2013
2013
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Record 469 of
Title:Experimental research of high gain and low noise figure optical amplifier based on erbium-doped fiber
Author(s):Zhang, Kewei(1,2); Zhao, Wei(1); Xie, Xiaoping(1,3); Wang, Wei(1); Qian, Fengchen(1,3); Han, Biao(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 33 Issue: 5 DOI: 10.3788/AOS201333.0506003 Published: May 2013Abstract:Considering the trade-off between the high gain and low noise figure in optical amplifier, a two-stage amplifier which has the structure to suppress the forward and backward-travelling amplified spontaneous emission noise with high gain and low noise figure based on Erbium-doped fiber is set up. Interpolation is used to test the power of amplified spontaneous emission (ASE) noise accurately. The gain and noise figures and some other parameters of the amplifier are analyzed. Comparison between the erbium-doped fiber amplifer (EDFA) and the commercial low noise EDFA is carried out. The results show that the highest gain of the EDFA in the experiment is 40.1 dB and the noise figure is 3.8 dB which is 0.8 dB above quantum-limit. The results when testing the amplifier and commercial EDFA in the same input power and gain show that the noise figure of the amplifier is 0.3 dB lower than the commercial EDFA.Accession Number: 20132616448231 -
Record 470 of
Title:A stable polarization switching laser from a bidirectional passively mode-locked thuliumdoped fiber oscillator
Author(s):Zhou, Wei(1,2); Shen, Deyuan(1); Wang, Yishan(1); Ma, Hefeng(1,3); Wang, Fei(1,3)Source: Optics Express Volume: 21 Issue: 7 DOI: 10.1364/OE.21.008945 Published: April 8, 2013Abstract:We report on a novel polarization switching laser from a bidirectional passively mode-locked thulium(Tm)-doped fiber oscillator, which was characterized by the periodical change of polarization state of every pulse. The switching laser was created by combing two orthogonally stable vector solitons, which were found to be wave-breaking-free pulses in the all-anomalous- dispersion regime. The measured repetition rates of switching laser and the corresponding vector solitons were 49.596 MHz, 24.798 MHz, and 24.798MHz. By controlling wave plates, either of the polarized pulse trains can be switched on or off. To our knowledge, this is the first report of polarization switching laser with vector solitons in Tm fiber oscillators. ? 2013 Optical Society of America.Accession Number: 20131616207206 -
Record 471 of
Title:Learning saliency by MRF and differential threshold
Author(s):Zhu, Guokang(1); Wang, Qi(1); Yuan, Yuan(1); Yan, Pingkun(1)Source: IEEE Transactions on Cybernetics Volume: 43 Issue: 6 DOI: 10.1109/TSMCB.2013.2238927 Published: December 2013Abstract:Saliency detection has been an attractive topic in recent years. The reliable detection of saliency can help a lot of useful processing without prior knowledge about the scene, such as content-aware image compression, segmentation, etc. Although many efforts have been spent in this subject, the feature expression and model construction are far from perfect. The obtained saliency maps are therefore not satisfying enough. In order to overcome these challenges, this paper presents a new psychologic visual feature based on differential threshold and applies it in a supervised Markov-random-field framework. Experiments on two public data sets and an image retargeting application demonstrate the effectiveness, robustness, and practicability of the proposed method. ? 2013 IEEE.Accession Number: 20135117095004 -
Record 472 of
Title:Yb-doped passively mode-locked fiber laser based on a single wall carbon nanotubes wallpaper absorber
Author(s):Li, Xiaohui(1,2); Wang, Yonggang(3); Wang, Yishan(1); Liu, Xianglian(1,2); Zhao, Wei(1); Hu, Xiaohong(1); Yang, Zhi(1); Zhang, Wei(1); Gao, Cunxiao(1); Shen, Deyuan(1); Li, Cheng(1); Tsang, Yuen H.(3)Source: Optics and Laser Technology Volume: 47 Issue: DOI: 10.1016/j.optlastec.2012.08.010 Published: April 2013Abstract:A passively mode-locked Yb-doped fiber laser is demonstrated based on a band-pass filter together with a novel fabricated single-wall carbon nanotubes (SWCNT) wallpaper absorber. Mode-locking can be achieved with a low threshold pump power of 32 mW. The proposed fiber laser operates at 1064 nm with the spectral width of about 0.57 nm and pulse repetition rate of about 19.45 MHz. The pulse duration is about 276 ps, which can be used directly as seed source for chirped pulse amplification (CPA) system.Accession Number: 20124715685968 -
Record 473 of
Title:A passively Q-switched thulium-doped fiber laser with single-walled carbon nanotubes
Author(s):Ma, H.F.(1); Wang, Y.G.(1,2); Zhou, W.(1,3); Long, J.Y.(1); Shen, D.Y.(1); Wang, Y.S.(1)Source: Laser Physics Volume: 23 Issue: 3 DOI: 10.1088/1054-660X/23/3/035109 Published: March 2013Abstract:We demonstrate a passively Q-switched thulium-doped fiber laser by using single-walled carbon nanotube (SWCNT) polyvinyl alcohol (PVA) composite film as the saturable absorber (SA). A relatively large mode area on the SA was employed to avoid damage of the SWCNT/PVA film and benefit pulsed laser operation. Stable pulses of 85-164 kHz repetition rate were generated at 1967 nm with a maximum average output power of 103 mW. The single pulse energy was up to ～0.63 μJ with ～0.87 μs pulse duration. ? 2013 Astro Ltd.Accession Number: 20132616445002 -
Record 474 of
Title:Adaptively post-encoding multiple description video coding
Author(s):Lan, Xuguang(1); Yang, Meng(1); Yuan, Yuan(2); Zhao, Songlin(1); Zheng, Nanning(1)Source: Neurocomputing Volume: 101 Issue: DOI: 10.1016/j.neucom.2012.08.015 Published: February 4, 2013Abstract:In video coding and transmission, the network conditions are crucial, i.e., bandwidth, delay and other factors. However, how to effectively take these factors into account is still a challenge, as heterogeneous networks are dynamic, and therefore it is difficult to predict their changes. This paper first reports a post-encoding of Scalable Multiple Description Coding (SMDC), which is towards self-adaptive video delivery under different conditions of the network. The proposed scheme contains three major steps: (1) spatiotemporal wavelet transformation of input video sequence; (2) context-based adaptive binary arithmetic coding; and (3) rate allocation under the conditions of the network and analysis of the principle relationship of the rate-distortion slope ratio with packet-loss probability in network links. The performance of the SMDC is compared with that of scalable video coding and scalable H.264, and SMDC is demonstrated to effectively optimize the video delivery to adapt to the dynamics of heterogeneous networks. Part of this work has been published on Data Compression Conference 2009 as a short abstract version [37]. ? 2012 Elsevier B.V.Accession Number: 20124615668521 -
Record 475 of
Title:Multi-spectral saliency detection
Author(s):Wang, Qi(1,2); Yan, Pingkun(1); Yuan, Yuan(1); Li, Xuelong(1)Source: Pattern Recognition Letters Volume: 34 Issue: 1 DOI: 10.1016/j.patrec.2012.06.002 Published: January 1, 2013Abstract:Visual saliency detection has been applied in many tasks in the fields of pattern recognition and computer vision, such as image segmentation, object recognition, and image retargeting. However, the accurate detection of saliency remains a challenge. The reasons behind this are that: (1) well-defined mechanism for saliency definition is rarely established; and (2) supporting information for detecting saliency is limited in general. In this paper, a multi-spectrum based saliency detection algorithm is proposed. Instead of only using the conventional RGB information as what existing algorithms do, this work incorporates near-infrared clues into the detection framework. Features of color and texture from both types of image modes are explored simultaneously. When calculating the color contrast, an effective color component analysis method is employed to produce more precise results. With respect to the texture analysis, texton representation is adopted for fast processing. Experiments are done to compare the proposed algorithm with other 11 state-of-the-art algorithms and the results indicate that our algorithm outperforms the others. ? 2012 Elsevier B.V. All rights reserved.Accession Number: 20124715687935 -
Record 476 of
Title:Solid-state ultrafast all-optical x-ray imaging sensor enabling picosecond temporal resolution
Author(s):Wang, Bo(1,2); Bai, Yonglin(1); Xu, Peng(1,2); Liu, Baiyu(1); Zhu, Bingli(1); Yang, Wenzheng(1); Bai, Xiaohong(1); Qin, Junjun(1); Gou, Yongsheng(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8908 Issue: DOI: 10.1117/12.2034893 Published: 2013Abstract:Here we report an ultrafast x-ray imaging sensor based on optical measurement of the effects of x-ray absorption and electron hole pair creation in a direct band-gap semiconductor. Our results indicate that this technology can be used to provide a new approach for x-ray detectors and x-ray imaging systems with picosecond temporal resolution at x-ray energies ~10 keV. The x-ray absorption in GaAs produces a transient, non-equilibrium, electron-hole pair distribution which is then sensed by the phase modulation of the optical probe beam. The basic physics of the detector, implementation considerations, and preliminary experimental data are presented and discussed. Through further development, this x-ray imaging sensor could provide insight into previously unmeasurable phenomena in many fields. ? 2013 SPIE.Accession Number: 20134216857710 -
Record 477 of
Title:Theoretical and experimental research on ultrafast electron diffraction system
Author(s):Wang, Xingchao(1,3); Tian, Jinshou(1); Liu, Hulin(1); Lu, Yu(1); Cao, Ziqiang(2)Source: Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams Volume: 25 Issue: 7 DOI: 10.3788/HPLPB20132507.1630 Published: July 2013Abstract:An ultrafast electron diffraction system with both ultrafast temporal resolution and ultrahigh spatial resolution was established. The temporal resolution of the system is 300 fs and spatial resolution 160 lp/mm in theory. Investigation and optimization on spatial resolution of the system was performed. The experimental results demonstrate that the system can provide an electron beam diameter less than 300 μm and an incidence angle less than 0.09°. The x-y deflection plates and stability of the electron beam were quantitatively analyzed. The diffraction pattern of Al was obtained by this system and it demonstrates that the system can distinguish diffraction peak position changes of 0.36%.Accession Number: 20132916509411 -
Record 478 of
Title:Terahertz spectroscopy of DNA nucleobases: Cytosine and thymine
Author(s):Yan, Hui(1,2); Fan, Wen-Hui(1); Zheng, Zhuan-Ping(1); Liu, Jia(1)Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 33 Issue: 10 DOI: 10.3964/j.issn.1000-0593(2013)10-2612-05 Published: October 2013Abstract:The absorption features of DNA nucleobases cytosine and thymine were measured by terahertz time-domain spectroscopy (THz-TDS) from 0.1 to 3.5 THz. Our experimental results clearly show that these important biomolecules exhibit distinctive absorption features in THz region. To the best of our knowledge, the subtle absorption peak of cytosine at 2.53 THz is reported for the first time. Moreover, geometry optimizations and lattice dynamic calculations on cytosine crystal were also performed with the pseudo-potential plane wave method of density functional theory by taking periodic boundary conditions into account. All measured terahertz absorption features of cytosine were assigned successfully and its absorption spectrum was reproduced according to our calculations. Furthermore, our results show that absorption features of cytosine below 3.5 THz arise from external modes in translation and rotation motions, which are dominated by the intermolecular hydrogen bonds.Accession Number: 20134316893779 -
Record 479 of
Title:SIFT on manifold: An intrinsic description
Author(s):Zhu, Guokang(1,2); Wang, Qi(1); Yuan, Yuan(1); Yan, Pingkun(1)Source: Neurocomputing Volume: 113 Issue: DOI: 10.1016/j.neucom.2013.01.020 Published: August 3, 2013Abstract:Scale Invariant Feature Transform is a widely used image descriptor, which is distinctive and robust in real-world applications. However, the high dimensionality of this descriptor causes computational inefficiency when there are a large number of points to be processed. This problem has led to several attempts at developing more compact SIFT-like descriptors, which are suitable for faster matching while still retaining their outstanding performance. This paper focuses on the SIFT descriptor and explore a dimensionality reduction for its local representation. By using the manifold learning algorithm of Locality Preserving Projections, a more effective and efficient descriptor LPP-SIFT can be obtained. A large number of experiments have been carried out to demonstrate the effectiveness of LPP-SIFT. Besides, the practicability of LPP-SIFT is also shown in another set of experiments for image similarity measurement. ? 2013 Elsevier B.V.Accession Number: 20132016333246 -
Record 480 of
Title:Ghosting theoretical model of single photon counting imagers with Vernier anode
Author(s):Yang, Hao(1); Zhao, Baosheng(2); Yan, Qiurong(2); Liu, Yongan(2)Source: Science China: Physics, Mechanics and Astronomy Volume: 56 Issue: 8 DOI: 10.1007/s11433-013-5088-3 Published: August 2013Abstract:In this paper, the distribution of the phase deviations for the ghosting of Vernier based imagers is provided. The equality of the phase errors is shown. The relationship between the charge noise amplitude of electrodes and the total charge noise amplitude is provided. The relationship between the phase error and the total charge noise amplitude is also provided, which reveals the magnitude of 104 electrons for the ghosting occurrence threshold for the 4-coarse-pixel anode imagers. ? 2013 Science China Press and Springer-Verlag Berlin Heidelberg.Accession Number: 20133016529908