2012
2012
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Record 385 of
Title:Experimental study on partially coherent combination of a 2×2 all-fiber laser array
Author(s):Zhao, Baoyin(1,2); Duan, Kailiang(1); Zhao, Wei(1); Qian, Fengchen(1,2,3)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 41 Issue: 1 DOI: Published: January 2012Abstract:By using partially coherent combining technique, beam combining of a 2×2 all-fiber laser array was experimentally studied. The laser array consisted of two incoherent laser groups. Each group contained two all-fiber lasers which were phase-locked by using direct mode mutual injection method through a fiber Bragg grating with proper reflectivity. The four laser beams were arranged symmetrically. And they were placed as close as possible by using a four-right-angle prism. In the experiment, two groups of clear interfere strips with maximum visibility of about 43% and 38% were observed, respectively. The whole laser array finally generates 925 W output power when the total pump power was 1624 W. The beam-quality value BQ of the combined beam emitting from the laser array was 1.95 when the fill factor of the laser array was 0.54. This fiber laser combining array was constructed by all-fiber components, thereby was monolithic with stable performance. During the long time of high power operation, the monolithic fiber laser array works with excellent stability, no thermal distortion and damage are observed.Accession Number: 20121114853049 -
Record 386 of
Title:Portable fiber group velocity test method with a gain-switched laser
Author(s):Feng, Ye(1,2); Zou, Lin(3); Wang, Yi Shan(1); Zhao, Wei(1); Yang, Zhi(1); Zhang, Wei(1); Hu, Xiao Hong(1)Source: Applied Optics Volume: 51 Issue: 32 DOI: 10.1364/AO.51.007745 Published: November 10, 2012Abstract:A portable method of group velocity measurement is proposed based on a self-seeded gain-switched laser. The calculated group velocity in the optical fiber is obtained by measuring the round-trip frequencies of the gain-switched laser diode with different external cavities, and only a 2 m long fiber is needed. The measurement can be accomplished without oscilloscope or optical spectrum analyzer. The error associated with this test is within 0.65%, which is limited by the jitter of the voltage-controlled oscillator. Its spectrum resolution is 0.1 nm. ? 2012 Optical Society of America.Accession Number: 20124815715031 -
Record 387 of
Title:Performances of non-line-of-sight ultraviolet multi-scatter propagation for noncoplanar geometries
Author(s):Yinan, Tang(1); Xiaoping, Xie(1); Wei, Zhao(1)Source: Advanced Materials Research Volume: 571 Issue: DOI: 10.4028/www.scientific.net/AMR.571.214 Published: 2012Abstract:A multi-scatter propagation model based on Monte Carlo method is presented. This model can be applied to all the geometries, including coplanar or noncoplanar scenario. The mathematical description of this model is deduced. We obtain the spatial positions of photon with three Cartesian coordinates after each propagation step and the received judgment conditions. Employing a photon tracing technique, Monte Carlo simulation is performed to investigate the signal impulse response and the path loss. The results indicate that, when the off-axis angle increases, the amplitude of the impulse response decreases, while the path loss increases. In addition, it is observed that the pulse width increases with the off-axis angle. ? (2012) Trans Tech Publications, Switzerland.Accession Number: 20124815717029 -
Record 388 of
Title:Yb3+ doped fluorophosphate laser glasses with high gain coefficient and improved laser property
Author(s):Wang, P.F.(1); Peng, B.(1); Li, W.N.(1); Hou, Ch.Q.(1); She, J.B.(1); Guo, H.T.(1); Lu, M.(1)Source: Solid State Sciences Volume: 14 Issue: 4 DOI: 10.1016/j.solidstatesciences.2011.12.004 Published: April 2012Abstract:Yb3+ doped fluorophosphate glasses with high stimulated emission cross-section, large gain coefficient and low hydroxyl absorption coefficient were prepared by high temperature melting for fiber laser applications, and their spectral, general laser parameters were investigated accordingly by means of fluorescence emission spectrum, decay cure and infrared absorption spectra. Compared with previously reported fluorophosphate glasses, the investigated fluorophosphate glasses have highest grain coefficient and maintain a maximum laser systematical factor over other various types of laser glasses. The introduction of fluorides to fluorophosphate glasses results in the low level of hydroxyl absorption coefficient and concentration. All these advantages might mean that Yb3+ doped fluorophosphate glasses are a good candidate as an active laser media for short pulse, high power laser generation used for next generation nuclear fusion. ? 2012 Elsevier Masson SAS. All rights reserved.Accession Number: 20121214884533 -
Record 389 of
Title:Influence of aperture averaging on bit-error rate of spatial coherent optical communication systems using phase compensation technique
Author(s):Yu, Gang(1,2); Xie, Xiaoping(1,3); Zhao, Wei(1); Wang, Wei(1); Duan, Tao(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 32 Issue: 9 DOI: 10.3788/AOS201232.0906006 Published: September 2012Abstract:Based on the model of the spatial coherent optical communication system under the influence of the atmospheric turbulence and the plane-wave propagation model of aperture averaging, by using of numerical simulation, under the weak irradiance fluctuation condition the influence of aperture averaging including the atmospheric turbulence inner scale and outer scale is investigated on the bit-error rate and the optimum receiver aperture diameter of the coherent optical communication system. The results show that aperture averaging can decrease the bit-error rate effectively; the improved effect of aperture averaging on the bit-error rate is more obvious for the higher original SNR, the shorter transmission distance, the longer wavelength, the larger value of the phase compensation mode J and the receiver aperture diameter which is closer to the optimum value; aperture averaging affects the optimum value of the receiver aperture diameter, and if the value of the phase compensation mode J is larger, the influence is more obvious; the bit-error rate and the optimum receiver aperture diameter will increase with the increase of atmospheric turbulence inner scale and decrease with the decrease of atmospheric turbulence outer scale. This will provide the necessary theoretical basis for the design of a coherent optical communication system.Accession Number: 20124515645165 -
Record 390 of
Title:Research on design of a cubic conjugate phase mask having the capability of controlling the bandwidth of wave-front coding system
Author(s):Zhao, Hui(1,2); Li, Yingcai(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8557 Issue: DOI: 10.1117/12.981932 Published: 2012Abstract:In this paper, an extended cubic phase mask used to realize wave-front coding technique is derived in frequency domain. Then by splitting and re-combining the terms of the phase function, a new mask containing two conjugate cubic terms is generated and can be physically realized by shifting and superposing two cubic phase mask having relative displacement with respect to the center of the pupil plane. Simulation results indicate that this phase mask has the capability of changing the system effective bandwidth while maintaining the defocus invariance characteristic. The work reported can be extended to other phase masks and could be considered to be complementary to the existing researches. ? 2012 SPIE.Accession Number: 20132916515041 -
Record 391 of
Title:Modulation instability of bright photovoltaic solitons on a partially incoherent background
Author(s):Zhang, M.(1); Huo, G.(2); Zhang, Y.(3); Kang, Y.(4); Duan, Z.(1)Source: Laser Physics Volume: 22 Issue: 8 DOI: 10.1134/S1054660X12080178 Published: August 2012Abstract:We present the observation of incoherent anti-dark photovoltaic solitons in LiNbO3:Fe crystal. This new class of soliton states involves bright photovoltaic solitons on a background beam meeting κ > 1, where κ is the ratio of background illumination photovoltaic constant to that of soliton beam. For κAccession Number: 20123615403607 -
Record 392 of
Title:Passively Q-switched Tm-doped fiber lasers with carbon nanotubes
Author(s):Zhou, Wei(1,2); Wang, Yonggang(3); Li, Xiaohui(1,2); Long, Jingyu(1); Shen, Deyuan(1); Wang, Yishan(1)Source: Chinese Optics Letters Volume: 10 Issue: SUPPL.2 DOI: 10.3788/COL201210.S21411 Published: December 2012Abstract:We demonstrate a passively Q-switched Tm-doped fiber laser with carbon nantubes (CNTs), yielding a maximum output average power of around 82 mW and the corresponding pulse energy of 1.2 μJ. The laser operates at ~1.985 μm with repetition rates ranging from 26 to 69 kHz and pulse-duration from 1.5 to 2.6 μs. Our proposed laser shows that the CNTs are promising for the potential Q-switched Tm-doped fiber laser with high energy and tunable wavelength operation. To the best of our knowledge, this is the first report of a Q-switched Tm-doped fiber laser with CNTs as saturable absorber. ? 2012 Chinese Optics Letters.Accession Number: 20131016087945 -
Record 393 of
Title:Wavelength-switchable and wavelength-tunable all-normal-dispersion mode-locked yb-doped fiber laser based on single-walled carbon nanotube wall paper absorber
Author(s):Li, Xiao-Hui(1,2); Wang, Yong-Gang(3); Wang, Yi-Shan(1); Hu, Xiao-Hong(1); Zhao, Wei(1); Liu, Xiang-Lian(1,2); Yu, Jia(1); Gao, Cun-Xiao(1); Zhang, Wei(1); Yang, Zhi(1); Li, Cheng(1); Shen, De-Yuan(1)Source: IEEE Photonics Journal Volume: 4 Issue: 1 DOI: 10.1109/JPHOT.2012.2183862 Published: 2012Abstract:We demonstrate a compact wavelength-tunable and -switchable mode-locked Yb-doped fiber (YDF) laser based on single-walled carbon nanotube (SWCNT) wall paper absorber. Two mechanisms coexist in the fiber cavity. The switchable mode-locked state can be obtained between two wavelengths depending on the fiber-loop-induced cavity birefringence. Because of the intensity-dependent transmission distribution, the proposed fiber laser can be operated in the tunable wavelength mode-locked state from 1025 to 1037 nm. The spectral bandwidth varied from 1.1 to 2.4 nm depending on the operating wavelength and the pump power with pulse duration of hundreds of picoseconds. The average wavelength spacing is 3.6 nm, which can be changed, corresponding to the birefringence of the fiber cavity. Moreover, stable wavelength-tunable mode locking is obtained at room temperature. ? 2009 IEEE.Accession Number: 20120714769695 -
Record 394 of
Title:Characteristics of the annular beam using a single axicon and a pair of lens
Author(s):Ji, Ke(1,2); Lei, Ming(2); Yao, Baoli(2); Yan, Shaohui(2); Yang, Yanlong(2); Li, Ze(2); Dan, Dan(2); Menke, Neimule(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8418 Issue: DOI: 10.1117/12.976027 Published: 2012Abstract:In optical trapping, annular beam as a kind of hollow beam is used to increase the axial trapping efficiency as well as the trapping stability. In this paper, a method for producing an annular beam by a system consisting of a single axicon and a pair of lens is proposed. The generated beam was also used as the optical tweezers. We use the geometrical optics to describe the propagation of light in the system. The calculated intensity distribution in three-dimensional space after the system shows a good agreement with the experimental results. The advantages of this method are simplicity of operation, good stability, and high transmittance, having possible applications in fields like optical microscopic, optical manipulation and electronic acceleration, etc. ? 2012 SPIE.Accession Number: 20131416173482 -
Record 395 of
Title:Cylindrically symmetric vector beams obtained by overlapping optical vortices
Author(s):Zong, Zhengyue(1); Menke, Neimule(1); Cheng, Ming(1); Bo, Bin(1); Hua, Chuyi(1); Ji, Ke(1); Yao, Baoli(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8417 Issue: DOI: 10.1117/12.975742 Published: 2012Abstract:In recent years, cylindrically symmetric vector beams are widely used in many fields, such as high-resolution microscopy, micro printing and nonlinear optics et al. The intensity and polarization of cylindrically symmetric vector beams are symmetrical around the optical axis. Radially polarized beam and azimuthally polarized beam are the most common cylindrically symmetric vector beams. In this paper, first by using numerical methods it is calculated that the cylindrically symmetric vector beams can be obtained by overlapping two optical vortices or by overlapping an optical vortices with topological charge of two and a plane wave. Then, a radially polarized beam and azimuthally polarized beam were experimentally obtained by overlapping a right-circularly polarized plane light and a left-circularly polarized optical vortices with topological charge of two, which is obtained by using a reflective liquid crystal spatial light modulator (SLM) and a quarter-wave plate. The experimental results show that, by using this method, different kinds of cylindricany symmetric vector beams can be obtained very simply and easily, and could be switched to each other at video rate, and has higher energy conversion efficiency (up to 60%). ? 2012 SPIE.Accession Number: 20131416173299