| Record 1 of 9 |
| Author(s): Jia, LX (Jia, Lianxi); Geng, MM (Geng, Minming); Zhang, L (Zhang, Lei); Yang, L (Yang, Lin); Chen, P (Chen, Ping); Liu, YL (Liu, Yuliang); Fang, Q (Fang, Qing); Yu, MB (Yu, Mingbin) |
| Title: Effects of waveguide length and pump power on the efficiency of wavelength conversion in silicon nanowire waveguides |
| Source: OPTICS LETTERS, 34 (22): 3502-3504 NOV 15 2009 |
| Abstract: We point out the use of a wrong definition for conversion efficiency in the literature and analyze the effects of the waveguide length and pump power on conversion efficiency according to the correct definition. The existence of the locally optimal waveguide length and pump power is demonstrated theoretically and experimentally. Further analysis shows that the extremum of conversion efficiency can be achieved by global optimization of the waveguide length and pump power simultaneously, which is limited by just the linear propagation loss and the effective carrier lifetime. (C) 2009 Optical Society of America |
| ISSN: 0146-9592 |
| Record 2 of 9 |
| Author(s): Zhu, JH (Zhu, J. H.); Wang, LJ (Wang, L. J.); Zhang, SM (Zhang, S. M.); Wang, H (Wang, H.); Zhao, DG (Zhao, D. G.); Zhu, JJ (Zhu, J. J.); Liu, ZS (Liu, Z. S.); Jiang, DS (Jiang, D. S.); Qiu, YX (Qiu, Y. X.); Yang, H (Yang, H.) |
| Title: The investigation on strain relaxation and double peaks in photoluminescence of InGaN/GaN MQW layers |
| Source: JOURNAL OF PHYSICS D-APPLIED PHYSICS, 42 (23): Art. No. 235104 DEC 7 2009 |
| Abstract: Two emission peaks were observed in the low temperature photoluminescence (LTPL) spectra of an InGaN/GaN multiple quantum well (MQW) structure before and after nanopillar fabrication. After nanopillar fabrication it is found that among the two peaks the longer wavelength peak exhibits a clear blue shift and has a much stronger enhancement in LTPL intensity than the shorter one. Combined with x-ray diffraction and spatially resolved cathodoluminescence analyses, the difference induced by nanopillar fabrication is ascribed to different strain relaxation states in the lower and upper quantum well layers. It is found that the lower QW layers of the as-grown MQW which causes the longer wavelength PL peak are more strained, while the upper ones are almost fully strain-relaxed. Therefore, the nanopillar fabrication induces much less strain relaxation in the upper part of the MQW than in the lower one. |
| ISSN: 0022-3727 |
| Article Number: 235104 |
| DOI: 10.1088/0022-3727/42/23/235104 |
| Record 3 of 9 |
| Author(s): Xu, XS (Xu, X. S.); Yamada, T (Yamada, T.); Yokoyama, S (Yokoyama, S.) |
| Title: Correlations between antibunching and blinking of photoluminescence from a single CdSe quantum dot |
| Source: EUROPEAN PHYSICAL JOURNAL D, 55 (3): 691-697 DEC 2009 |
| Abstract: The antibunching and blinking from a single CdSe/ZnS nanocrystal with an emission wavelength of 655 nm were investigated under different excitation powers. The decay process of the photoluminescence from nanocrystal was fitted into a stretched exponential, and the small lifetime and the small stretching exponent under a high excitation power were explained by using nonradiative multi-channel model. The probability of distributions for off-times from photoluminescence intermittence was fitted into the power law, and the power exponents were explained by using a tunneling model. For higher excitation power, the Auger-assisted tunneling model takes effect, where the tunneling rate increases and the observed lifetime decreases. For weak excitation power, the electron directly tunnels between the nanocrystal and trapping state without Auger assistance. The correlation between antibunching and blinking from the same nanocrystal was analyzed. |
| ISSN: 1434-6060 |
| DOI: 10.1140/epjd/e2009-00266-6 |
| Record 4 of 9 |
| Author(s): Li, F (Li, Feng); Li, XQ (Li, Xin-Qi); Zhang, WM (Zhang, Wei-Min); Gurvitz, SA (Gurvitz, S. A.) |
| Title: Magnetic field switching in parallel quantum dots |
| Source: EPL, 88 (3): Art. No. 37001 NOV 2009 |
| Abstract: We show that the Coulomb blockade in parallel dots pierced by magnetic flux Phi completely blocks the resonant current for any value of Phi except for integer multiples of the flux quantum Phi(0). This non-analytic (switching) dependence of the current on Phi arises only when the dot states that carry the current are of the same energy. The time needed to reach the steady state, however, diverges when Phi -> n Phi(0). Copyright (C) EPLA, 2009 |
| ISSN: 0295-5075 |
| Article Number: 37001 |
| DOI: 10.1209/0295-5075/88/37001 |
| Record 5 of 9 |
| Author(s): Xu, Y (Xu, Y.); Hu, H (Hu, H.); Chen, L (Chen, L.); Song, G (Song, G.); Zhuang, W (Zhuang, W.) |
| Title: Analysis on the high luminous flux white light from GaN-based laser diode |
| Source: APPLIED PHYSICS B-LASERS AND OPTICS, 98 (1): 83-86 JAN 2010 |
| Abstract: We fabricated a phosphor-conversion white light using an InGaN laser diode that emits 445 nm and phosphor that emits in the yellow region when excited by the blue laser light. At 500 mA injection current the luminous flux and the luminous efficacy were 113 lm and 44 lm/W, respectively. The relationship of the luminous flux and the luminous efficacy of the white light with an injection current were discussed. Based on the evaluation method for luminous efficacy of light sources established by the Commission International de I'Eclairage (CIE) and the phosphor used in this experiment, a theoretical analysis of the experiment results and the maximum luminous efficacy of this white light fabrication method were also presented. |
| ISSN: 0946-2171 |
| DOI: 10.1007/s00340-009-3651-4 |
| Record 6 of 9 |
| Author(s): Huang, YZ (Huang YongZhen); Yang, YD (Yang YueDe); Wang, SJ (Wang ShiJiang); Xiao, JL (Xiao JinLong); Che, KJ (Che KaiJun); Du, Y (Du Yun) |
| Title: Whispering-gallery microcavity semiconductor lasers suitable for photonic integrated circuits and optical interconnects |
| Source: SCIENCE IN CHINA SERIES E-TECHNOLOGICAL SCIENCES, 52 (12): 3447-3453 DEC 2009 |
| Abstract: The characteristics of whispering-gallery-like modes in the equilateral triangle and square microresonators are introduced, including directional emission triangle and square microlasers connected to an output waveguide. We propose a photonic interconnect scheme by connecting two directional emission microlasers with an optical waveguide on silicon integrated circuit chip. The measurement indicates that the triangle microlasers can work as a resonance enhanced photodetector for optical interconnect. |
| ISSN: 1006-9321 |
| DOI: 10.1007/s11431-009-0306-y |
| Record 7 of 9 |
| Author(s): Chen, L (Chen, L.); Yan, S (Yan, S.); Xu, PF (Xu, P. F.); Lu, J (Lu, J.); Wang, WZ (Wang, W. Z.); Deng, JJ (Deng, J. J.); Qian, X (Qian, X.); Ji, Y (Ji, Y.); Zhao, JH (Zhao, J. H.) |
| Title: Low-temperature magnetotransport behaviors of heavily Mn-doped (Ga,Mn)As films with high ferromagnetic transition temperature |
| Source: APPLIED PHYSICS LETTERS, 95 (18): Art. No. 182505 NOV 2 2009 |
| Abstract: We report the low-temperature magnetotransport behaviors of (Ga,Mn)As films with the nominal Mn concentration x larger than 10%. The ferromagnetic transition temperature T-C can be enhanced to 191 K after postgrowth annealing (Ga,Mn)As with x=20%. The temperature T-m, corresponding to the resistivity minimum in the curve of resistivity versus temperature at temperature below T-C, depends on Mn concentration, annealing condition, and magnetic field. Moreover, we find that the variable-range hopping may be the main conductive mechanism when temperature is lower than T-m. |
| ISSN: 0003-6951 |
| Article Number: 182505 |
| DOI: 10.1063/1.3259821 |
| Record 8 of 9 |
| Author(s): Zhang, S (Zhang Shuang); Zhao, DG (Zhao De-Gang); Liu, ZS (Liu Zong-Shun); Zhu, JJ (Zhu Jian-Jun); Zhang, SM (Zhang Shu-Ming); Wang, YT (Wang Yu-Tian); Duan, LH (Duan Li-Hong); Liu, WB (Liu Wen-Bao); Jiang, DS (Jiang De-Sheng); Yang, H (Yang Hui) |
| Title: Influence of penetrating V-pits on leakage current of GaN based p-i-n UV detector |
| Source: ACTA PHYSICA SINICA, 58 (11): 7952-7957 NOV 2009 |
| Abstract: The leakage mechanism of GaN-based p-i-n (p-AlGaN/i-GaN/n-GaN) UV detector has been investigated. With the same dislocation density, devices made from material with higher density of V-pits on surface produce larger leakage current. SEM images show that some V-pits penetrate into i-GaN layer, sometimes even the n-GaN layer. If p-ohmic contact metal (Ni/Au) deposits in the V-pits, Schottky contact would be formed at the interface of metal and i-GaN, or form ohmic contact at the interface of metal and n-GaN. The existence of parallel Schottky junction and ohmic contact resistance enhances the leakage current greatly. |
| ISSN: 1000-3290 |
| Record 9 of 9 |
| Author(s): Bai, WL (Bai Wen-Li); Guo, BS (Guo Bao-Shan); Cai, LK (Cai Li-Kang); Gan, QQ (Gan Qiao-Qiang); Song, GF (Song Guo-Feng) |
| Title: Simulation of light coupling enhancement and localization of transmission field via subwavelength metallic gratings |
| Source: ACTA PHYSICA SINICA, 58 (11): 8021-8026 NOV 2009 |
| Abstract: Surface plasmons(SPs) generated in nano metallic gratings on medium layer can greatly enhance the transmission field through the metallic gratings. The enhancement effect is achieved from lambda = 500 nm to near-infrared domain. The enhancement rate is about 110 % at the wavelength of about 6 10 nm and about 180 % at lambda = 700 nm and 740 nm where most kinds of thin film solar cells have a high spectral response. These structures should provide a promising way to increase the coupling efficiency of thin film solar cells and optical detectors of different wavelength response. |
| ISSN: 1000-3290 |
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