2012
2012
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Record 265 of
Title:All optical nanostructed sensor based on metal-dielectric-metal plasmonic waveguide
Author(s):Gong, Yongkang(1,2); Copner, N.J.(1); Davies, Antony(3); Li, Kang(1,2); Huang, Jungang(1)Source: 2012 Symposium on Photonics and Optoelectronics, SOPO 2012 Volume: Issue: DOI: 10.1109/SOPO.2012.6270564 Published: 2012Abstract:Based on a two-dimensional plasmonic metal-dielectric-metal waveguide with a thin metallic layer and dual nanocavites inserted in the core, a novel nanostructured absorber is presented. A transfer matrix model for the proposed structure is established, and the optical spectra are investigated. Design results show that a narrow reflection spectrum occurs at position of the near-unity absorption, and is significantly influenced by the environment. It is able to generate a sensitivity as high as 1000 nm/RIU, which be used as an excellent sensing platform for chemical and biochemically relevant molecules. ? 2012 IEEE.Accession Number: 20124315589204 -
Record 266 of
Title:Theoretical study on instantaneous linewidth of Fourier-domain mode-locked fiber lasers
Author(s):Tu, Chenghou(1,2); Deng, Yixin(1); Cai, Mengqiang(1); Huang, Zhangchao(1); Li, Yongnan(1); Lu, Fuyun(1); Li, Enbang(3)Source: Optics Communications Volume: 285 Issue: 24 DOI: 10.1016/j.optcom.2012.06.072 Published: November 1, 2012Abstract:We have numerically simulated the operation of the Fourier-domain mode-locked (FDML) fiber laser based on the wavelength reconstruction method instead of numerical solving the nonlinear Schr?dinger equation. We studied the influences of the filter bandwidth and the relative time delay caused by the fiber chromatic dispersion on the instantaneous linewidth of the FDML fiber laser. The results show that the instantaneous linewidth broadens as the filter bandwidth and the relative time delay increase. When the filter has the bandwidth of 0.02 nm, the narrowest and broadest instantaneous linewidths are 0.024 and 0.042 nm, respectively. We give an understanding for the oscillation of the instantaneous linewidth of FDML. The presented result can be used to evaluate the performance achievable in the FDML fiber lasers. ? 2012 Elsevier B.V. All rights reserved.Accession Number: 20124315591025 -
Record 267 of
Title:Spoof four-wave mixing for all-optical wavelength conversion
Author(s):Gong, Yongkang(1,2); Huang, Jungang(1); Li, Kang(1,2); Copner, Nigel(1); Martinez, J.J.(1); Wang, Leirang(2); Duan, Tao(2); Zhang, Wenfu(2); Loh, W.H.(3)Source: Optics Express Volume: 20 Issue: 21 DOI: 10.1364/OE.20.024030 Published: October 8, 2012Abstract:We present for the first time an all-optical wavelength conversion (AOWC) scheme supporting modulation format independency without requiring phase matching. The new scheme is named "spoof" four wave mixing (SFWM) and in contrast to the well-known FWM theory, where the induced dynamic refractive index grating modulates photons to create a wave at a new frequency, the SFWM is different in that the dynamic refractive index grating is generated in a nonlinear Bragg Grating (BG) to excite additional reflective peaks at either side of the original BG bandgap in reflection spectrum. This fundamental difference enable the SFWM to avoid the intrinsic shortcoming of stringent phase matching required in the conventional FWM, and allows AOWC with modulation format transparency and ultrabroad conversion range, which may have great potential applications for next generation of all-optical networks. ? 2012 Optical Society of America.Accession Number: 20124215571498 -
Record 268 of
Title:Defect modes in optically induced photonic lattices in biased photovoltaic-photorefractive crystals
Author(s):Lu, Keqing(1); Guo, Jianbang(2); Li, Kehao(2); Chen, Weijun(1); Sun, Tongtong(1); Yao, Fengxue(1); Niu, Pingjuan(1); Xu, Jingjun(3)Source: Optical Materials Volume: 34 Issue: 8 DOI: 10.1016/j.optmat.2012.01.036 Published: June 2012Abstract:We show that defect modes in optically induced photonic lattices are possible in biased photovoltaic-photorefractive crystals. These defect modes exist in different bandgaps when the defect strength is changed. When the defect strength is positive, there is a defect-mode branch in each bandgap. When the defect strength is negative, there is a defect-mode branch in the first bandgap and are many defect-mode branches in higher bandgaps. For a given defect strength, the strongest confinement of the defect modes appears in the semi-infinite bandgap when the defect strength is positive and in the first bandgap when the defect strength is negative. On the other hand, these defect modes are those studied previously in optically induced photonic lattices in biased non-photovoltaic-photorefractive crystals when the bulk photovoltaic effect is negligible and predict those in optically induced photonic lattices in photovoltaic-photorefractive crystals when the external bias field is absent. Crown Copyright ? 2012 Published by Elsevier B.V. All rights reserved.Accession Number: 20122515123272 -
Record 269 of
Title:Local structure divergence index for image quality assessment
Author(s):Gao, Fei(1); Tao, Dacheng(2); Li, Xuelong(3); Gao, Xinbo(1); He, Lihuo(1)Source: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) Volume: 7667 LNCS Issue: PART 5 DOI: 10.1007/978-3-642-34500-5_40 Published: 2012Abstract:Image quality assessment (IQA) algorithms are important for image-processing systems. And structure information plays a significant role in the development of IQA metrics. In contrast to existing structure driven IQA algorithms that measure the structure information using the normalized image or gradient amplitudes, we present a new Local Structure Divergence (LSD) index based on the local structures contained in an image. In particular, we exploit the steering kernels to describe local structures. Afterward, we estimate the quality of a given image by calculating the symmetric Kullback-Leibler divergence (SKLD) between kernels of the reference image and the distorted image. Experimental results on the LIVE database II show that LSD performs consistently with the human perception with a high confidence, and outperforms representative structure driven IQA metrics across various distortions. ? 2012 Springer-Verlag.Accession Number: 20124715683405 -
Record 270 of
Title:The computer-aided alignment study of three-mirror off-axis field bias optical system
Author(s):Pang, Zhi-Hai(1,2); Fan, Xue-Wu(1); Ma, Zhen(1); Chen, Qin-Fang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8417 Issue: DOI: 10.1117/12.970651 Published: 2012Abstract:Determine the misalignment of optical element quickly and exactly is the key to the technology of computer-aided alignment (CAA). For alignment a three-mirror off-axis field bias system, the sensitivity matrix method was used to simulate the alignment process. The results of simulation show that the sensitivity matrix method was not convergence. A new CAA method to get misalignment was put forward; the misalignment was obtained by programming the function of optical design software CODE V's auto-optimization option. The system's alignment characteristic was analysis and made use of this new method put up a computer simulation. The results of simulation show that the misalignment determined by only once auto-optimization and guidable to alignment of this system. After alignment, the optical system produced a measured wave front error across the all image plane less than 0.08 waves RMS at λ=0.6328μm. ? 2012 SPIE.Accession Number: 20131416173312 -
Record 271 of
Title:Face sketch-photo synthesis and retrieval using sparse representation
Author(s):Gao, Xinbo(1); Wang, Nannan(1); Tao, Dacheng(2); Li, Xuelong(3)Source: IEEE Transactions on Circuits and Systems for Video Technology Volume: 22 Issue: 8 DOI: 10.1109/TCSVT.2012.2198090 Published: 2012Abstract:Sketch-photo synthesis plays an important role in sketch-based face photo retrieval and photo-based face sketch retrieval systems. In this paper, we propose an automatic sketch-photo synthesis and retrieval algorithm based on sparse representation. The proposed sketch-photo synthesis method works at patch level and is composed of two steps: sparse neighbor selection (SNS) for an initial estimate of the pseudoimage (pseudosketch or pseudophoto) and sparse-representation-based enhancement (SRE) for further improving the quality of the synthesized image. SNS can find closely related neighbors adaptively and then generate an initial estimate for the pseudoimage. In SRE, a coupled sparse representation model is first constructed to learn the mapping between sketch patches and photo patches, and a patch-derivative-based sparse representation method is subsequently applied to enhance the quality of the synthesized photos and sketches. Finally, four retrieval modes, namely, sketch-based, photo-based, pseudosketch-based, and pseudophoto-based retrieval are proposed, and a retrieval algorithm is developed by using sparse representation. Extensive experimental results illustrate the effectiveness of the proposed face sketch-photo synthesis and retrieval algorithms. ? 2012 IEEE.Accession Number: 20123315335488 -
Record 272 of
Title:Creation of periodic subwavelength ripples on tungsten surface by ultra-short laser pulses
Author(s):Xue, Lu(1); Yang, Jianjun(1); Yang, Yang(1); Wang, Yishan(2); Zhu, Xiaonong(1)Source: Applied Physics A: Materials Science and Processing Volume: 109 Issue: 2 DOI: 10.1007/s00339-012-7261-3 Published: November 2012Abstract:Formation of periodic subwavelength ripples on a metallic tungsten surface is investigated through a linescribing method under the irradiation of 800 nm, 50 fs to 8 ps ultra-short laser pulses. The distinctive features of the induced ripple structures are described in detail with different laser parameters. Experimental measurements reveal that with gradual decrease of the laser fluence, the pulse duration or the scanning speed, the ripple period is inclined to reduce but the ripple depth tends to become pronounced. Theoretical analyses suggest that the transient dielectric function change of the tungsten surface mainly originates from the nonequilibrium distribution of electrons due to the d-band transitions. A sandwich-like physical model of air-plasma- target is proposed and the excitation of a surface plasmon polaritonic (SPP) wave is supposed to occur on the interface between the metallic target and the electron plasma layer. Formation of ripples can be eventually attributed to the laser-SPP interference. Theoretical interpretations are consistent with the experimental observations. ? Springer-Verlag Berlin Heidelberg 2012.Accession Number: 20124915746479 -
Record 273 of
Title:Spectroscopic properties of new Yb3+-doped TeO 2-ZnO-Nb2O5 based tellurite glasses with high emission cross-section
Author(s):Wang, Cuicui(1); Wang, Pengfei(2); Zheng, Ruilin(1); Xu, Shennuo(2); Wei, Wei(1,2); Peng, Bo(1,2)Source: Optical Materials Volume: 34 Issue: 9 DOI: 10.1016/j.optmat.2012.03.026 Published: July 2012Abstract:Novel Yb3+-doped TeO2-ZnO-Nb2O5 based tellurite glasses with high stimulated emission cross-section were prepared by melt-quenching method, and their spectroscopic and gain properties were investigated by means of absorption spectrum, fluorescence decay curve and fluorescence emission spectrum. The results show that the stimulated emission cross-section of the Pb2+-doped glass increases with the increase of PbF2 concentration. Toward the samples with co-existence of Pb 2+ and Zr4+ ions, the stimulated emission cross-sections achieve 1.42 pm2 and 1.48 pm2 when PbF2 concentrations are 2 mol% and 6 mol%, respectively. All these indicate that the Yb3+-doped TeO2-ZnO-Nb2O5-PbF 2-ZrF4 glasses are a good candidate working as an active laser media for solid lasers. ? 2012 Elsevier B.V. All rights reserved.Accession Number: 20122215063429 -
Record 274 of
Title:Femtosecond laser-induced surface structures to significantly improve the thermal emission of light from metals
Author(s):Yang, J.(1,2); Yang, Y.(1); Zhao, B.(1); Wang, Y.(1,2); Zhu, X.(1)Source: Applied Physics B: Lasers and Optics Volume: 106 Issue: 2 DOI: 10.1007/s00340-011-4834-3 Published: February 2012Abstract:Extraordinary thermal emission properties of the metallic surface microstructures induced by femtosecond lasers are investigated in both experiment and theory. Within the spectral range of 4-17 μm, the measured maximum thermal emissivities at different temperatures enhance significantly to about 100%. Especially for the coral-like surface structure, the improved thermal emission behaviors can extend largely over the whole spectrum rather than happening at some distinctive wavelengths. Moreover, the enhancement factor of the thermal emissivity is observed to depend on the wavelength and the idiographic morphology of the microstructures. This phenomenon can be understood well by equivalent recognizing the SPP field coupling assisted transmission of blackbody radiation through the microstructured interfaces, and the finite-difference time-domain simulations elucidate the underlying physical pictures. ? Springer-Verlag 2011.Accession Number: 20121614951819 -
Record 275 of
Title:Investigation on modeling methods of axial magnetic field error characteristics in small fiber optic gyroscope
Author(s):Wang, Li-Hui(1,2); Xu, Xiao-Su(1); Liu, Xi-Xiang(1); Cai, Yu-Feng(3)Source: Zhongguo Guanxing Jishu Xuebao/Journal of Chinese Inertial Technology Volume: 20 Issue: 1 DOI: Published: February 2012Abstract:A significant feature of small interferometric fiber optic gyroscope is that the fiber ring radial size is becoming smaller, and the axial dimension is becoming larger. As a consequence, the axial magnetic field error becomes one of the important factors that affects the gyroscope precision. By studing the Faraday phase error of axial direction magnetic field in small interferometric fiber optic gyroscope, the coil helical angle expansion method is proposed based on fiber loop's quadrupolar winding distribution structure. Then, the transmission matrix and magnetic phase error models of interferometric depolarized fiber optic gyroscope and interferometric polarization maintaining fiber optic gyroscope in axial direction are respectively established by using Jones matrix. Based on these models, the relations between Faraday magnetic field non-reciprocal phase error and residual circular birefringence coming from twist of fiber in fiber loop, axial dimension are studied. Then the axial phase drift in interferometric depolarized fiber optic gyroscope and polarized interferometric polarization maintaining fiber optic gyroscope are deduced and described mathematically. Based on the theoretical models, the factors of axial magnetic field error in small fiber optic gyroscope are discussed, and the measures to deal with them are proposed.Accession Number: 20121614955307 -
Record 276 of
Title:New measurement of the alignment of the deployable telescope
Author(s):Feng, Xuegui(1); Li, Chuang(1); Zhao, Chao(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8417 Issue: DOI: 10.1117/12.977843 Published: 2012Abstract:As one type of the deployable telescope, the deployable space telescope under researching uses tape springs as the support structure of secondary mirror. Before launch, the support structure of secondary mirror is folded, and when on orbit the structure is deployed. Usually the secondary mirror is not on the nominal position after deploying, so the alignment of the secondary mirror is needed. To achieve this we need to obtain the deployment errors. So the measuring of secondary mirror deployment errors of thus deployable telescope is an important topic. In this paper, we designed an accurate measuring system based on position sensitive detectors (PSDs) to measure the deployment errors, through measuring the six-degree-of-freedom motions of the secondary mirror. The measuring system contains 3 twodimensional PSDs, 3 laser diodes and 3 small mirrors. In order to resolve the deployment errors, the equations linking the PSD readings and the six-degree-of-freedom displacement of the secondary mirror were deduced. These equations are solved through a numerical method. Finally, we did measuring experiments on a deployable prototype. The experimental results show that this deployable prototype has deployment errors about 100um. ? 2012 SPIE.Accession Number: 20131416173403