2012
2012
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Record 361 of
Title:Observation of pulse trapping in a near-zero dispersion regime
Author(s):Mao, Dong(1); Liu, Xueming(1); Lu, Hua(1)Source: Optics Letters Volume: 37 Issue: 13 DOI: 10.1364/OL.37.002619 Published: July 1, 2012Abstract:We report pulse trapping in passively mode-locked fiber lasers operating in a near-zero dispersion regime. Two polarization components of vector pulses have different central wavelengths while copropagating as a unit in fiber lasers. The vector pulses exhibit smooth Gaussian spectral profile without any sidebands, qualitatively distinct from those observed in net-anomalous and net-normal fiber lasers. Numerical simulations suggest that the pulse trapping depends not only on fiber birefringence and cavity dispersion but also on saturable absorption effect. The experimental observations are in good agreement with the numerical simulations. ? 2012 Optical Society of America.Accession Number: 20122915253146 -
Record 362 of
Title:Numerical simulation of the energy distribution characteristics in the far-field of the single-mode annular core optical fibers
Author(s):Hui, Xiangyun(1); Duan, Kailiang(1)Source: 2012 2nd International Conference on Consumer Electronics, Communications and Networks, CECNet 2012 - Proceedings Volume: Issue: DOI: 10.1109/CECNet.2012.6201496 Published: 2012Abstract:The far-field intensity distribution characteristics of fundamental mode of the annular core optical fibers (ACF) are calculated theoretically based on the weak waveguide approximation in this paper. The simulation results demonstrate that provided the parameters of the ACF are designed properly, the ACF can realize single-mode operation. Besides, the beam will concentrate to the principal maximum position to form a central bright spot indicating great enhancement for the energy focusability of beam, which is valuable for the energy-demand applications in the far-field. These theoretical results possess great significance in designing and manufacturing ACF. ? 2012 IEEE.Accession Number: 20122415104037 -
Record 363 of
Title:Impact of phase noise on coherent BPSK homodyne systems in long-haul optical fiber communications
Author(s):Yu, Gang(1); Xie, Xiaoping(1); Zhao, Wei(1); Wang, Wei(1); Yan, Shuangyi(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8331 Issue: DOI: 10.1117/12.915964 Published: 2012Abstract:The impact of phase noise induced by amplified spontaneous emission and nonlinear Kerr effect is analyzed in investigating the performance of BPSK homodyne systems based OPLL in long-haul optical fiber communications. Under the Gaussian probability density function assumption the equivalent power spectral density of linear and nonlinear phase noise are determined, respectively. Using the power spectral density function the expressions of phase error variance taking into account linear phase noise, nonlinear phase noise and shot noise of corresponding photodiodes are determined. The impact of the number of amplifiers, bit rate and signal power on the phase error variance is analyzed. Using the minimum phase error variance and corresponding BER expression the receiver sensitivity and BER curves are given, respectively. Under the required BER, it is shown that there is a limitation on the maximum transmission distance of the BPSK homodyne system based OPLL. The theory expressions and numerical results obtained in this paper are helpful for designing OPLL and evaluating the impact of phase noise on the receivers based OPLL in long-haul optical fiber communications. ? 2012 SPIE.Accession Number: 20121915010561 -
Record 364 of
Title:Trapping of surface plasmon waves in graded grating waveguide system
Author(s):Wang, Guoxi(1); Lu, Hua(1); Liu, Xueming(1)Source: Applied Physics Letters Volume: 101 Issue: 1 DOI: 10.1063/1.4733477 Published: July 2, 2012Abstract:We have proposed a graded grating plasmonic system with a significant slow-light effect for the propagation of high-confinement surface plasmon (SP) wave. Theoretical analysis and numerical simulations show that the localized position of SP wave in the plasmonic waveguide is dependent on the operating frequency. It is found that the slow-light effect exhibits an obvious enhancement with propagation. The proposed ultracompact configuration offers the advantage of a large trapping bandwidth of 90 THz, which may find excellent applications on slow-light systems, especially optical buffers. ? 2012 American Institute of Physics.Accession Number: 20122915253509 -
Record 365 of
Title:Intelligent streak camera with OLED display
Author(s):Zhang, Wenwen(1,2); Bai, Yonglin(1); Ouyang, Xian(1); Liu, Baiyu(1); Hou, Xun(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 41 Issue: 2 DOI: Published: February 2012Abstract:In order to make the streak camera more effective in some special circumstances, an intelligent UV picoseconds streak camera was designed, which was based on embedded computer PC-104, microcontroller 8051, and organic light emitting display (OLED). The streak camera control system was composed of digital control multiplied sweep circuit, working condition set circuit, strobe circuit for the image intensifier and adjustable high voltage power supply circuit. These circuits were implemented by embedded PC-104 via many interfaces, such as input/output (I/O) interface, analogue to digital (A/D) and digital to analogue (D/A) controller. The camera system was superior to conventional streak cameras in automatically adjusting the parameters, remote operating and system diagnostics. The experimental results show that the control system is stable, time resolution is up to 100 ps, and sweep nonlinearity is less than 5%.Accession Number: 20121514940940 -
Record 366 of
Title:Tunable high-channel-count bandpass plasmonic filters based on an analogue of electromagnetically induced transparency
Author(s):Lu, Hua(1); Liu, Xueming(1); Wang, Guoxi(1); Mao, Dong(1)Source: Nanotechnology Volume: 23 Issue: 44 DOI: 10.1088/0957-4484/23/44/444003 Published: November 9, 2012Abstract:We have proposed a novel type of bandpass plasmonic filter consisting of metal-insulator-metal bus waveguides coupled with a series of side-coupled cavities and stub waveguides. The theoretical modeling demonstrates that our waveguide-resonator system performs a plasmonic analogue of electromagnetically induced transparency (EIT) in atomic systems, as is confirmed by numerical experiments. The plasmonic EIT-like response enables the realization of nanoscale bandpass filters with multiple channels. Additionally, the operating wavelengths and bandwidths of our filters can be efficiently tuned by adjusting the geometric parameters such as the lengths of stub waveguides and the coupling distances between the cavities and stub waveguides. The ultracompact configurations contribute to the achievement of wavelength division multiplexing systems for optical computing and communications in highly integrated optical circuits. ? 2012 IOP Publishing Ltd.Accession Number: 20124415613028 -
Record 367 of
Title:Efficient terahertz-wave generation via fourwave mixing in silicon membrane waveguides
Author(s):Wang, Zhaolu(1); Liu, Hongjun(1); Huang, Nan(1); Sun, Qibing(1); Wen, Jin(1)Source: Optics Express Volume: 20 Issue: 8 DOI: 10.1364/OE.20.008920 Published: April 9, 2012Abstract:Terahertz (THz) wave generation via four-wave mixing (FWM) in silicon membrane waveguides is theoretically investigated with midinfrared laser pulses. Compared with the conventional parametric amplification or wavelength conversion based on FWM in silicon waveguides, which needs a pump wavelength located in the anomalous group-velocity dispersion (GVD) regime to realize broad phase matching, the pump wavelength located in the normal GVD regime is required to realize collinear phase matching for the THz-wave generation via FWM. The pump wavelength and rib height of the silicon membrane waveguide can be tuned to obtain a broadband phase matching. Moreover, the conversion efficiency of the THz-wave generation is studied with different pump wavelengths and rib heights of the silicon membrane waveguides, and broadband THz-wave can be obtained with high efficiency exceeding 1%. ? 2012 Optical Society of America.Accession Number: 20121714971508 -
Record 368 of
Title:Geometry constrained sparse coding for single image super-resolution
Author(s):Lu, Xiaoqiang(1); Yuan, Haoliang(1); Yan, Pingkun(1); Yuan, Yuan(1); Li, Xuelong(1)Source: Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition Volume: Issue: DOI: 10.1109/CVPR.2012.6247858 Published: 2012Abstract:The choice of the over-complete dictionary that sparsely represents data is of prime importance for sparse coding-based image super-resolution. Sparse coding is a typical unsupervised learning method to generate an over-complete dictionary. However, most of the sparse coding methods for image super-resolution fail to simultaneously consider the geometrical structure of the dictionary and corresponding coefficients, which may result in noticeable super-resolution reconstruction artifacts. In this paper, a novel sparse coding method is proposed to preserve the geometrical structure of the dictionary and the sparse coefficients of the data. Moreover, the proposed method can preserve the incoherence of dictionary entries, which is critical for sparse representation. Inspired by the development on non-local self-similarity and manifold learning, the proposed sparse coding method can provide the sparse coefficients and learned dictionary from a new perspective, which have both reconstruction and discrimination properties to enhance the learning performance. Extensive experimental results on image super-resolution have demonstrated the effectiveness of the proposed method. ? 2012 IEEE.Accession Number: 20124015484282 -
Record 369 of
Title:Ultrabroadband flat dispersion tailoring of dualslot silicon waveguides
Author(s):Zhu, Ming(1); Liu, Hongjun(1); Li, Xuefeng(2); Huang, Nan(1); Sun, Qibing(1); Wen, Jin(1); Wang, Zhaolu(1)Source: Optics Express Volume: 20 Issue: 14 DOI: 10.1364/OE.20.015899 Published: July 2, 2012Abstract:We propose a new strip/slot hybrid waveguide with double slots, which exhibits a flat and low dispersion over a 1098-nm bandwidth with four zero-dispersion wavelengths. Dispersion of dual-slot silicon waveguide is mainly determined by mode transition from a strip mode to a slot mode rather than by material dispersion. Dispersion tailoring is investigated by tuning different structural parameters of waveguides. Moreover, nonlinear coefficient of dual-slot silicon waveguide and phase-matching condition in FWM are both explored in detail. The dual-slot waveguide can be used to generate supercontinuum with bandwidth extending up to 1630 nm pumped by femtosecond pulses. This waveguide will have a great potential for ultrabroadband signal processing applications from near-infrared region to mid-infrared region. ? 2012 Optical Society of America.Accession Number: 20122915258790 -
Record 370 of
Title:Optical sorting of particles by dual-channel line optical tweezers
Author(s):Ma, Baiheng(1,2); Yao, Baoli(1); Peng, Fei(1,2); Yan, Shaohui(1); Lei, Ming(1); Rupp, Romano(3)Source: Journal of Optics (United Kingdom) Volume: 14 Issue: 10 DOI: 10.1088/2040-8978/14/10/105702 Published: October 2012Abstract:A novel configuration of dual-channel line optical tweezers with a Y shape is constructed for sorting of particles within a microfluidic chip. When yeast cells with different size pass the intersection of the specially designed line optical tweezers, they are separated and transported to different channels due to a difference in the forces exerted by the line tweezers that depends on the size of the cells. The influences of some experimental conditions, such as laser power and flow velocity, on the sorting efficiency are discussed. ? 2012 IOP Publishing Ltd.Accession Number: 20124215565655 -
Record 371 of
Title:Generation of single-cycle mid-infrared pulses via coherent synthesis
Author(s):Ma, Fen(1); Liu, Hongjun(1); Huang, Nan(1); Sun, Qibing(1)Source: Optics Express Volume: 20 Issue: 27 DOI: 10.1364/OE.20.028455 Published: December 17, 2012Abstract:A new approach for the generation of single-cycle mid-infrared pulses without complicated control systems is proposed, which is based on direct coherent synthesis of two idlers generated by difference frequency generation (DFG) processes. It is found that the waveform of synthesized pulses is mainly determined by the spectra superposition, the carrierenvelope phase (CEP) difference, the relative timing and the chirp ratio between the idlers. The influences of these parameters on the synthesized waveform are also numerically calculated and analyzed via second-order autocorrelation, which offers general guidelines for the waveform optimization. The single-cycle synthesized mid-infrared pulses, which are centered at 4233 nm with the spectrum spanning from 3000 nm to 7000 nm, are achieved by carefully optimizing these parameters. The single-cycle mid-infrared laser source presents the possibility of investigating and controlling the strong field light-matter interaction. ? 2012 Optical Society of America.Accession Number: 20130215899113 -
Record 372 of
Title:Generation and propagation of bound-state pulses in a passively mode-locked figure-eight laser
Author(s):Yun, Ling(1); Liu, Xueming(1)Source: IEEE Photonics Journal Volume: 4 Issue: 2 DOI: 10.1109/JPHOT.2012.2191948 Published: 2012Abstract:We have investigated the generation and propagation of robust bound-state pulses emitted from a passively mode-locked figure-eight laser with net-anomalous dispersion. Two pulses with the pulse duration of ～1.3 ps and the separation of ～2.2 ps exhibit a strongly modulated spectral profile. The experimental observations show that the pulse duration and the separation increase approximately linearly along the extracavity single-mode fiber (SMF). The pulse duration and separation are broadened by a factor of ～7 and ～5.7, respectively, after the pulse pair propagates through the standard SMF of 202 m. The theoretical results well agree with the experimental observations. ? 2012 IEEE.Accession Number: 20121714965929