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ABSTRACT: We report on a passively mode-locked Nd:YVO4 laser using a novel graphene oxide saturable absorber fabricated by vertical evaporation method. An 880 nm LD pump source
was used to reduce the thermal load of the laser crystal. At the pump power of 7.4 W, 1.2 W average output power of continuous
wave mode-locked laser with optical conversion efficiency of 16.2% was achieved. To the best of our knowledge, this is the
highest output power of passively mode-locked solid-state laser using graphene oxide saturable absorber. The repetition rate
of passively mode-locked pulse was 88 MHz with the pulse energy of 13.6 nJ.
Laser Physics 05/2012; 21(12):2072-2075. · 3.61 Impact Factor
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ABSTRACT: A diode end-pumped passively Q-switched Nd:YVO4 laser with a transmission-type single-walled carbon nanotube saturable absorber is first demonstrated in this paper. The
maximum continuous wave (CW) output power of 477 mW is obtained at the incident pump power of 1490 mW with the output transmission
T = 10%, resulting in slope efficiency of 41.3%. For Q-switching operation, the measured pulse duration of 332 ns, the pulse
energy of 326 nJ and the peak power of 982 mW are respectively obtained.
Laser Physics 04/2012; 21(9):1562-1565. · 3.61 Impact Factor
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ABSTRACT: Using the vertical evaporation technique we fabricated saturable absorbers by transferring the double-wall carbon nanotubes
(DWCNT) onto a hydrophilic quartz substrate. The fast recovery time and the saturation intensity of the absorber were measured
to be 228 fs and 130 μJ/cm2, respectively, at 1060 nm. The modulation depth of the absorber was about 3.7%. Passive mode-locked Nd:GdVO4 laser was demonstrated. The continuous wave mode-locked pulses pulse duration is 5.6 ps and the largest average output power
is 1.2 W at the pump power of 9.5 W. To the best of our knowledge, this is the first demonstration of high power continuous
wave mode locking laser with DWCNT absorber.
Laser Physics 04/2012; 21(10):1689-1693. · 3.61 Impact Factor
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ABSTRACT: A single-wall carbon nanotubes based saturable absorber wafer with absorption wavelength around 1047 nm was fabricated by
electric Arc discharge method and employed in a diode end-pumped Nd:YLF laser as saturable absorber. Passively continuous
wave mode-locking oscillation was achieved in the pump range form 6.7 to 8.0 W. The duration and repetition rate of the mode-locked
pulses were 10 ps and 59 MHz, respectively. The average output power was 280 mW.
Laser Physics 04/2012; 21(8):1353-1357. · 3.61 Impact Factor
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ABSTRACT: China is one of the countries most severely affected by desertification. Haloxylon ammodendron is an ecologically important component of the desert ecosystem and is one of the main shrub species used for ecological restoration.
We compared the genetic variation in seed and seedling traits among six H. ammodendron provenances arrayed from east to west in China. The experiment was carried out in a greenhouse in well-prepared seedling
beds (lines 1.5m apart and seeds with in lines 1.0m apart, 2.0cm deep) with five lines (seven seeds per line) per provenance
in a randomized block design with six replicates. The seed traits of fruit wing length, kernel weight, germination rate, and
survival rate were compared, as were the seedling traits of internode length, branch number, assimilation shoot diameter,
height, collar diameter, new shoot length, main root number, main root length, aboveground fresh weight, and underground fresh
weight. Moreover, correlations between each seed and seedling trait and climate and geographical factors were assessed. The
results show that the seeds from Dengkou County, Inner Mongolia had the best performance. Germination rate and survival rate
were significantly positively correlated with longitude; and fruit wing length, kernel weight, seedling height, and new shoot
length were significantly negatively correlated with latitude. Fruit wing length was significantly correlated with altitude.
Among the climatic factors, the temperature in January had a strong direct effect on fruit wing length, germination rate,
seedling height, and new shoot length. The mean annual rainfall had a strong direct effect on collar diameter. Humidity had
a strong direct effect on survival rate. Seedling height, aboveground weight, and collar diameter could be important criteria
for early provenance selection in the seedling stage. This study provides a reference for the selection of high-quality H. ammodendron seeds for drylands of northwest China.
Keywords
Haloxylon ammodendron provenances–Seed and seedling traits–Climatic influences–Genetic variation
Agroforestry Systems 04/2012; 81(2):135-146. · 1.38 Impact Factor
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ABSTRACT: Diode-end-pumped passively mode-locked Yb3+:Lu2SiO5 (Yb:LSO) lasers both in the picosecond and the femtosecond regimes were demonstrated in this paper. The mode-locked lasers
were initiated by using of semiconductor saturable absorber mirrors (SESAM). In the absence of intra-prisms for pulse compression,
the laser emitted 1.6 W of output power with pulses width of about 4.3 ps. A pair of SF10 prisms was inserted into the laser
cavity, pulses as short as 699 fs was generated around a center wavelength of 1043.6 nm with an average output power of 800
mW and a peak power of 11.0 kW.
Laser Physics 04/2012; 20(4):740-744. · 3.61 Impact Factor
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ABSTRACT: The cylindrical Ni–lead zirconate titanate (PZT)–Ni laminated composites with various magnetostrictive–piezoelectric phase
thickness ratios were synthesized by electroless deposition. The influences of the bias magnetic field (H
dc) and the ac magnetic field frequency (f) on magnetoelectric (ME) effect are discussed. It is seen that the ME voltage coefficient depends strongly on H
dc and f. The ME voltage coefficient and electromechanical resonance frequency increase as the magnetostrictive–piezoelectric phase
thickness ratio increases. The calculated resonant frequency increases with the magnetostrictive–piezoelectric phase thickness
ratio, which agrees well with the experimental results. The maximum ME voltage coefficient of the cylindrical Ni–PZT–Ni laminated
composite is 3.256Vcm−1Oe−1, which is much higher than that of the plate laminated composite with the same magnetostrictive–piezoelectric phase thickness
ratio. Electroless deposition is an efficient method to prepare ME laminated composites with complex structures. Proper resonant
frequency and stronger ME effect can be obtained by optimizing the structure.
Journal of Materials Science 04/2012; 46(6):1602-1605. · 2.02 Impact Factor
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ABSTRACT: Passive mode locking of a solid-state Nd:GdVO4 laser is demonstrated. The laser is mode locked by use of a semiconductor absorber mirror (SAM). A low Nd3+ doped Nd:GdVO4 crystal is used to mitigate the thermal lens effect of the laser crystal at a high pump power. The maximum average output
power is up to 6.5 W, and the pulse duration is as short as 6.2 ps. The optic-to-optic conversion efficiency is 32.5% and
the repetition rate is about 110 MHz.
Laser Physics 04/2012; 17(8):1033-1036. · 3.61 Impact Factor
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ABSTRACT: Thermodynamic equilibrium condensed phases for chemical vapor deposition of ZrC-SiC from the MTS-ZrCl4-CH4-H2 system were calculated by FactSage programs based on Gibbs free energy minimization of the reaction system. The deposition
phase diagrams, which indicated the condense phases, were constructed according to the calculation results. The effects of
temperature and partial pressure of precursors on the final condensed phases were studied. The results indicate that the codeposition
is more effective in the presence of an independent carbon source, CH4, with a reasonable partial pressure than in the absence of CH4. The experimental results are in good agreement with the thermodynamic calculation results.
Inorganic Materials 04/2012; 46(10):1090-1095. · 0.41 Impact Factor
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ABSTRACT: A diode-pumped passively Q-switched Nd:Lu0.33Y0.37Gd0.3VO4 (Nd:LuYGdVO4) laser at 1.06 µm with a single-walled carbon nanotube saturable absorber is demonstrated. At the incident pump power 9.1 W, the minimum pulse width of 52 ns and the maximum peak power 66.5 W can be obtained. In order to compare different gain media, the passively Q-switched Nd:LuVO4 and Nd:Lu0.15Y0.85VO4 (Nd:LuYVO4) lasers under the same laser cavity are also investigated. The experimental results show that Nd:LuYGdVO4 crystal is more suitable for passively Q-switched laser with single-walled carbon nanotube saturable absorber than Nd:LuVO4 or Nd:LuYVO4 crystals. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Laser Physics Letters 04/2011; 8(6):418 - 422. · 9.97 Impact Factor
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ABSTRACT: Patterns separated by approximately 55-nm-wide lines on Co/Pt multilayers have been fabricated using a focused ion beam with
a 30-keV Ga+ ion source. The ion irradiation allows the magnetic moment in the irradiated lines to rotate 45deg to 90deg toward the
film plane. The in-plane magnetization component of the irradiated lines increases as the ion dose increases. The balance
of incoming and outgoing flux at intersections is maintained in orthogonal patterns, while exceptions have been observed in
hexagonal and triangular patterns. In all patterns, irradiated lines and adjacent unirradiated elements have no magnetic interaction.
Journal of Electronic Materials 02/2009; 38(3):468-474. · 1.47 Impact Factor
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ABSTRACT: Molecular dynamics (MD) simulation was performed to investigate the ionic current through charged nanopores, and the results were compared with the calculation of Poisson–Nernst–Planck (PNP) equations based on the continuum theory. Results show that the current obtained by MD simulation is lower than the current calculated by PNP equations, and the discrepancy depends on the surface charge density of the nanopores. Also, MD simulation shows that the contribution of the electro-osmotic flow effect on ionic current could be 10% higher than the results obtained by solving PNP equations. Since the PNP equations do not take the effect of the pore wall into consideration, we suggest that adjusting the diffusion coefficient in the PNP equations can obtain more accurate results when calculating the ionic current through charged nanopores.
J. Phys. D: Appl. Phys. 01/2009; 42:105308-7.
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ABSTRACT: A diode-pumped passively mode-locked YVO4/Nd:YVO4 composite crystal green laser with a semiconductor saturable absorber mirror (SESAM) and a intracavity frequencydoubling KTP crystal was realized. The maximum average output power of 2.06 W at 532 nm with a repetition rate of 100 MHz was obtained at a pump power of 15 W, corresponding to optical slop efficiency 17.2%. The 532 nm mode-locked pulse width was estimated to be approximately 18-ps. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Laser Physics Letters 12/2008; 6(1):30 - 33. · 9.97 Impact Factor
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ABSTRACT: A passively mode-locked all-solid-state YVO4/Nd:YVO4 composite crystal laser was realized with a low temperature (LT) In0.25Ga0.75As semiconductor saturable absorber mirror. The saturable absorber was used as nonlinear absorber and output coupler simultaneously. Both the Q-switch and continuous-wave mode locking operation were experimentally realized. At a pump power of 4 W, the Q-switched mode locking changed to continuous wave mode locking. An average output power of 4.1 W with 5 ps pulse width was achieved at the pump power of 12 W, corresponding to an optical-optical conversion efficiency of 34.2%. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Laser Physics Letters 04/2008; 5(5):350 - 352. · 9.97 Impact Factor
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ABSTRACT: A passively mode-locked diode end-pumped YVO4/Nd:YVO4 composite crystal laser with a five-mirror folded cavity was first demonstrated in this paper by using a low temperature semiconductor saturable absorber mirror grown by metal organic chemical vapor deposition. Both the Q-switching and continuous-wave mode locking operation were realized experimentally. A stable averaged output power of 10.15 W with pulse width of about 11.2-ps at a repetition rate of 113 MHz was obtained, and the optical-to-optical efficiency of 43% was achieved. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Laser Physics Letters 02/2008; 5(6):421 - 424. · 9.97 Impact Factor
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ABSTRACT: Modification of silicon nitride nanopores under electron beam (e-beam) irradiation was investigated using a scanning electron microscope (SEM). Under e-beam irradiation, all pores with diameters ranging from 40 to 200 nm undergo shrinkage, and the shrinkage rate increases with the rate of energy deposition. By using the selected-area scanning tool in the SEM, the silicon nitride nanopores can be selectively reshaped based on localized e-beam irradiation, with a characteristic dimension smaller than 10 nm. A selected-area shaping technique was proposed to controllably shrink and shape the nanopores to a special structure.
Applied Physics Letters 04/2007; 90(16):163102-163102-3. · 3.84 Impact Factor
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Z M Wang,
X J Luo,
S Wang,
C X Luo,
M H Sun,
K Bao,
B Zhang,
G Y Zhang, Y G Wang,
Y Chen,
H Ji,
Q Ouyang
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ABSTRACT: We report a simple and inexpensive method to enhance the light output efficiency of a GaN-based light-emitting diode (LED). The method employs polydimethylsiloxane (PDMS) films prepared by nanoimprinting on the surface. Two kinds of PDMS films were prepared: one without a pattern and the other with a triangular pattern. After covering with a PDMS film, the light output was increased by about 25% for the LED with a no-pattern film, and about 33% for that with a triangular pattern film. These results can be explained by the surface roughening between the PDMS/air interfaces, which give more opportunity for photons generated in the LED active layer to escape. The research suggests that it is applicable to prepare patterned films by a nanoimprint technique to improve the light output of a GaN-based LED.
Semiconductor Science and Technology 02/2007; 22(3):279. · 1.72 Impact Factor
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ABSTRACT: By using a composite semiconductor absorber and an output coupler, we demonstrated a Q-switched and mode-locked diode-pumped
microchip Nd:YVO4 laser. With a 350-μm-thick crystal, the width of the Q-switched envelope was as short as 12 ns; the repetition rate of the
mode-locked pulses inside the Q-switched pulse was more than 10 GHz. The average output power was 335 mW at a maximum pump
power of 1.6 W. Q-switched envelope widths of 21 and 31 ns were also achieved with crystals 0.7 and 1.0 mm thick, respectively.
Laser Physics 11/2006; 16(12):1601-1604. · 3.61 Impact Factor
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ABSTRACT: In the Co 39 Ni 33 Al 28 alloy, the ferromagnetic shape memory effect was investigated. A martensitic transformation (MT) occurred in the Co 39 Ni 33 Al 28 alloy when the temperature was lower than the martensitic start transformation temperature, M S = 233 K. The morphologies and microstructures of the martensitic phase characterized by transmission electron microscope (TEM) showed a new 28-layered (28M) modulated martensite consisting of pinstripes and co-existing with the non-modulated martensite. Anomalies in magnetic properties and strain emerging around the MT have been briefly discussed.
Journal of Alloys and Compounds 01/2005; 400:145-149. · 2.29 Impact Factor
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ABSTRACT: The average longitudinal size of ultrasonic speckles back-scattered from a rough interface is investigated theoretically and experimentally in this paper. When a rough interface is insonified by ultrasound pulses, the average longitudinal size of the speckles in the space is found to be related not to the spatial coherence but to the temporal coherence of the ultrasound waves on the interface. Further theoretical analysis shows that the average longitudinal size of speckles is dependent on the sound speed and the time duration of the ultrasound pulse incident on the interface. To verify this theoretical conclusion, experiments are performed with a special experimental set-up. The experimental results are in good agreement with the theoretical ones.
Archive of Applied Mechanics 05/2004; 73(11):841-845. · 0.95 Impact Factor
