2013
2013
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Record 313 of
Title:The generation of dissipative solitons in an all-fiber passively mode-locked laser based on semiconduct type of carbon nanotubes absorber
Author(s):Wang, Yishan(1); Liu, Xianglian(1,2,4); Wang, Yonggang(1,3); Li, Xiaohui(1,2); Zhao, Wei(1); Hu, Xiaohong(1); Zhang, Wei(1); Wang, Hushan(1); Yang, Zhi(1); Shen, Deyuan(1); Li, Cheng(1); Chen, Guangde(1); Tsang, Yuen Hong(3)Source: Optical Fiber Technology Volume: 19 Issue: 3 DOI: 10.1016/j.yofte.2013.01.007 Published: June 2013Abstract:We report theoretically and experimentally on the formation and compensation of dissipative soliton (DS) in an all-normal dispersion fiber laser mode locked with semiconductor type of carbon nanotubes (CNTs) absorber fabricated by vertical evaporation method. The pulses with bandwidth of 2.2 nm and duration of 11.7 ps are obtained at 1051 nm. The DS is linearly chirped and can be compressed to 1.8 ps by a grating pair. By this method the carbon nanotubes absorbers is can be mass produced cost effectively and easier to control the absorber parameters, e.g. initial transmission of the absorber, therefore this method is more suitable to be industrialized. ? 2013 Elsevier Inc. All rights reserved.Accession Number: 20131516186404 -
Record 314 of
Title:Broadband tunable all-fiber polarization interference filter based on 45° tilted fiber gratings
Author(s):Yan, Zhijun(1); Wang, Hushan(1,2); Zhou, Kaiming(1); Wang, Yishan(2); Zhao, Wei(2); Zhang, Lin(1)Source: Journal of Lightwave Technology Volume: 31 Issue: 1 DOI: 10.1109/JLT.2012.2225022 Published: 2013Abstract:We have theoretically and experimentally designed and demonstrated an all-fiber polarization interference filter (AFPIF), which is formed by a polarization-maintaining (PM) fiber cavity structure utilizing two 45° tilted fiber gratings (45°-TFGs) inscribed by UV laser on the PM fiber. Such a filter could generate modulated transmission of linear polarization status. It has been revealed that the modulation depth of the transmission depends on the coupling angle between the 45°-TFGs and the PM fiber cavity. When the two 45°-TFGs in PM fiber are oriented at 45° to the principal axis of the PM fiber cavity, the maximum modulation depth is achievable. Due to the thermal effect on birefringence of the PM fiber, the AFPIF can be tuned over a broad wavelength range just by simple thermal tuning of the cavity. The experiment results show that the temperature tuning sensitivity is proportional to the length ratio of the PM fiber cavity under heating. For 18 and 40 cm long cavities with 6 cm part under heating, the thermal tuning sensitivities are 0.616 and 0.31 nm/° C, respectively, which are almost two orders of magnitude higher than normal fiber Bragg gratings. ? 1983-2012 IEEE.Accession Number: 20130215889923 -
Record 315 of
Title:Ultrafast laser machine based on all-fiber femtosecond laser system
Author(s):Li, Dongjuan(1,2); Cheng, Guanghua(1); Yang, Zhi(1,2); Wang, Yishan(1)Source: Advanced Materials Research Volume: 652-654 Issue: DOI: 10.4028/www.scientific.net/AMR.652-654.2374 Published: 2013Abstract:A femtosecond laser machine consisting of femtosecond fiber laser, trepanning head, linear motor stages system and Siemens 840D system has been integrated for industry application. The femtosecond laser source is all fiber system which contains a fiber mode-lock laser at 1053 nm with a repetition rate of 3.9 MHz, a double-cladding gain fiber amplifiers and a PCF amplifier. An acoustical modulator has employed to tune repetition rate from 3.9 MHz to 100 KHz. An in-line fiber chirped grating is used to stretch the pulse duration to 700 ps. After the PCF amplifier pulse is compressed to sub-ps with 50% efficiency based two grating compressor. The system outputs an average power of 15 W at 100 KHz and 800 fs. Using four wedges trepanning head, cylinder hole is drilled in 1mm thickness SiC ceramics in 30 s. ? (2013) Trans Tech Publications, Switzerland.Accession Number: 20130916069927 -
Record 316 of
Title:Theoretical and experimental study of 37-core waveguides with large mode area
Author(s):Wang, Ping(1,2); Cheng, Guanghua(3); Yi, Ruimin(1); Liu, Xin(3); Shang, Tao(1); Wang, Zhansheng(1); Guo, Lixin(2)Source: Applied Optics Volume: 52 Issue: 33 DOI: 10.1364/AO.52.007981 Published: November 20, 2013Abstract:The evanescently coupled multicore waveguide lattice composed of 37 linear type I cores hexagonally arranged has been theoretically studied and fabricated by low-repetition-rate femtosecond laser inscription of bulk fused silica. The effects of the single corés numerical apertures (NAs) and spacing on the mode characteristics of the 37-core waveguide were calculated by the finite-element method. It was found that the mode field areas of the fundamental mode LP01 with 5 μm spacing of different NAs were all larger than 577 μm2, which was confirmed by the experiments. The measured near-field mode profiles for different writing conditions and different spacing also showed that the waveguide supported both a single mode (LP 01) and two modes (LP01 and LP11). The multicore waveguide, according to our study, is particularly interesting for mode converters. ? 2013 Optical Society of America.Accession Number: 20135017079648 -
Record 317 of
Title:Double-cutting beam shaping technique for high-power diode laser area light source
Author(s):Huang, Zhihua(1,2); Xiong, Lingling(1); Liu, Hui(1); Wang, Zhenfu(1); Zhang, Pu(1); Nie, Zhiqiang(1); Wu, Dihai(1); Liu, Xingsheng(1,3)Source: Optical Engineering Volume: 52 Issue: 10 DOI: 10.1117/1.OE.52.10.106108 Published: October 2013Abstract:A new beam-shaping technique is proposed to improve the beam quality of a high-power diode laser area light source. It consists of two staggered prism arrays and a reflector array, which can cut the slow axis beam twice and rearrange the divided beams in fast axis to make the beam quality of both axes approximately equal. Furthermore, the beam transformation and compression can be carried out simultaneously, and the assembly error of this technique induced by the machining accuracy of prism's dimensions also can be greatly decreased. By this technique, a fiber-coupled system for one three-bar laser diode stack is designed and characterized. The experimental results demonstrate that the laser beams could be transformed into the required distribution with ～93.4% reshaped efficiency and coupled into a 400 μm/0.22 NA fiber, which are consistent with the theory. ? 2013 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20135117116072 -
Record 318 of
Title:Face recognition using Weber local descriptors
Author(s):Li, Shutao(1); Gong, Dayi(1); Yuan, Yuan(2)Source: Neurocomputing Volume: 122 Issue: DOI: 10.1016/j.neucom.2013.05.038 Published: December 25, 2013Abstract:This paper presents a method for face recognition using multi-scale Weber local descriptors (WLDs) and multi-level information fusion. Our method introduces the WLD, a novel and robust local descriptor, to describe the facial images and modifies it by a non-linear quantization approach to enhance its discriminative power. Moreover, a multi-scale framework for WLD extraction with multi-level information fusion approaches is provided for face representation and recognition. The proposed method has four main steps: (1) image partition: under given rules, each facial image is uniformly divided into a set of non-overlapped sub-regions; in this way, for a set of facial images, we therefore have a large pool of this type of sub-regions; (2) feature extraction: in this pool of sub-regions, taking one sub-region as a center, a group of similar ones are chosen for extraction of WLD histogram features; (3) features measurement: these WLD histograms are then fused into a single vector - as the feature of the center sub-region. Nearest neighborhood on chi-square is employed for similarity measurement between two sub-regions; and (4) voting: the recognition result of the entire probe (a face in sub-regions) is obtained via a voting function on the recognition result of all its sub-regions. Experimental results demonstrate the effectiveness of the proposed method upon three popular datasets. ? 2013 Elsevier B.V.Accession Number: 20133816768754 -
Record 319 of
Title:Atmospheric channel simplification single scatter model
Author(s):Tang, Yi'nan(1,2); Zhao, Wei(1); Xie, Xiaoping(1)Source: Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams Volume: 25 Issue: 1 DOI: 10.3788/HPLPB20132501.0022 Published: January 2013Abstract:Most existing study on non-line-of-sight solar-blind ultraviolet communication single scatter models use the prolate-spheroidal coordinates to obtain solutions. In the solving process, the effective scattering volume must undergo the difficult numerical integration and the three groups of integral limits which determine the volume can be calculated. The widely adopted yet complex single-scatter channel model is significantly simplified by means of a closed-form expression for tractable analysis in this paper. And the path loss is given as a function of transceiver geometries as well as scattering and absorption coefficient. The simulation results of transmission distance and path loss show that the approximated path loss matches that from direct numerical integration very well. Using the closed-form expression of path loss, the influence of atmospheric visibility on the path loss and bit-error-rate of the ultraviolet communication system is simulated. The simulation results show that; the better weather and the higher visibility do not result in greater system performances, but when the visibility equals 9-10 km, the best performance can be obtained.Accession Number: 20130315915091 -
Record 320 of
Title:Phase retrieval with resolution enhancement by using structured illumination
Author(s):Gao, Peng(1,2); Pedrini, Giancarlo(1); Osten, Wolfgang(1)Source: Optics Letters Volume: 38 Issue: 24 DOI: 10.1364/OL.38.005204 Published: December 15, 2013Abstract:In this Letter, we present referenceless phase retrieval methods with resolution enhancement. Structured illuminations with different orientations and phase shifts are generated by a spatial light modulator and are used to illuminate the specimen. The generated diffraction patterns are recorded by a CCD camera, and the phase of the wavefront is reconstructed from these patterns. ? 2013 Optical Society of America.Accession Number: 20135217126804 -
Record 321 of
Title:Manifold regularized sparse NMF for hyperspectral unmixing
Author(s):Lu, Xiaoqiang(1); Wu, Hao(2); Yuan, Yuan(1); Yan, Pingkun(1); Li, Xuelong(1)Source: IEEE Transactions on Geoscience and Remote Sensing Volume: 51 Issue: 5 DOI: 10.1109/TGRS.2012.2213825 Published: 2013Abstract:Hyperspectral unmixing is one of the most important techniques in analyzing hyperspectral images, which decomposes a mixed pixel into a collection of constituent materials weighted by their proportions. Recently, many sparse nonnegative matrix factorization (NMF) algorithms have achieved advanced performance for hyperspectral unmixing because they overcome the difficulty of absence of pure pixels and sufficiently utilize the sparse characteristic of the data. However, most existing sparse NMF algorithms for hyperspectral unmixing only consider the Euclidean structure of the hyperspectral data space. In fact, hyperspectral data are more likely to lie on a low-dimensional submanifold embedded in the high-dimensional ambient space. Thus, it is necessary to consider the intrinsic manifold structure for hyperspectral unmixing. In order to exploit the latent manifold structure of the data during the decomposition, manifold regularization is incorporated into sparsity-constrained NMF for unmixing in this paper. Since the additional manifold regularization term can keep the close link between the original image and the material abundance maps, the proposed approach leads to a more desired unmixing performance. The experimental results on synthetic and real hyperspectral data both illustrate the superiority of the proposed method compared with other state-of-the-art approaches. ? 2012 IEEE.Accession Number: 20134116839368 -
Record 322 of
Title:Mid-infrared fluorescence of Ho-doped water-free fluorotellurite glasses
Author(s):He, Jianli(1,2); Zhan, Huan(1,2); Zhou, Zhiguang(1,2); Zhang, Aidong(1); Lin, Aoxiang(1)Source: Asia Communications and Photonics Conference, ACP Volume: Issue: DOI: 10.1364/acpc.2013.af2d.7 Published: 2013Abstract:Ho3+-doped water-free fluorotellurite glasses and fiber canes were reported. Comparable long fluorescence lifetimes of 0.81 ms at 2.85 μm and 10.01 ms at 2.04 μm were obtained. ? OSA 2013.Accession Number: 20142017710723 -
Record 323 of
Title:Mid-infrared fluorotellurite glasses and fibers
Author(s):Zhan, Huan(1,2); Zhang, Aidong(1); He, Jianli(1,2); Zhou, Zhiguang(1); Li, Lu(1,2); Lin, Aoxiang(1)Source: 2013 Conference on Lasers and Electro-Optics, CLEO 2013 Volume: Issue: DOI: 10.1364/cleo_at.2013.jtu4a.11 Published: 2013Abstract:We report on the fabrication and characterization of rare earth ions-doped water-free fluorotellurite glasses and fibers. For 2.8 mm glass fiber rods, its background loss was -12 dB/m in the range of 2.5-4.2 urn. ? 2013 The Optical Society.Accession Number: 20142817926612 -
Record 324 of
Title:Large mode area waveguides with polarization functions by volume ultrafast laser photoinscription of fused silica
Author(s):Cheng, G.(1,2); D'Amico, C.(1); Liu, X.(2); Stoian, R.(1)Source: Optics Letters Volume: 38 Issue: 11 DOI: 10.1364/OL.38.001924 Published: June 1, 2013Abstract:We present optical designs allowing large mode area light guiding by ultrafast laser photoinscription of bulk fused silica. If usual concepts are based on large core and depressed cladding, evanescently coupled multicore waveguides with coherent mode superposition can be effective solutions, where the introduction of nanostructured defects determines additional polarization functions. ? 2013 Optical Society of America.Accession Number: 20132416413133