2015
2015
-
Record 361 of
Title:All-normal dispersion passively mode-locked Yb-doped fiber laser with Bi2Te3 absorber
Author(s):Li, Lu(1,2); Wang, Yonggang(1); Sun, Hang(1); Duan, Lina(1); Wang, Xi(1); Si, Jinhai(2)Source: Optical Engineering Volume: 54 Issue: 4 DOI: 10.1117/1.OE.54.4.046101 Published: April 1, 2015Abstract:An all-normal dispersion passively mode-locked Yb-doped fiber laser with a Bi2Te3 absorber is presented. The modulation depth of this kind of saturable absorber was measured to be 8.4%. By incorporating a Bi2Te3/PVA film into a Yb-doped fiber laser oscillator, a mode-locked fiber laser oscillator was achieved. The repetition rate and the central wavelength are 25.6 MHz and 1052.7 nm, respectively. The 3-dB spectral width is 0.45 nm and the pulse duration is 417 ps. The results indicate that topological insulator Bi2Te3 possesses the potential for ultrafast fiber laser application. ? 2015 Society of Photo-Optical Instrumentation Engineers.Accession Number: 20151500736500 -
Record 362 of
Title:Single-walled carbon nanotube solution-based saturable absorbers for mode-locked fiber laser
Author(s):Li, Lu(1,2,3); Wang, Yonggang(1); Sun, Hang(1,3); Duan, Lina(1,3); Wang, Xi(1,3); Si, Jinhai(2)Source: Optical Engineering Volume: 54 Issue: 8 DOI: 10.1117/1.OE.54.8.086103 Published: August 1, 2015Abstract:The report proposed a saturable absorber based on a D-shaped fiber embedded in a single-walled carbon nanotube solution. Such a saturable absorber solution method with a D-shaped fiber has the virtues of good antioxidant capacity, excellent scattering resistance, high heat dissipation, and high damage threshold. The nonsaturable loss of this kind of saturable absorber was evaluated to be 3%. To the best of our knowledge, this is the lowest value compared with other carbon nanotube saturable absorbers. By incorporating the saturable absorber into a Yb-doped fiber laser cavity, a mode-locked fiber laser was achieved with a central wavelength of 1054.16 nm. The repetition rate was 23 MHz with a signal-to-noise ratio of 60 dB, and the pulse duration was measured to be 194 ps. The long-term working stability of working is also good. The results indicated that the solution method with a D-shaped fiber possesses a potential for fiber laser stability applications. ? 2015 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20153501219024 -
Record 363 of
Title:Substance dependence constrained sparse NMF for hyperspectral unmixing
Author(s):Yuan, Yuan(1); Fu, Min(1); Lu, Xiaoqiang(1)Source: IEEE Transactions on Geoscience and Remote Sensing Volume: 53 Issue: 6 DOI: 10.1109/TGRS.2014.2365953 Published: June 1, 2015Abstract:Hyperspectral unmixing is one of the most important problems in analyzing remote sensing images, which aims to decompose a mixed pixel into a collection of constituent materials named endmembers and their corresponding fractional abundances. Recently, various methods have been proposed to incorporate sparse constraints into hyperspectral unmixing and achieve advanced performance. However, most of them ignore the complex distribution of substances in hyperspectral data so that they are only effective in limited cases. In this paper, the concept of substance dependence is introduced to help hyperspectral unmixing. Generally, substance dependence can be considered in a local region by K-nearest neighbors method. However, since substances of hyperspectral images are complicatedly distributed, number K of the most similar substances to each substance is difficult to decide. In this case, substance dependence should be considered in the whole data space, and the number of the K most similar substances to each substance can be adaptively determined by searching from the whole space. Through maintaining the substance dependence during unmixing, the abundances resulted from the proposed method are closer to the real fractions, which lead to better unmixing performance. The following contributions can be summarized. 1) The concept of substance dependence is proposed to describe the complicated relationship between substances in the hyperspectral image. 2) We propose substance dependence constrained sparse nonnegative matrix factorization (SDSNMF) for hyperspectral unmixing. Using SDSNMF, we meet or exceed state-of-the-art unmixing performance. 3) Adequate experiments on both synthetic and real hyperspectral data have been tested. Compared with the state-of-the-art methods, the experimental results prove the superiority of the proposed method. ? 2015 IEEE.Accession Number: 20150800559699 -
Record 364 of
Title:Tunable continuous wave and passively Q-switched Nd:LuLiF4 laser with monolayer graphene as saturable absorber
Author(s):Wang, Feng(1,3); Li, Shixia(2); Li, Tao(2); Luo, Jianjun(1); Li, Ming(3)Source: Laser Physics Volume: 25 Issue: 1 DOI: 10.1088/1054-660X/25/1/015805 Published: January 1, 2015Abstract:Tunable continuous wave and passively Q-switched Nd:LuLiF4 laser performances were demonstrated. Employing a 2 mm thick quartz plate as the birefringence filter, three continuous tuning ranges from 1045.2 to 1049.9 nm, 1051 to 1055.1 nm and 1072.1 to 1074.3 nm could be obtained. Q-switched laser operation was realized by using a monolayer graphene as a saturable absorber. At an incident pump power of 5.94 W, the maximum average output power was 669 mW with the pulse duration of 210 ns and the pulse repetition rate of 145 kHz at T = 10%. ? 2015 Astro Ltd.Accession Number: 20145300389146 -
Record 365 of
Title:Image quality assessment: A sparse learning way
Author(s):Yuan, Yuan(1); Guo, Qun(1); Lu, Xiaoqiang(1)Source: Neurocomputing Volume: 159 Issue: 1 DOI: 10.1016/j.neucom.2015.01.066 Published: 2015Abstract:Full reference image quality assessment is very important for many image processing applications. The challenge of image quality assessment lies in two aspects: (1) formulating perceptual meaningful features and (2) finding a way to pool them into a single quality score. A novel two-step approach is proposed to address these problems. In the first step, sparse representations of local image patches are computed to simulate the low level characteristic of the human vision system (HVS) and represent the meaningful image structures. The differences between the representations of distorted and undistorted patches are utilized to measure the local distortion. In the second step, these local distortion measurements are fused into a single image quality score by using kernel ridge regression (KRR). Kernel ridge regression can mimic the complex high level behaviors of human vision system and is shown to be an effective way to learn the relationship between local quality measurements and quality score. The contributions of this paper would be summarized as follows: (1) extracting approximate perceptual meaningful features in image quality assessment is transformed as a sparse representation problem. In this case, the sparse representation coefficients can reflect the salient local structures and give local quality assessments. (2) The KRR is utilized to pool the local quality assessments into a single image quality score. Thus, the nonlinear relationship between the objective model outputs and the subjective quality ratings can be learned by exploiting the KRR. (3) Extensive experiments are conducted on six public databases. Compared with other approaches, the proposed approach has achieved the best performance, which demonstrates the effectiveness and robustness of the proposed approach. ? 2015 Elsevier B.V.Accession Number: 20151100636405 -
Record 366 of
Title:Dynamics of optically excited tungsten and silicon for ripples formation
Author(s):Zhang, Hao(1); Li, Chen(1,2); Colombier, Jean-Philippe(1); Cheng, Guanghua(2); Stoian, Razvan(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9351 Issue: DOI: 10.1117/12.2076593 Published: 2015Abstract:We measured the dielectric constant of optically excited silicon and tungsten using a dual-Angle femtosecond reflectivity pump-probe technique. The energy deposition in the formation of laser-induced periodic surface structures (LIPSS) is then investigated by simulating the laser pulse interaction with an initially random distributed rough surface using 3D-Finite Difference Time Domain (FDTD) method, with the measured dielectric constant as a material input. We found in the FDTD simulation periodic energy deposition patterns both perpendicular and parallel to the laser polarization. The origin of them are discussed for originally plasmonic and non-plasmonic material.Accession Number: 20152200896853 -
Record 367 of
Title:High-speed quantum-random number generation by continuous measurement of arrival time of photons
Author(s):Yan, Qiurong(1,2); Zhao, Baosheng(2); Hua, Zhang(1); Liao, Qinghong(1); Yang, Hao(3)Source: Review of Scientific Instruments Volume: 86 Issue: 7 DOI: 10.1063/1.4927320 Published: July 1, 2015Abstract:We demonstrate a novel high speed and multi-bit optical quantum random number generator by continuously measuring arrival time of photons with a common starting point. To obtain the unbiased and post-processing free random bits, the measured photon arrival time is converted into the sum of integral multiple of a fixed period and a phase time. Theoretical and experimental results show that the phase time is an independent and uniform random variable. A random bit extraction method by encoding the phase time is proposed. An experimental setup has been built and the unbiased random bit generation rate could reach 128 Mb/s, with random bit generation efficiency of 8 bits per detected photon. The random numbers passed all tests in the statistical test suite. ? 2015 AIP Publishing LLC.Accession Number: 20153101100718 -
Record 368 of
Title:High power diode laser stack development using gold-tin bonding technology
Author(s):Hou, Dong(1); Wang, Jingwei(1); Zhang, Pu(2); Cai, Lei(1); Dai, Ye(1); Li, Yingjie(1); Liu, Xingsheng(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9346 Issue: DOI: 10.1117/12.2079610 Published: 2015Abstract:High power diode lasers have increased application in many fields. In this work, a sophisticated high power and high performance conduction cooled diode laser stack has been developed for long pulse duration and high duty cycle using gold-tin (AuSn) bonding technology. The transient thermal behavior and optical simulation of the laser diode stack module are investigated to optimize the laser device structure. CTE-matched submount and AuSn hard solder are used for bonding the laser diode bar to achieve higher reliability and longer lifetime. Guided by the numerical simulation and analytical results, conduction cooled diode laser stack with high power, long pulse duration and high duty cycle is fabricated and characterized. Compared with the conventional indium bonding technology, the new design is a promising approach to obtain improved performance with high reliability and long lifetime. ? 2015 SPIE.Accession Number: 20152600969173 -
Record 369 of
Title:Noise-hidden signal recovery via stochastic resonance in the SOI waveguide resonator
Author(s):Sun, Heng(1); Liu, Hongjun(1); Sun, Qibing(1); Huang, Nan(1); Wang, Zhaolu(1); Han, Jing(1); Li, Shaopeng(1)Source: Journal of Physics D: Applied Physics Volume: 49 Issue: 4 DOI: 10.1088/0022-3727/49/4/045107 Published: December 29, 2015Abstract:We propose a method to recover weak pulse signals buried in noise via stochastic resonance (SR) based on optical bistability induced by the free-carrier dispersion effect in the silicon-on-insulator (SOI) waveguide resonator. The bistable system threshold is determined by the resonator parameters including the waveguide length, mirror reflectivity, and the free-carrier lifetime. A signal with different power levels can be detected by changing the free-carrier lifetime using a reverse-biased p-i-n junction embedded in the SOI waveguide. The influence of the system parameters on the SR is quantitatively analyzed by calculating the cross-correlation coefficient between the input and output signals. A cross-correlation gain of 5.6 is obtained by optimizing the system parameters of the SOI waveguide resonator. The results show the potential of using this structure to reconstruct and extract weak signals in all-optical integrated systems. ? 2016 IOP Publishing Ltd.Accession Number: 20160401843653 -
Record 370 of
Title:Extracting nanosecond pulse signals via stochastic resonance generated by surface plasmon bistability
Author(s):Han, Jing(1); Liu, Hongjun(1); Sun, Qibing(1); Huang, Nan(1); Wang, Zhaolu(1); Li, Shaopeng(1)Source: Optics Letters Volume: 40 Issue: 22 DOI: 10.1364/OL.40.005367 Published: November 15, 2015Abstract:A technology is investigated to extract nanosecond pulse noise hidden signals via stochastic resonance, which is based on surface plasmon bistability. A theoretical model for recovering nanosecond pulse signals is derived to describe the nonlinear process. It is found that the incident angle, polarization state, medium properties, and input noise intensity all determine the efficiency and fidelity of the output signal. The bistable behavior of the output intensity can be accurately controlled to obtain a cross-correlation gain larger than 6 in a wide range of input signal-to-noise ratio from 1:5 to 1:30. Meanwhile, the distortion in the time domain induced by phase shift can be reduced to a negligible level. This work provides a potential method for detecting low-level or hidden pulse signals in various communication fields. ? 2015 Optical Society of America.Accession Number: 20160701924160 -
Record 371 of
Title:Theoretical and experimental study of structural slow light in a microfiber coil resonator
Author(s):Ma, Cheng-Ju(1,2); Ren, Li-Yong(2); Xu, Yi-Ping(2); Wang, Ying-Li(2); Zhou, Hong(1); Fu, Hai-Wei(1); Wen, Jin(1)Source: Applied Optics Volume: 54 Issue: 18 DOI: 10.1364/AO.54.005619 Published: June 20, 2015Abstract:In this paper, a compact slow-light microfiber coil resonator (MCR) is fabricated and the slow-light properties of it are analyzed and tested. Based on coupled-wave theory, a theoretical model for describing the slow-light propagation in the MCR is established. Experimentally, the MCR slow-light element is fabricated and its relative slow-light time delay is measured. The group velocity of the light pulse in the MCR slow-light element can be reduced to about 0.47c (c is the speed of light in vacuum) and the shape of the light pulse passing through the MCR is well preserved. ? 2015 Optical Society of America.Accession Number: 20153801297430 -
Record 372 of
Title:High time resolved transient spectrum detection technique based on area CCD
Author(s):Jin, Jing(1); Bai, Yong-Lin(1); Yang, Wen-Zheng(1); Zhu, Bing-Li(1); Wang, Bo(1); Gou, Yong-Sheng(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 44 Issue: 9 DOI: 10.3788/gzxb20154409.0930002 Published: September 1, 2015Abstract:To raise the scan rate of CCD and apply to the hundred nanosecond scale transient phenomena detection, a transient spectrum detection method with high time resolution was proposed and demonstrated by experiment, based on area CCD. By reforming time sequence of CCD and utilizing principle of frame restore, detection with high time resolution was achieved. LED impulse light experiment was performed to demonstrate feasibility of the method. Experiment results show that this transient phenomena acquisition method based on area CCD is efficacious. Detection frame rate can be as high as 10 Mfps. Time resolution is less than 100 ns, and can be able to image 2048 frames continuously. The experiment is of importance to expand application of CCD in the transient spectrum detection area. ?, 2015, Chinese Optical Society. All right reserved.Accession Number: 20154601533901