2010

• Record 205 of
  
  Title:Performance analysis of semiconductor optical amplifier under double assist light injection near transparency wavelength
  
  Author(s):Hui, Zhan-Qiang(1,2)
  Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering  Volume: 39  Issue: 4  DOI:   Published: August 2010  
  Abstract:A theory model was presented, which account for the impacts of amplified spontaneous emission and double continuous-wave assist light beams on the carrier dynamics in a semiconductor optical amplifier(SOA), and was used to numerically simulate transparency wavelength shift, gain saturation and effective carrier lifetime variation. Firstly, as a verification of the model, the dependence of transparency wavelength on both probe wavelength and probe power was provided. This numerical result was in agreement with the previous experiment. Secondly, based on this temporal gain dynamics model, the SOA behaviors of gain saturation and effective carrier lifetime under double assist light beams separately near material and device transparency wavelengths were investigated. It is demonstrated that the saturation output power and the gain recovery time can be greatly improved by using double assist light injection without sacrificing the available SOA gain compared with the scheme of single assist light injection. These simulation results suggest that using double assist light beams near transparency wavelength are useful for improving SOA performance in ultrafast photonic networks.
  Accession Number: 20104313323776
• Record 206 of
  
  Title:Characteristics of the aluminum alloy plasma produced by a 1064 nm Nd:YAG laser with different irradiances
  
  Author(s):Luo, W.F.(1); Zhao, X.X.(2); Sun, Q.B.(1); Gao, C.X.(1); Tang, J.(1); Wang, H.J.(1); Zhao, W.(1)
  Source: Pramana - Journal of Physics  Volume: 74  Issue: 6  DOI: 10.1007/s12043-010-0086-8  Published: June 2010  
  Abstract:The plasma generated by 1064 nm Nd:YAG laser irradiation of aluminum alloy in air at atmospheric pressure was studied spectroscopically. The electron density inferred by measuring the Stark-broadened line profile of Si(I) 288.16 nm decreases with increasing distance from the target surface. The electron temperature was determined using the Boltzmann plot method with nine strong neutral aluminum lines. Due to the thermal conduction towards the solid target and radiative cooling of the plasma as well as conversion of thermal energy into kinetic energy, the electron temperature decreases both at the plasma edge and close to the target surface. Electron density and electron temperature were also studied as functions of laser power density. At the same time, the validity of the assumption of local thermodynamic equilibrium and the effect of selfabsorption were discussed in light of the results obtained. © Indian Academy of Sciences.
  Accession Number: 20102813065825
• Record 207 of
  
  Title:Research on the half-wave voltage stability of Y waveguide in FOG
  
  Author(s):Liu, Ying(1,2); Li, Yan(1); Ji, Zhongxiao(2); Xu, Jintao(2)
  Source: Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument  Volume: 31  Issue: 2  DOI:   Published: February 2010  
  Abstract:Y waveguide is a key component of digital closed-loop fiber optic gyroscope, and the stability of its half-wave voltage directly affects the scale factor stability of FOG. Working temperature is the main factor that influences on the stability of Y waveguide half-wave voltage. Theoretical deduction of Y waveguide physical properties and ex-periment of half-wave voltage changing along with temperature indicate that the relationship between half-wave voltage and temperature is nearly linear. The non-linear errors are induced by Y waveguide electric field and mechanical stress. Through calibrating the Y waveguide half-wave voltage and making compensation, the optimal modulation state of FOG can be achieved and highly stable FOG scale factor can be obtained.
  Accession Number: 20101612868541
• Record 208 of
  
  Title:Compact tunable 10 W picosecond source based on Yb-doped fiber amplification of gain switch laser diode
  
  Author(s):Liu, Hongjun(1); Gao, Cunxiao(1); Tao, Jintao(1); Zhao, Wei(1); Wang, Yishan(1)
  Source: World Academy of Science, Engineering and Technology  Volume: 40  Issue:   DOI:   Published: 2010  
  Abstract:A compact tunable 10 W picosecond source based on Yb-doped fiber amplification of gain switch laser diode has been demonstrated. A gain switch semiconductor laser diode was used as the seed source, and a multi-stage single mode Yb-doped fiber preamplifier was combined with two large mode area double-clad Yb-doped fiber main amplifiers to construct the amplification system. The tunable pulses with high stability and excellent beam quality (M2
  Accession Number: 20125115827571
• Record 209 of
  
  Title:Characterization and mechanism studies of dielectric barrier discharges generated at atmospheric pressure
  
  Author(s):Tang, Jie(1); Duan, Yixiang(1); Zhao, Wei(1)
  Source: Applied Physics Letters  Volume: 96  Issue: 19  DOI: 10.1063/1.3430008  Published: 2010  
  Abstract:A dielectric barrier discharge (DBD) device operated at ambient air with an ac power supply was designed and examined. The discharge power and active current of DBD were characterized. Experimental results show that the discharge power does not proportionally increase all along with voltage. Through in-depth analysis of typical waveforms of instantaneous applied voltage and discharge current, and images of microdischarges in the gas gap, it is inferred that considerable reduction in charges transferred through discharge channels is most likely due to recombination and attachment to electronegative molecules, nonuniform highly distorted electric fields, and repulse of more homogeneous electric charges. © 2010 American Institute of Physics.
  Accession Number: 20102312980970
• Record 210 of
  
  Title:Three operating modes of femtosecond and picosecond pulses in a Ti: sapphire laser
  
  Author(s):Zhu, Chang-Jun(1); He, Jun-Fang(2); Zhai, Xue-Jun(1); Xue, Bing(1); Zhang, Ying-Tang(1); Zhang, Chong-Hui(1)
  Source: Guangdianzi Jiguang/Journal of Optoelectronics Laser  Volume: 21  Issue: 6  DOI:   Published: June 2010  
  Abstract:Three operating modes of femtosecond and picosecond pulses, which are independent self mode-locking, cross mode-locking and multi-pulse operating, are presented in a two-beam-pumped Ti: sapphire laser. Group velocity dispersion, self-phase modulation, cross-phase modulation, gain competition and self-amplitude modulation in the femtosecond and picosecond cavities are analyzed. The results show that, in the independent self mode-locking mode, group velocity dispersion and self-phase modulation largely determine the properties of the self mode-locked pulses, and in the cross mode-locking mode, the femtosecond and picosecond pulses are highly synchronized with a timing jitter of 517 fs and wavelength tuning ranges of 36 and 22 nm in the femtosecond and picosecond cavities, respectively. In the multi-pulse mode, the femtosecond pulse is still a single pulse, while the picosecond pulse splits into three sub-pulses, which is separated in time by 426 fs.
  Accession Number: 20102813064316
• Record 211 of
  
  Title:Generation of synchronized femtosecond and picosecond laser pulses in a two-beam-pumped Ti:sapphire laser
  
  Author(s):Zhu, Changjun(1); He, Junfang(2); Zhai, Xuejun(1); Xue, Bing(1); Zhang, Chonghui(1)
  Source: Chinese Optics Letters  Volume: 8  Issue: 2  DOI: 10.3788/COL20100802.0194  Published: February 2010  
  Abstract:Two operating modes, independent self-mode-locking and cross-mode-locking, are presented in a two-beam-pumped double-cavity dual-wavelength femtosecond Ti:sapphire laser. Synchronization of femtosecond and picosecond laser pulses is achieved by properly adjusting the cavity length matching and distributing the pump laser powers in the two laser cavities, and moreover, a timing jitter of 517 fs between femtosecond and picosecond pulses is obtained, with wavelength tuning ranges around 36 and 22 nm in the femtosecond and picosecond cavities, respectively. © 2010 Chinese Optics Letters.
  Accession Number: 20101412826687
• Record 212 of
  
  Title:Narrow linewidth and widely tunable operation of Tm-doped fiber laser with volume Bragg gratings
  
  Author(s):Shen, Deyuan(1); Wang, Yishan(1); Zhao, Wei(1); Long, Jingyu(1); Li, Cheng(1); Duan, Kailiang(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 7843  Issue:   DOI: 10.1117/12.870061  Published: 2010  
  Abstract:High power and widely tunable operation of Tm-doped silica fiber laser around 2 μm has been demonstrated using volume Bragg grating as the wavelength selection and spectrum narrowing element. The operating wavelength was continuously tunable from 1930 to 1821 nm, with > 52 W output power over a tuning range of 104 nm and a relatively narrow spectra width of 2 ∼ 1.5) CW output power was generated for 137 W of launched pump power, corresponding to a slope efficiency with respect to launched pump power of 46%. Output characteristics with a conventional replica diffraction grating for wavelength selection were also investigated as a comparison with that of using a volume Bragg grating. A maximum output power of 30.6 W at 1963 nm was generated for 79 W of launched pump power and the lasing wavelength could be tuned over 196 nm from 1859 to 2055 nm at output power levels in excess of 20 W. The bandwidth of the laser output was ∼ 0.8 nm. © 2010 Copyright SPIE - The International Society for Optical Engineering.
  Accession Number: 20110113550845
• Record 213 of
  
  Title:Nonlinear chirped-pulse propagation and supercontinuum generation in photonic crystal fibers
  
  Author(s):Hu, Xiaohong(1); Wang, Yishan(1); Zhao, Wei(1); Yang, Zhi(1); Zhang, Wei(1); Li, Cheng(1); Wang, Hushan(1)
  Source: Applied Optics  Volume: 49  Issue: 26  DOI: 10.1364/AO.49.004984  Published: September 10, 2010  
  Abstract:Based on the generalized nonlinear Schrödinger equation and waveguiding properties typical of the photonic crystal fiber structure, nonlinear chirped-pulse propagation and supercontinua generation in the femtosecond and picosecond regimes are investigated numerically. The simulation results indicate that an input chirp parameter mainly affects the initial stage of spectral broadening caused by the self-phase modulation (SPM) effect. In the femtosecond regime where the SPM effect plays an important role in the process of spectral broadening, an input positive chirp can enhance the supercontinuum bandwidth through a modified pulse compression phase and a decreased propagation distance required by soliton fission. In the picosecond regime, where the SPM effect contributes less to the continuum bandwidth and four-wave mixing process or modulational instability dominates the initial stage of spectral and temporal evolution, the output spectral shape and bandwidths are less sensitive to the input chirp parameters. © 2010 Optical Society of America.
  Accession Number: 20104113282393
• Record 214 of
  
  Title:Plasma properties of 532 nm laser-ablated aluminum E414d target with different power densities
  
  Author(s):Luo, Wenfeng(1); Sun, Qibing(1); Gao, Cunxiao(1); Tang, Jie(1); Wang, Haojing(1); Zhao, Wei(1)
  Source: Plasma Science and Technology  Volume: 12  Issue: 4  DOI: 10.1088/1009-0630/12/4/01  Published: August 2010  
  Abstract:Optical emission spectra of the plasma generated by a 532 nm Nd:YAG laser irradiation onto a standard aluminum alloy (E414d) was recorded and analyzed. The electron temperature was determined using the Boltzmann plot method with three aluminum spectral lines at 236.71 nm, 257.509 nm and 308.215 nm, whereas the electron density was inferred by measuring the Stark broadening line profile of Al(II) 281.619 nm. The experimental results confirmed that the local thermodynamic equilibrium was valid and the plasma was optically thin. The spectral line intensity increased initially with the increase in laser irradiance and saturated at higher irradiance levels. Results showed that the energy losses due to the reflection of laser beam from the plasma itself were insignificant. The absorption in the plasma through inverse bremsstrahlung and two-photon ionization were studied. At the same time, the variation of transition probability ratio of Al(I) 309.28 nm to Al(I) 308.21 nm with laser power density was also studied.
  Accession Number: 20104413336408
• Record 215 of
  
  Title:Investigation of soliton pairs in an erbium-doped fiber laser with large normal dispersion
  
  Author(s):Mao, D.(1); Liu, X.M.(1); Wang, L.R.(1); Lu, H.(1); Hu, X.H.(1)
  Source: Optics Communications  Volume: 283  Issue: 18  DOI: 10.1016/j.optcom.2010.04.107  Published: September 15, 2010  
  Abstract:We experimentally investigate the soliton pairs in a passively mode-locked erbium-doped fiber laser with large normal cavity dispersion. By adjusting the polarization state, four different kinds of soliton pairs are achieved. The pulses in soliton pairs exhibit different temporal separations, and show randomly distributed spikes on the top-flat of spectra. The pulse-pulse interactions in the soliton pairs are investigated, and it is suggested that the pulse separation, pulse duration, and their relative intensities all determine the strength of pulse interactions. © 2010 Elsevier B.V. All rights reserved.
  Accession Number: 20102513020632
• Record 216 of
  
  Title:Dynamic evolution of temporal dissipative-soliton molecules in large normal path-averaged dispersion fiber lasers
  
  Author(s):Liu, Xueming(1)
  Source: Physical Review A - Atomic, Molecular, and Optical Physics  Volume: 82  Issue: 6  DOI: 10.1103/PhysRevA.82.063834  Published: December 28, 2010  
  Abstract:The robust dissipative soliton molecules (DSM's) exhibiting as the quasirectangular spectral profile are investigated numerically and observed experimentally in mode-locked fiber lasers with the large normal path-averaged dispersion and the large net cavity dispersion. These DSM's have an independently evolving phase with a pulse duration T0 of about 20 ps and a peak-to-peak separation of about 8T0. Under laboratory conditions, the proposed laser delivers vibrating DSM's with an oscillating amplitude of less than a percent of peak separation. Numerical simulations show that DSM's are characterized by a spectral modulation pattern with about a 3-dB modulation depth measured as an averaged value. The experimental observations are in excellent agreement with the numerical predictions. © 2010 The American Physical Society.
  Accession Number: 20110213570547