2011
2011
-
Record 229 of
Title:Packaging of high power density double quantum well semiconductor laser array using double-side cooling technology
Author(s):Wang, Jingwei(1); Zhang, Pu(2); Xiong, Lingling(2); Li, Xiaoning(2,3); Yuan, Zhenbang(1); Guo, Lu(1); Liu, Xingsheng(1,2)Source: ICEPT-HDP 2011 Proceedings - 2011 International Conference on Electronic Packaging Technology and High Density Packaging Volume: Issue: DOI: 10.1109/ICEPT.2011.6066941 Published: 2011Abstract:High power diode laser arrays offer a variety of applications in pumping of solid state laser systems for industry, scientific research, entertainment display and medical treatment etc, due to their higher electrical-optical conversion efficiency, compact size and long lifetime. Currently, most of commercial high power semiconductor laser array/bar products use single quantum well (SQW) construction in the active region. In order to achieve higher optical power at lower driving current without altering the radiation characteristics of the laser diodes, a new laser chip constructed by double quantum well (DQW) active region has been developed. For the DQW laser, two layers of individual emitters are stacked on top of each other. The two layers of emitters in a DQW are in serial connection. Hence, compared with the conventional SQW laser, a doubled output power from DQW under the same drive current could be obtained. However, the transient/peak thermal density generated from these lasers is very high, especially for the up layer in the active region of DQW laser. Therefore, the DQW can more suitably operate in quasi-continuous wave (QCW) mode. It is a challenge to dissipate the heat generated from the up layer of DQW laser. In this work, a double-side cooling technology was developed and the packaging of high power density DQW semiconductor laser array using that technology was presented. Finite element numerical analysis based simulations to analyze the transient thermal behavior of a water-cooled-packaged semiconductor laser array operating at QCW mode was also presented in this paper. Based on the numerical simulation and analysis, a series of DQW semiconductor lasers with high performances were fabricated. The performances of laser diode arrays operating at QCW mode, including the characteristics of Power-Current-Voltage (LIV), spectrum, near-field, and lifetime were characterized. ? 2011 IEEE.Accession Number: 20114714539948 -
Record 230 of
Title:RGB high brightness LED modules for projection display application
Author(s):Peng, Chenhui(1); Li, Xiaoning(1); Zhang, Pu(1); Xiong, Lingling(1); Liu, Xingsheng(1,2)Source: IEEE/OSA Journal of Display Technology Volume: 7 Issue: 8 DOI: 10.1109/JDT.2011.2132693 Published: 2011Abstract:Light-emitting diodes (LEDs) have numerous advantages, such as long lifetime, large color gamut, small size, and absence of mercury vapor. In recent years, there has been recognition that high brightness LED could be an alternative light source for projection display application. In this work, dielectric compound parabolic concentrators (CPCs) were designed and optimized for multiple-LED array package for projection display application. The performance of rectangular CPC was studied and compared to theoretical simulations. More than 85% light, emitted by multiple-LED arrays, can be collected by the CPC and transmitted within the designed angle. A rectangular CPC was fabricated as the collector and collimator. The CPC was integrated with multiple-LED array package, and RGB high brightness LED modules with rectangular CPCs were fabricated and their performances were characterized. ? 2011 IEEE.Accession Number: 20112714115192 -
Record 231 of
Title:Supercontinuum generation employing the high-energy wave-breaking-free pulse in a compact all-fiber laser system
Author(s):Wang, L.R.(1); Liu, X.M.(1); Gong, Y.K.(1); Mao, D.(1); Duan, L.N.(1)Source: Laser Physics Volume: 21 Issue: 10 DOI: 10.1134/S1054660X11170245 Published: October 2011Abstract:Supercontinuum (SC) generation is experimentally achieved in a compact all-fiber laser system by using high-energy wave-breaking-free dissipative soliton (DS) pulses. The pulses exhibit Gaussian (rectangular) shape profiles in spectral (temporal) domain, which is even reversed of the typical rectangular-spectrum DSs. With the increase of pump power the pulse duration enlarges dramatically whereas the bandwidth and peak power of the pulse keep almost constant, which enables the pulse to accumulate much higher energy during the pulse-shaping process. When inputting the amplified pulse into the single-mode fiber, SC with excellent flatness is generated with the spectral range from about 1550 to 1700 nm. Broader SC with the bandwidth of even larger than 1000 nm can also be generated by this kind of pulse in the near-zero-dispersion-flattened photonic-crystal fiber through strong nonlinear effects. ? 2011 Pleiades Publishing, Ltd.Accession Number: 20114314447210 -
Record 232 of
Title:Comparison of supercontinuum generation based on high-energy nanosecond pulses via single-mode and photonic-crystal fibers
Author(s):Duan, L.N.(1); Liu, X.M.(1); Wang, L.R.(1); Mao, D.(1); Wang, G.X.(1)Source: Laser Physics Volume: 21 Issue: 10 DOI: 10.1134/S1054660X11190091 Published: October 2011Abstract:We have experimentally investigated the supercontinuum (SC) generation based on high-energy Gaussian-spectrum pulses emitted from an erbium-doped fiber laser with large-anomalous dispersion. The pulses exhibit rectangular shape in temporal domain with the pulse duration of about 16 ns. When the amplified pulses propagate through 10-km single-mode fiber, the SC ranged from 1530 to 1750 nm arises from the stimulated-Raman-scattering effect and the pulses break up due to the modulation instability. Comparatively, when the amplified pulses propagate through a segment of highly-nonlinear zero-dispersion-flattened photonic crystal fiber, super-broad SC beyond the range of 1300-1750 nm is generated due to strong four-wave mixing effect, whereas the pulses almost maintain their shapes. ? 2011 Pleiades Publishing, Ltd.Accession Number: 20114314447218 -
Record 233 of
Title:Optimized synthesis of fiber Bragg gratings with triangular spectrum for wavelength-interrogation application
Author(s):Gong, Yongkang(1); Liu, Xueming(1); Wang, Leiran(1)Source: Optical Engineering Volume: 50 Issue: 2 DOI: 10.1117/1.3533030 Published: February 2011Abstract:A novel method for synthesizing arbitrary-shape triangular-spectrum fiber Bragg gratings (TS-FBGs) is proposed. It involves the use of a discrete layer peeling method for exploiting initial guess and a simulated annealing method for optimizing the desired grating parameter. By comparing it to the reported TS-FBGs synthesis methods, the proposed method has advantages of reducing the maximum index modulation and smoothing index modulation profile simultaneously. We employ the proposed method to synthesize FBGs with symmetric, asymmetric, and right-angled triangular spectrum, all of which have the low and smooth index modulation profiles. The synthesized gratings can act simple and cost-effective wavelength-interrogation devices in optical sensor systems. ? 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20110613653583 -
Record 234 of
Title:Summarizing tourist destinations by mining user-generated travelogues and photos
Author(s):Pang, Yanwei(1); Hao, Qiang(1); Yuan, Yuan(2); Hu, Tanji(1); Cai, Rui(3); Zhang, Lei(3)Source: Computer Vision and Image Understanding Volume: 115 Issue: 3 DOI: 10.1016/j.cviu.2010.10.010 Published: March 2011Abstract:Automatically summarizing tourist destinations with both textual and visual descriptions is highly desired for online services such as travel planning, to facilitate users to understand the local characteristics of tourist destinations. Travelers are contributing a great deal of user-generated travelogues and photos on the Web, which contain abundant travel-related information and cover various aspects (e.g., landmarks, styles, activities) of most locations in the world. To leverage the collective knowledge of travelers for destination summarization, in this paper we propose a framework which discovers location-representative tags from travelogues and then select relevant and representative photos to visualize these tags. The learnt tags and selected photos are finally organized appropriately to provide an informative summary which describes a given destination both textually and visually. Experimental results based on a large collection of travelogues and photos show promising results on destination summarization. ? 2010 Elsevier Inc. All rights reserved.Accession Number: 20110813678734 -
Record 235 of
Title:Aurora image segmentation by combining patch and texture thresholding
Author(s):Gao, Xinbo(1); Fu, Rong(1); Li, Xuelong(2); Tao, Dacheng(3); Zhang, Beichen(4); Yang, Huigen(4)Source: Computer Vision and Image Understanding Volume: 115 Issue: 3 DOI: 10.1016/j.cviu.2010.11.011 Published: March 2011Abstract:The proportion of aurora to the field-of-view in temporal series of all-sky images is an important index to investigate the evolvement of aurora. To obtain such an index, a crucial phase is to segment the aurora from the background of sky. A new aurora segmentation approach, including a feature extraction method and the segmentation algorithm, is presented in this paper. The proposed feature extraction method, called adaptive local binary patterns (ALBP), selects the frequently occurred patterns to construct the main pattern set, which avoids using the same pattern set to describe different texture structures in traditional local binary patterns. According to the different morphologies and different semantics of aurora, the segmentation algorithm is designed into two parts, texture part segmentation based on ALBP features and patch part segmentation based on modified Otsu method. As it is simple and efficient, our implementation is suitable for large-scale datasets. The experiments exhibited the segmentation effect of the proposed method is satisfactory from human visual aspect and segmentation accuracy. ? 2010 Elsevier Inc. All rights reserved.Accession Number: 20110813678738 -
Record 236 of
Title:Cantaliver error analysis and correction for lateral optics system of photoelectric theodolite
Author(s):Can, Wang(1); Xiaoxu, Yang(1); Sizhong, Zhou(1); Bo, Jiang(1); Humin, Jin(1)Source: 2011 International Conference on Consumer Electronics, Communications and Networks, CECNet 2011 - Proceedings Volume: Issue: DOI: 10.1109/CECNET.2011.5768978 Published: 2011Abstract:After analyzing the reasons and effect of cantaliver deformation of optic measurement system which was on photoelectric theodolite laterals side. Measurement error brought by it was corrected according to reasonable simplification and mathematic model built by a coordinate transformation method. Then date come from ANSYS theoretic analysis and experiment of one of those theodolites were used to simulating the error model based on MATLAB. And the error model was proved by comparing the simulating result with the practical measurement date, which provides reference and theoretic elements for error analysis and correction of this type photoelectric theodolite. ? 2011 IEEE.Accession Number: 20112414059988 -
Record 237 of
Title:Continuous measurement of the arrival times of x-ray photon sequence
Author(s):Yan, Qiurong(1,2); Zhao, Baosheng(1); Sheng, Lizhi(1,2); Liu, Yongan(1)Source: Review of Scientific Instruments Volume: 82 Issue: 5 DOI: 10.1063/1.3592333 Published: May 2011Abstract:In order to record x-ray pulse profile for x-ray pulsar-based navigation and timing, this paper presents a continuous, high-precision method for measuring arrival times of photon sequence with a common starting point. In this method, a high stability atomic clock is counted to measure the coarse time of arrival photon. A high resolution time-to-digital converter is used to measure the fine time of arrival photon. The coarse times and the fine times are recorded continuously and then transferred to computer memory by way of memory switch. The pulse profile is obtained by a special data processing method. A special circuit was developed and a low-level x-ray pulse profile measurement experiment system was setup. The arrival times of x-ray photon sequence can be consecutively recorded with a time resolution of 500 ps and the profile of x-ray pulse was constructed. The data also can be used for analysis by many other methods, such as statistical distribution of photon events per time interval, statistical distribution of time interval between two photon events, photon counting histogram, autocorrelation and higher order autocorrelation. ? 2011 American Institute of Physics.Accession Number: 20112314046559 -
Record 238 of
Title:Ghosting phenomena in single photon counting imagers with Vernier anode
Author(s):Yang, Hao(1); Zhao, Baosheng(1); Qiurong, Yan(1); Liu, Yongan(1); Hu, Huijun(1,2)Source: Review of Scientific Instruments Volume: 82 Issue: 2 DOI: 10.1063/1.3544018 Published: February 2011Abstract:We provide the ghosting theory of two-dimensional Vernier anode based imagers. The single photon counting detection system based on Vernier anode is constructed. The ghosting, which occurs during the decoding of two-dimensional Vernier anode, and its possible solutions are described in detail. On the basis of the discussion of the decoding algorithm, the ghosting theoretical model is established. Phase conditions on which imaging ghosting can be avoided and the probability distribution function are proposed; the root causes of ghosting of two-dimensional Vernier anode are also discussed. ? 2011 American Institute of Physics.Accession Number: 20111013718840 -
Record 239 of
Title:Shifting the spherical focus of a 4Pi focusing system
Author(s):Yan, Shaohui(1); Yao, Baoli(1); Rupp, Romano(2)Source: Optics Express Volume: 19 Issue: 2 DOI: 10.1364/OE.19.000673 Published: January 17, 2011Abstract:In a 4Pi focusing system radially polarized laser beams can be focused to a spherical focal spot. For many applications, e.g., for moving trapped particles or for scanning a specimen, one would like to change the position of focal spot along the optical axis without moving lenses or laser beams. We demonstrate how this can be achieved by modulating the phase of the input field at the pupil plane of the lens. The required phase modulation function is determined by spherical wave expansion of the plane wave factors in the Richards-Wolf integral. ? 2011 Optical Society of America.Accession Number: 20110413617938 -
Record 240 of
Title:Nonparaxial propagation of vectorial hollow Gaussian beams diffracted at an annular aperture
Author(s):Yang, Yuanjie(1); Li, Xiaofeng(1); Duan, Kailiang(2)Source: Optical Engineering Volume: 50 Issue: 7 DOI: 10.1117/1.3595864 Published: July 2011Abstract:Based on the vectorial Raleigh-Sommerfeld diffraction integral, an analytical propagation equation of vectorial nonparaxial hollow Gaussian beams (HGBs) through an annular aperture is derived. The corresponding closed-forms for a circular aperture, a circular black screen, and unapertured case are given as special cases of the general results. The typical numerical examples are given to illustrate our analytical results. It is shown that the f parameter plays an important role in determining the nonparaxiality of vectorial apertured HGBs. ? 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20114514495716