| Record 1 of 12 |
| Author(s): Liu, JG (Liu, Jianguo); Cheng, TH (Cheng, Tee Hiang); Yeo, YK (Yeo, Yong Kee); Wang, YX (Wang, Yixin); Xue, LF (Xue, Lifang); Zhu, NH (Zhu, Ninghua); Xu, ZW (Xu, ZhaoWen); Wang, DW (Wang, Dawei) |
| Title: All-optical continuously tunable delay with a high linear-chirp-rate fiber Bragg grating based on four-wave mixing in a highly-nonlinear photonic crystal fiber |
| Source: OPTICS COMMUNICATIONS, 282 (22): 4366-4369 NOV 15 2009 |
| Abstract: A scheme for hi-fi all-optical continuously tunable delay is proposed. The signal wavelength is converted to a desired idler wavelength and converted back after being delayed by a high linear-chirp-rate (HLCR) fiber Bragg grating (FBG) based on four-wave mixing (FWM) in a highly-nonlinear photonic crystal fiber (HN-PCF). In our experiment, 400 ps (more than 8 full width of half maximum, FWHM) tunable delay is achieved for a 10 GHz clock pulse with relative pulse width broaden ratio (RPWBR) of 2.08%. The power penalty is only 0.3 dB at 10(-9) BER for a 10 Gb/s 2(31)-1 pseudo random bit sequence (PRBS) data. (c) 2009 Elsevier B.V. All rights reserved. |
| ISSN: 0030-4018 |
| DOI: 10.1016/j.optcom.2009.08.022 |
| Record 2 of 12 |
| Author(s): Lu, SL (Lu, Shulong); Nosho, H (Nosho, Hidetaka); Tackeuchi, A (Tackeuchi, Atsushi); Bian, LF (Bian, Lifeng); Dong, JR (Dong, Jianrong); Niu, ZC (Niu, Zhichuan) |
| Title: Spin-Polarized Localized Exciton Photoluminescence Dynamics in GaInNAs Quantum Wells |
| Source: JAPANESE JOURNAL OF APPLIED PHYSICS, 48 (10): Art. No. 100206 OCT 2009 |
| Abstract: We have investigated spin polarization-related localized exciton photoluminescence (PL) dynamics in GaInNAs quantum wells by time-resolved PL spectroscopy. The emission energy dependence of PL polarization decay time as well as polarization-independent PL decay time suggests that the acoustic phonon scattering in the process of localized exciton transfer from the high-energy localized states to the low-energy ones dominates the PL polarization relaxation. By increasing the excitation power from 1 to 10 mW, the PL polarization decay time is changed from 0.17 to more than 1 ns, which indicates the significant effect of the trapping of localized electrons by nonradiative recombination centers. These experimental findings indicate that the spin-related PL polarization in diluted nitride semiconductors can be manipulated through carrier scattering and recombination process. (C) 2009 The Japan Society of Applied Physics |
| ISSN: 0021-4922 |
| Article Number: 100206 |
| DOI: 10.1143/JJAP.48.100206 |
| Record 3 of 12 |
| Author(s): Yang, YD (Yang, Yue-De); Huang, YZ (Huang, Yong-Zhen); Wang, SJ (Wang, Shi-Jiang) |
| Title: Mode Analysis for Equilateral-Triangle-Resonator Microlasers with Metal Confinement Layers |
| Source: IEEE JOURNAL OF QUANTUM ELECTRONICS, 45 (12): 1529-1536 DEC 2009 |
| Abstract: Mode characteristics are analyzed for electrically injected equilateral-triangle-resonator (ETR) semiconductor microlasers, which are laterally confined by insulating barrier SiO2 and electrode metals Ti-Au. For the ETR without metal layers, the totally confined mode field patterns are derived based on the reflection phase shifts, and the Q-factors are calculated from the far-field emission of the analytical near field distribution, which are agreement very well with the numerical results of the finite-difference time-domain (FDTD) simulation. The polarization dependence reflections for light rays incident on semiconductor-SiO2 -Ti-Au multi-layer structures are accounted in considering the confinement of TE and TM modes in the ETR with the metal layers. The reflectivity will greatly reduce with a Ti layer between SiO2 and Au for light rays with incident angle less than 30 especially for the TE mode, even the thickness of the Ti layer is only 10 nm. If the ETR is laterally confined by SiO2-Au layers without the Ti layer, the Fabry-Perot type modes with an incident angle of zero on one side of the ETR can also have high Q-factor. The FDTD simulation for the ETR confined by metal layers verifies the above analysis based on multi-layer reflections. The output spectra with mode intervals of whispering-gallery modes and Fabry-Perot type modes are observed from different ETR lasers with side length of 10 m, respectively. |
| ISSN: 0018-9197 |
| DOI: 10.1109/JQE.2009.2024006 |
| Record 4 of 12 |
| Author(s): Liu, FQ (Liu, Feng-Qi); Li, L (Li, Lu); Wang, LJ (Wang, Lijun); Liu, JQ (Liu, Junqi); Zhang, W (Zhang, Wei); Zhang, QD (Zhang, Quande); Liu, WF (Liu, Wanfeng); Lu, QY (Lu, Quanyong); Wang, ZG (Wang, Zhanguo) |
| Title: Solid source MBE growth of quantum cascade lasers |
| Source: APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 97 (3): 527-532 NOV 2009 |
| Abstract: High material quality is the basis of quantum cascade lasers (QCLs). Here we report the solid source molecular beam epitaxy (MBE) growth details of realizing high quality of InGaAs/InAlAs QCL structures. Accurate control of material compositions, layer thickness, doping profile, and interface smoothness can be realized by optimizing the growth conditions. Double crystal x-ray diffraction discloses that our grown QCL structures possess excellent periodicity and sharp interfaces. High quality laser wafers are grown in a single epitaxial run. Room temperature continuous-wave (cw) operation of QCLs is demonstrated. |
| ISSN: 0947-8396 |
| DOI: 10.1007/s00339-009-5423-8 |
| Record 5 of 12 |
| Author(s): Zhu, ZY (Zhu, Zheng-Yong); Li, SS (Li, Shu-Shen) |
| Title: Symmetry and optical transition rule for low-dimensional semiconductor system with spin-orbit interaction and magnetic field |
| Source: SUPERLATTICES AND MICROSTRUCTURES, 46 (4): 627-636 OCT 2009 |
| Abstract: Starting from effective mass Hamiltonian, we systematically investigate the symmetry of low-dimensional structures with spin-orbit interaction and transverse magnetic field. The position-dependent potentials are assumed to be space symmetric, which is ever-present in theory and experiment research. By group theory, we analyze degeneracy in different cases. Spin-orbit interaction makes the transition between Zeeman sub-levels possible, which is originally forbidden within dipole approximation. However, a transition rule given in this paper for the first time shows that the transition between some levels is forbidden for space symmetric potentials. (C) 2009 Elsevier Ltd. All rights reserved. |
| ISSN: 0749-6036 |
| DOI: 10.1016/j.spmi.2009.07.014 |
| Record 6 of 12 |
| Author(s): Gai, YQ (Gai, Yanqin); Li, JB (Li, Jingbo); Li, SS (Li, Shu-Shen); Xia, JB (Xia, Jian-Bai); Yan, YF (Yan, Yanfa); Wei, SH (Wei, Su-Huai) |
| Title: Design of shallow acceptors in ZnO through compensated donor-acceptor complexes: A density functional calculation |
| Source: PHYSICAL REVIEW B, 80 (15): Art. No. 153201 OCT 2009 |
| Abstract: The intrinsic large electronegativity of O 2p character of the valence-band maximum (VBM) of ZnO renders it extremely difficult to be doped p type. We show from density functional calculation that such VBM characteristic can be altered by compensated donor-acceptor pairs, thus improve the p-type dopability. By incorporating (Ti+C) or (Zr+C) into ZnO simultaneously, a fully occupied impurity band that has the C 2p character is created above the VBM of host ZnO. Subsequent doping by N in ZnO: (Ti+C) and ZnO: (Zr+C) lead to the acceptor ionization energies of 0.18 and 0.13 eV, respectively, which is about 200 meV lower than it is in pure ZnO. |
| ISSN: 1098-0121 |
| Article Number: 153201 |
| DOI: 10.1103/PhysRevB.80.153201 |
| Record 7 of 12 |
| Author(s): Li, J (Li, Jun); Chang, K (Chang, Kai); Peeters, FM (Peeters, F. M.) |
| Title: Dyakonov-Perel spin relaxation in InSb/AlxIn(1-x)Sb quantum wells |
| Source: PHYSICAL REVIEW B, 80 (15): Art. No. 153307 OCT 2009 |
| Abstract: We investigate theoretically the Dyakonov-Perel spin relaxation time by solving the eight-band Kane model and Poisson equation self-consistently. Our results show distinct behavior with the single-band model due to the anomalous spin-orbit interactions in narrow band-gap semiconductors, and agree well with the experiment values reported in recent experiment [K. L. Litvinenko et al., New J. Phys. 8, 49 (2006)]. We find a strong resonant enhancement of the spin relaxation time appears for spin align along [1 (1) over bar0] at a certain electron density at 4 K. This resonant peak is smeared out with increasing the temperature. |
| ISSN: 1098-0121 |
| Article Number: 153307 |
| DOI: 10.1103/PhysRevB.80.153307 |
| Record 8 of 12 |
| Author(s): Liang, S (Liang, S.); Zhu, HL (Zhu, H. L.); Wang, W (Wang, W.) |
| Title: Size distributions of quantum islands on stepped substrates |
| Source: JOURNAL OF CHEMICAL PHYSICS, 131 (15): Art. No. 154704 OCT 21 2009 |
| Abstract: The size distributions of self-assembled quantum islands on stepped substrates are studied using kinetic Monte Carlo simulations. It is found that the energy barrier E-SW between the step and the terrace region is the key factor in affecting the size distribution of islands. With small E-SW (<= 0.1 eV), lines of uniform islands can be obtained at relative low surface coverage. As the surface coverage is increased, wirelike islands can be obtained. Scaling behavior is obeyed for the size distributions of the wirelike islands. When the size distributions are separated into their width and length components, however, scaling is only observed in the length distribution of the wirelike islands. With larger E-SW, the size distribution of islands shows a clear bimodal size distribution and anomalous growth temperature dependent island size evolutions are observed. The simulation results reproduce qualitatively the phenomena observed in the cases of InAs islands grown on stepped GaAs substrates. (c) 2009 American Institute of Physics. [doi:10.1063/1.3248367] |
| ISSN: 0021-9606 |
| Article Number: 154704 |
| DOI: 10.1063/1.3248367 |
| Record 9 of 12 |
| Author(s): Wang, ZG (Wang, Zhiguo); Gao, F (Gao, Fei); Li, JB (Li, Jingbo); Zu, XT (Zu, Xiaotao); Weber, WJ (Weber, William J.) |
| Title: Stone-Wales defects created by low energy recoils in single-walled silicon carbide nanotubes |
| Source: JOURNAL OF APPLIED PHYSICS, 106 (8): Art. No. 084305 OCT 15 2009 |
| Abstract: The defect creation at low energy events was studied using density functional theory molecular dynamics simulations in silicon carbide nanotubes, and the displacement threshold energies determined exhibit a dependence on sizes, which decrease with decreasing diameter of the nanotubes. The Stone-Wales (SW) defect, which is a common defect configurations induced through irradiation in nanotubes, has also been investigated, and the formation energies of the SW defects increase with increasing diameter of the nanotubes. The mean threshold energies were found to be 23 and 18 eV for Si and C in armchair (5,5) nanotubes. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3238307] |
| ISSN: 0021-8979 |
| Article Number: 084305 |
| DOI: 10.1063/1.3238307 |
| Record 10 of 12 |
| Author(s): Jiang, XW (Jiang, Xiang-Wei); Deng, HX (Deng, Hui-Xiong); Li, SS (Li, Shu-Shen); Luo, JW (Luo, Jun-Wei); Wang, LW (Wang, Lin-Wang) |
| Title: Quantum mechanical simulation of nanosized metal-oxide-semiconductor field-effect transistor using empirical pseudopotentials: A comparison for charge density occupation methods |
| Source: JOURNAL OF APPLIED PHYSICS, 106 (8): Art. No. 084510 OCT 15 2009 |
| Abstract: The atomistic pseudopotential quantum mechanical calculations are used to study the transport in million atom nanosized metal-oxide-semiconductor field-effect transistors. In the charge self-consistent calculation, the quantum mechanical eigenstates of closed systems instead of scattering states of open systems are calculated. The question of how to use these eigenstates to simulate a nonequilibrium system, and how to calculate the electric currents, is addressed. Two methods to occupy the electron eigenstates to yield the charge density in a nonequilibrium condition are tested and compared. One is a partition method and another is a quasi-Fermi level method. Two methods are also used to evaluate the current: one uses the ballistic and tunneling current approximation, another uses the drift-diffusion method. (C) 2009 American Institute of Physics. [doi:10.1063/1.3248262] |
| ISSN: 0021-8979 |
| Article Number: 084510 |
| DOI: 10.1063/1.3248262 |
| Record 11 of 12 |
| Author(s): Ma, SS (Ma Shan-Shan); Dou, XM (Dou Xiu-Ming); Chang, XY (Chang Xiu-Ying); Sun, BQ (Sun Bao-Quan); Xiong, YH (Xiong Yong-Hua); Niu, ZC (Niu Zhi-Chuan); Ni, HQ (Ni Hai-Qiao) |
| Title: Spin Relaxation of Electrons in Single InAs Quantum Dots |
| Source: CHINESE PHYSICS LETTERS, 26 (11): Art. No. 117201 NOV 2009 |
| Abstract: By using polarization-resolved photoluminescence spectra, we study the electron spin relaxation in single InAs quantum dots (QDs) with the configuration of positively charged excitons X+ (one electron, two holes). The spin relaxation rate of the hot electrons increases with the increasing energy of exciting photons. For electrons localized in QDs the spin relaxation is induced by hyperfine interaction with the nuclei. A rapid decrease of polarization degree with increasing temperature suggests that the spin relaxation mechanisms are mainly changed from the hyperfine interaction with nuclei into an electron-hole exchange interaction. |
| ISSN: 0256-307X |
| Article Number: 117201 |
| Record 12 of 12 |
| Author(s): Zhang, JY (Zhang, Jiang-Yong); Cai, LE (Cai, Li-E); Zhang, BP (Zhang, Bao-Ping); Hu, XL (Hu, Xiao-Long); Jiang, F (Jiang, Fang); Yu, JZ (Yu, Jin-Zhong); Wang, QM (Wang, Qi-Ming) |
| Title: Efficient hole transport in asymmetric coupled InGaN multiple quantum wells |
| Source: APPLIED PHYSICS LETTERS, 95 (16): Art. No. 161110 OCT 19 2009 |
| Abstract: InGaN based light emitting devices (LEDs) with asymmetric coupled quantum wells (AS-QWs) and conventional symmetric coupled quantum wells (CS-QWs) active structures were grown by metal-organic chemical vapor deposition technique. The LEDs with AS-QWs active region show improved light emission intensity and reduced forward voltage compared with LEDs with CS-QWs active region. Based on the electroluminescence measurements and the devices structure analysis, it can be concluded that these improvements are mainly attributed to the efficient hole tunneling through barriers and consequently the uniform distribution of carriers in the AS-QWs. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3254232] |
| ISSN: 0003-6951 |
| Article Number: 161110 |
| DOI: 10.1063/1.3254232 |
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