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Your search keyword '"Gang, Zhao"' showing total 48 results
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48 results on '"Gang, Zhao"'

1. Broadband Sheet Parametric Oscillator for χ (2) Optical Frequency Comb Generation via Cavity Phase Matching

Author

Baicheng Yao, Shining Zhu, Jian Guo, Hua-Ying Liu, Nicolò Sernicola, Shu-Wei Huang, Zhenlin Wang, Xin Ni, Xinjie Lv, Xiaohan Wang, Zhenda Xie, Kunpeng Jia, and Gang Zhao

Subjects
Optics, Materials science, business.industry, Broadband, General Physics and Astronomy, Optical frequency comb, Parametric oscillator, business, Phase matching
Abstract

We demonstrate a broadband optical parametric oscillation, using a sheet cavity, via cavity phase-matching. A 21.2 THz broad comb-like spectrum is achieved, with a uniform line spacing of 133.0 GHz, despite a relatively large dispersion of 275.4 fs2/mm around 1064 nm. With 22.6% high slope efficiency, and 14.9 kW peak power handling, this sheet optical parametric oscillator can be further developed for χ (2) comb.

Published
2021

2. Localization and Steering of Light in One-Dimensional Parity-Time Symmetric Photonic Lattices

Author

Zhenda Xie, Yan-Xiao Gong, Shining Zhu, Xing Wei, Xinjie Lv, and Gang Zhao

Subjects
Physics, Computation, Optical beam, Optical communication, Physics::Optics, General Physics and Astronomy, Parity (physics), 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Nonlinear system, Quantum mechanics, 0103 physical sciences, Integrated optics, 010306 general physics, 0210 nano-technology, Photonic lattices
Abstract

We theoretically study the propagation dynamics of input light in one-dimensional mixed linear-nonlinear photonic lattices with a complex parity-time symmetric potential. Numerical computation shows simultaneous localization and steering of the optical beam due to the asymmetric scatter and interplay between Kerr-type nonlinearity and PT symmetry. This may provide a feasible measure for manipulation light in optical communications, integrated optics and so on.

Published
2019

3. Trainsient Accretion Disk and Energy Mechanism of Gamma Ray Bursts

Author

Lan-Tian Yang, Guang-Sheng Zheng, Gang Zhao, and Ye Lu

Subjects
Black hole, Physics, Supermassive black hole, Active galactic nucleus, Intermediate polar, Rotating black hole, Astrophysics::High Energy Astrophysical Phenomena, X-ray binary, General Physics and Astronomy, Stellar black hole, Astrophysics, Spin-flip, Astrophysics::Galaxy Astrophysics
Abstract

We suggest that a rotating massive black hole (106 M⊙) located at an inactive galaxy may convert its host into a transient active phase by capturing and disrupting a star. During this period, a transient accretion disk is formed and a strong transient magnetic field can be produced in the inner boundary of the accretion disk. A large amount of rotational energy of the black hole is extracted and released in the ultra relativistic jet with a bulk Lorentz factor larger than 103 via Blandford-Znajek process. The relativistic jet energy can be converted into γ-ray radiation in the shock region located at a distance of about 1.4 × 1016 cm via the external shock mechanism. The observed properties of GRB971214 is used to illustrate our model.

Published
2000

4. Methodological Study on AMS Measurement of U Isotope Ratios in Nanogram U Samples

Author

X. G. Wang, X.-L. Zhao, Xinyi Yin, Kejun Dong, Qubo You, Shan Jiang, Shaoyong Wu, Ming He, Yong-Gang Zhao, Lin-Bo Xie, Liang Dou, De-Yu Lin, Hongtao Shen, Wang Chen, and Li-Li Li

Subjects
Measurement method, Isotope, chemistry, Radiochemistry, General Physics and Astronomy, Environmental science, chemistry.chemical_element, Methodological study, Uranium, Isotopic composition, Accelerator mass spectrometry
Abstract

The determination of uranium isotopic composition in trace samples is important in different fields. A new measurement method that uses an accelerator mass spectrometry (AMS) technique has been developed for the analysis of uranium isotopic ratios in ultra-trace uranium samples at the China Institute of Atomic Energy. As a result, about 5-nanogram level uranium samples analyzed with AMS is achieved.

Published
2014

5. Generating a 2.4-W cw Green Laser by Intra-Cavity Frequency Doubling of a Diode-Pumped Nd:GdVO 4 Laser with a MgO:PPLN Crystal

Author

Shining Zhu, Jun Lu, Xiaopeng Hu, Gang Zhao, and Yanhua Liu

Subjects
Materials science, business.industry, Green laser, Energy conversion efficiency, General Physics and Astronomy, Radiation, Laser, law.invention, Crystal, Optics, law, Optoelectronics, business, Beam (structure), Power Fluctuation, Diode
Abstract

High-power cw green laser radiation is generated by intra-cavity frequency doubling of a diode-pumped Nd:GdVO4 laser with a MgO-doped periodically-poled LiNbO3 (MgO:PPLN) crystal at room temperature. An average power of 2.4 W at 0.53 μm is obtained under the pump 15 W at 808 nm, corresponding to an overall optical-to-optical conversion efficiency of 16%. The M2 factor of the green beam is 3.90 and 1.34 for the horizontal and vertical direction, respectively. In addition, the power fluctuation is measured to be about ±5%.

Published
2012

6. Room-Temperature Continuous-Wave Operation of InGaN-Based Blue-Violet Laser Diodes with a Lifetime of 15.6 Hours

Author

Chang, Zeng, primary, Shu-Ming, Zhang, additional, Lian, Ji, additional, Huai-Bing, Wang, additional, De-Gang, Zhao, additional, Jian-Jun, Zhu, additional, Zong-Shun, Liu, additional, De-Sheng, Jiang, additional, Qing, Cao, additional, Ming, Chong, additional, Li-Hong, Duan, additional, Hai, Wang, additional, Yong-Sheng, Shi, additional, Su-Ying, Liu, additional, Hui, Yang, additional, and Liang-Hui, Chen, additional

Published
2010
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9. Preparation and Properties of Diluted Magnetic Semiconductors GaMnAs by Low-Temperature Molecular Epitaxy

Author

Gang Zhao, Wen-Jing Wang, Cheng-Qiang Zhang, Hui-Min Yuan, Chang-Jian Ji, Qi-Feng Han, and Gang Sun

Subjects
Materials science, Ferromagnetism, Condensed matter physics, Magnetism, Annealing (metallurgy), Transition temperature, General Physics and Astronomy, Curie temperature, Magnetic semiconductor, Thin film, Molecular beam epitaxy
Abstract

GaMnAs films are prepared by low-temperature molecular beam epitaxy. Based on the experimental results, the influence of growth and annealing conditions on the physical properties and defect configurations is discussed. In particular, the major compensating defects, such as As antisite (AsGa) and Mn interstitials (MnI), are studied in detail. Thereby, the relationship between structure and magnetic properties is given. It is indicated that a higher annealing temperature can remove MnI out of the GaMnAs lattices so as to raise the Curie temperature TC. Meticulous optimization of growth techniques (TS = 230°C, As2 : Ga = 5/1 and Ta = 250°C) leads to reproducible physical properties and ferromagnetic transition temperatures well above 148 K.

Published
2011

20. Continuous-Wave Operation of GaN Based Multi-Quantum-Well Laser Diode at Room Temperature

Author

Li-Qun, Zhang, primary, Shu-Ming, Zhang, additional, Hui, Yang, additional, Qing, Cao, additional, Lian, Ji, additional, Jian-Jun, Zhu, additional, Zong-Shun, Liu, additional, De-Gang, Zhao, additional, De-Sheng, Jiang, additional, Li-Hong, Duan, additional, Hai, Wang, additional, Yong-Sheng, Shi, additional, Su-Ying, Liu, additional, Liang-Hui, Chen, additional, and Jun-Wu, Liang, additional

Published
2008
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41. A High Power InGaN-Based Blue-Violet Laser Diode Array with a Broad-Area Stripe.

Author

Ping, Chen, De-Gang, Zhao, Mei-Xin, Feng, De-Sheng, Jiang, Zong-Shun, Liu, Li-Qun, Zhang, De-Yao, Li, Jian-Ping, Liu, Hui, Wang, Jian-Jun, Zhu, Shu-Ming, Zhang, Bao-Shun, Zhang, and Hui, Yang

Subjects
*SEMICONDUCTOR laser arrays, *OPTICAL properties of gallium nitride, *ELECTRODES, *VAPOR-plating, *OPTOELECTRONICS, *INTEGRATED circuits, *ELECTRONIC materials
Abstract

An array of high power InGaN/GaN multi-quantum-well laser diodes with a broad waveguide is fabricated. The laser diode structure is grown on a GaN substrate by metal-organic chemical vapor deposition. The laser diode array consists of five emitter stripes which share common electrodes on one laser chip. The electrical and optical characteristics of the laser diode array are investigated under the pulse current injection with 10kHz frequency and 100 ns pulse width. The laser diode array emits at the wavelength of 409 nm, which is located in the blue-violet region, and the threshold current is 2.9 A. The maximum output light peak power is measured to be 7.5 W at the wavelength of 411.8 nm under the current of 25 A. [ABSTRACT FROM AUTHOR]

Published
2013
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42. Dislocation Behavior in AlGaN/GaN Multiple Quantum-Well Films Grown with Different Interlayers.

Author

He-Hui Sun, Feng-Yun Guo, Deng-Yue Li, Lu Wang, De-Gang Zhao, and Lian-Cheng Zhao

Subjects
ALUMINUM gallium nitride films, DISLOCATIONS in crystals, QUANTUM wells, ANNIHILATION reactions, SUPERLATTICES, ALUMINUM nitride
Abstract

Dislocation behaviors are analyzed in AlGaN/GaN multiple-quantum-well films grown with different strainmodified interlayers. In the case of multiple-quantum-well layers grown on a GaN buffer layer without the interlayer, many threading dislocations interact and annihilate within about 100nm below the multiple quantum well layer. For multiple-quantum-well layers grown with the AlGaN interlayer, misfit dislocations between the GaN buffer layer and the AlGaN interlayer enter multiple-quantum-well layers and result in an increase of threading dislocation density. Besides misfit dislocations, the edge-type dislocation is another dislocation origin attributed to the dissociation of Shockley partials bounding the stacking fault in AlN/GaN superlattices below the interlayer interface. [ABSTRACT FROM AUTHOR]

Published
2012
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43. Formation of Low-Resistant and Thermally Stable Nonalloyed Ohmic Contact to N-Face n-GaN.

Author

Chang, Zeng, Shu-Ming, Zhang, Hui, Wang, Jian-Ping, Liu, Huai-Bing, Wang, Zeng-Cheng, Li, Mei-Xin, Feng, De-Gang, Zhao, Zong-Shun, Liu, De-Sheng, Jiang, and Hui, Yang

Subjects
ELECTRIC contacts, GALLIUM nitride, ELECTRIC resistance, THERMAL analysis, STABILITY (Mechanics), LIGHT sources, DIFFUSION, X-ray diffraction
Abstract

We report on the formation of Ohmic contacts with low resistance and high thermal stability to N-face n-GaN for vertical structure light emitters using a Ti(50nm)/Pt(50nm)/Au(50nm) metal scheme, where the Pt layer is introduced as a blocking layer to suppress the diffusion of Au onto the N-face n-GaN surface. It is shown that unlike the conventional Ti/Al/Ti/Au contacts, the Ti/Pt/Au contacts exhibit an Ohmic behavior with a relatively low specific contact resistivity of 1.1×10-4 Ω·cm2 even after annealing at 350°C. X-ray diffraction (XRD) measurements by synchrotron radiation and Auger electron spectroscopy (AES) examination are performed to understand the effects of heat treatment. [ABSTRACT FROM AUTHOR]

Published
2012
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44. Photoionization of Ge13+ in the Inner-Shell 2p Excitation Energy Region

Author

Gui-Yun, Liang LG and Gang, Zhao ZG

Abstract

The photoionization cross sections of the levels belonging to the ground configuration [Ne]3s23p63d of Ge13+ are investigated using the fully relativistic R-matrix method in the 2p−3d excitation region. The photoionization cross section is dominated by 2p−3d resonances. The detailed resonance structures are described and analysed with the resonance positions, widths and oscillator strengths to be determined. Good agreement is obtained between the length and velocity forms of the resonance oscillator strengths. The relative difference is less than 8%.

Published
2006

45. Methodological Study on AMS Measurement of U Isotope Ratios in Nanogram U Samples.

Author

Ke-Jun, Dong, Chen, Wang, Ming, He, De-Yu, Lin, Xing-Hong, Zhao, Li-Li, Li, Yong-Gang, Zhao, Liang, Dou, Lin-Bo, Xie, Shao-Yong, Wu, Xin-Yi, Yin, Xiang-Gao, Wang, Hong-Tao, Shen, Qu-Bo, You, and Shan, Jiang

Subjects
URANIUM isotopes, ACCELERATOR mass spectrometry, ISOTOPE separation, IRON powder, ELECTROSTATIC analyzers
Abstract

The determination of uranium isotopic composition in trace samples is important in different fields. A new measurement method that uses an accelerator mass spectrometry (AMS) technique has been developed for the analysis of uranium isotopic ratios in ultra-trace uranium samples at the China Institute of Atomic Energy. As a result, about 5-nanogram level uranium samples analyzed with AMS is achieved. [ABSTRACT FROM AUTHOR]

Published
2014
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46. Generating a 2.4-W cw Green Laser by Intra-Cavity Frequency Doubling of a Diode-Pumped Nd:GdVO4 Laser with a MgO:PPLN Crystal.

Author

Jun Lu, Yan-Hua Liu, Gang Zhao, Xiao-Peng Hu, and Shi-Ning Zhu

Subjects
LASER beams, DIODES, MAGNESIUM oxide, LITHIUM niobate, TEMPERATURE effect, SOLID-state lasers
Abstract

High-power cw green laser radiation is generated by intra-cavity frequency doubling of a diode-pumped Nd:GdVO4 laser with a MgO-doped periodically-poled LiNbO3 (MgO:PPLN) crystal at room temperature. An average power of 2.4W at 0.53&mgr;m is obtained under the pump 15W at 808 nm, corresponding to an overall optical-to-optical conversion efficiency of 16%. The M2 factor of the green beam is 3.90 and 1.34 for the horizontal and vertical direction, respectively. In addition, the power fluctuation is measured to be about ±5%. [ABSTRACT FROM AUTHOR]

Published
2012
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47. Performance Improvement of GaN-Based Violet Laser Diodes.

Author

De-Gang Zhao, De-Sheng Jiang, Ling-Cong Le, Jing Yang, Ping Chen, Zong-Shun Liu, Jian-Jun Zhu, and Li-Qun Zhang

Subjects
*GALLIUM nitride, *SEMICONDUCTOR lasers, *QUANTUM wells, *TEMPERATURE effect, *STRAY currents
Abstract

The influences of InGaN/GaN multiple quantum wells (MQWs) and AlGaN electron-blocking layers (EBL) on the performance of GaN-based violet laser diodes are investigated. Compared with the InGaN/GaN MQWs grown at two different temperatures, the same-temperature growth of InGaN well and GaN barrier layers has a positive effect on the threshold current and slope efficiency of laser diodes, indicating that the quality of MQWs is improved. In addition, the performance of GaN laser diodes could be further improved by increasing Al content in the AlGaN EBL due to the fact that the electron leakage current could be reduced by properly increasing the barrier height of AlGaN EBL. The violet laser diode with a peak output power of 20 W is obtained. [ABSTRACT FROM AUTHOR]

Published
2017
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48. Emission Lines of Boron, Carbon, Oxygen and Iron in Tokamak Plasma.

Author

Long, Di, Jian, Shi, Shou, Wang, Quan, Dong, Jing, Zhao, Yu, Li, Jia, Fu, Fu, Wang, Yue, Shi, Bao, Wan, Gang, Zhao, and Jie, Zhang

Subjects
TOKAMAKS, PLASMA gases, FIELD emission, SPECTRUM analysis, COLLISIONS (Nuclear physics), HYDROCYANIC acid, ATOMIC theory
Abstract

The emission lines of B, C, O and Fe in tokamak plasma are reported. The spectra are compared with those calculated by the CHIANTI code, which is based on the collisional-radiative models with a large amount of accurate atomic data. General agreement is obtained between the results of experiment and computation. Most of the lines in the spectra are identified, and the relative number density ratios of B, C, O and Fe are determined. It is found that the processes of line formation in our experiment are similar to those in the stellar coronae. The line-averaged electron density of the tokamak plasma is measured by the HCN laser, indicating a good agreement with the theoretical prediction by the density-dependent line ratio of Fe XXI. [ABSTRACT FROM AUTHOR]

Published
2011
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