2013
2013
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Record 409 of
Title:Steady-state multiple dark spatial solitons in closed-circuit photovoltaic media
Author(s):Zhang, Y.H.(1); Hu, X.H.(2); Lu, K.Q.(2); Liu, B.Y.(1); Liu, W.Y.(1); Guo, R.L.(1)Source: Journal of Optical Technology (A Translation of Opticheskii Zhurnal) Volume: 80 Issue: 3 DOI: 10.1364/JOT.80.000135 Published: March 1, 2013Abstract:We theoretically study the formation of the steady state multiple dark photovoltaic solitons in the closed-circuit photovoltaic photorefractive crystal. The results indicate that the formation of the multiple dark photovoltaic solitons in the closed-circuit photovoltaic crystal is dependent on the initial width of the dark notch at the entrance face of the crystal. The number of the solitons generated increases with the initial width of the dark notch. If the initial width of the dark notch is small, only a fundamental soliton or Y-junction soliton pair is generated. As the initial width of the dark notch is increased, the dark notch tends to split into an odd (or even) number of multiple dark photovoltaic solitons sequence, which realizes a progressive transition from a lower-order soliton to a higher-order solitons sequence. When the multiple solitons are generated, the separations between adjacent dark solitons become slightly smaller. The soliton pairs far away from the center have bigger width and less visibility and they move away from each other as they propagate in the photorefractive nonlinear crystal. ? 2013 Optical Society of America.Accession Number: 20132016327496 -
Record 410 of
Title:An all-optical encryption system scheme for 8 wave signals based on LiNbO3 waveguide
Author(s):Xie, Xiao-Ping(1,2); Duan, Jie(1,2); Duan, Tao(2); Wen, Yu(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 42 Issue: 10 DOI: 10.3788/gzxb20134210.1169 Published: October 2013Abstract:Owing to based on the nonlinear effect, the all-optical encryption scheme can only be applied to encrypt signal wave optical signal, in order to solve the problem that recent all-optical scheme can not be applied to encrypt multi-wave signal simulatanously, an all-optical encryption system scheme which can simultaneously encrypt multi-wave optical signals is proposed. This scheme is based on pockels effect of LiNbO3 waveguide and achieves signals encrypting operation by interference of coherent optical signals and keys. Because the difference of modulated phase shift of different wavelength through the same external electric field in LiNbO3 waveguide is very small, so, this scheme can be used to encrypt multi-wave signals simultaneously. The simulation of encrypting operation of 8×10 Gbps multe-wave signals whose interval of wavelength is 0.8 nm has been realized, the code type is NRZ with rise and fall time of 10ps, the BER of the encrypted output is smaller than 4.30×10-86. And the Q factor of the encrypted output is larger than 21.51. It is verified that this all-optical encryption scheme can achieve encrypting operation for multi-wave input signals within 400 nm by theoretic analyzing and simulative experiment. Moreover, when the wavelegth range of multi-wave signal is small than 78 nm, the operation of all-optical enctyption can improve the extinction ratio of input signals. Theoretic analyzing and simulative experiment comfirm the feasibility and effectiveness of this multi-wave all-optical encryption system.Accession Number: 20135117103916 -
Record 411 of
Title:Accurate measurement of the jitter time of GaAs photoconductive semiconductor switches triggered by a one-to-two optical fiber
Author(s):Shi, Wei(1,2); Zhang, Lin(1); Gui, Huaimeng(1); Hou, Lei(1); Xu, Ming(1); Qu, Guanghui(1)Source: Applied Physics Letters Volume: 102 Issue: 15 DOI: 10.1063/1.4802755 Published: April 15, 2013Abstract:An improved method is proposed to measure the jitter time of the photoconductive semiconductor switches (PCSSs). A one-to-two fiber is utilized to separate and guide the 1053 nm laser beam to trigger two identical 3-mm-gap GaAs PCSSs synchronously. The jitter time is derived from the time lags of two switches turn-on by the error transfer theory. At a bias voltage of 1 kV, the jitter time is measured as 14.41 ps, which is the lowest jitter of GaAs PCSS that has been reported so far. ? 2013 AIP Publishing LLC.Accession Number: 20131916320759 -
Record 412 of
Title:Spin Hall effect of the reflected and transmitted vector light beam between the interfaces
Author(s):Duan, Tao(1); Xie, Xiao-Ping(1,2); Duan, Jie(2); Qian, Feng-Chen(1,2); Yan, Shao-Hui(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 42 Issue: 5 DOI: 10.3788/gzxb20134205.0511 Published: May 2013Abstract:The finite electromagnetic vector is achieved by factorizing into a mapping matrix and a Jones vector. The vectorial property can be described by a degree of freedom of the mapping matrix that can be determined by the azimuthal angle of a fixed unit vector with respect to the wave vector. The representation formalism of the reflected and transmitted vector light beams is theoretically developed between the interfaces. The transverse shift, which is correlative with the spin Hall effect, is discussed. The transverse shift of the linearly polarized light beam (σ=0) is zero. The transverse shift of the circularly polarized light beam (σ=±1) is maximum and the left and right circularly polarized light beam is the same.The dependence of transverse shift of the left circularly polarized light beam on the incidence angle is algo analyzed.Accession Number: 20132516430750 -
Record 413 of
Title:Study on coherent dynamics of alkali metal atomic wave packets
Author(s):Zhu, Changjun(1); He, Junfang(2)Source: Key Engineering Materials Volume: 538 Issue: DOI: 10.4028/www.scientific.net/KEM.538.285 Published: 2013Abstract:A theoretical model consisting of 5 energy levels, with the three upper states coherently excited, was proposed to analyze the coherent characteristics of atomic wave packets using perturbative theory. Pump-probe technique was implemented to detect coupled difference frequency four-wave mixing processes for studying the coherent characteristics of Rb atomic wave packets. Quantum beats were extracted the time domain signal by Fourier transform. Moreover, the variation of quantum beats was gained by time-dependent Fourier transform. The results show that the coherent characteristics of alkali metal atomic wave packets are closely related to quantum beats embedded in the time delayed four-wave mixing signal. Theoretical results are consistent with experimental observations, possessing potential applications in multi-channel information encoding and decoding. ? (2013) Trans Tech Publications, Switzerland.Accession Number: 20130816035549 -
Record 414 of
Title:Study of multiple quantum beats in atomic wavepackets
Author(s):Zhu, Chang Jun(1); Xue, Bing(1); Zhai, Xue Jun(1); He, Jun Fang(2)Source: Applied Mechanics and Materials Volume: 327 Issue: DOI: 10.4028/www.scientific.net/AMM.325-326.119 Published: 2013Abstract:A theoretical model consisting of 5 energy levels in coupled four-wave mixing processes was proposed to analyze the coherent characteristics of atomic wavepackets using perturbative theory. The equations of motions of the density matrix were derived and the third-order density matrix elements were presented. Under the condition that the duration of laser pulses is sufficiently short, the system response was treated as impulse response. Moreover, in the lowest order perturbation theory, the third-order nonlinear polarization was obtained using rotating-wave approximation. The results show that multiple quantum beats are embedded in the coupled four-wave mixing signals, and coherent dynamics of wavepackets can be retrieved from the quantum beat dynamics. ? (2013) Trans Tech Publications, Switzerland.Accession Number: 20132716474492 -
Record 415 of
Title:Study of multiple quantum beats in atomic wavepackets
Author(s):Zhu, Chang Jun(1); Xue, Bing(1); Zhai, Xue Jun(1); He, Jun Fang(2)Source: Applied Mechanics and Materials Volume: 325-326 Issue: DOI: Published: 2013Abstract:A theoretical model consisting of 5 energy levels in coupled four-wave mixing processes was proposed to analyze the coherent characteristics of atomic wavepackets using perturbative theory. The equations of motions of the density matrix were derived and the third-order density matrix elements were presented. Under the condition that the duration of laser pulses is sufficiently short, the system response was treated as impulse response. Moreover, in the lowest order perturbation theory, the third-order nonlinear polarization was obtained using rotating-wave approximation. The results show that multiple quantum beats are embedded in the coupled four-wave mixing signals, and coherent dynamics of wavepackets can be retrieved from the quantum beat dynamics. ? (2013) Trans Tech Publications, Switzerland.Accession Number: 20132916506343 -
Record 416 of
Title:Femtosecond-laser-written waveguide in magneto-optical glass
Author(s):Hou, Fang(1,2); Li, Weinan(2); Bai, Jing(2); Zhou, Kaiming(2); Long, Xuewen(2); Hui, Rongqing(2); Zhang, Xiaolin(1); Cheng, Guanghua(2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 33 Issue: 3 DOI: 10.3788/AOS201333.0314002 Published: March 2013Abstract:Femtosecond-laser-induced refractive index modification has provided a flexible tool to fabricate three-dimensional photonic devices. Magneto-optical (MO) glass is widely used in integrated optics because of its Faraday rotation. Femtosecond laser at 1 kHz repetion rate is used to write waveguides in MO glass, then near-field modes of waveguides written by different focusing parameters are measured, and the refractive index changes in the written regions and mode field diameters as functions of writing parameters (scanning speed and writing power) are obtained, which show a writing window of waveguide formation in MO glass. Experimental results show that the Verdet constant in the written region only has a slight reduction (about 2.8%) under a special writing parameter set (10×, objective scanning speed 40 μm/s, laser power 3 mW); the loss of the waveguide is 1.53 dB/cm, and its mode field diameter is 10 μm injected by 980 nm, so it is practicable to couple light from fiber into waveguide written by femtosecond laser.Accession Number: 20131516200059 -
Record 417 of
Title:Thermal crosstalk of high-power diode laser array
Author(s):Zhang, Zhiyong(1); Zhang, Pu(1); Nie, Zhiqiang(1); Li, Xiaoning(1); Xiong, Lingling(1); Liu, Hui(1); Wang, Zhenfu(1); Liu, Xingsheng(1,2)Source: Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams Volume: 25 Issue: 8 DOI: 10.3788/HPLPB20132508.1904 Published: August 2013Abstract:A three-dimensional thermal model is established for a hard solder packaged, conduction-cooled diode laser array, which contains 19 emitters, its fill factor is 30%, and the width of emitting area is 150 μm. The thermal crosstalk among emitters in the diode laser array has been studied systematically. It is found that there is an obvious thermal crosstalk among the emitters in the diode laser array after the device is operated for more than 1.2 ms in continuous wave mode. While the sub-mount material changes from copper-tungsten alloy to copper-diamond composites, the thermal resistance of each emitter and the interactive thermal resistance among adjacent emitters in the diode laser array decrease obviously. It is shown that this package structure design can reduce the thermal crosstalk behavior of the emitters effectively. The effect of the emitter size and pitch on the thermal characteristics of device is analyzed while the output power of the device, the number of the emitters, the cycle of the emitters and the width of the diode laser array are kept constant. The results show that both the thermal resistance of device and the thermal resistance of each emitter decrease exponentially with the increasing of the fill factor of the diode laser array, but the thermal crosstalk characteristics among emitters are not sensitive to the emitter size and pitch. On the other hand, keeping the output power of each single emitter, the emitter size and pitch, and the width of diode laser array constant, the thermal crosstalk behavior of the emitters is heavily influenced by the number of the emitters in diode laser array. Specifically, the higher the fill factor is, the more quickly the temperature of diode laser array rises. But during the first 70 μs, the highest temperature difference among these devices containing different number of emitters is about 0.5°C, it is benefited to the high-power output of device having high fill factor in this period. This research is significant to the design of the structure of diode laser array, especially to the optimization of the fill factor, the emitter size and pitch of diode laser arrays. More importantly, it also presents necessary references for the package structure design of diode laser array.Accession Number: 20133416646616 -
Record 418 of
Title:Pulse contrast measurement of femtosecond lasers using chalcohalide glass
Author(s):Wu, Dengke(1); He, Junfang(1); Guo, Haitao(1); Zhu, Changjun(2); Wang, Yishan(1); Zhao, Wei(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8796 Issue: DOI: 10.1117/12.2011984 Published: 2013Abstract:A chalcogenide glass was used for an optical Kerr gate to sampling pulse contrast of femtosecond lasers with low repetition rate ( 40 Hz). The dynamic range of this method reached 103, with a scanning range of 150ps and temporal sampling rate of 6.3 fs. The advantage of this method lies in its broad spectrum range including visible and NIR spectral region and easy operation. ? 2013 SPIE.Accession Number: 20133216576183 -
Record 419 of
Title:Design of Topas porous fiber for low-loss Terahertz wave guiding
Author(s):Wang, Doudou(1); Wang, Lili(2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 42 Issue: 9 DOI: Published: September 2013Abstract:A kind of porous fiber for low-loss Terahertz wave guiding was designed based on Topas cyclic olefin copolymer (Topas COC). Topas COC is a kind of novel Terahertz low-loss material. Terahertz wave was well confined in a series of subwavelength air holes, which were arranged in base material with triangular lattice. Propagation properties of the designed porous fiber were investigated by using the full-vector finite element method. The results indicated that the designed Topas porous fiber had low loss and low dispersion properties within Terahertz frequency. The loss was less than 0.2 cm-1 from 0.4 THz to 1.5 THz, and the dispersion was 1.8±0.3 ps/THz/cm within 0.48-1.5 THz. The designed fiber structure was relatively simple and feasible for fabrication. It can be fabricated by the thermo-drawing techniques of polymer preforms invented by our group. The results provided theoretical references for fabrication of Topas Terahertz low-loss and flexible fiber waveguides.Accession Number: 20134817040190 -
Record 420 of
Title:Rainbow trapping of surface plasmon polariton waves in metal-insulator- metal graded grating waveguide
Author(s):Zeng, Chao(1); Cui, Yudong(1)Source: Optics Communications Volume: 290 Issue: DOI: 10.1016/j.optcom.2012.10.020 Published: March 1, 2013Abstract:A new metal-insulator-metal (MIM) graded grating waveguide, based on surface plasmon polaritons (SPPs), is proposed and numerically investigated to realize the rainbow trapping of SPP waves. We find that the localized positions of SPP waves depend on the frequencies of the incident light. The theoretical results show that the trapping time of SPP waves can be up to 83.4 fs and the proposed compact configuration can be operated in a broad bandwidth of 90 THz. Our MIM graded grating waveguide may find significant applications on plasmonic slow-light systems, especially chip-based optical buffers and spectrometers. ? 2012 Elsevier B.V. All rights reserved.Accession Number: 20124915769362