioxidants were negatively correlated; therefore, there is no single treatment suitable for obtaining the highest yield in both groups of compounds simultaneously. The greatest yield of steviol glycosides was obtained with microwave energy (3.30 W/g extract, 2 min), whereas, the conventional method (90 °C, 1 min) was the most suitable for antioxidant extraction. Consequently, the best process depends on the subsequent use (sweetener or antioxidant) of the aqueous extract of Stevia leaves. PMID:25726419

  13. Co-composting of eggshell waste in self-heating reactors: monitoring and end product quality.

    Soares, Micaela A R; Quina, Margarida M J; Quinta-Ferreira, Rosa M

    2013-11-01

    Industrial eggshell waste (ES) is classified as an animal by-product not intended to human consumption. For reducing pathogen spreading risk due to soil incorporation of ES, sanitation by composting is a pre-treatment option. This work aims to evaluate eggshell waste recycling in self-heating composting reactors and investigate ES effect on process evolution and end product quality. Potato peel, grass clippings and rice husks were the starting organic materials considered. The incorporation of 30% (w/w) ES in a composting mixture did not affect mixture biodegradability, nor its capacity to reach sanitizing temperatures. After 25 days of composting, ES addition caused a nitrogen loss of about 10 g N kg(-1) of initial volatile solids, thus reducing nitrogen nutritional potential of the finished compost. This study showed that a composting mixture with a significant proportion of ES (30% w/w) may be converted into calcium-rich marketable compost to neutralize soil acidity and/or calcium deficiencies. PMID:24055972

  14. In vitro simulation of transurethral microwave thermal distribution in canine prostate%离体犬前列腺经尿道微波热场的计算机模拟研究

    王颖; 张炽敏; 李嘉; 张中林; 李岭; 苏俊; 王玲

    2008-01-01

    目的 研究前列腺微波热场的分布规律,探讨计算机模拟经尿道前列腺微波辐射热场的可行性.方法 根据前列腺的大小选择微波治疗的最佳时间/功率组合(30 W/180 s),用计算机模拟该时间/功率组合下的微波热场分布情况.对54个离体犬前列腺进行324(54×6)个点次的实际测温,验证计算机模拟热场的准确性.结果 30 W/180 s条件下计算机模拟的温升曲线与实际测温曲线有较好的一致性(占96.29%),两者的时点平面热场分布的规律相符.结论 用计算机模拟离体犬前列腺热场分布可靠准确,这一方法可用于微波治疗前列腺增生时热场的预测和精确调控.

  15. Effects of wheat distillers dried grains with solubles with or without protease and β-mannanase on the performance of turkey hen poults.

    Opoku, E Y; Classen, H L; Scott, T A

    2015-02-01

    Expansion in bioethanol production has resulted in distillers dried grains with solubles (DDGS) being readily available as a major protein source in the poultry industry. Two experiments were conducted to investigate effects of wheat DDGS (wDDGS) and enzyme on nutrient digestibility and performance of turkey hen poults (7 to 21 d). Two starter diets (0 or 30% wDDGS) were formulated to meet or exceed the nutrient requirements for Hybrid Converter female turkeys. These diets were then mixed in different proportions to obtain 2 additional wDDGS inclusion levels (10 and 20%). In Experiment 1, 0 and 30% wDDGS diets were each subdivided into 3 portions and supplemented with no enzyme (E-), protease (P+; 0.125 g/kg) or β-mannanase (M+; 0.5 g/kg). A total of 144, 7-day-old poults were randomly distributed in groups of 4 in 6 replicate cages per treatment. There were no significant main effects or interactions on feed intake from 7 to 21 d. However, a positive (PWheat DDGS is a valuable energy source and as high as 30% can be incorporated in turkey hen poults (7 to 21 d) diets. PMID:26353159

  16. Ultrasound stimulated release of mimosa medicine from cellulose hydrogel matrix.

    Jiang, Huixin; Tovar-Carrillo, Karla; Kobayashi, Takaomi

    2016-09-01

    Ultrasound (US) drug release system using cellulose based hydrogel films was developed as triggered to mimosa. Here, the mimosa, a fascinating drug to cure injured skin, was employed as the loading drug in cellulose hydrogel films prepared with phase inversion method. The mimosa hydrogels were fabricated from dimethylacetamide (DMAc)/LiCl solution in the presence of mimosa, when the solution was exposed to ethanol vapor. The US triggered release of the mimosa from the hydrogel matrix was carried out under following conditions of US powers (0-30W) and frequencies (23, 43 and 96kHz) for different mimosa hydrogel matrix from 0.5wt% to 2wt% cellulose solution. To release the drug by US trigger from the matrix, the better medicine release was observed in the matrix prepared from the 0.5wt% cellulose solution when the 43kHz US was exposed to the aqueous solution with the hydrogel matrix. The release efficiency increased with the increase of the US power from 5 to 30W at 43kHz. Viscoelasticity of the hydrogel matrix showed that the hydrogel became somewhat rigid after the US exposure. FT-IR analysis of the mimosa hydrogel matrixes showed that during the US exposure, hydrogen bonds in the structure of mimosa-water and mimosa-cellulose were broken. This suggested that the enhancement of the mimosa release was caused by the US exposure. PMID:27150786

  17. γ-Fe{sub 2}O{sub 3} by sol–gel with large nanoparticles size for magnetic hyperthermia application

    Lemine, O.M., E-mail: leminej@yahoo.com [Physics Department, College of Sciences, Al Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh (Saudi Arabia); Omri, K. [Laboratory of Physics of Materials and Nanomaterials Applied at Environment (LaPhyMNE), Faculty of Sciences in Gabes, Gabes (Tunisia); Iglesias, M.; Velasco, V. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC (Spain); Crespo, P.; Presa, P. de la [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC (Spain); Dpto. Física de Materiales, Universidad Complutense de Madrid (Spain); El Mir, L. [Physics Department, College of Sciences, Al Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh (Saudi Arabia); Laboratory of Physics of Materials and Nanomaterials Applied at Environment (LaPhyMNE), Faculty of Sciences in Gabes, Gabes (Tunisia); Bouzid, Houcine [Promising Centre for Sensors and Electronic Devices (PCSED), Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Laboratoire des Matériaux Ferroélectriques, Faculté des Sciences de Sfax, Route Soukra Km 3 5, B.P. 802, F-3018 Sfax (Tunisia); Yousif, A. [Department of Physics, College of Science, Sultan Qaboos University, P.O. Box 36, Code 123, Al Khoud (Oman); Al-Hajry, Ali [Promising Centre for Sensors and Electronic Devices (PCSED), Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia)

    2014-09-01

    Highlights: • Iron oxides nanoparticles with different sizes are successfully synthesized using sol–gel method. • The obtained nanoparticles are mainly composed of maghemite phase (γ-Fe{sub 2}O{sub 3}). • A non-negligible coercive field suggests that the particles are ferromagnetic. • A mean heating efficiency of 30 W/g is obtained for the smallest particles at 110 kHz and 190 Oe. - Abstract: Iron oxides nanoparticles with different sizes are successfully synthesized using sol–gel method. X-ray diffraction (XRD) and Mössbauer spectroscopy show that the obtained nanoparticles are mainly composed of maghemite phase (γ-Fe{sub 2}O{sub 3}). XRD and transmission electron microscopy (TEM) results suggest that the nanoparticles have sizes ranging from 14 to 30 nm, which are indeed confirmed by large magnetic saturation and high blocking temperature. At room temperature, the observation of a non-negligible coercive field suggests that the particles are ferro/ferrimagnetic. The specific absorption rate (SAR) under an alternating magnetic field is investigated as a function of size, frequency and amplitude of the applied magnetic field. A mean heating efficiency of 30 W/g is obtained for the smallest particles at 110 kHz and 190 Oe, whereas further increase of particle size does not improve significantly the heating efficiency.

  18. Effects of W Contents in Co Matrix of the Thermal Sprayed WC-Co on the Corrosion Behavior in Molten Zinc

    This study sought to investigate the reaction of Co-binder containing tungsten with molten zinc. Four kinds of Co-W alloys (pure, 10%W, 20%W, 30%W) were prepared using the powder metallurgy method. The specimens were immersion-tested in molten pure zinc baths at 460 .deg. C. To evaluate the corrosion property in molten zinc, the weight loss of the specimen was measured after the immersion tests at different immersion times (10∼300 min.). Co-10%W alloys, compared with pure cobalt, showed no effect of tungsten addition on the reaction rate in molten zinc. The relationship between the weight loss and the square root of immersion period represents a straight line in both pure cobalt and Co-10%W alloy. The Co-Zn reaction layer in Co-10%W alloy consists of γ 2, γ 1, γ and β 1 phases. The rate of weight loss significantly increases and the weight loss behavior is not well accord with the linear relationship as the tungsten content in the Co-W alloy increases. The β 1 layer was not formed on the Co-20%W alloy and neither was a stable Co-Zn intermetallic compound layer found on the Co-30%W alloy. The main cause of increase in reaction rate with increasing tungsten content is related with the instability of the Co-Zn reaction phases as seen on micro-structural analysis

  19. Effects of W Contents in Co Matrix of the Thermal Sprayed WC-Co on the Corrosion Behavior in Molten Zinc

    Seong, Byeong Geun; Hwang, Sun Young [New Metals Research Department, RIST, Pohang (Korea, Republic of); Kim, Kyoo Young [POSTECH, Pohang (Korea, Republic of); Lee, Kee Ahn [Andong National University, Andong (Korea, Republic of)

    2007-08-15

    This study sought to investigate the reaction of Co-binder containing tungsten with molten zinc. Four kinds of Co-W alloys (pure, 10%W, 20%W, 30%W) were prepared using the powder metallurgy method. The specimens were immersion-tested in molten pure zinc baths at 460 .deg. C. To evaluate the corrosion property in molten zinc, the weight loss of the specimen was measured after the immersion tests at different immersion times (10{approx}300 min.). Co-10%W alloys, compared with pure cobalt, showed no effect of tungsten addition on the reaction rate in molten zinc. The relationship between the weight loss and the square root of immersion period represents a straight line in both pure cobalt and Co-10%W alloy. The Co-Zn reaction layer in Co-10%W alloy consists of {gamma} 2, {gamma} 1, {gamma} and {beta} 1 phases. The rate of weight loss significantly increases and the weight loss behavior is not well accord with the linear relationship as the tungsten content in the Co-W alloy increases. The {beta} 1 layer was not formed on the Co-20%W alloy and neither was a stable Co-Zn intermetallic compound layer found on the Co-30%W alloy. The main cause of increase in reaction rate with increasing tungsten content is related with the instability of the Co-Zn reaction phases as seen on micro-structural analysis

  20. MR evaluation of pulmonary vein diameter reduction after radiofrequency catheter ablation of atrial fibrillation

    Fifty consecutive patients aged 52±12 years suffering from drug refractory atrial fibrillation (AF) underwent baseline and post-ablation MR angiography (MRA) at a mean follow-up of 4±3.5 months. Pulmonary vein (PV) disconnection was performed with a maximum energy delivery of 30 W. MRA allowed a two-plane measurement of each PV ostium. After ablation, no significant stenosis was observed, and only 1/194 (0.5%) and 3/194 (2%) PVs had a diameter reduction of 31-40% in the coronal and axial planes, respectively. There was a significant overall post-procedural PV narrowing of 4.9% in the coronal plane and 6.5% in the axial plane (P=ns between both planes). MRA is an efficient technique that can be used in pre- and postoperative evaluation of AF patients. Using a maximal power delivery limited to 30 W, no significant PV stenosis was observed at mid-term follow-up. Late PV anatomical assessment is needed to confirm these results on long-term follow-up. (orig.)

  1. MR evaluation of pulmonary vein diameter reduction after radiofrequency catheter ablation of atrial fibrillation

    Anselme, Frederic; Savoure, Arnaud; Mabru, Mikael; Cribier, Alain [Rouen University Hospital, Department of Cardiology, Rouen (France); Gahide, Gerald [Rouen University Hospital, Department of Radiology and Laboratoire QuantIF, Rouen (France); Gerbaud, Edouard [Rouen University Hospital, Department of Cardiology, Rouen (France); Rouen University Hospital, Department of Radiology and Laboratoire QuantIF, Rouen (France); Dacher, Jean-Nicolas [Rouen University Hospital, Department of Radiology and Laboratoire QuantIF, Rouen (France); University Hospital, Department of Radiology, Rouen, Cedex (France)

    2006-11-15

    Fifty consecutive patients aged 52{+-}12 years suffering from drug refractory atrial fibrillation (AF) underwent baseline and post-ablation MR angiography (MRA) at a mean follow-up of 4{+-}3.5 months. Pulmonary vein (PV) disconnection was performed with a maximum energy delivery of 30 W. MRA allowed a two-plane measurement of each PV ostium. After ablation, no significant stenosis was observed, and only 1/194 (0.5%) and 3/194 (2%) PVs had a diameter reduction of 31-40% in the coronal and axial planes, respectively. There was a significant overall post-procedural PV narrowing of 4.9% in the coronal plane and 6.5% in the axial plane (P=ns between both planes). MRA is an efficient technique that can be used in pre- and postoperative evaluation of AF patients. Using a maximal power delivery limited to 30 W, no significant PV stenosis was observed at mid-term follow-up. Late PV anatomical assessment is needed to confirm these results on long-term follow-up. (orig.)

  2. Evaluation and characterization of 30 solar home systems (SHS) Ovonic-Unisolar; Caracterizacion y evaluacion de 30 sistemas FV domiciliarios ovonic-unisolar

    Flores, J. Roberto; Agredano, Jaime; Munguia, Gonzalo; Lagunas, Javier; Huacuz, Jorge [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico); Brennan, Steve [Troy, MI (United States)

    2000-07-01

    In this work the first results of the evaluation and characterization of 30 solar home systems (SHS) Ovonic-Unisolar (16 of 30 W and 14 of 60 W of capacity) are presented. The components of the SHS are: One or two PV modules, a charge controller, a nickel metal-hybride (NiMH) battery with a nominal capacity of 85 Ah rated at 3 hours, two or four 8 W lamps, and a CD/CD converter for connecting a radio or a TV W/B a maximum power of 20W. Of all systems evaluated, 29 were installed in three communities of the Oaxaca State, and the other 2 are installed at the Instituto de Investigaciones Electricas (IIE) the laboratory as prototype systems. Before the systems installation at the rural communities, all of them were tested in laboratory. Eight systems installed in the field are being monitoring with data acquisition systems. The main motivation of this projects is to know the behavior of the NiMH battery in the SHS. [Spanish] En este trabajo se presentan los primeros resultados de la caracterizacion y evaluacion de 30 sistemas fotovoltaicos (FV) domiciliarios Ovonic-Unisolar (16 con capacidad de 30 W y 14 con capacidad de 60 W). Los sistemas estan integrados por uno o dos modulos FV de 30 W (dependiendo de la capacidad del sistema), un controlador de carga con termo-interuptor, una bateria del tipo niquel hidruros metalicos (NiHM) con capacidad de 85 Ah a una razon de descarga de 3 horas, 2 o 4 lamparas compactas de alta eficiencia de 8 W y un convertidor CD/CD que permite a los usuarios utilizar una radiograbadora y/o una television B/N con potencia no mayor a 20 W. De estos 30 sistemas FV, 28 se instalaron en 3 comunidades rurales del Estado de Oaxaca y los dos sistemas restantes se tienen instalados en el laboratorio FV del Instituto de Investigaciones Electricas (IIE) como sistemas testigos. Previo a la instalacion en campo, todos los sistemas fueron evaluados en el laboratorio para garantizar su operacion en las comunidades rurales. De los 28 sistemas instalados en

  3. Optimization of methane conversion to liquid fuels over W-Cu/ZSM-5 catalysts by response surface methodology

    Didi Dwi Anggoro; Istadi

    2008-01-01

    The conversion of methane to liquid fuels is still in the development process. The modified HZSM-5 by loading with Tungsten (W) enhanced its heat resistant performance, and the high reaction temperature (800 ℃) did not lead to the loss of W component by sublimation. The loading of ZSM-5 with Tungsten and Copper (Cu) resulted in an increment in the methane conversion, CO2, and C5+ selectivities. The high methane conversion and C5+ selectivity, and low H2O selectivity are obtained by using W/3.OCu/ZSM-5. The optimization of methane conversion over 3.0 W/3.0Cu/ZSM-5 under different temperature and oxygen concentration using response surface methodology (RSM) are studied. The optimum point for methane conversion is 19% when temperature is 753 ℃, and oxygen concentration is 12%. The highest C5+ selectivity is 27% when temperature is 751 ℃, and oxygen concentration is 11%.

  4. Physical properties of pre-crystallized mixtures of cocoa butter and cupuassu fat

    Quast, L.B.; Luccas, V.; Kieckbusch, T.G.

    2011-07-01

    The physical characteristics of pre-crystallized binary mixtures of cocoa butter (Bahia + Indonesian blend) and 5, 10, 15, 20, 25 and 30% (w/w) cupuassu fat were determined. recrystallization was carried out using a lab-scale agitated jacket vessel reactor (700 mL). Samples were submitted to differential scanning calorimetry and X-Ray diffraction. The solid fat content and rupture force were also quantified. The snap values of the crystallized mixture decreased with an increase in the amount of alternative fat. A similar trend was observed with respect to the melting point values. The cocoa butter and cupuassu fat X-ray diffraction patterns confirmed the predominant formation of the a-circumflex polimorph. The addition of up to 30% cupuassu fat did not significantly affect the values of the physical properties when compared to pure cocoa butter (Author).

  5. Paclitaxel loaded biodegradable poly (sebacic acid-co-ricinoleic acid cylindrical implants for local delivery-in vitro characterization

    Jagadeesh G Hiremath

    2013-01-01

    Full Text Available The aim of the present research work was to develop the biodegradable polymeric implant for the delivery of antineoplastic drug, paclitaxel (PTX using poly (sebacic-co-recinoleic acid 70:30 w/w. PTX loaded implants were prepared by indigenously developed melt molding technique. Implants were characterized in terms of physico-chemical evaluations, drug content, drug stability and intactness, thermal analysis, drug physical state and crystallinity, surface morphology, hydrolytic degradation, drug release and its kinetics. Prepared implants were yellow and cylindrical in shape with smooth surfaces. Drug in the implants was found to be stable, intact and uniformly dispersed as amorphous state within the polymer matrix. In vitro release, kinetic studies showed zero order and Korsmeyer-Peppas model release being exhibited. Drug release from the polymeric implants was occurred could be as results of diffusion.

  6. High power, continuous-wave, single frequency fiber amplifier at 1091 nm and frequency doubling to 545.5 nm

    Stappel, M; Kolbe, D; Walz, J

    2012-01-01

    We present a high power single-frequency ytterbium fiber amplifier system with an output power of 30 W at 1091 nm. The amplifier system consists of two stages, a preamplifier stage in which amplified spontaneous emission is efficiently suppressed (>40 dB) and a high power amplifier with an efficiency of 52 %. Two different approaches of frequency doubling are compared. We achieve 8.6 W at 545.5 nm by single-pass frequency doubling in a MgO-doped periodically poled stoichiometric LiTaO3 and up to 19.3 W at 545.5 nm by frequency doubling with a lithium-triborate (LBO) crystal in an external enhancement cavity.

  7. All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 9.6 W output power at 458 nm

    Li, B.; Zhao, L.; Zhang, Y. B.; Zheng, Q.; Zhao, Y.; Yao, Y.

    2013-02-01

    An efficient and compact red laser at 458 nm is generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:LuVO4 laser at 916 nm under the condition of suppression the higher gain transition near 1064 nm. With 30 W diode pump power and a frequency doubling crystal LBO, as high as 9.6 W of CW output power at 458 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 32.0% and the output power stability in 8 hours is better than 2.35%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 458 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 916 nm.

  8. Over 0.5 MW green laser from sub-nanosecond giant pulsed microchip laser

    Zheng, Lihe; Taira, Takunori

    2016-03-01

    A sub-nanosecond green laser with laser head sized 35 × 35 × 35 mm3 was developed from a giant pulsed microchip laser for laser processing on organic superconducting transistor with a flexible substrate. A composite monolithic Y3Al5O12 (YAG) /Nd:YAG/Cr4+:YAG/YAG crystal was designed for generating giant pulsed 1064 nm laser. A fibercoupled 30 W laser diode centered at 808 nm was used with pump pulse duration of 245 μs. The 532 nm green laser was obtained from a LiB3O5 (LBO) crystal with output energy of 150 μJ and pulse duration of 268 ps. The sub-nanosecond green laser is interesting for 2-D ablation patterns.

  9. High-power efficient diode-pumped Nd:YVO4/LiB3O5 457 nm blue laser with 4.6 W of output power.

    Xue, Q H; Zheng, Q; Bu, Y K; Jia, F Q; Qian, L S

    2006-04-15

    Continuous-wave 457 blue laser emission at powers as high as 4.6 W is achieved by using a fiber-coupled laser diode array with a power of 30 W to pump 0.1 at. % low-doped bulk Nd:YVO4 crystal, with intracavity frequency doubling in a 15 mm long type I critical phase-matched LiB3O5 (LBO) crystal in a compact three-fold cavity with a length of less than 100 mm. The optical-optical conversion efficiency is greater than 15.3%, and the stability of the output power is better than 3% for an hour. PMID:16625906

  10. Total solids content and degree of hydrolysis influence proteolytic inactivation kinetics following whey protein hydrolysate manufacture.

    Conesa, Celia; FitzGerald, Richard J

    2013-10-23

    The kinetics and thermodynamics of the thermal inactivation of Corolase PP in two different whey protein concentrate (WPC) hydrolysates with degree of hydrolysis (DH) values of ~10 and 21%, and at different total solids (TS) levels (from 5 to 30% w/v), were studied. Inactivation studies were performed in the temperature range from 60 to 75 °C, and residual enzyme activity was quantified using the azocasein assay. The inactivation kinetics followed a first-order model. Analysis of the activation energy, thermodynamic parameters, and D and z values, demonstrated that the inactivation of Corolase PP was dependent on solution TS. The intestinal enzyme preparation was more heat sensitive at low TS. Moreover, it was also found that the enzyme was more heat sensitive in solutions at higher DH. PMID:24047254

  11. Lipid-nanoemulsions as drug delivery carriers for poorly-water soluble drug

    Veerendra K. Nanjwade

    2013-03-01

    Full Text Available To enhance the bioavailability of the poorly water-soluble drug Aceclofenac, a lipidnanoemulsion comprising ethanolic solution of phospholipid 90 G and tween 80 in 1:1 ratio (Smix, triacetin and anseed oil as oil phase and distilled water as aqueous phase, in the ratio of 55:15:30 (% w/w was developed by constructing pseudo-ternary phase diagrams and evaluated for viscosity, % transmittance, and surface morphology of nanoemulsions. In vitro diffusion (release of Aceclofenac from three different bases to an aqueous receptor phase through cellophane membrane was monitored spectrophotometrically at 273 nm. Compared with hydroalcoholic drug solution, oily solution, and conventional emulsion and suspension. The lipid-nanoemulsion showed increase in drug release compared to drug suspension. This may be attributed to increased solubility of the drug from nanosized emulsion.

  12. Laser resonant-ionization mass spectrometry of actinides

    Laser resonant-ionization mass spectrometry has been used to determine small amounts of actinides. The high sensitivity and selectivity of this method has been achieved by three-step photoionization of actinide atoms followed by time-of-flight measurement. The laser system for photoionization consists of a pulsed copper vapour laser of 30 W average power at a pulse repetition rate of 6.5 kHz which is coupled to three dye lasers. The time-of-flight spectrometer has a mass resolution of about 2500. Resonance signals with count rates of several kilohertz were obtained with actinide samples of 1010-1012 atoms yielding a detection limit of 108 atoms in the sample. With some improvements a detection sensitivity of about 106 atoms of plutonium, americium and curium should be reached. (orig.)

  13. Laser resonance ionization mass spectrometry as a sensitive analytical method for actinides and technetium

    Laser resonance ionization mass spectrometry has been investigated as a method for the determination of trace amounts of actinides and technetium. A high sensitivity and selectivity have been achieved by three-step photoionization of the elements in the atomic state followed by time-of-flight measurement for mass analysis. The system for photoionization consists of three dye lasers which are pumped simultaneously by a copper vapour laser of 30 W average power at a pulse repetition rate of 6.5 KHz. The time-of-flight spectrometer has a mass resolution better than 2500. By ionization via autoionization states and by saturation in each excitation step a detection limit of less than 108 atoms of actinides or of technetium in the sample can be reached. (author)

  14. Experimental study on active cooling systems used for thermal management of high-power multichip light-emitting diodes.

    Kaya, Mehmet

    2014-01-01

    The objective of this study was to develop suitable cooling systems for high-power multichip LEDs. To this end, three different active cooling systems were investigated to control the heat generated by the powering of high-power multichip LEDs in two different configurations (30 and 2 × 15 W). The following cooling systems were used in the study: an integrated multi-fin heat sink design with a fan, a cooling system with a thermoelectric cooler (TEC), and a heat pipe cooling device. According to the results, all three systems were observed to be sufficient for cooling high-power LEDs. Furthermore, it was observed that the integrated multifin heat sink design with a fan was the most efficient cooling system for a 30 W high-power multichip LED. The cooling system with a TEC and 46 W input power was the most efficient cooling system for 2 × 15 W high-power multichip LEDs. PMID:25162058

  15. Impact of tool wear on joint strength in friction stir spot welding of DP 980 steel

    Miles, Michael; Ridges, Chris; Hovanski, Yuri; Peterson, Jeremy; Santella, M. L.; Steel, Russel

    2011-09-14

    Friction stir spot welding has been shown to be a viable method of joining ultra high strength steel (UHSS), both in terms of joint strength and process cycle time. However, the cost of tooling must be reasonable in order for this method to be adopted as an industrial process. Recently a new tool alloy has been developed, using a blend of PCBN and tungsten rhenium (W-Re) in order to improve the toughness of the tool. Wear testing results are presented for two of these alloys: one with a composition of 60% PCBN and 40% W-Re, and one with 70% PCBN and 30% W-Re. The sheet material used for all wear testing was 1.4 mm DP 980. Lap shear testing was used to show the relationship between tool wear and joint strength. The Q70 tool provided the best combination of wear resistance and joint strength.

  16. Improvements in exercise performance with high-intensity interval training coincide with an increase in skeletal muscle mitochondrial content and function

    Jacobs, Robert Acton; Flueck, Daniela; Bonne, Thomas Christian;

    2013-01-01

    Six sessions of high-intensity interval training (HIT) are sufficient to improve exercise capacity. The mechanisms explaining such improvements are unclear. Accordingly, the aim of this study was to perform a comprehensive evaluation of physiologically relevant adaptations occurring after six...... sessions of HIT to determine the mechanisms explaining improvements in exercise performance. Sixteen untrained (43 +/- 6 ml.kg(-1).min(-1)) subjects completed six sessions of repeated (8-12) 60 s intervals of high-intensity cycling (100% peak power output elicited during incremental maximal exercise test......) intermixed with 75 s of recovery cycling at a low intensity (30 W) over a 2-wk period. Potential training-induced alterations in skeletal muscle respiratory capacity, mitochondrial content, skeletal muscle oxygenation, cardiac capacity, blood volumes, and peripheral fatigue resistance were all assessed prior...

  17. Refractive index matching to develop transparent polyaphrons: Characterization of immobilized proteins.

    Ward, Keeran; Stuckey, David C

    2016-06-01

    Refractive index matching was used to create optically transparent polyaphrons to enable proteins adsorbed to the aphron surface to be characterized. Due to the significant light scattering created by polyaphrons, refractive index matching allowed for representative circular dichroism (CD) spectra and acceptable structural characterization. The method utilized n-hexane as the solvent phase, a mixture of glycerol and phosphate buffer (30% [w/v]) as the aqueous phase, and the non-ionic surfactants, Laureth-4 and Kolliphor P-188. Deconvolution of CD spectra revealed that the immobilized protein adapted its native conformation, showing that the adsorbed protein interacted only with the bound water layer ("soapy shell") of the aphron. Isothermal calorimetry further demonstrated that non-ionic surfactant interactions were virtually non-existent, even at the high concentrations used (5% [w/v]), proving that non-ionic surfactants can preserve protein conformation. PMID:26952359

  18. Material properties of concentrated pectin networks.

    Zsivanovits, Gabor; MacDougall, Alistair J; Smith, Andrew C; Ring, Stephen G

    2004-05-17

    We have examined the mechanical behaviour of different types of pectin at high concentrations (> 30% w/w), relevant to the behaviour of pectin in the plant cell wall, and as a film-forming agent. Mechanical properties were examined as a function of counterion type (K(+), Ca(2+), Mg(2+)), concentration and extent of hydration. Hydration was controlled in an osmotic stress experiment where pectin films were exposed to concentrated polyethylene glycol [PEG] solutions of known osmotic pressure. We investigated the mechanical behaviour under simple extension. The results show that the swelling and stiffness of the films are strongly dependent on pectin source and ionic environment. At a fixed osmotic stress, both Ca(2+) or Mg(2+) counterions reduce swelling and increase the stiffness of the film. PMID:15113669

  19. Purification, crystallization and preliminary crystallographic analysis of Streptococcus pyogenes laminin-binding protein Lbp

    Linke, Christian, E-mail: clin180@ec.auckland.ac.nz [School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland (New Zealand); Caradoc-Davies, Tom T. [School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland (New Zealand); Australian Synchrotron, Clayton, Victoria 3168 (Australia); Proft, Thomas [School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland (New Zealand); Baker, Edward N. [School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland (New Zealand)

    2008-02-01

    The S. pyogenes laminin-binding protein Lbp, which is essential for adhesion to human laminin, has been expressed, purified and crystallized. The laminin-binding protein Lbp (Spy2007) from Streptococcus pyogenes (a group A streptococcus) mediates adhesion to the human basal lamina glycoprotein laminin. Accordingly, Lbp is essential in in vitro models of cell adhesion and invasion. However, the molecular and structural basis of laminin binding by bacteria remains unknown. Therefore, the lbp gene has been cloned for recombinant expression in Escherichia coli. Lbp has been purified and crystallized from 30%(w/v) PEG 1500 by the sitting-drop vapour-diffusion method. The crystals belonged to the monoclinic space group P2{sub 1}, with unit-cell parameters a = 42.62, b = 92.16, c = 70.61 Å, β = 106.27°, and diffracted to 2.5 Å resolution.

  20. An overview of the development of lead/acid traction batteries for electric vehicles in India

    Sivaramaiah, G.; Subramanian, V. R.

    Electric vehicles (EVs) made an entry into the Indian scene quite recently in the area of passenger transportation, milk floats and other similar applications. The industrial EV market, with various models of fork-lift trucks and platform trucks already in wide use all over India, is a better understood application of EV batteries. The lead/acid traction batteries available in India are not of high-energy density. The best available indigenous lead/acid traction battery has an energy density ( C/5 rate) of 30 W h kg -1 as against 39 W h kg -1 available abroad. This paper reviews the developmental efforts relating to lead/acid traction batteries for electric vehicle applications in India, such as prototype road vehicles, commercial vehicles, rail cars, and locomotives. Due to the need for environmental protection and recognition of exhaustible, finite supplies of petroleum fuel, the Indian government is presently taking active interest in EV projects.

  1. Obtaining of ceramics biphasic dense and porous

    Among the bioceramic hydroxyapatite (HAP) and beta-tricalcium phosphate (beta-TCP) are materials commonly used in biomedical field. Their combined properties result in a material with absorbable and at the same time with bioactive surface. Called biphasic ceramics such materials respond more quickly when exposed to physiological environment. In this work, powders of HAP/beta-TCP were obtained by chemical precipitation. After obtaining the post-phase was added at a ratio of 0, 15% and 30w% aqueous solutions of corn starch in order to obtain porous bodies. After mixing the resulting solutions were dried, resigned in tablet form and sintered at 1300 deg C. The initial powder was characterized by X-ray diffraction with Rietveld refinement to quantify the phases present. Bodies-of-evidence has been characterized by calculating the bulk density, X-ray diffraction (XRD), scanning electron microscopy and diametral compression. (author)

  2. Enhanced performance of a wide-aperture copper vapour laser with hydrogen additive in neon buffer gas

    Bijendra Singh; V V Subramaniam; S R Daultabad; Ashim Chakraboty

    2010-11-01

    A wide-aperture copper vapour laser was demonstrated at ∼ 10 kHz rep-rate with hydrogen additive in its buffer gas. Maximum power in excess of ∼ 50 W (at 10 kHz) was achieved by adding 1.96% hydrogen to the neon buffer gas at 20 mbar total gas pressure. This increase in output power was about 70% as compared to ∼ 30 W achieved with pure neon at 5.5 kHz rep-rate. The 70% enhancement achieved was significantly higher than the maximum reported value of 50% so far in the literature. The enhancement was much higher (about 150%) as compared to its 20 W power at 10 kHz rep-rate using pure neon as the standard CVL operation.

  3. Hemostatic efficacy evaluation of radiation crosslinked carboxymethyl kappa-carrageenan and chitosan with varying degrees of substitution

    Tranquilan-Aranilla, Charito; Barba, Bin Jeremiah D.; Vista, Jeanina Richelle M.; Abad, Lucille V.

    2016-07-01

    Carboxymethyl derivatives of kappa-carrageenan and chitosan, with varying degrees of substitution, were synthesized by multi-step reaction technique and evaluated for hemostatic efficacy through in vitro assays. FTIR analysis confirmed the presence of carboxymethyl group while 1H NMR spectroscopy indicated degrees of substitution ranging from 1.15-1.58 and 0.45-0.51 for carboxymethyl-κ-carrageenan and carboxymethylchitosan, respectively. Derivatives formed into paste consistency (30% w/v) were successfully crosslinked by gamma irradiation at 30 kGy. The data obtained from whole blood clotting and platelet adhesion assays showed a significant increase in hemostatic capability of κ-carrageenan and chitosan as a consequence of carboxymethylation and crosslinking modifications. In addition, the level of efficacy was comparable to that of a chitosan-based commercial product. These results suggest the potential of κ-carrageenan and chitosan derivatives for development into hemostatic agents.

  4. Selective removal of carious human dentin using a nanosecond pulsed laser operating at a wavelength of 5.85 μ m

    Ishii, Katsunori; Kita, Tetsuya; Yoshikawa, Kazushi; Yasuo, Kenzo; Yamamoto, Kazuyo; Awazu, Kunio

    2015-05-01

    Less invasive methods for treating dental caries are strongly desired. However, conventional dental lasers do not always selectively remove caries or ensure good bonding to the composite resin. According to our previous study, demineralized dentin might be removed by a nanosecond pulsed laser operating at wavelengths of around 5.8 μm. The present study investigated the irradiation effect of the light on carious human dentin classified into "remove," "not remove," and "unclear" categories. Under 5.85-μm laser pulses, at average power densities of 30 W/cm2 and irradiation time of 2 s, the ablation depth of "remove" and "not remove," and also the ablation depth of "unclear" and "not remove," were significantly different (p<0.01). The ablation depth was correlated with both Vickers hardness and Ca content. Thus, a nanosecond pulsed laser operating at 5.85 μm proved an effective less-invasive caries treatment.

  5. Generation of Terahertz Surface Plasmon Polaritons Using Nondiffractive Bessel Beams with Orbital Angular Momentum

    Knyazev, B. A.; Choporova, Yu. Yu.; Mitkov, M. S.; Pavelyev, V. S.; Volodkin, B. O.

    2015-10-01

    Bessel vortex beams with topological charges of l =±1 and l =±2 were produced in the terahertz spectral range from a free electron laser Gaussian beam (λ =141 μ m ) transformed using silicon binary diffractive optical elements. The spatial characteristics of the beams were obtained using a microbolometer array. A radius to path length ratio of 1 ∶100 was achieved for nondiffractive beams with the average power of 30 W. Surface plasmon polaritons (SPPs) on gold-zinc-sulphide-air interfaces were generated due to diffraction of vortex beams on a sample edge. A new effect, a dependence of the efficiency of SPP generation on the direction of the azimuthal component of incident-radiation Poynting vector, was revealed.

  6. CTD data from the N.E. Atlantic 31 deg N - 46 deg N, July 1982 Discovery cruise 130

    This report presents lists and graphs of CTD (conductivity, temperature and depth) data obtained aboard RRS Discovery during July 1982. A series of 14 stations were occupied between approximate 31 deg N 24 deg W and 46 deg N 14 deg W in support of sound ranging trials. A further 20 stations were occupied in the vicinity of Discovery Gap, a channel for deep flow between the Madeira and Iberian basins near 37 deg 30' N 15 deg 30' W. All CTD data were reconciled with reversing thermometer measurements, and salinity and oxygen samples. Root mean square differences for pressure, temperature, salinity and oxygen were 7db, .012 deg C, .007 PSU and 0.3 ml/l in the depth interval 0 to 2,000 db and 6 db, .005 deg C, .003 PSU and .16 ml/l for depths 2,000 to 5,600 db. (author)

  7. Surface longwave fluxes from satellite observations: a critical review

    Several different techniques have been proposed for estimating the net longwave radiation at the Earth's surface from satellite observations. Many of these show considerable promise over ocean surfaces, although their accuracies are limited to the order to 20–30 W m−2 for individual satellite observations given the current uncertainties in satellite estimates of the vertical distribution of water vapor, cloud cover, cloud base altitude, and near-surface temperatures. The uncertainties over land surfaces are higher due to the larger uncertainties in estimating the surface temperature and emissivity. All of the flux estimation techniques suffer from an absence of absolute calibration, and little information is available to estimate the uncertainties of surface longwave radiation budgets over extended tines for large areas. Nevertheless, this is an area of active research, and a narrowing of the uncertainties is expected to occur with the results of current and planned field programs. (author)

  8. Obtaining of ceramics biphasic dense and porous; Obtencao de ceramicas bifasicas densas e porosas

    Pallone, E.M.J.A.; Rigo, E.C.S., E-mail: eliria@usp.b [Universidade de Sao Paulo (FZEA/USP), Pirassununga, SP (Brazil). Dept. de Ciencias Basicas; Silva, K.L. [Universidade Estadual de Campinas (FEM/UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica; Rezende, M.E. [Universidade Sao Francisco, Itatiba, SP (Brazil); Fraga, A.F. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais; Marques, R.F.C. [Universidade Federal de Alfenas (UNIFAL), Pocos de Caldas, MG (Brazil)

    2010-07-01

    Among the bioceramic hydroxyapatite (HAP) and beta-tricalcium phosphate (beta-TCP) are materials commonly used in biomedical field. Their combined properties result in a material with absorbable and at the same time with bioactive surface. Called biphasic ceramics such materials respond more quickly when exposed to physiological environment. In this work, powders of HAP/beta-TCP were obtained by chemical precipitation. After obtaining the post-phase was added at a ratio of 0, 15% and 30w% aqueous solutions of corn starch in order to obtain porous bodies. After mixing the resulting solutions were dried, resigned in tablet form and sintered at 1300 deg C. The initial powder was characterized by X-ray diffraction with Rietveld refinement to quantify the phases present. Bodies-of-evidence has been characterized by calculating the bulk density, X-ray diffraction (XRD), scanning electron microscopy and diametral compression. (author)

  9. Surface Coating of Epoxy Acrylate Polymer on Teak Block Parquet (Tectona Grandis L.f.) by Ultra Violet Irradiation

    An experiment on surface coating of teak block parquet (Tectona Grandis L.f.) has been conducted using epoxy acrylate resin with the trade name of Laromer EA-81. Resin was used as the coating materials after being added with tripropylene glycol diacrylate (TPGDA) and photoinisiator Darocur 1173. Irradiation was conducted using UV light at the conveyor speed of 2, 3, 4, and 5 m/min. Observed parameter were glossyness, adhesion, hardness, abrasion resistance and chemical, solvent and stain resistance. The result of the epoxy acrylate films obtained has excellent adhesion, hardness, glossyness and has good chemicals, solvent, and stain resistance except to 10 % sodium hydroxide. The coating materials of formulations II (30 % w/w TPGDN) produced better coating compared with formulation I (20 % w/w TPGDN), either for performance and film properties point of view. (author)

  10. Measurements of local temperature distributions in rod bundles with sodium flow

    In an electrically heated 19-rod bundle (P/D = 1.30, W/R = 1.40) with sodium flow the three-dimensional temperature fields in the rod clads were measured. The main characteristics of the test section are three adjacent heater rods in the duct wall zone instrumented on four measuring planes and rotatable by 3600 under full power conditions; furthermore spacer grids which are axially movable, and a system allowing to bow one heater rod over the last third of its heated length. The results of measurements of the azimuthal temperature variations of the rotatable rods are presented for different operating conditions (80 2), different spacer grid positions relative to the measuring planes and different bowing positions of one rod. For better understanding of the experimental results cross sections of the 19-rod bundle were prepared. It became evident, that a well-known bundle geometry is very important for the interpretation of the experimental results. (orig.)

  11. Modifying the composition of hydrogen-terminated silicon nanoparticles synthesized in a nonthermal rf plasma

    Hydrogen-terminated silicon nanoparticles were synthesized over a broad range of conditions in a continuous flow, nonthermal rf plasma. The effects of three operating parameters--rf power, reactor pressure, and hydrogen flow rate--were examined in terms of their effects on particle crystallinity, size, and surface composition. Silicon-hydrogen composition was characterized in situ by Fourier transform infrared spectrometry, and particle structural morphology was examined with a transmission electron microscope. Amorphous or crystalline particles could be synthesized by appropriately adjusting the operating parameters. Over the majority of settings examined, the minimum power required to produce discrete crystalline particles was ∼20-30 W. Depending on the parameter settings, particles also exhibited hydrogen coverage ranging from predominantly monohydride (SiH) functional groups to more complex compositions of higher hydrides. Particles with the highest proportion of surface SiH bonds were consistently synthesized in the smallest diameter (4 mm i.d.) tube reactor.

  12. Left Atrial Linear Ablation of Paroxysmal Atrial Fibrillation Guided by Three-dimensional Electroanatomical System

    Zhang, Dai-Fu; Li, Ying; Qi, Wei-Gang;

    2005-01-01

    Objective To investigate the safety and efficacy of Left atrial linear ablation of paroxysmal atrial fibrillation guided by three-dimensional electroanatomical system. Methods 29 patients with paroxysmal atrial fibrillation in this study. A nonfluoroscopic mapping system was used to generate a 3D...... electroanatomic LA mapping, and all pulmonary vein ostia were marked under the help of pulmonary veins angiography on the 3D map. Radiofrequency (RF) energy was delivered to create continuous linear lesions encircling the pulmonary veins, it was delivered with a target temperature of 43¿, a maximal power limit of...... 30W and applied for =20 seconds until the maximal local electrogram amplitude decreased by =50%. The ablation was completed by finishing the circular line. Results The mean procedure duration was 180±18 minutes, with mean fluoroscopy time of 80±20 minutes. The average number of RE pulses was 120...

  13. The effectiveness of a high output/short duration radiofrequency current application technique in segmental pulmonary vein isolation for atrial fibrillation

    Nilsson, Brian; Chen, Xu; Pehrson, Steen;

    2006-01-01

    AIMS: Segmental pulmonary vein (PV) isolation by radiofrequency (RF) catheter ablation has become a curative therapy for atrial fibrillation (AF). However, the long procedure time limits the wide application of this procedure. The aim of the current study was to compare a novel ablation technique...... with a high power output and short application time vs. a conventional technique using a low power output and long application time. METHODS AND RESULTS: The study included 90 consecutive patients (age 53+/-10 years; 66 men). Segmental PV isolation was performed by irrigated RF catheter ablation in...... both groups. In the conventional group (Group 1, 45 patients), the power output was limited to 30 W with a target temperature of 50 degrees C and an RF preset duration of 120 s. In the novel group (Group 2, 45 patients), the maximum power output was preset to 45 W, with a target temperature of 55...

  14. SF6气体的回收

    张晓娜

    2012-01-01

      由于SF6断路器具有技术性能好、使用寿命长、维护工作量小的优点,在电力系统得到广泛使用,但随着使用年限的增加,部分SF6断路器进入了A级检修周期,如何进行SF6气体回收及处理成为一道难题.本文通过对LH-6.5Y30W A·Z型SF6气体回收装置的使用简单介绍如何回收SF6气体.

  15. Brioflora epífita e epífila da RPPN Frei Caneca, Jaqueira, PE, Brasil A checklist of epiphyllous and epiphytic bryophytes from Frei Caneca RPPN, Jaqueira, Pernambuco State, Northeastern Brazil

    Maria Jaciane de Almeida Campelo; K��tia Cavalcanti Pôrto

    2007-01-01

    Foi realizado um inventário da brioflora epífita e epífila da RPPN Frei Caneca (8º42'41"S e 35º50'30"W, 750 m alt., 630 ha), remanescente de Floresta Atlântica, localizado no município de Jaqueira, Pernambuco. Um total de 120 amostras de briófitas epífitas foi coletado desde a base até a primeira ramificação do tronco em forófitas arbóreas representativas na área de estudo. Para o inventário das epífilas foram coletadas 40 amostras compostas de três a cinco folhas de arbustos e árvores, desde...

  16. Interaction of near-IR laser radiation with plasma of a continuous optical discharge

    The interaction of 1.07-μm laser radiation with plasma of a continuous optical discharge (COD) in xenon and argon at a pressure of p = 3–25 bar and temperature of T = 15 kK has been studied. The threshold power required to sustain COD is found to decrease with increasing gas pressure to Pt < 30 W in xenon at p > 20 bar and to Pt < 350 W in argon at p > 15 bar. This effect is explained by an increase in the coefficient of laser radiation absorption to 20−25 cm–1 in Xe and 1−2 cm–1 in Ar due to electronic transitions between the broadened excited atomic levels. The COD characteristics also depend on the laser beam refraction in plasma. This effect can be partially compensated by a tighter focusing of the laser beam. COD is applied as a broadband light source with a high spectral brightness

  17. Structural and thermal properties of nanocrystalline CuO synthesized by reactive magnetron sputtering

    Recent research has shown immense application of metal oxides like CuO, MgO, CaO, Al2O3, etc. in different areas which includes chemical warfare agents, medical drugs, magnetic storage media and solar energy transformation. Among the metal oxides, CuO nanoparticles are of special interest because of their excellent gas sensing and catalytic properties. In this paper we report structural and thermal properties of CuO synthesized by reactive magnetron DC sputtering. The synthesized nanoparticles were characterized by X-ray diffractometer. The XRD result reveals that as DC power increased from 30W to 80W, size of the CuO nanoparticles increased. The same results have been verified through TEM analysis. Thermal properties of these particles were studied using thermogravimetry

  18. Effect of sulfonation and diethanolamine addition on the mechanical and physicochemical properties of SEPS copolymer

    Patiño, D.; Correa, E.; Acevedo-Morantes, M.

    2016-02-01

    Modification techniques have been developed to achieve changes in the processing of polymers, and modification of their mechanical, thermal and morphological properties, as well as their hydrophobicity and conductivity. Sulfonation improves ion conductivity, antistatic behaviour, hydrophilicity and solubility of the polymers. These characteristics are related to the presence of sulfonic groups in the polymer matrix. This research project focuses on the evaluation of mechanical, physical and chemical properties of membranes that are based on a sulfonated Styrene-Ethylene-Propylene-Styrene (SEPS) copolymer. The membranes were functionalized with diethanolamine at 5, 15 and 30% w/w, to separate carbon dioxide. FTIR and XRD analyses were used to characterize the membranes. The sulfonated-loaded membrane with 15% of diethanolamine showed the best results in each characterization.

  19. Ciclismo de estrada : indicadores de desempenho para jovens atletas

    Teixeira, Paulina Conde

    2014-01-01

    O objectivo deste estudo foi obter indicadores de desempenho para atletas de ciclismo de estrada adolescentes estudar a sua cinética do V̇ O2. Catorze atletas com 15.8 anos de idade (média) fizeram 3 testes em laboratório, utilizando a própria bicicleta num simulador de treino: teste progressivo de 30W.min-1; teste de potência aeróbia máxima (PAM), e contra-relógio de 20 minutos. Nos dois primeiros testes mediram-se as trocas gasosas, e em todos os testes mediram-se a potência (PO), veloci...

  20. Purification, crystallization and preliminary crystallographic analysis of Streptococcus pyogenes laminin-binding protein Lbp

    The S. pyogenes laminin-binding protein Lbp, which is essential for adhesion to human laminin, has been expressed, purified and crystallized. The laminin-binding protein Lbp (Spy2007) from Streptococcus pyogenes (a group A streptococcus) mediates adhesion to the human basal lamina glycoprotein laminin. Accordingly, Lbp is essential in in vitro models of cell adhesion and invasion. However, the molecular and structural basis of laminin binding by bacteria remains unknown. Therefore, the lbp gene has been cloned for recombinant expression in Escherichia coli. Lbp has been purified and crystallized from 30%(w/v) PEG 1500 by the sitting-drop vapour-diffusion method. The crystals belonged to the monoclinic space group P21, with unit-cell parameters a = 42.62, b = 92.16, c = 70.61 Å, β = 106.27°, and diffracted to 2.5 Å resolution

  1. Dielectric properties measurement method in the microwave frequencies range for non-polar/polar liquid mixtures characterization

    Surducan, E.; Neamtu, C.; Ienciu, M.; Surducan, V.; Limare, A.; Fourel, L.

    2015-12-01

    We present a method based on dielectric properties measurements over a large spectrum of frequencies, in the microwave (MW) domain, in order to characterize a liquid mixture. The liquid mixtures consist of non-polar fluids (silicone oil, diesel fuel) and polar additives, in order to increase the specific MW absorption of the mixture for further MW power processing. We have measured the MW specific absorptions for mixtures of silicone oil with 20% and 30% (w/w) isopropanol. In both cases, the mixtures are sufficiently stable over time to allow further studies of thermal convection dynamics initiated by MW heating. For a mixture of diesel fuel with 10% (w/w) alkyl polyglycoside, the main observation was that its MW specific absorption varies over time after the mechanical mixing process.

  2. Optimization of Fluorine Plasma Treatment for Interface Improvement on HfO2/In0.53Ga0.47As MOSFETs

    Yen-Ting Chen

    2012-03-01

    Full Text Available This paper reports significant improvements in the electrical performance of In0.53Ga0.47As metal-oxide-semiconductor field-effect transistors (MOSFET by a post-gate CF4/O2 plasma treatment. The optimum condition of CF4/O2 plasma treatment has been systematically studied and found to be 30 W for 3–5 min. Approximately 5× reduction in interface trap density from 2.8 × 1012 to 4.9 × 1011 cm−2eV−1 has been demonstrated with fluorine (F incorporation. Subthreshold swing has been improved from 127 to 109 mV/dec. Effective channel mobility has been enhanced from 826 to 1,144 cm2/Vs.

  3. Steady-state, local temperature fields with turbulent liquid sodium flow in nominal and disturbed bundle geometries with spacer grids

    The operating reliability of nuclear reactors calls for a reliable strength analysis of the highly loaded core elements, one of its prerequisites being the reliable determination of the three-dimensional velocity and temperature fields. To verify thermohydraulics computer programs, extensive local temperature measurements in the rod claddings of the critical bundle zone were performed on a heated 19-rod bundle model with sodium flow and provided with spacer grids (P/D = 1.30; W/D = 1.19). The essential results are: - Outside the spacer grids, the azimuthal temperature variations of the side and corner rods are approximately 10-fold those of rods in the central bundle zone. - The spacer grids investigated give rise to great local temperature peaks and correspondingly great temperature gradients in the axial and azimuthal directions immediately around the support points. - Continuous reduction of a subchannel by rod bowing results in substantial rises of temperature which, however, are limited to adjacent cladding tubes. (orig.)

  4. A composição dos bandos mistos de aves na Mata Atlântica da Serra de Paranapiacaba, no sudeste brasileiro Mixed flocks of birds in Atlantic Rain Forest in Serra de Paranapiacaba, southeastern Brazil

    C. G. MACHADO

    1999-01-01

    Bandos mistos de aves são agrupamentos de duas ou mais espécies cuja formação e coesão se devem a interações comportamentais entre seus integrantes. Este estudo investigou a composição dos bandos mistos na Mata Atlântica do Parque Estadual Intervales, no alto da Serra de Paranapiacaba, SP, Brasil (24º12' a 24º25'S; 48º03' a 48º30'W). Foram feitas visitas mensais de abril de l990 a março de l991. A cada bando contatado registrava-se o número de indivíduos, composição e distribuição específica ...

  5. Formulation and Characterization of Fast Disintegrating Tablet of Aceclofenac by using Sublimation Method

    Kalpesh Gaur

    2011-01-01

    Full Text Available In the present work, fast disintegrating tablets of Aceclofenac were prepared by subliming method with a view to enhance patient compliance. In this paper, two super-disintegrants, viz., crospovidone and sodium starch glycolate were used in different ratio (2-8 % w/w with camphor (30 % w/w as subliming agent. The prepared batches of tablets were evaluated for thickness, weigh variation, hardness, friability, drug content uniformity, wetting time, water absorption ratio, in-vitro disintegration time and in-vitro drug release. Based on disintegration time (approximately 21 second, three formulations were tested for the in-vitro drug release pattern (in pH 7.4 phosphate buffer. Among the three promising formulations, the formulation prepared by using 8% w/w of crospovidone and emerged as the overall best formulation based on the in-vitro drug release characteristics.

  6. Impact of BaB2O4 growth method on frequency conversion to the deep ultra-violet

    Deyra, L.; Maillard, A.; Maillard, R.; Sangla, D.; Salin, F.; Balembois, F.; Kokh, A. E.; Georges, P.

    2015-12-01

    In this article, we report how the growth method used for barium beta-borate β-BaB2O4 (BBO) impacts its high power second harmonic generation properties in the deep-UV. We compared a BBO crystal grown by flux (Top Seeded Solution Growth or TSSG) and a BBO crystal grown by the Czochralski (CZ) method. We first characterized their transparency properties, then we measured their single-pass second harmonic conversion efficiencies with both a low average power and a high average power nanosecond pulsed lasers. We show that both crystals have comparable linear absorption and conversion efficiencies at low power, whereas in a high power experiment, the CZ-grown BBO yields higher conversion efficiency than the TSSG grown BBO. With a 30 W, 150 kHz, 8 ns green laser, the use of a CZ BBO led at best to a 40% increase in available average output power at 257 nm.

  7. Biodrying for mechanical-biological treatment of wastes: a review of process science and engineering.

    Velis, C A; Longhurst, P J; Drew, G H; Smith, R; Pollard, S J T

    2009-06-01

    Biodrying is a variation of aerobic decomposition, used within mechanical-biological treatment (MBT) plants to dry and partially stabilise residual municipal waste. Biodrying MBT plants can produce a high quality solid recovered fuel (SRF), high in biomass content. Here, process objectives, operating principles, reactor designs, parameters for process monitoring and control, and their effect on biodried output quality are critically examined. Within the biodrying reactors, waste is dried by air convection, the necessary heat provided by exothermic decomposition of the readily decomposable waste fraction. Biodrying is distinct from composting in attempting to dry and preserve most of biomass content of the waste matrix, rather than fully stabilise it. Commercial process cycles are completed within 7-15 days, with mostly H(2)O((g)) and CO(2) loses of ca. 25-30% w/w, leading to moisture contents of MBT process operators, regulators and end-users of SRF. PMID:19216072

  8. High-power picoseconds 355 nm laser by third harmonic generation based on CsB3O5 crystal

    Guo, L.; Wang, G. L.; Zhang, H. B.; Cui, D. F.; Wu, Y. C.; Lu, L.; Zhang, J. Y.; Huang, J. Y.; Xu, Z. Y.

    2007-07-01

    We report on the high average power third harmonic generation (THG) of a mode-locked picosecond laser in a CsB3O5 (CBO) crystal. The picosecond laser beam at 1064 nm is produced by a home-made 30 W master oscillator power-amplifier (MOPA) Nd:YVO4 laser system. The maximum THG output at 355 nm is up to 5.4 W. We also investigate the phase matching angle at different temperatures. During high power operation, the temperature of the CBO crystal is set at a high temperature of more than 100 °C. The THG system has shown a fine long-term stability for more than two months of operation.

  9. Impact of sodium dodecyl sulphate on the dissolution of poorly soluble drug into biorelevant medium from drug-surfactant discs

    Madelung, Peter; Ostergaard, Jesper; Bertelsen, Poul; Jørgensen, Erik V; Jacobsen, Jette; Müllertz, Anette

    The purpose was to elucidate the mechanism of action of sodium dodecyl sulphate (SDS) on drug dissolution from discs under physiologically relevant conditions. The effect of incorporating SDS (4-30%, w/w) and drug into discs on the dissolution constant and solubility were evaluated for the poorly...... discs is not caused by an increased surface area as SDS dissolves, micelles in the bulk medium or changes in the solid state properties of the drugs. The proposed mechanism involves a high local concentration of SDS at the solid-liquid interface as SDS dissolves and this solubilizes the drug. The...... soluble drugs griseofulvin and felodipine in a biorelevant dissolution medium (BDM). Dissolution constants from dissolution profiles of drug discs with and without SDS were measured using miniaturized rotating disc dissolution. Solid state changes were investigated by X-ray diffraction. Solubility was...

  10. A Primary Study of the Variations of Vertical Radiation with the Beijing 325-m Meteorological Tower

    WANG Yuesi; HU Bo; LIU Guangren

    2005-01-01

    The Beijing 325-m Meteorological Tower (325MT) is used to observe the vertical variation of solar radiation. Results of the experiments indicate that the automatic radiation monitoring system, including a sun tracker and data collection system, works well and all the specifications meet WMO observation standards. The measurement data show that there is a significant radiation decrease from 320 m to the surface, where the difference is only about 30 W m-2 on light air-pollution days, while the maximum reaches about 110 W m-2 when heavy pollution appears near the ground. The global UV radiation decreases on heavy air-pollution days and under poor visibility conditions, and the difference between 300 m and 8 m is larger than on clear days.

  11. Effect of non-starch polysaccharides on the in vitro digestibility and rheological properties of rice starch gel.

    Sasaki, Tomoko; Kohyama, Kaoru

    2011-07-15

    The starch digestibility and rheological properties of gels were evaluated in the presence of three non-starch polysaccharides (agar, xanthan gum and konjac glucomannan) with rice starch. Each polysaccharide was added to 30% (w/w) rice starch suspension at defined concentrations and starch gels were prepared. The extent of starch gel digestibility was determined by an in vitro method and rheological properties by a dynamic oscillatory test and a compression test. The added polysaccharides suppressed starch hydrolysis in the gels compared with the control, and a concentration dependency of this suppressive effect was observed. Adding agar and xanthan gum increased the storage shear modulus (G') of starch gels, while adding konjac glucomannan decreased G' values. The results indicate that the suppressive effect of non-starch polysaccharides on starch digestibility appears to be not only due to the rigidity of the gel, but also the interaction between starch and non-starch polysaccharides. PMID:23140698

  12. EFFECT OF SOME PLANT EXTRACT AGAINST SEED BORNE INFECTION OF COLLECTOTRICHUM DESTRUCTIVUM ON VIGNA UNIGUCULATA L.

    Umesh P. Mogle1 and

    2012-06-01

    Full Text Available The cowpea, Vigna unguiculata L. Walp is an ancient food crop, suffering from many fungal diseases. Collectotrichum destructivum is a harmful seed borne pathogen causing disease to the cowpea plant. Control of seed borne infection would be a possible means of reducing losses due to this disease, attempts were made, fungal species isolated from cowpea seeds were used as inocula. The effects of leaf extracts of Argemone mexicana L., Semecarpus anacardium L., Cassia fistula L., Tephrosia purpurea (L. Pers., were evaluated for the control of Collectotrichum destructivum on seeds of cowpea. The seeds were soaked in sterile distilled water extract (10, 20 and 30%, w/v of the leaves for 5, 10 and 15 h. All these plant extracts had significant inhibitory growth effect on the fungal pathogen. Argemone mexicana extract was more effective followed by Semecarpus anacardium, Cassia fistula and Tephrosia purpurea plant extracts and compared favorably with benomyl in the control of the pathogen.

  13. Highly nonlinear dispersion-flattened photonic crystal fibers for supercontinuum generation in a telecommunication window

    Saitoh, Kunimasa; Koshiba, Masanori

    2004-05-01

    We propose a new structure of highly nonlinear dispersion-flattened (HNDF) photonic crystal fiber (PCF) with nonlinear coefficient as large as 30 W-1km-1 at 1.55 µm designed by varying the diameters of the air-hole rings along the fiber radius. This innovative HNDF-PCF has a unique effective-index profile that can offer not only a large nonlinear coefficient but also flat dispersion slope and low leakage losses. It is shown through numerical results that the novel microstructured optical fiber with small normal group-velocity dispersion and nearly zero dispersion slope offers the possibility of efficient supercontinuum generation in the telecommunication window using a few ps pulses.

  14. 1.1.5. Synthesis and characterization of silver(I complexes with ligands having anti-inflammatory properties

    M. I. Azócar*, H. Muñoz, P. Levin, N. Dinamarca, G. Gómez, A. Ibañez, M.T. Garland and M. A. Paez

    2014-04-01

    Full Text Available Five water soluble silver(I  complex with Ibuprofen (AgIbu, Naproxen (AgNap,  Mefenamic acid (AgMef, acetyl salicylic acid(AgAsp and salicylic acid (AgSal were synthesized and characterized by elemental analysis, FT-IR, 1H and 13C NMR. Data suggest coordination of the ligand to Ag(I through the oxygen atom of the carboxylic group. AgAsp was obtained as a mixture of AgAsp and Ag(I-2-hydroxybenzoate (AgSal due to decomposition by thermal and hydrolysis of acetylsalicylic acid into salicylic acid. AgSal structure was confirmed by FT-IR, NMR and X-ray diffraction. Synthesized compounds were tested toward UV-radiation (258 nm, 30 W and compared with AgCl in order to characterize their light sensibility.

  15. Structural and thermal properties of nanocrystalline CuO synthesized by reactive magnetron sputtering

    Verma, M. [Department of Chemistry, IIT Roorkee, Roorkee-247667, India and Nano Science Laboratory, Institute Instrumentation Centre, IIT Roorkee, Roorkee-247667 (India); Gupta, V. K. [Department of Chemistry, IIT Roorkee, Roorkee-247667 (India); Gautam, Y. K.; Dave, V.; Chandra, R. [Nano Science Laboratory, Institute Instrumentation Centre, IIT Roorkee, Roorkee-247667 (India)

    2014-01-28

    Recent research has shown immense application of metal oxides like CuO, MgO, CaO, Al{sub 2}O{sub 3}, etc. in different areas which includes chemical warfare agents, medical drugs, magnetic storage media and solar energy transformation. Among the metal oxides, CuO nanoparticles are of special interest because of their excellent gas sensing and catalytic properties. In this paper we report structural and thermal properties of CuO synthesized by reactive magnetron DC sputtering. The synthesized nanoparticles were characterized by X-ray diffractometer. The XRD result reveals that as DC power increased from 30W to 80W, size of the CuO nanoparticles increased. The same results have been verified through TEM analysis. Thermal properties of these particles were studied using thermogravimetry.

  16. Bronchography in dogs. Comparative study with two barium sulphate solutions

    Two solutions of barium sulphate, 60 and 30% w/v, were compared with the ''overflow'' Bronchographic method. Two groups of eight healthy adult does of both sexes, weighing 7 to 18 kg were used for the study. The dogs were anaesthetised with thiopentone sodium 2% (20 mg/kg iv). After intubation, each dog received contrast medium by a catheter connected to a syringe, in a 9 mi dose. Two series of two x-rays plates were taken in left lateral recumbent, 3 and 6 min after administering the contrast medium and in ventrodorsal projection, 30 sec. later. The x-ray plates obtained were analysed and compared intra and inter group considering the advance speed of the contrast medium, the radiographic density and outlines. Adverse reactions were controlled

  17. Experimental investigation on CFRP milling by low power Q-switched Yb:YAG laser source

    Genna, S.; Tagliaferri, F.; Papa, I.; Leone, C.; Palumbo, B.

    2016-05-01

    In the present study, laser milling of CFRP plate by means of a 30W Q-Switched Yb:YAG fiber laser is investigated through statistical analysis. Milling tests were performed at the nominal power changing the pulse power; the scanning speed, the hatch distance and the released energy. Design of Experiments (DoE) and ANalysis Of VAriance (ANOVA) were applied with the aim to improve the process performances in term of material removal rate and heat affected zone extension. The results show that, the adopted laser is an effective solution for the CFRP milling. Moreover, adopting an accurate approach to the problem, process variability and material damages can be easily reduced.

  18. Study on iron oxide nanoparticles coated with glucose-derived polymers for biomedical applications

    Herea, D. D.; Chiriac, H.; Lupu, N.; Grigoras, M.; Stoian, G.; Stoica, B. A.; Petreus, T.

    2015-10-01

    This study reports an approach for a facile one-step synthesis of magnetic nanoparticles (MNPs) coated with glucose-derived polymers (GDP) through a mechanochemical hydrothermal process for biomedical applications. Polymer-coated magnetic nanoparticles (Fe2O3/Fe3O4), with sizes below 10 nm, exhibited superparamagnetic behavior, with a specific magnetization saturation value of about 40 emu/g, and a maximum specific absorption rate (SAR) of 30 W/g in AC magnetic fields. Depending on the intensity of the applied AC magnetic field, a temperature of 42 °C can be achieved in 4-17 min. The surface polymerized layer affords functional hydroxyl groups for binding to biomolecules containing carboxyl, thiol, or amino groups, thereby making the coated nanoparticles feasible for bio-conjugation. In vitro cytotoxicity evaluation pointed out that a relatively high concentration of polymer-coated magnetic nanoparticles (GDP-MNPs) did not induce severe cell alteration, suggesting a good biocompatibility.

  19. EFFECT OF THE ADDITION OF COMMON BEAN FLOUR ON THE COOKING QUALITY AND ANTIOXIDANT CHARACTERISTICS OF SPAGHETTI

    José Alberto

    2012-10-01

    Full Text Available Pasta is a nutritionally unbalanced food, due to its low fat and fiber and low value of its protein. It is considered an adequate vehicle for food supplementation with minerals, proteins and other healthy components such as bioactive compounds present in common beans. The effect of composite pasta (wheat – common bean; 30 % w/w on the cooking quality (optimal cooking time, cooking loss, weight loss, firmness, color, total phenolic content, antioxidant capacity by DPPH and ORAC assays and phenolic acid profile was investigated. According to the quality parameters, pasta added with bean flour was less hard with respect to the pasta made from durum wheat. The total phenolic content and antioxidant capacity by DPPH and ORAC assays were higher in the pasta with common bean flour than in the pasta control. Also, more phenolic acids were identified in cooked pasta containing common bean flour as analyzed by HPLC.

  20. A diet rich in green and yellow vegetables inhibits atherosclerosis in mice.

    Adams, Michael R; Golden, Deborah L; Chen, Haiying; Register, Thomas C; Gugger, Eric T

    2006-07-01

    Although dietary patterns characterized by a high intake of fruits and vegetables are associated with reduced risk of coronary heart disease, the mechanisms involved are uncertain. We determined the effects of a diet rich in green and yellow vegetables on the development of atherosclerosis, the underlying cause of coronary heart disease, in a mouse model of atherosclerosis, the LDL receptor -/-, apolipoprotein B transgenic mouse. The mice were randomized into 2 diet groups: 1) a vegetable-free control diet (n = 53) and 2) the same diet with 30% (w:w) replaced by an equal-parts mixture of freeze-dried peas, green beans, broccoli, corn, and carrots (n = 54). Mice were fed these diets for 16 wk. Aortic atherosclerosis, as estimated by cholesteryl ester content, was reduced 38% (P yellow vegetables inhibits the development of atherosclerosis and may therefore lead to a reduction in the risk of coronary heart disease. PMID:16772454

  1. Biological responses to current UV-B radiation in Arctic regions

    Albert, Kristian; N. Mikkelsen, Teis; Ro-Poulsen, Helge

    Depletion of the ozone layer and the consequent increase in solar ultraviolet-B radiation (UV-B) may impact living conditions for arctic plants significantly. In order to evaluate how the prevailing UV-B fluxes affect the heath ecosystem at Zackenberg (74°30'N, 20°30'W) and other high......-arctic regions, manipulation experiments with various set-ups have been performed. Activation of plant defence mechanisms by production of UV-B absorbing compounds was significant in ambient UV-B in comparison to a filter treatment reducing the UV-B radiation. Despite the UV-B screening response, ambient UV...... symbionts (mycorrhiza) or in the biomass of microbes in the soil of the root zone. However, the composition of the soil microbial community was different in the soils under ambient and reduced UV radiation after three treatment years. These results provide new insight into the negative impact of current UV...

  2. Generation of high energy square-wave pulses in all anomalous dispersion Er:Yb passive mode locked fiber ring laser.

    Semaan, Georges; Ben Braham, Fatma; Salhi, Mohamed; Meng, Yichang; Bahloul, Faouzi; Sanchez, François

    2016-04-18

    We have experimentally demonstrated square pulses emission from a co-doped Er:Yb double-clad fiber laser operating in anomalous dispersion DSR regime using the nonlinear polarization evolution technique. Stable mode-locked pulses have a repetition rate of 373 kHz with 2.27 µJ energy per pulse under a pumping power of 30 W in cavity. With the increase of pump power, both the duration and the energy of the output square pulses broaden. The experimental results demonstrate that the passively mode-locked fiber laser operating in the anomalous regime can also realize a high-energy pulse, which is different from the conventional low-energy soliton pulse. PMID:27137277

  3. Generation of Terahertz Surface Plasmon Polaritons Using Nondiffractive Bessel Beams with Orbital Angular Momentum.

    Knyazev, B A; Choporova, Yu Yu; Mitkov, M S; Pavelyev, V S; Volodkin, B O

    2015-10-16

    Bessel vortex beams with topological charges of l=±1 and l=±2 were produced in the terahertz spectral range from a free electron laser Gaussian beam (λ=141  μm) transformed using silicon binary diffractive optical elements. The spatial characteristics of the beams were obtained using a microbolometer array. A radius to path length ratio of 1:100 was achieved for nondiffractive beams with the average power of 30 W. Surface plasmon polaritons (SPPs) on gold-zinc-sulphide-air interfaces were generated due to diffraction of vortex beams on a sample edge. A new effect, a dependence of the efficiency of SPP generation on the direction of the azimuthal component of incident-radiation Poynting vector, was revealed. PMID:26550877

  4. Measurement of Deeply Virtual Compton Scattering at HERA

    Andreev, V; Aplin, S; Asmone, A; Babaev, A; Backovic, S; Bähr, J; Baghdasaryan, A; Baranov, P; Barrelet, E; Bartel, Wulfrin; Baudrand, S; Baumgartner, S; Becker, J; Beckingham, M; Behnke, O; Behrendt, O; Belousov, A; Berger, C; Berger, N; Bizot, J C; Boenig, M O; Boudry, V; Bracinik, J; Brandt, G; Brisson, V; Brown, D P; Bruncko, Dusan; Büsser, F W; Bunyatyan, A; Buschhorn, G; Bystritskaya, L; Campbell, A J; Caron, S; Cassol-Brunner, F; Cerny, K; Chekelian, V; Contreras, J G; Coughlan, J A; Cox, B E; Cozzika, G; Cvach, J; Dainton, J B; Dau, W D; Daum, K; Delcourt, B; Demirchyan, R; de Roeck, A; Desch, Klaus; De Wolf, E A; Diaconu, C; Dodonov, V; Dubak, A; Eckerlin, G; Efremenko, V; Egli, S; Eichler, R; Eisele, F; Ellerbrock, M; Elsen, E; Erdmann, W; Essenov, S; Faulkner, P J W; Favart, L; Fedotov, A; Felst, R; Ferencei, J; Finke, L; Fleischer, M; Fleischmann, P; Fleming, Y H; Flucke, G; Fomenko, A; Foresti, I; Formánek, J; Franke, G; Frising, G; Frisson, T; Gabathuler, Erwin; Garutti, E; Gayler, J; Gerhards, R; Gerlich, C; Ghazaryan, S; Ginzburgskaya, S; Glazov, A; Glushkov, I; Görlich, L; Göttlich, M; Gogitidze, N; Gorbounov, S; Goyon, C; Grab, C; Greenshaw, T; Gregori, M; Grindhammer, G; Gwilliam, C; Haidt, D; Hajduk, L; Haller, J; Hansson, M; Heinzelmann, G; Henderson, R C W; Henschel, H; Henshaw, O; Herrera-Corral, G; Herynek, I; Heuer, R D; Hildebrandt, M; Hiller, K H; Hoffmann, D; Horisberger, R P; Hovhannisyan, A; Ibbotson, M; Ismail, M; Jacquet, M; Janauschek, L; Janssen, X; Jemanov, V; Jönsson, L B; Johnson, D P; Jung, H; Kapichine, M; Karlsson, M; Katzy, J; Keller, N; Kenyon, I R; Kiesling, C; Klein, M; Kleinwort, C; Klimkovich, T; Kluge, T; Knies, G; Knutsson, A; Korbel, V; Kostka, P; Koutouev, R; Krastev, K; Kretzschmar, J; Kropivnitskaya, A; Krüger, K; Kuckens, J; Landon, M P J; Lange, W; Lastoviicka, T; Laycock, P; Lebedev, A; Leiner, B; Lendermann, V; Levonian, S; Lindfeld, L; Lipka, K; List, B; Lobodzinska, E; Loktionova, N; López-Fernandez, R; Lubimov, V; Lucaci-Timoce, A I; Lüders, H; Lüke, D; Lux, T; Lytkin, L; Makankine, A; Malden, N; Malinovskii, E I; Mangano, S; Marage, P; Marshall, R; Martisikova, M; Martyn, H U; Maxfield, S J; Meer, D; Mehta, A; Meier, K; Meyer, A B; Meyer, H; Meyer, J; Mikocki, S; Milcewicz-Mika, I; Milstead, D; Mohamed, A; Moreau, F; Morozov, A; Morris, J V; Mozer, M U; Müller, K; Murn, P; Nankov, K; Naroska, Beate; Naumann, J; Naumann, T; Newman, P R; Niebuhr, C B; Nikiforov, A; Nikitin, D K; Nowak, G; Nozicka, M; Oganezov, R; Olivier, B; Olsson, J E; Osman, S; Ozerov, D; Pascaud, C; Patel, G D; Peez, M; Pérez, E; Perez-Astudillo, D; Perieanu, A; Petrukhin, A; Pitzl, D; Placakyte, R; Pöschl, R; Portheault, B; Povh, B; Prideaux, P; Raicevic, N; Reimer, P; Rimmer, A; Risler, C; Rizvi, E; Robmann, P; Roland, B; Roosen, R; Rostovtsev, A; Rurikova, Z; Rusakov, S V; Salvaire, F; Sankey, D P C; Sauvan, E; Schatzel, S; Scheins, J; Schilling, F P; Schmidt, S; Schmitt, S; Schmitz, C; Schoeffel, L; Schöning, A; Schröder, V; Schultz-Coulon, H C; Schwanenberger, C; Sedlak, K; Sefkow, F; Shevyakov, I; Shtarkov, L N; Sirois, Y; Sloan, T; Smirnov, P; Soloviev, Yu; South, D; Spaskov, V; Specka, A; Stella, B; Stiewe, J; Strauch, I; Straumann, U; Tchoulakov, V; Thompson, G; Thompson, P D; Tomasz, F; Traynor, D; Truöl, P; Tsakov, I; Tsipolitis, G; Tsurin, I; Turnau, J; Tzamariudaki, E; Urban, M; Usik, A; Utkin, D; Valkár, S; Valkárová, A; Vallée, C; Van Mechelen, P; Van Remortel, N; Vargas-Trevino, A; Vazdik, Ya A; Veelken, C; Vest, A; Vinokurova, S; Volchinski, V; Vujicic, B; Wacker, K; Wagner, J; Weber, G; Weber, R; Wegener, D; Werner, C; Werner, N; Wessels, M; Wessling, B; Wigmore, C; Winter, G G; Wissing, C; Wolf, R; Wünsch, E; Xella, S M; Yan, W; Yeganov, V; Zaicek, J; Zaleisak, J; Zhang, Z; Zhelezov, A; Zhokin, A; Zimmermann, J; Zohrabyan, H G; Zomer, F

    2005-01-01

    A measurement is presented of elastic deeply virtual Compton scattering \\gamma* p \\to \\gamma p made using e^+ p collision data corresponding to a luminosity of 46.5 pb^{-1}, taken with the H1 detector at HERA. The cross section is measured as a function of the photon virtuality, Q^2, the invariant mass of the \\gamma* p system, W, and for the first time, differentially in the squared momentum transfer at the proton vertex, t, in the kinematic range 2 < Q^2 < 80 GeV^2, 30 < W < 140 GeV and |t| < 1 GeV^2. QCD based calculations at next-to-leading order using generalized parton distributions can describe the data, as can colour dipole model predictions.

  5. Physical properties of pre-crystallized mixtures of cocoa butter and cupuassu fat

    The physical characteristics of pre-crystallized binary mixtures of cocoa butter (Bahia + Indonesian blend) and 5, 10, 15, 20, 25 and 30% (w/w) cap.'s fat were determined. recrystallization was carried out using a lab-scale agitated jacket vessel reactor (700 ml). Samples were submitted to differential scanning calorimetry and X-Ray diffraction. The solid fat content and rupture force were also quantified. The snap values of the crystallized mixture decreased with an increase in the amount of alternative fat. A similar trend was observed with respect to the melting point values. The cocoa butter and cap.'s fat X-ray diffraction patterns confirmed the predominant formation of the a-circumflex polymorph. The addition of up to 30% cap.'s fat did not significantly affect the values of the physical properties when compared to pure cocoa butter (Author).

  6. Estudios ictiologicos en la laguna La Cuarentena (Isla Carabajal), rio Parana, Argentina : edad y crecimiento del "sabalo" (Prochilodus lineatus (Val.), periodo 1984-1985 (Pisces, Curimatidae)

    Carozza, C.; Cordiviola de Yuan, E.

    1991-01-01

    L'objectif est de connaître l'âge et la croissance du #Prochilodus lineatus$ dans la lagune La Cuarentena (31°45'15"S - 60°37'30"W) et d'établir des comparaisons avec d'autres milieux lenitiques et lotiques du Parana moyen, les échantillons ont été obtenus mensuellement (mai 1984-août 1985). On a capturé 496 exemplaires, de longueur comprise ebtre 35 et 58 cm. L'âge a été déterminé par la lecture des écailles. On a obtenu les relations entre la longueur du poisson et le rayons des écailles et...

  7. Facile synthesis of water-soluble carbon nano-onions under alkaline conditions

    Ahmed, Gaber Hashem Gaber; Laíño, Rosana Badía; Calzón, Josefa Angela García

    2016-01-01

    Summary Carbonization of tomatoes at 240 °C using 30% (w/v) NaOH as catalyst produced carbon onions (C-onions), while solely carbon dots (C-dots) were obtained at the same temperature in the absence of the catalyst. Other natural materials, such as carrots and tree leaves (acer saccharum), under the same temperature and alkaline conditions did not produce carbon onions. XRD, FTIR, HRTEM, UV–vis spectroscopy, and photoluminescence analyses were performed to characterize the as-synthesized carbon nanomaterials. Preliminary tests demonstrate a capability of the versatile materials for chemical sensing of metal ions. The high content of lycopene in tomatoes may explain the formation of C-onions in alkaline media and a possible formation mechanism for such structures was outlined. PMID:27335764

  8. Isolation and fusion of protoplasts from the phytopathogenic fungus Sclerotium rolfsii (Sacc.

    Sikandar Hayat

    2010-03-01

    Full Text Available Sclerotium rolfsii (Sacc. is a serious plant pathogenic fungus and lacks perfect (basidial stage in production. Protoplast fusion technology was employed to reconstruct fusants from this fungus. Two strains designated as A and R were used. Maximum protoplast yields of 3.8x10(5 /g mycelia and 2.8x10(5 /g mycelia were formed in strains A and R respectively. Osmotic stabilizer sucrose 1M gave maximum yield. Lysing enzyme at the rate of 15mg/ml was found best for yield. Fusion of protoplasts from strains A and R was carried out in fusion media containing PEG 4000 30% (w/v with 0.2mM CaCl2. Four fusants F1, F2, F3 and F4 were recovered. Morphological, physiological and pathogenic characters of fusants were compared with parent strains on carrots, beans and tomato.

  9. A 0.35μm 50V CMOS Sliding-Mode Control IC for Buck Converters

    Høyerby, Mikkel Christian Wendelboe; Andersen, Michael Andreas E.; Andreani, Pietro

    2007-01-01

    external N-channel power MOSFET. The total control loop delay using the implemented IC is 35ns, this is shown to be a 30% reduction compared to a state-of-the-art discrete IC based solution. The presented results also show that it is viable to integrate a 100MHz operational amplifier on the same die as a...... high-voltage MOSFET driver operating with slew rates in excess of 5V/ns. The IC is demonstrated in a tracking power supply with 30W output power and 3μs rise/fall time, running from a 40V input. The complete IC, including pads, takes up 4mm2 in a 0.35μm 50V CMOS process....

  10. High-power Kerr-lens mode-locked Yb:YAG thin-disk oscillator in the positive dispersion regime.

    Pronin, O; Brons, J; Grasse, C; Pervak, V; Boehm, G; Amann, M-C; Apolonski, A; Kalashnikov, V L; Krausz, F

    2012-09-01

    We demonstrate a self-starting Kerr-lens mode-locked (KLM) Yb:YAG thin-disk oscillator operating in the regime of positive intracavity group-delay dispersion (GDD). It delivers 1.7 ps pulses at an average power of 17 W and a repetition rate of 40 MHz. Dispersive mirrors compress the pulses to a duration of 190 fs (assuming sech2 shape; Fourier limit: 150 fs) at an average power level of 11 W. To our knowledge, this is the first KLM thin-disk oscillator with positive GDD. Output powers of up to 30 W were achieved with an increased output coupler transmission and intracavity GDD. We demonstrate increase of the pulse energy with increasing positive intracavity GDD, limited by difficulties in initiating mode-locking. PMID:22940943

  11. Effect of carbamazepine on viscoelastic properties and hot melt extrudability of Soluplus ®.

    Gupta, Simerdeep Singh; Parikh, Tapan; Meena, Anuprabha K; Mahajan, Nidhi; Vitez, Imre; Serajuddin, Abu T M

    2015-01-15

    The purpose of this study was to apply viscoelastic properties of polymer and drug-polymer mixtures to determine processing conditions for the preparation of amorphous solid dispersion by melt extrusion. A poorly water-soluble drug, carbamazepine (CBZ), was mixed with Soluplus(®) as the carrier. Torque analysis using a melt extruder was performed at 10, 20 and 30% w/w drug concentrations and the effect of barrel temperature was studied. Viscosity of the mixtures either at fixed temperatures with different angular frequencies or as a function of temperature with the same frequency was studied using a rheometer. The viscosity of Soluplus(®) and the torque exerted on the twin screws decreased with the increase in CBZ concentration. The viscosity versus temperature plots for different CBZ concentrations were parallel to each other, without the drug melting transition, indicating complete drug-polymer miscibility. Thus, the drug-polymer mixtures could be extruded at temperature as low as 140°C with 10% w/w drug load, 135°C with 20% w/w drug and 125°C with 30% w/w drug, which were, respectively, ∼ 50°C, 55°C and 65°C below the melting point of 191°C for CBZ. The differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD) analyses of the binary mixtures extruded at 125-150°C showed absence of crystalline drug. A systematic study of miscibility and extrudability of drug-polymer mixtures by rheological and torque analysis as a function of temperature will help formulators select optimal melt extrusion processing conditions to develop solid dispersions. PMID:25448585

  12. Inorganic ion exchangers based on manganese and potassium for recovery and removal of pollutant metals of aqueous effluents; Trocadores ionicos inorganicos a base de manganes e potassio para recuperacao e remocao de metais poluentes de efluentes aquosos

    Santos, Jacinete Lima dos

    2001-07-01

    This work presents a study on the synthesis, characterization and ion exchange properties of inorganic ion exchangers based on manganese and potassium. The ion exchangers were synthesized by calcination of the mixture of manganese(II) oxalate and potassium oxalate and were characterized by granulometer distribution analysis, X-ray powder diffraction, infrared spectroscopy and scanning electron microscopic. From the data obtained in characterization it was observed that exist two distinguished groups of these materials. The first group belong to ion exchangers with up to 30% w/w potassium and the second group formed by the ion exchangers with more than 30% w / w of content of potassium in their compositions. The studies of adsorption of these materials showed that the adsorption of Cd{sup 2+} is a function of the following parameters as pH, concentration of Cd{sup 2+}, time of contact between the ion exchangers the concentration of the Cd{sup 2+} solution and the interference of other ions like Ni{sup 2+}. The great pH of adsorption for these materials occur in pH 9, the study of the influence of the cadmium concentration in the adsorption showed that for a group of exchangers the adsorption decreases with the increase of cadmium concentration and for the other group the adsorption increases with the increase of cadmium concentration. The kinetics of adsorption occur in a contact time between the ion exchangers and the Cd{sup 2+} solutions relatively short, at about 15 minutes is necessary to establish the equilibrium. The presence of Ni{sup 2+} as interfering ion decreases the adsorption of cadmium of 99,7% to 65%. These inorganic ion exchangers showed be good exchangers for Cd{sup 2+}. (author)

  13. (Th-U)O2 MOX fuel fabrication and dry recycling of the sintered rejects

    Thorium is an important nuclear material. Due to its abundance in large quantity in India our preceptors have envisaged three stage nuclear power programme. Thoria based fuel is planned to be used in the third stage of nuclear power programme. (Th-LEU)O2 mixed oxide (MOX) is the proposed fuel for AHWR- LEU-300 in which UO2 content varies from 13 to 30 w%. Fabrication of ThO2-NU fuel of similar composition varying from 13% to 30 % UO2 has been carried out in kg scale at Radiometallurgy Division. Conventional Powder Metallurgical processes like mixing; cold compaction and sintering were employed for fabrication of ThO2-UO2 fuel pellets. Density up to 93-94% TD was achieved in the sintered pellets. XRD result on sintered pellet showed single phase formation. Fuel fabrication process is always associated with generation of green/sintered rejects. Recycling of the sintered reject is important to judiciously utilize the feed material and avoid the accumulation of the waste. As thorium dioxide is a stable compound, recycling of process rejects of thoria based fuels either by dry or wet route is difficult unlike UO2 based fuels. The stable oxidation state of thorium oxide limits oxidative-reductive processing of sinter rejects. Dissolution of thoria fuels in nitric acid is also difficult. The presence of UO2 (13w% to 30w %) in the ThO2-UO2 fuel pellets makes it amenable to oxidative-reductive processing by modifying the fabrication parameters. A process for recycling of the sintered reject has been successfully worked out. This paper discusses the fabrication aspects of Th-NU MOX fuel and dry recycling of process rejects. (author)

  14. CO2 and Nd:YAP laser interaction with lithium disilicate and Zirconia dental ceramics: A preliminary study

    Rocca, Jean-Paul; Fornaini, Carlo; Brulat-Bouchard, Nathalie; Bassel Seif, Samy; Darque-Ceretti, Evelyne

    2014-04-01

    Lithium disilicate and Zirconia ceramics offer a high level of accuracy when used in prosthetic dentistry. Their bonding using different resins is highly dependent on micro-mechanical interlocking and adhesive chemical bonding. Investigation of the performances of high strength ceramics when their surface is modified for chemical and mechanical bonding is then required. The aim of this study is to investigate the possibility of using laser for surface treatment of different high strength CAD/CAM ceramics and thus to improve their mechanical and chemical properties. Thirty two CAD/CAM ceramic discs were divided into two different groups: lithium disilicate ceramics (IPS e.max CAD®, Ivoclar, Vivadent, Italy) and Zirconia ceramics (IPS e.max ZirCAD®, Ivoclar, Vivadent, Italy). The Laser surface treatment was performed by Carbon Dioxide laser (Dream Pulse Laser®, Daeshin Enterprise Corp., Korea) at 20 W, 25 W and 30 W CW and by Neodymium Yttrium Aluminum Perovskite laser (Nd:YAP Lokki®, Lobel Medical, France) at 10 W and 30 Hz. Physical modifications of the irradiated ceramic discs were observed by scanning electron microscopy (SEM) and chemically analyzed by Energy-Dispersive Spectroscopy (EDS). Surface wettability was tested using the water drop test and the crystalline structure was investigated using X-ray diffraction (XRD). The macroscopic observation showed a shinier structure in all the groups, while at the SEM observation only CO2 25 W and 30 W treated groups showed cracks and fissures. In the conditions of this study, CO2 laser and Nd:YAP laser with the parameters used create chemical and physical surface modifications of the ceramics, indicating the possibility of an improvement in adhesion of the tested ceramics.

  15. Factorial study on influence of gas generating agent and diluent on drug release kinetics of clopidogrel bisulfate floating tablets

    K R Koteswara Rao

    2013-01-01

    Full Text Available The purpose of present work was to formulate and characterize a floating drug delivery system for Clopidogrel bisulphate to improve bioavailability and to minimize the side-effects of the drug such as gastric bleeding and drug resistance development. Clopidogrel floating tablets were prepared by direct compression technique by the use of xanthan gum at different concentrations (20%, 25% and 30% w/w. Sodium bicarbonate (15% w/w and microcrystalline cellulose (MCC (30% w/w were used as gas generating agent and diluent respectively. The effects of sodium bicarbonate and MCC on the drug release kinetics and floating properties were investigated. A 2 2 factorial design was applied systematically to optimized formulation. The percentage amount of sodium bicarbonate (X 1 and percentage amount of MCC (X 2 were selected as independent variables. The drug release rate constant (K and time required for 85% drug dissolution (T85 was selected as dependent variables. Factorial design revealed that the percentage amount of sodium bicarbonate and MCC had insignificant effect on drug release kinetics (K, T85 within the chosen levels and a high level of sodium bicarbonate (X 1 and the low level of MCC (X 2 favor the preparation of clopidogrel floating tablets. All the Clopidogrel floating formulations followed first order kinetics, Higuchi drug release kinetics with diffusion as the dominant mechanism of drug release. As per Korsmeyer-Peppas equation, the release exponent "n" ranged 0.455-0.654 indicating that drug release from all the formulations was by non-fickian diffusion mechanism.

  16. High drug load, stable, manufacturable and bioavailable fenofibrate formulations in mesoporous silica: a comparison of spray drying versus solvent impregnation methods.

    Hong, Shiqi; Shen, Shoucang; Tan, David Cheng Thiam; Ng, Wai Kiong; Liu, Xueming; Chia, Leonard S O; Irwan, Anastasia W; Tan, Reginald; Nowak, Steven A; Marsh, Kennan; Gokhale, Rajeev

    2016-01-01

    Encapsulation of drugs in mesoporous silica using co-spray drying process has been recently explored as potential industrial method. However, the impact of spray drying on manufacturability, physiochemical stability and bioavailability in relation to conventional drug load processes are yet to be fully investigated. Using a 2(3) factorial design, this study aims to investigate the effect of drug-loading process (co-spray drying and solvent impregnation), mesoporous silica pore size (SBA-15, 6.5 nm and MCM-41, 2.5 nm) and percentage drug load (30% w/w and 50% w/w) on material properties, crystallinity, physicochemical stability, release profiles and bioavailability of fenofibrate (FEN) loaded into mesoporous silica. From the scanning electronic microscopy (SEM) images, powder X-ray diffraction and Differential scanning calorimetry measurements, it is indicated that the co-spray drying process was able to load up to 50% (w/w) FEN in amorphous form onto the mesoporous silica as compared to the 30% (w/w) for solvent impregnation. The in vitro dissolution rate of the co-spray dried formulations was also significantly (p = 0.044) better than solvent impregnated formulations at the same drug loading. Six-month accelerated stability test at 40 °C/75 RH in open dish indicated excellent physical and chemical stability of formulations prepared by both methods. The amorphous state of FEN and the enhanced dissolution profiles were well preserved, and very low levels of degradation were detected after storage. The dog data for the three selected co-spray-dried formulations revealed multiple fold increment in FEN bioavailability compared to the reference crystalline FEN. These results validate the viability of co-spray-dried mesoporous silica formulations with high amorphous drug load as potential drug delivery systems for poorly water soluble drugs. PMID:24853963

  17. Radiative effect differences between multi-layered and single-layer clouds derived from CERES, CALIPSO, and CloudSat data

    Clouds alter general circulation through modification of the radiative heating profile within the atmosphere. Their effects are complex and depend on height, vertical structure, and phase. The instantaneous cloud radiative effect (CRE) induced by multi-layered (ML) and single-layer (SL) clouds is estimated by analyzing data collected by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat, and Clouds and Earth's Radiation Energy Budget System (CERES) missions from March 2007 through February 2008. The CRE differences between ML and SL clouds at the top of the atmosphere (TOA) and at the surface were also examined. The zonal mean shortwave (SW) CRE differences between the ML and SL clouds at the TOA and surface were positive at most latitudes, peaking at 120 W m-2 in the tropics and dropping to -30 W m-2 at higher latitudes. This indicated that the ML clouds usually reflected less sunlight at the TOA and transmitted more to the surface than the SL clouds, due to their higher cloud top heights. The zonal mean longwave (LW) CRE differences between ML and SL clouds at the TOA and surface were relatively small, ranging from -30 to 30 W m-2. This showed that the ML clouds only increased the amount of thermal radiation at the TOA relative to the SL clouds in the tropics, decreasing it elsewhere. In other words, ML clouds tended to cool the atmosphere in the tropics and warm it elsewhere when compared to SL clouds. The zonal mean net CRE differences were positive at most latitudes and dominated by the SW CRE differences.

  18. Inorganic ion exchangers based on manganese and potassium for recovery and removal of pollutant metals of aqueous effluents

    This work presents a study on the synthesis, characterization and ion exchange properties of inorganic ion exchangers based on manganese and potassium. The ion exchangers were synthesized by calcination of the mixture of manganese(II) oxalate and potassium oxalate and were characterized by granulometer distribution analysis, X-ray powder diffraction, infrared spectroscopy and scanning electron microscopic. From the data obtained in characterization it was observed that exist two distinguished groups of these materials. The first group belong to ion exchangers with up to 30% w/w potassium and the second group formed by the ion exchangers with more than 30% w / w of content of potassium in their compositions. The studies of adsorption of these materials showed that the adsorption of Cd2+ is a function of the following parameters as pH, concentration of Cd2+, time of contact between the ion exchangers the concentration of the Cd2+ solution and the interference of other ions like Ni2+. The great pH of adsorption for these materials occur in pH 9, the study of the influence of the cadmium concentration in the adsorption showed that for a group of exchangers the adsorption decreases with the increase of cadmium concentration and for the other group the adsorption increases with the increase of cadmium concentration. The kinetics of adsorption occur in a contact time between the ion exchangers and the Cd2+ solutions relatively short, at about 15 minutes is necessary to establish the equilibrium. The presence of Ni2+ as interfering ion decreases the adsorption of cadmium of 99,7% to 65%. These inorganic ion exchangers showed be good exchangers for Cd2+. (author)

  19. Hydroxyapatite scaffolds infiltrated with thermally crosslinked polycaprolactone fumarate and polycaprolactone itaconate.

    Sharifi, Shahriar; Shafieyan, Yousef; Mirzadeh, Hamid; Bagheri-Khoulenjani, Shadab; Rabiee, Sayed Mahmood; Imani, Mohammad; Atai, Mohammad; Shokrgozar, Mohammad Ali; Hatampoor, Ali

    2011-08-01

    In this work, two unsaturated derivatives of polycaprolactone (PCL), polycaprolactone fumarate (PCLF), and polycaprolactone itaconate (PCLI), have been synthesized and used as an infiltrating polymer to improve the mechanical properties of brittle hydroxyapatite (HA) scaffolds. PCLF and PCLI were first synthesized through polyesterification of the low molecular weight PCL diols with fumaryl chloride and itaconyl chloride respectively, and then characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, and differential scanning calorimetry analysis. HA scaffolds were sintered using a foam replication technique, with porosity of about 60%. Polymer-HA composites were obtained by infiltrating the HA scaffolds with PCLF and PCLI solution (12.5 and 30 w/v in dichloromethane) followed by thermal crosslinking. The polymer infiltrated HA scaffolds were characterized by scanning electron microscopy, porosimetry, and gravimetrical analysis. The polyesterification reaction of PCL diols with fumarate chloride was more efficient than itaconyl chloride and dependent upon the molecular weight of the initial PCL precursor; the resultant PCLF demonstrated a degree of substitution of 1.2, 4.2, and 2.7 times higher than PCLIs. Polymer infiltration improved the compressive strength of the HA scaffolds, and based upon the type of macromer (PCLF or PCLI) and also their concentration in infiltrating solution (12.5 or 30 w/v %) compressive strength increased about 14-328%. In all studied samples, the reinforcement effect of PCLF infiltration was higher than PCLI. The macromers and their corresponding infiltrated HA scaffolds did not show any significant cytotoxicity toward human primary osteogenic sarcoma cell (G92 cell lines), in vitro. PMID:21626657

  20. Accelerating protein release from microparticles for regenerative medicine applications

    There is a need to control the spatio-temporal release kinetics of growth factors in order to mitigate current usage of high doses. A novel delivery system, capable of providing both structural support and controlled release kinetics, has been developed from PLGA microparticles. The inclusion of a hydrophilic PLGA–PEG–PLGA triblock copolymer altered release kinetics such that they were decoupled from polymer degradation. A quasi zero order release profile over four weeks was produced using 10% w/w PLGA–PEG–PLGA with 50:50 PLGA whereas complete and sustained release was achieved over ten days using 30% w/w PLGA–PEG–PLGA with 85:15 PLGA and over four days using 30% w/w PLGA–PEG–PLGA with 50:50 PLGA. These three formulations are promising candidates for delivery of growth factors such as BMP-2, PDGF and VEGF. Release profiles were also modified by mixing microparticles of two different formulations providing another route, not previously reported, for controlling release kinetics. This system provides customisable, localised and controlled delivery with adjustable release profiles, which will improve the efficacy and safety of recombinant growth factor delivery. Highlights: ► A new delivery system providing controlled release kinetics has been developed. ► Inclusion of hydrophilic PLGA–PEG–PLGA decoupled release kinetics from degradation. ► Using 10% triblock copolymer produced quasi zero order release over four weeks. ► Mixing microparticle formulations provided another route for controlling release. ► This system provides customisable, localised and controlled delivery of growth factors