2013

• Record 445 of
  
  Title:Intersubband optical absorption of semiconductor quantum wells driven by in-plane terahertz field
  
  Author(s):Zhu, Haiyan(1); Luo, Wenfeng(1); Li, Xiaoli(1); Zhang, Tongyi(2)
  Source: Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams  Volume: 25  Issue: 6  DOI: 10.3788/HPLPB20132506.1460  Published: June 2013  
  Abstract:The intersubband optical absorption of a semiconductor quantum well driven by an in-plane terahertz electric field is investigated theoretically by employing the extended semiconductor Bloch equations. Our results show that in-plane polarized terahertz fields induce a variety of behavior in the absorption spectra, including terahertz replicas of the main absorption peak and the dynamical Franz-Keldysh effect. The dependence of the absorption of the probe field on frequency and phase of the terahertz field is also very remarkable.
  Accession Number: 20132516429446
• Record 446 of
  
  Title:Influence of three-photon absorption on mid-infrared cross-phase modulation in silicon-on-sapphire waveguides
  
  Author(s):Wang, Zhaolu(1); Liu, Hongjun(1); Huang, Nan(1); Sun, Qibing(1); Wen, Jin(1); Li, Xuefeng(2)
  Source: Optics Express  Volume: 21  Issue: 2  DOI: 10.1364/OE.21.001840  Published: January 28, 2013  
  Abstract:The influence of three-photon absorption (3PA) on cross-phase modulation (XPM) effect in the mid-infrared (IR) region is theoretically investigated in silicon-on-sapphire (SOS) waveguides. It is found that the 3PA-induced nonlinear losses in the SOS waveguide will be considerable for the pulse propagation in the wavelength region of 2300 nm-3300 nm when the pump peak intensity is high enough. For the XPM process, the 3PA and 3PA-induced free-carrier effects can affect the spectrum and temporal profiles of the pump and signal pulses for sufficiently high pump peak intensities. Moreover, the XPM-induced frequency shift of signal spectrum is also discussed with different pump peak intensities, and the XPM-induced blue and red shifts are reduced due to 3PA. © 2013 Optical Society of America.
  Accession Number: 20130916050723
• Record 447 of
  
  Title:Graphene and nanotube mode-locked fiber laser emitting dissipative and conventional solitons
  
  Author(s):Cui, Yudong(1); Liu, Xueming(1)
  Source: Optics Express  Volume: 21  Issue: 16  DOI: 10.1364/OE.21.018969  Published: August 12, 2013  
  Abstract:We propose a bidirectional erbium-doped fiber laser modelocked with a mixture of graphene and single-walled carbon nanotubes for the first time to our best knowledge. The fiber laser can deliver dissipative soliton (DS) and conventional soliton (CS), circulating in opposite directions. The net-cavity dispersion is normal in the clockwise direction and anomalous in counter clockwise direction, respectively, and then DS and CS are generated with the suitable adjustment of attenuators. The output DS and CS approximately have the same central wavelength, but exhibit different optical spectra, pulse durations, and repetition rates. The all-fiber switchable laser can provide two different pulse sources, which is convenient for practical applications. © 2013 Optical Society of America.
  Accession Number: 20133416639631
• Record 448 of
  
  Title:Theoretical and experimental study on nonintrusive light injection via cladding in plastic optical fibers
  
  Author(s):Lin, Xiao(1); Ren, Liyong(1); Qu, Enshi(1); Liang, Jian(1); Ju, Haijuan(1)
  Source: Journal of Lightwave Technology  Volume: 31  Issue: 3  DOI: 10.1109/JLT.2012.2230434  Published: 2013  
  Abstract:Based on the fiber macrobending and the refractive index matching technologies, a novel scheme of nonintrusive light injection, namely, the light signal is injected into the fiber core from the fiber cladding without any destruction, is proposed in plastic optical fibers (POFs). Using the ray-tracing method, a 3-D theoretical model is established to characterize the performance of the light injection. The influences of the fiber bending radius, the light source placement, and the surrounding medium refractive index on the light injection efficiency are investigated and assessed. Meanwhile, correlative experiments have also been conducted to contrast theoretical simulations. The experiment results fit theoretical ones well. This nonintrusive light injection technology in POFs might have many potential applications such as the optical signal uploading and downloading, the optical coupling, and the local area networks. © 2012 IEEE.
  Accession Number: 20130215898323
• Record 449 of
  
  Title:A sub-nanosecond narrow-linewidth pulsed laser source with controllable repetition rate
  
  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: 7  DOI: 10.1088/1054-660X/23/7/075101  Published: July 2013  
  Abstract:A compact all-fiber sub-nanosecond narrow-linewidth Yb-doped fiber amplifier with a controllable repetition rate has been investigated. Tunable temporal pulses ranging from sub-nanoseconds to 10 ns with repetition rates from 10 kHz to 1 MHz are obtained by controlling the waveform of the injected electrical-pulse signal. Due to the practical requirements of our intended applications, a distributed feedback semiconductor laser with a wavelength of 1064 nm, pulse duration of 802 ps, repetition rate of 500 kHz and average power of 20 μW is used to seed a dual-stage single mode Yb-doped fiber amplifier. The characteristics of the amplified pulses are measured and exhibit a temporal duration of 810 ps with an average power of 31.2 mW. The gain of the amplified pulse is about 32 dB at the maximum output power. A notable feature of the amplifier pulses is that the spectral linewidth can be maintained to less than 0.1 nm during the dual-stage amplifier process. The noise level lies more than 22 dB below the peak value of the amplified spectrum, which represents an excellent signal-to-noise ratio. © 2013 Astro Ltd.
  Accession Number: 20132516432278
• Record 450 of
  
  Title:Design, fabrication and characteristics of cyclic olefin copolymers lens for terahertz application
  
  Author(s):Ji, Jiangjun(1); Fan, Wenhui(1); Kong, Depeng(1); Wang, Lili(1)
  Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering  Volume: 42  Issue: 5  DOI:   Published: May 2013  
  Abstract:The refractive index and absorption features of a novel polymer-cyclic olefin copolymers(trade names Topas COC) were studied in 0.1-3 THz band. With SolidWorks software, a common double-convex spherical lens of 100 mm focal length with effective aperture of 1.75 inches was designed, and then a set of mold for manufacturing the lens was designed. By hot compression molding, the Topas COC terahertz lens was fabricated, and the effects of heating temperature and time on the lens surface morphology was analyzed. The effects of the wavelength, thickness, radius of curvature and refractive index on focal length of the lens in the terahertz wavelength of 150 μm, 300 μm and 600 μm was simulated and analyzed by using Zemax software. Studies have shown that the lens made by this method has surface smooth, high accuracy and defect-free structure, so the performance is very superior and meets linear and compact requirements of the terahertz system, and plays the role of collimating and focusing in the visible region and terahertz band.
  Accession Number: 20132816483983
• Record 451 of
  
  Title:Slow light engineering in periodic-stub-assisted plasmonic waveguide
  
  Author(s):Wang, Guoxi(1)
  Source: Applied Optics  Volume: 52  Issue: 9  DOI: 10.1364/AO.52.001799  Published: March 20, 2013  
  Abstract:We investigate the slow light engineering in periodic-stub-assisted plasmonic waveguide based on transmission line theory. It is found that the dispersion relationship of the proposed waveguide can be easily modified by tuning the stub depth and the period. The theoretical results show that a large normalized delay bandwidth product of 0.65 can be achieved at 1550nm, meanwhile maintaining the group index of 35. In addition, the proposed waveguide shows 'S-shaped' dispersion curve, which implies that the group velocity dispersion parameter at the inflection point equals zero and a dispersion-free slow light waveguide can be realized. Due to the excellent buffering capacity, the proposed compact configuration can find important applications on optical buffers in highly integrated optical circuits. © 2013 Optical Society of America.
  Accession Number: 20131416181500
• Record 452 of
  
  Title:Stability-improved slow light in polarization-maintaining fiber based on polarization-managed stimulated Brillouin scattering
  
  Author(s):Ju, Haijuan(1); Ren, Liyong(1); Liang, Jian(1); Ma, Chengju(1)
  Source: Journal of Optics (United Kingdom)  Volume: 15  Issue: 3  DOI: 10.1088/2040-8978/15/3/035404  Published: March 2013  
  Abstract:With the idea of controlling the polarizations of the pump and Stokes beams in an optical fiber, a simple scheme is presented for enhancing the stability of the stimulated Brillouin scattering (SBS) interaction and thus that of the SBS-based slow light. For this purpose, a special slow-light element is constructed by fusing a polarization-maintaining circulator (its fast axis being blocked) to each terminal of the polarization-maintaining fiber (PMF). This configuration ensures that the pump and Stokes beams always have identical polarization in the whole fiber during the SBS interaction. An experimental setup is established accordingly. The SBS gain feature and the slow-light performance are studied. A tunable time delay with a slope of 0.82 ns dB -1 is demonstrated for a Gaussian pulse with a width of 88.9 ns. The experimental results with and without polarization management are compared. It is found that such a polarization-managed scheme can improve both the stability of the Brillouin gain and that of the time delay of the Stokes pulse. Moreover, for the same pump power, the Brillouin gain is also enhanced. © 2013 IOP Publishing Ltd.
  Accession Number: 20131116111757
• Record 453 of
  
  Title:Theoretical analysis of the Ho:YAG laser threshold characteristics
  
  Author(s):Wang, Fei(1); Shen, De-Yuan(1); Wang, Yi-Shan(1); Zhou, Wei(1); Ma, He-Feng(1)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 42  Issue: 10  DOI: 10.3788/gzxb20134210.1158  Published: October 2013  
  Abstract:Based on the theory of quasi-three-level, a model of threshold pump power of Ho:YAG laser was built and the formula of threshold pump power of Ho laser was derived. The relationship between the threshold pump power and the absorption efficiency of gain medium or the transmission of output coupler was analyzed. The mW-level threshold pump power of Ho laser can be obtained by optimizing parameters of Ho laser, which was pumped at 1907 nm or wing-pumped at 1930 nm. Furthermore, center wavelength lasing at 2092 nm or 2124 nm should be achievable by choosing an output coupler of suitable transmission.
  Accession Number: 20135117103914
• Record 454 of
  
  Title:Wide-range continuously-tunable slow-light delay line based on stimulated brillouin scattering
  
  Author(s):Ju, Haijuan(1); Ren, Liyong(1); Lin, Xiao(1); Liang, Jian(1); Ma, Chengju(1)
  Source: IEEE Photonics Technology Letters  Volume: 25  Issue: 19  DOI: 10.1109/LPT.2013.2278536  Published: 2013  
  Abstract:Through selectively controlling the stimulated Brillouin scattering in optical fibers with different lengths, a continuously tunable time-delay scheme enabling to work in a large range is proposed in this letter. This is realized by connecting a fixed long single-mode fiber (SMF) to one of the several selectable short SMFs that successively have an equal increment in length. These short-length fibers are, respectively, fixed to the different channels between two identical optical switches. Therefore, a wide-range and continuously tunable slow-light delay line can be constructed by changing the power of the pump beam, assisted by switching to different channels. In the experiment, a time delay from 0 to 201.29 ns is demonstrated for a five-channel configuration. A further large-range time delay can be expected if one adds the number of channels accordingly. © 2013 IEEE.
  Accession Number: 20134016793882
• Record 455 of
  
  Title:Engineering of phase matching for mid-infrared coherent anti-Stokes Raman wavelength conversion with orthogonally polarized pump and Stokes waves in silicon-on-sapphire waveguides
  
  Author(s):Wang, Zhaolu(1); Liu, Hongjun(1); Huang, Nan(1); Sun, Qibing(1); Li, Xuefeng(2)
  Source: Applied Optics  Volume: 52  Issue: 33  DOI: 10.1364/AO.52.008095  Published: November 20, 2013  
  Abstract:The conversion efficiency of mid-infrared wavelength conversion based on coherent anti-Stokes Raman scattering with TE-polarized pump and TM-polarized Stokes waves is theoretically investigated in silicon-on-sapphire (SOS) waveguides. The peak conversion efficiency of -10 dB is obtained when the linear propagation loss is 1 dB/cm at δk = 0; however, it is reduced to -13.6 dB when the linear propagation loss is 2 dB/cm. The phase matching for wavelength conversion with orthogonally polarized pump and Stokes waves can be realized by engineering the birefringence in SOS waveguides, because proper phase mismatch induced by birefringence together with material dispersion-induced phase mismatch can counteract the large phase mismatch induced by waveguide dispersion. Moreover, compared with the phase matching for identically polarized pump and Stokes waves, the phase matching for orthogonally polarized pump and Stokes waves can be realized in a SOS waveguide with much smaller cross section, which reduces the power requirement for optical systems. © 2013 Optical Society of America.
  Accession Number: 20135017079644
• Record 456 of
  
  Title:Robust visual tracking with discriminative sparse learning
  
  Author(s):Lu, Xiaoqiang(1); Yuan, Yuan(1); Yan, Pingkun(1)
  Source: Pattern Recognition  Volume: 46  Issue: 7  DOI: 10.1016/j.patcog.2012.11.016  Published: July 2013  
  Abstract:Recently, sparse representation in the task of visual tracking has been obtained increasing attention and many algorithms are proposed based on it. In these algorithms for visual tracking, each candidate target is sparsely represented by a set of target templates. However, these algorithms fail to consider the structural information of the space of the target templates, i.e., target template set. In this paper, we propose an algorithm named non-local self-similarity (NLSS) based sparse coding algorithm (NLSSC) to learn the sparse representations, which considers the geometrical structure of the set of target candidates. By using non-local self-similarity (NLSS) as a smooth operator, the proposed method can turn the tracking into sparse representations problems, in which the information of the set of target candidates is exploited. Extensive experimental results on visual tracking have demonstrated the effectiveness of the proposed algorithm. © 2013 Elsevier Ltd. All rights reserved.
  Accession Number: 20131316148899