2013
2013
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Record 433 of
Title:Experimental investigations of pulse shape control in passively mode-locked fiber lasers with net-normal dispersion
Author(s):Wang, L.R.(1); Han, D.D.(1)Source: Laser Physics Volume: 23 Issue: 3 DOI: 10.1088/1054-660X/23/3/035106 Published: March 2013Abstract:Pulse shape control in passively mode-locked fiber lasers with net-normal dispersion is investigated experimentally. Three kinds of pulses with different spectral and temporal shapes are observed, and their pulse-shaping mechanisms are discussed. After a polarization-resolved system external to the cavity, the maximum intensity differences of the two polarization components for the rectangular-spectrum (RS), Gaussian-spectrum (GS), and super-broadband (SB) pulses are measured as ～20 dB, ～15 dB, and ～1 dB, respectively. It is suggested that the equivalent saturable absorption effect plays an increasingly important role from the RS to GS and then to SB pulses in the pulse-shaping processes, while the spectral filtering effect declines. This work could help in systematically understanding pulse formation and proposing guidelines for the realization of pulses with better performance in fiber lasers. ? 2013 Astro Ltd.Accession Number: 20132616444999 -
Record 434 of
Title:Visual saliency by selective contrast
Author(s):Wang, Qi(1); Yuan, Yuan(1); Yan, Pingkun(1)Source: IEEE Transactions on Circuits and Systems for Video Technology Volume: 23 Issue: 7 DOI: 10.1109/TCSVT.2012.2226528 Published: July 2013Abstract:Automatic detection of salient objects in visual media (e.g., videos and images) has been attracting much attention. The detected salient objects can be utilized for segmentation, recognition, and retrieval. However, the accuracy of saliency detection remains a challenge. The reason behind this challenge is mainly due to the lack of a well-defined model for interpreting saliency formulation. To tackle this problem, this letter proposes to detect salient objects based on selective contrast. Selective contrast intrinsically explores the most distinguishable component information in color, texture, and location. A large number of experiments are thereafter carried out upon a benchmark dataset, and the results are compared with those of 12 other popular stateof-the-art algorithms. In addition, the advantage of the proposed algorithm is also demonstrated in a retargeting application. ? 2012 IEEE.Accession Number: 20141117451274 -
Record 435 of
Title:Study on THz spectra and vibrational modes of benzoic acid and sodium benzoate
Author(s):Zheng, Zhuan-Ping(1); Fan, Wen-Hui(1); Yan, Hui(1); Liu, Jia(1); Xu, Li-Min(1)Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 33 Issue: 3 DOI: 10.3964/j.issn.1000-0593(2013)03-0582-04 Published: March 2013Abstract:Terahertz time-domain spectroscopy was employed to measure the terahertz absorption spectra of benzoic acid and sodium benzoate at room temperature. The origins of the measured features of benzoic acid were summarized based on previous study. Density functional theory was used to compute and analyze the molecular structure and vibrational modes of sodium benzoate in monomer. Based on the obtained results, the authors found that the THz spectral features can be used to distinguish benzoic acid and sodium benzoate totally; the essential reason for the THz spectral difference between benzoic acid and sodium benzoate is that the electrovalent bond of sodium benzoate affects the values of covalent bond lengths and bond angles, as well as the molecular interactions and arrangement in unit cell; the measured features of benzoic acid and sodium benzoate come from the collective vibrations except the peaks located at 107 cm-1 of benzoic acid and 54 cm-1 of sodium benzoate.Accession Number: 20131116114652 -
Record 436 of
Title:Compact all-fiber laser delivering conventional and dissipative solitons
Author(s):Mao, Dong(1); Liu, Xueming(1); Han, Dongdong(1); Lu, Hua(1)Source: Optics Letters Volume: 38 Issue: 16 DOI: 10.1364/OL.38.003190 Published: 2013Abstract:We report the simultaneous generation of conventional soliton (CS) and dissipative soliton (DS) in a mode-locked fiber laser exploiting chirped fiber Bragg grating and four-port circulator. The bandwidth and duration of the CS are 0.28 nm and 15.1 ps, respectively. However, the giant-chirp DS exhibits a quasi-rectangular spectrum with a bandwidth of 9.5 nm. The duration of the output DS is 7.3 ps and can be compressed to 0.55 ps external to the cavity. Our numerical results agree well with the experimental observations. The flexible all-fiber laser can provide three different pulse sources, which is convenient and attractive for practical applications. ? 2013 Optical Society of America.Accession Number: 20133416654651 -
Record 437 of
Title:Gain-assisted trapping of light in tapered plasmonic waveguide
Author(s):Wang, Guoxi(1); Lu, Hua(1); Liu, Xueming(1)Source: Optics Letters Volume: 38 Issue: 4 DOI: 10.1364/OL.38.000558 Published: February 15, 2013Abstract:We have investigated the slow light and trapping effects in tapered metal-insulator-metal plasmonic waveguides. It is found that a significant reduction of group velocity (Accession Number: 20130916050961 -
Record 438 of
Title:Single-step fabrication of stressed waveguides with tubular depressed-cladding in phosphate glasses using ultrafast vortex laser beams
Author(s):Cheng, Guanghua(1); Long, Xuewen(1)Source: MATEC Web of Conferences Volume: 8 Issue: DOI: 10.1051/matecconf/20130806008 Published: 2013Abstract:We report on the fabrication of the stressed optical waveguide with tubular depressed-refractive-index cladding in phosphate glasses by use of femtosecond vortex beam. Strained regions were emerged in domains surrounding the tubular track. Waveguiding occurs mainly within the tube induced by femtosecond laser. ? Owned by the authors, published by EDP Sciences, 2013.Accession Number: 20142717887166 -
Record 439 of
Title:Long-term stable bright amplitude-squeezed state of light at 1064 nm for quantum imaging
Author(s):Feng, Fei(1); Bi, Si Wen(1); Lu, Bao Zhu(1); Kang, Meng Hua(1)Source: Optik Volume: 124 Issue: 11 DOI: 10.1016/j.ijleo.2013.01.005 Published: June 2013Abstract:Bright amplitude-squeezed light at 1064 nm is generated with excellent long-term stability by utilizing the degenerate optical parametric amplifier (OPA) based on periodically poled KTiOPO4 (PPKTP) crystal. Amplitude noise reduction of as much as -5.5 dB is observed directly at an output power of 0.3 mW. This corresponds to a squeezing of -6.22 dB in the beam, the detection efficiency and the propagation efficiency are taken into account. The average value of the detected noise reduction in continuous operation over 5 h is -3.8 dB by locking the cavity length of the OPA. The squeezed state light is applied for imaging of virtual object. The experimental results indicate that the obtained image is more distinct and has less distortion compared to that obtained by infrared coherent light. ? 2013 Elsevier GmbH. All rights reserved.Accession Number: 20131516204736 -
Record 440 of
Title:Theoretical study of stimulated Brillouin scattering in high-power dual-clad fiber lasers
Author(s):Yang, Hening(1); Duan, Kailiang(1); Zhao, Baoyin(1); Zhang, Entao(1)Source: Optik Volume: 124 Issue: 11 DOI: 10.1016/j.ijleo.2013.01.010 Published: June 2013Abstract:A theoretical analysis of stimulated Brillouin scattering (SBS) in linear cavity Yb3+ doped dual-clad fiber lasers is presented by solving the steady-state rate equations with SBS included. Solutions to suppress the detrimental effect in the fiber laser are discussed. It is shown that the first-order Stokes initiated by forward and backward pump light changes exponentially along the fiber, and laser power reduces greatly in the presence of SBS under bidirectional end pump. Furthermore, it is found that the SBS threshold power can be improved effectively by using large mode area fiber and shortening the cavity length. ? 2013 Elsevier GmbH. All rights reserved.Accession Number: 20131516204740 -
Record 441 of
Title:Bidirectional fiber soliton laser mode-locked by single-wall carbon nanotubes
Author(s):Zeng, Chao(1); Liu, Xueming(1); Yun, Ling(1)Source: Optics Express Volume: 21 Issue: 16 DOI: 10.1364/OE.21.018937 Published: August 12, 2013Abstract:We report on the experimental observation of a bidirectional fiber soliton laser passively mode-locked by single-wall carbon nanotubes. Two stable pulse trains in opposite directions are delivered simultaneously from the ring cavity. The counterpropagating pulses have different central wavelengths, pulse durations, and repetition rates. By adjusting the fiber birefringence and cavity length, the central wavelengths of two solitons can be the same or different. Experimental observations and analyses demonstrate that the different operating wavelengths result in the unequal repetition rates of two pulses. These unique features may be attributed to the cavity asymmetry and fiber birefringence. ? 2013 Optical Society of America.Accession Number: 20133416639629 -
Record 442 of
Title:Condition for realizing single-mode operation and energy distribution characteristics in far-field of annular core fibers
Author(s):Hui, Xiangyun(1); Duan, Kailiang(1); Yan, Hongwei(1)Source: Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams Volume: 25 Issue: 4 DOI: 10.3788/HPLPB20132504.0841 Published: April 2013Abstract:Based on the weak guidance approximation, the condition for realizing single mode operation of annular core fiber (ACF) and the energy distribution in far-field are discussed. The theoretical results demonstrate that when an ACF realizes single-mode operation, the annular beam emitted from the end of ACF diffracts to a central circular area in the far-field with good energy focusability. Besides, the beam width gets smaller when the thickness of the guiding section and the refractive index difference between the cladding and fiber core are reduced.Accession Number: 20131616214073 -
Record 443 of
Title:Super-resolution microscopy with DMD-based LED-illumination
Author(s):Lei, M.(1); Dan, D.(1); Yao, B.(1); Qi, Y.(1); Yan, S.(1); Yang, Y.(1); Gao, P.(1); Ye, T.(1); Zhao, W.(1)Source: Nanophotonics, Nanoelectronics and Nanosensor, N3 2013 Volume: Issue: DOI: 10.1364/n3.2013.nsu3c.2 Published: 2013Abstract:Super-resolution optical microscopy has some incomparable comprehensive advantages ver various other microscopic technologies such as electron microscopy, atomic force icroscopy and so on, especially in the study of biological molecules, pathways and events in live cells and tissues. In this report, we present a novel structured illumination microscopy (SIM) based on digital micromirror device (DMD) fringe projection with the low-coherence LED light as illumination source. A 90nm in-plane resolution was achieved with gold nano-particles and BPAE cells. ? OSA 2013.Accession Number: 20134717010725 -
Record 444 of
Title:A two-dimensional linear array fiber amplifier based on the MOPA configuration
Author(s):Niu, L.Q.(1); Gao, C.X.(1); He, H.D.(1); Feng, L.(1); Cao, Z.Y.(1); Sun, C.D.(1); Zhu, S.L.(1)Source: Laser Physics Volume: 23 Issue: 9 DOI: 10.1088/1054-660X/23/9/095103 Published: September 2013Abstract:A two-dimensional linear array fiber amplifier based on the master oscillator power amplifier (MOPA) configuration is constructed and employed as the laser source of a high resolution 3D imaging LIDAR system. Each branch of the linear array system comprises a dual-stage Yb3+-doped large-mode-area double-clad fiber amplifier. The amplified pulse is of 2.3 ns temporal duration and 30 kHz repetition rate with an average power of 8.5 W when the pump power is 20 W. The optical-optical conversion efficiency is 41.8%. Furthermore, the SRS effect can be suppressed effectively. The M2 values of the output beam are 1.35 and 1.33 in the x- and y-axis directions, respectively. ? 2013 Astro Ltd.Accession Number: 20133816755719