2011
2011
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Record 265 of
Title:Coexistence of strong and weak pulses in a fiber laser with largely anomalous dispersion
Author(s):Liu, Xueming(1)Source: Optics Express Volume: 19 Issue: 7 DOI: 10.1364/OE.19.005874 Published: March 28, 2011Abstract:The coexistence of weakly sech-shaped solitons and strongly dissipative solitons is experimentally observed in an ultra-large net-anomalous-dispersion mode-locked fiber laser for the first time to author's best knowledge. Both sech-shaped and dissipative solitons appear to be the asymmetrically combined pulse state with one pulse component much smaller than the other. The energy of dissipative solitons is over three orders of magnitude larger than that of sech-shaped solitons. Two different types of pulse-shaping mechanisms coexist in the laser: one is the dissipative processes and the other is the balance between anomalous dispersion and nonlinear Kerr effect. Numerical simulations and analysis confirm the experimental observations. ? 2011 Optical Society of America.Accession Number: 20111413889859 -
Record 266 of
Title:High power all-fiber structured supercontinuum source with variable spectral coverage
Author(s):Yang, Z.(1); Hu, X.H.(1); Wang, Y.S.(1); Zhang, W.(1); Zhao, W.(1)Source: Laser Physics Volume: 21 Issue: 4 DOI: 10.1134/S1054660X11070310 Published: April 2011Abstract:An all-fiber structured supercontinuum source based on chirped pulse amplification (CPA) technology and the use of nonlinear photonic crystal fiber was constructed. By experimentally varying fiber stretcher length in CPA laser source, we can change the spectral coverage and therefore the percentage of visible light in the produced supercontinuum at output of nonlinear photonic crystal fiber, while the average supercontinuum power always keeps at watts of level. The all-fiber structured feature and the capability of changing supercontinuum spectral coverage make this CPA system a promising implement for different applications that require different broad band spectrum. ? 2011 Pleiades Publishing, Ltd.Accession Number: 20112013983982 -
Record 267 of
Title:Enhancement of transmission efficiency of nanoplasmonic wavelength demultiplexer based on channel drop filters and reflection nanocavities
Author(s):Lu, Hua(1); Liu, Xueming(1); Gong, Yongkang(1); Mao, Dong(1); Wang, Leiran(1)Source: Optics Express Volume: 19 Issue: 14 DOI: 10.1364/OE.19.012885 Published: July 4, 2011Abstract:We propose and numerically investigate a novel kind of nanoscale plasmonic wavelength demultiplexing (WDM) structure based on channel drop filters in metal-insulator-metal waveguide with reflection nanocavities. By using finite-difference time-domain simulations, it is found that the transmission efficiency of the channel drop filter can be significantly enhanced by selecting the proper distance between the drop and reflection cavities. The result can be exactly analyzed by the temporal coupled-mode theory. According to this principle, a nanoscale triple-wavelength demultiplexer with high drop efficiencies is designed. The proposed structure can find more applications for the ultra-compact WDM systems in highly integrated optical circuits. ? 2011 Optical Society of America.Accession Number: 20112714123802 -
Record 268 of
Title:Two-dimensional sub-half-wavelength atom localization via controlled spontaneous emission
Author(s):Wan, Ren-Gang(1); Zhang, Tong-Yi(1)Source: Optics Express Volume: 19 Issue: 25 DOI: 10.1364/OE.19.025823 Published: December 5, 2011Abstract:We propose a scheme for two-dimensional (2D) atom localization based on the controlled spontaneous emission, in which the atom interacts with two orthogonal standing-wave fields. Due to the spatially dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the resulting spontaneously emission spectrum. The phase sensitive property of the atomic system leads to quenching of the spontaneous emission in some regions of the standing-waves, which significantly reduces the uncertainty in the position measurement of the atom. We find that the frequency measurement of the emitted light localizes the atom in half-wavelength domain. Especially the probability of finding the atom at a particular position can reach 100% when a photon with certain frequency is detected. By increasing the Rabi frequencies of the driving fields, such 2D sub-half-wavelength atom localization can acquire high spatial resolution. ? 2011 Optical Society of America.Accession Number: 20115014594324 -
Record 269 of
Title:Soliton formation and evolution in passively-mode-locked lasers with ultralong anomalous-dispersion fibers
Author(s):Liu, Xueming(1)Source: Physical Review A - Atomic, Molecular, and Optical Physics Volume: 84 Issue: 2 DOI: 10.1103/PhysRevA.84.023835 Published: August 19, 2011Abstract:The soliton formation and evolution are numerically and experimentally investigated in passively-mode-locked lasers where pulses encounter ultralong anomalous-dispersion fibers. The pulse formation and evolution in lasers are determined by two balances, namely, nonlinearity and anomalous-dispersion balance and intracavity filtering and self-amplitude modulation balance. It is numerically found that a higher-energy soliton can be split into identical lower-energy multisolitons with exactly the same physical properties. Simulation results show that the separation of neighboring solitons is variational in the temporal domain. The temporal and spectral characteristics of solitons have large variations throughout the laser cavity, qualitatively distinct from the steady state of conventional solitons. The experimental observations confirm the theoretical predictions. ? 2011 American Physical Society.Accession Number: 20113414264253 -
Record 270 of
Title:Theoretical study and experimental scheme for the generation of a 1064-nm continuous variable entangled light source with quasi-phase-matching PPKTP crystal
Author(s):Liu, W.Y.(1); Bi, S.W.(1)Source: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 637 Issue: 1 SUPPL. DOI: 10.1016/j.nima.2010.02.045 Published: May 1, 2011Abstract:Beginning from Maxwell's equations, various factors required for the non-degenerate optical parametric amplifier (NOPA) to operate are considered step by step. Analytic expressions are obtained, generated from the experimental parameters and through the numerical simulation of the quantum-correlated spectrum between the signal and the idler modes from the NOPA operating below threshold. On this basis, an experimental program is designed for the generation of a 1064-nm continuous variable entanglement light source with a quasi-phase-matching periodical polarized KTiOPO4 (PPKTP) crystal through a below-threshold optical parametric down-conversion process. This will play a crucial role in subsequent experiments. ? 2010 Elsevier B.V. All rights reserved.Accession Number: 20112013983317 -
Record 271 of
Title:Experimental study on the imaging of the squeezed state light at 1064 nm
Author(s):Chen, L.(1); Bi, S.W.(1); Lu, B.Z.(1)Source: Laser Physics Volume: 21 Issue: 7 DOI: 10.1134/S1054660X11130056 Published: July 2011Abstract:Stable, low noise, infrared squeezed state tight at 1064 nm is generated by utilizing optical parametric down-conversion (OPDC) technique based on periodically poled KTiOPO4 in a optical parametric amplifier (OPA) resonator. A non-classical noise reduction of 2.58 dB below the shot noise is observed through balanced homodyne detection. The squeezed state light is used to set up an imaging system for high-resolution imaging, and it is found that the resolution of image based on the amplitude-squeezed light is 1.26 times larger than that of infrared coherent light under the same intensity. The experimental results indicate that squeezed light is an important non-classical light, which can overcome the coherent laser shot-noise, the classical diffraction limit and limit of quantum noise. ? 2011 Pleiades Publishing, Ltd.Accession Number: 20113314236778 -
Record 272 of
Title:Study on benzoic acid by THz time-domain spectroscopy and density functional theory
Author(s):Zheng, Zhuanping(1); Fan, Wenhui(1); Xue, Bing(1)Source: Chinese Optics Letters Volume: 9 Issue: SUPPL. 1 DOI: 10.3788/COL201109.S10506 Published: June 2011Abstract:In this letter, we employ terahertz time-domain spectroscopy (THz-TDS) technology to measure the THz absorption spectrum and refractive index of benzoic acid at room temperature. Linearity combination of atomic orbital (LCAO) within the density functional theory (DFT) is also used to compute the vibrational absorption spectra of benzoic acid in monomer and dimer. In addition, based on the results obtained from density functional calculation, the origins of observed intra-molecular and inter-molecular vibrational modes under specific peaks are interpreted. ? 2011 Chinese Optics Letters.Accession Number: 20113214224388 -
Record 273 of
Title:Experimental investigation of high-energy wave-breaking-free-pulse generation in bidirectional-pumping all-fiber laser
Author(s):Liu, Xueming(1); Mao, Dong(1); Wang, Leiran(1); Duan, Lina(1)Source: Applied Optics Volume: 50 Issue: 10 DOI: 10.1364/AO.50.001465 Published: April 1, 2011Abstract:We report a passively mode-locked all-fiber laser with bidirectional pumping, emitting high-energy wavebreaking- free pulses. Experimental investigations show that forward and backward pump powers mainly contribute on the chirp and the nonlinear phase shift of pulses, respectively. Nonlinear chirp pulses with 50 nJ pulse energy, 340 ps duration at a 8:2MHz repetition rate are directly emitted from the all-fiber laser pumped by two 550mW, 977nm laser diodes. The pulses cannot be compressed to near the transform limit, showing that the chirp of pulses is nonlinear. ? 2011 Optical Society of America.Accession Number: 20112414066675 -
Record 274 of
Title:Dispersion-insensitive low-coherent pulses emerging from nonlinear polarization switching
Author(s):Mao, D.(1); Liu, X.M.(1); Lu, H.(1); Wang, L.R.(1); Duan, L.N.(1)Source: Laser Physics Volume: 21 Issue: 11 DOI: 10.1134/S1054660X11190236 Published: November 2011Abstract:We have experimentally investigated low-repetition nanosecond pulses delivered from an erbiumdoped fiber (EDF) laser operating in ultra-large anomalous dispersion regime. The output pulses with rectangular profile and Gaussian spectrum almost keep invariable when they propagate through either normal-or anomalous-dispersion fibers. After nanosecond pulses are amplified via a two-stage EDF amplifier, they are broken up and exhibited as flatly broadened supercontinuum from 1520 to 1700 nm if amplified pulses are launched into a 10-km single-mode fiber, whereas the pulses retain the same duration with a broadband supercontinuum from 1200 to 1750 nm if they are input into a 100-m highly-nonlinear low-dispersion photonic-crystal fiber (PCF). The experimental observations demonstrate that the nanosecond pulses result from nonlinear polarization switching and can be regarded as dispersion-insensitive low-coherent pulses rather than compressible pulses. ? Pleiades Publishing, Ltd., 2011.Accession Number: 20120314700443 -
Record 275 of
Title:Multi-channel plasmonic waveguide filters with disk-shaped nanocavities
Author(s):Lu, Hua(1); Liu, Xueming(1); Gong, Yongkang(1); Wang, Leiran(1); Mao, Dong(1)Source: Optics Communications Volume: 284 Issue: 10-11 DOI: 10.1016/j.optcom.2011.01.046 Published: May 15, 2011Abstract:A kind of multi-channel plasmonic filters based on metal-insulator-metal waveguides with disk-shaped nanocavities is proposed and numerically investigated. By calculating the resonant mode of disk-shaped nanocavity, it is found that the radius and refractive index of the nanocavity effectively control the resonance wavelength, which is consistent with the results obtained by finite-difference time-domain method. The characteristics of resonance spectra are influenced by the gap width between the cavity and waveguide, as can be exactly analyzed by temporal coupled mode theory. In addition, multi-channel plasmonic filters are achieved by increasing the number of nanocavity. ? 2011 Elsevier B.V. All rights reserved.Accession Number: 20111013731362 -
Record 276 of
Title:Optical trapping with cylindrical vector beams
Author(s):Yao, Baoli(1); Yan, Shaohui(1); Lei, Ming(1); Peng, Fei(1); Ma, Baiheng(1); Ye, Tong(1)Source: 2011 Functional Optical Imaging, FOI 2011 Volume: Issue: DOI: 10.1109/FOI.2011.6154814 Published: 2011Abstract:Recent development of cylindrical vector beams prompts its application in optical trapping, which shows more effective and improved trapping efficiency in contrast to the traditional Gaussian beam of spatially homogeneous polarization. Using the T-matrix method and vectorial diffraction theory, we calculated and compared the radiation forces exerted on dielectric particles respectively by the linearly polarized, radially polarized and azimuthally polarized beams. Theoretical calculations show that the radially polarized beam can improve the axial trapping efficiency of high-refractive-index larger particles by reducing the scattering force due to the vanishing axial component of Poynting vector near the focus, while the azimuthally polarized beam can not only steadily trap low-refractive-index small particles at the focus center but also can trap multiple high-refractive-index particles around the focus center in virtue of the hollow-ring configuration. The dependences of the trapping efficiencies on the beam parameters, particle size and the numerical aperture of objective lens are discussed. The performances of optical trapping, manipulating and sorting of biological cells, organelles and various micro-particles are demonstrated. ? 2011 IEEE.Accession Number: 20121914992993