2010
2010
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Record 49 of
Title:Mid-infrared emission properties of Ho3+-doped Ge-Ga-S-CsI glasses
Author(s):Zhu, Jun(1); Dai, Shi-Xun(1,2); Peng, Bo(2); Xu, Tie-Feng(1); Wang, Xun-Si(1); Zhang, Xiang-Hua(1,3)Source: Wuji Cailiao Xuebao/Journal of Inorganic Materials Volume: 25 Issue: 5 DOI: 10.3724/SP.J.1077.2010.00546 Published: May 2010Abstract:A serial of chalcogenide glasses based on Ge-Ga-S-CsI system doped with the different Ho3+ ions were synthesized by melt-quenching technique. The properties of glasses including refractive indexes, absorption spectra, mid-infrared emission spectra and lifetimes of 5I6 level of Ho3+ions were measured. The Judd-Ofelt intensity parameters Ωi (i=2,4,6), oscillator strength fcal, spontaneous transition probabilities Arad for Ho3+ion were calculated by Judd-Ofelt theory. Multiphonon relaxation rates of the Ho3+:5I5 →5I6 and 5I6→5I7 in Ge-Ga-S-CsI glasses were evaluated. Effect of Ho3+ion concentration on the fluorescence spectra was investigated. The results indicate that the fluorescence under 900 nm excitation with peak wavelength at 2.81μm and 3.86μm are due to the Ho3+:5I5 →5I6 and 5I6→5I7 transition, respectively. The intensity of the mid-infrared fluorescence are enhanced with the Ho3+ ion concentration increasing from 0.5wt% to 1.0wt%. Multiphonon relaxation rates are 29 s-1 and 34 s-1 for the Ho3+:5I5 →5I6 and 5I6→5I7 transition, respectively.Accession Number: 20102413003779 -
Record 50 of
Title:Nd3+-doped LaF3 nanoparticles with a larger emission cross-section
Author(s):Cui, Xiaoxia(1,2); She, Jiangbo(1,2); Cui, Kai(1,2); Gao, Chao(1); Hou, Chaoqi(1,2); Wei, Wei(1,3); Peng, Bo(1,3)Source: Chemical Physics Letters Volume: 489 Issue: 4-6 DOI: 10.1016/j.cplett.2010.02.066 Published: April 9, 2010Abstract:A series of Nd3+-doped LaF3 nanoparticles with Nd3+ concentrations from 0.5 to 10 mol% were synthesized. The fluorescence intensity and lifetime of the nanoparticles at various Nd3+ doping concentration were investigated. The nanoparticles displayed strongest fluorescence intensity at 3 mol% Nd3+ concentration. Eighty-eight percentage quantum efficiency was obtained when the Nd3+ concentration was 0.5 mol%. Optical properties of nanoparticles were studied according to Judd-Ofelt theory. A larger emission cross-section, σem, for 4F3/2 → 4I11/2 transition of the Nd3+ ion was obtained as 3.21 × 10-20 cm2, which was two times of the currently reported value. The larger emission cross-section and strong fluorescence intensity demonstrate that these nanoparticles are promising materials for laser applications. ? 2010.Accession Number: 20101312812063 -
Record 51 of
Title:Tb3+/Yb3+ heavily-doped tellurite glasses with efficient green light emission
Author(s):Zhou, Zhiguang(1,3); Lin, Aoxiang(1,2); Guo, Haitao(1); Liu, Xueming(1); Hou, Chaoqi(1); Lu, Min(1); Wei, Wei(1); Peng, Bo(1); Zhao, Wei(1); Toulouse, Jean(2)Source: Journal of Non-Crystalline Solids Volume: 356 Issue: 50-51 DOI: 10.1016/j.jnoncrysol.2010.09.010 Published: November 2010Abstract:Without introducing concentration quenching phenomenon, a few wt.% of Tb3+ and Yb3+ ions were doped into a group of easily-fiberized tellurite glasses characterized by loose polyhedron structures and rich interstitial positions. Intense green upconversion emission from Tb3+ ions centered at 539 nm due to transition 5D 4 → 7F5 was observed by direct excitation of Yb3+ ions with a laser diode at 976 nm. Optimizing the concentration ratio of Tb3+/Yb3+, a tellurite glass with a composition of 80TeO2-10ZnO-10Na2O (mol%) + 1.0 wt.% Tb2O3 + 3.0 wt.% Yb2O3 was found to present the highest green light intensity and therefore is especially suitable for efficient green fiber laser development. ? 2010 Elsevier B.V. All rights reserved.Accession Number: 20104713408269 -
Record 52 of
Title:Gray photorefractive polymeric optical spatial solitons
Author(s):Lu, Keqing(1); Li, Kehao(2,6); Zhang, Yanpeng(3); Yuan, Chenzhi(3); Miao, Changyun(1); Chen, Li(4); Xu, Jingjun(5)Source: Optics Communications Volume: 283 Issue: 23 DOI: 10.1016/j.optcom.2010.06.102 Published: December 1, 2010Abstract:We show that gray spatial optical solitons are possible in biased photorefractive polymers under steady-state conditions. We find that for a given material parameter the absolute value of a gray photorefractive polymeric soliton's phase decreases with an increase in the beam's grayness, whereas it increases with the material parameter for a given beam's grayness and that the full width half maximum (FWHM) of the gray soliton beam's intensity increases with the beam's grayness when the normalized background intensity and the material parameter are fixed and decreases with an increase in the normalized background intensity when the material parameter is fixed. On the other hand, we also show that N coupled beam evolution equations in biased photorefractive polymers can exhibit multicomponent gray solitons. These multicomponent gray solitons can be obtained provided that the N coupled beams share the same polarization, wavelength, and are incoherent with one another. The characteristics and stability properties of these multicomponent gray solitons are also discussed in detail. ? 2010 Elsevier B.V. All rights reserved.Accession Number: 20104113287818 -
Record 53 of
Title:Optic effect of KCl on GeS2G-Ga2S3 chalcogenide glasses
Author(s):Wang, Xunsi(1); Liang, Xiaowei(2); Zhu, Mingxing(1); Dai, Shixun(1,3); Xu, Tiefeng(1); Nie, Qiuhua(1); Shen, Xiang(1); Dong, Furong(1); Huang, Yi(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 30 Issue: 7 DOI: 10.3788/AOS20103007.2047 Published: July 2010Abstract:Series of GeS2-Ga2S3-KCl chalcohalide glasses were prepared by traditional melt-quenching method. Thickness, density, refractive index, visible/near-infrared absorption and infrared transmission spectra were adopted to the analysis of the allowed direct interband optical transitions of optic gap with Tauc equation. The results show a good physical performance as it possesses a wide glass-forming regions of GeS2-Ga2S3-KCl pseudo-ternary glass system. With the increasing of KCl content, there were significant decreases in glass density and refractive index, but there is a significant augmentation of optic band gap. Others, some corresponding changes of glass host structure were deduced from FTIR and Raman spectra, as that the IR optic spectra was improved, just like the Raman spectrum changed by steps, IR absorption cutting-off edge red-shifted with regular. Based on the analysis of KCl adding in the glass host, a quantitative description was given about the correlations between IR multi-phonon absorption and fundamental phonon-vibration, as it shows a deterministic dependence of the optic optical properties of chalco-halide glasses on glass host.Accession Number: 20103113111303 -
Record 54 of
Title:Luminescent properties of Nd3+-doped LaF3 core/shell nanoparticles with enhanced near infrared (NIR) emission
Author(s):Cui, Xiaoxia(1,2); She, Jiangbo(1,2); Gao, Chao(1); Cui, Kai(1,2); Hou, Chaoqi(1,2); Wei, Wei(1,3); Peng, Bo(1,3)Source: Chemical Physics Letters Volume: 494 Issue: 1-3 DOI: 10.1016/j.cplett.2010.05.070 Published: July 9, 2010Abstract:A kind of Nd3+-doped LaF3 nanoparticles with core/shell structure were synthesized via a co-precipitation method. The possible formation mechanisms for the core/shell architectures were presented. The X-ray diffraction (XRD) patterns indicated that the obtained nanoparticles exhibit hexagonal structure. In comparison with LaF3:Nd core nanoparticles, the fluorescence intensity and lifetime were increased by 140% and 150% respectively in LaF3:Nd/LaF3 core/shell nanoparticles. The obvious features are mainly attributed to the formation of LaF3 shell which effectively protected the Nd3+ ions from surrounding influence. The results show that rare-earth-doped nanoparticles with core/shell structure have potential applications in biological labeling and light-emitting devices. ? 2010 Elsevier B.V. All rights reserved.Accession Number: 20103413184302 -
Record 55 of
Title:Improved digital processing method used for image motion measurement based on hybrid opto-digital joint transform correlator
Author(s):Yi, Hongwei(1); Zhao, Hui(1); Li, Yingcai(1); Wen, Desheng(1)Source: Chinese Optics Letters Volume: 8 Issue: 10 DOI: 10.3788/COL20100810.0989 Published: October 2010Abstract:Hybrid opto-digital joint transform correlator (HODJTC) is effective for image motion measurement, but it is different from the traditional joint transform correlator because it only has one optical transform and the joint power spectrum is directly input into a digital processing unit to compute the image shift. The local cross-correlation image can be directly obtained by adopting a local Fourier transform operator. After the pixel-level location of cross-correlation peak is initially obtained, the up-sampling technique is introduced to relocate the peak in even higher accuracy. With signal-to-noise ratio ≥ 20 dB, up-sampling factor k ≥ 10 and the maximum image shift ≤ 60 pixels, the root-mean-square error of motion measurement accuracy can be controlled below 0.05 pixels. ? 2010 Chinese Optics Letters.Accession Number: 20104713408869 -
Record 56 of
Title:Influence of the time modulation of the pump laser caused by mode beating on optical parametric process
Author(s):Sun, Qibing(1,2); Liu, Hongjun(1); Huang, Nan(1); Long, Hanbo(1,2); Wen, Jin(1,2); Zhu, Shaolan(1); Zhao, Wei(1)Source: Optics Express Volume: 18 Issue: 3 DOI: 10.1364/OE.18.003101 Published: February 1, 2010Abstract:Numerical simulation and analysis about the influence of the time modulation of the pump laser caused by mode beating on optical parametric process are presented with OPA and OPG as examples. It is shown that the output power of the generated beams from optical parametric process is modulated in the time domain and exhibits large power fluctuations, when a Q-switched laser oscillating on several random longitudinal modes is used as the pump laser. Irregular spike sequences of the generated beams are observed. We also find that the output power of the light from optical parametric process becomes more stable and exhibits a less fluctuation, when the number of the longitudinal modes (n) increases. ? 2010 Optical Society of America.Accession Number: 20100612700646 -
Record 57 of
Title:A technology to generate fast-edge pulses using step recovery diode
Author(s):Gou, Yongsheng(1); Liu, Baiyu(1); Bai, Yonglin(1); Ouyang, Xian(1); Zhang, Wei(1); Li, Yan(1); Xue, Yingdong(1)Source: Chinese Journal of Electronics Volume: 19 Issue: 2 DOI: Published: April 2010Abstract:A rectangular pulse generator circuit with fast rising and falling edge will be presented in this paper. The generator circuit was designed by controlling the quantity of carriers in the middle layer from regulating forward current of the SRD (Step recovery diode), and then indirectly controlling the pulse width. It is based on the principle that large reverse current will flow through the diode and last for a relatively long time when it is reverse biased. Experimental results have been analyzed in physical level. They are tallied with theoretical results. The circuit can generate rectangular pulses with rise time about 150ps, fall time about 250ps, amplitude about 10V and pulse width adjustable from Ins to 10ns in 50ω load. The trig jitter is less than 5ps and the amplitude jitter is better than 4%.Accession Number: 20101912920833 -
Record 58 of
Title:Prediction of optical modulation properties of twisted-nematic liquid-crystal display by improved measurement of Jones matrix
Author(s):Ma, Baiheng(1,2); Yao, Baoli(1); Ye, Tong(1); Lei, Ming(3)Source: Journal of Applied Physics Volume: 107 Issue: 7 DOI: 10.1063/1.3361238 Published: April 1, 2010Abstract:The optical modulation properties of twisted-nematic liquid-crystal display (TN-LCD) can be totally predicted and optimized when its Jones matrix is known. An improved method for determining the Jones matrix of the TN-LCD without knowing its internal parameters is presented in this paper. Only three sets of intensity measurements are needed for the complete determination of the TN-LCD's Jones matrix for a single wavelength, much less than the procedure offered by Moreno This method is easier and stable in data processing and capable of diminishing the calculation error resulting from the fluctuation of intensity measurement effectively. The validity of this method is verified experimentally, whose results coincide well with the optical modulation properties of the TN-LCD predicted by our determined Jones matrix. ? 2010 American Institute of Physics.Accession Number: 20101812906381 -
Record 59 of
Title:Study of photoinduced birefringence characteristics of B-type and M-type in bacteriorhodopsin film
Author(s):Han, Junhe(1); Yao, Baoli(2); Gao, Peng(2)Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 37 Issue: 8 DOI: 10.3788/CJL20103708.2045 Published: August 2010Abstract:The anisotropically absorbing bacteriorhodopsin (BR) molecules can be approximated by linear oscillators. BR film is isotropic in its initial state because of the random distribution of the BR molecules. Upon excitation by a linearly polarized light, those molecules with the dipole moment aligned closed to the polarization direction of the excitation light are dominantly pumped to the intermediate state and produce photoisomerization. However, those with the dipole vector in the perpendicular direction of the pumping beam have a little probability occurring the above change. Due to the change of molecular structure, the refractive index and absorption coefficient of the BR molecules change, then the macroscopic anisotropy was induced as a result. The photoinduced birefringence of the BR film is measured by the orthogonal polarization detection, the experimental results are basically consistent with the simulated results, which are obtained by utilizing the two-state model of BR molecule photocycle.Accession Number: 20103713225615 -
Record 60 of
Title:An open-loop sin microstepping driver based on FPGA and the co-simulation of modelsim and simulink
Author(s):Li, Yan(1); Huo, Jing(1); Li, Xin(1); Wen, Jin(1); Wang, Yaohui(1); Shan, Bin(1)Source: 2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering, CMCE 2010 Volume: 6 Issue: DOI: 10.1109/CMCE.2010.5609859 Published: 2010Abstract:This paper presents a Sin microstepping method which can achieve constant torque, accurate position control and eliminate low frequency oscillation. The driver adopts FPGA as core, achieving 256 subdividing and PID control algorithm. This paper uses EDA Simulator Link as a co-simulation tool, which provides an interface between Modelsim and Simulink accelerating the function verification. The co-simulation result verifies the performance of the control driver algorithm. ? 2010 IEEE.Accession Number: 20105013487050