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Record 421 of
Title:A nonuniform-polarization high-energy ultra-broadband laser with a long erbium-doped fiber
Author(s):Mao, Dong(1)
Source: Laser Physics Volume: 23 Issue: 3 DOI: 10.1088/1054-660X/23/3/035104 Published: March 2013
Abstract:We have experimentally investigated nonuniformly polarized broadband high-energy pulses delivered from a mode-locked laser with an ultra-long erbium-doped fiber (EDF). The pulses exhibit a broadband spectrum of ～73 nm and can avoid optical wave breaking at high-pump regimes. The polarization states of the pulses evolve from uniform to nonuniform at each round trip in the oscillator, which is distinct from other pulses. Remarkably, the output pulses broaden in anomalous- or normal-dispersion regimes while they can be shortened with an EDF amplifier external to the cavity. Our results suggest that the long EDF results in a nonuniform-polarization state and plays a decisive role in the formation of high-energy pulses. ? 2013 Astro Ltd.
Accession Number: 20132616444997
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Record 422 of
Title:Analysis of terahertz generation characteristic affected by injured photoconductive antenna
Author(s):Li, Hui(1); Fan, Wen-Hui(1); Liu, Jia(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8909 Issue: DOI: 10.1117/12.2033033 Published: 2013
Abstract:In this paper, we deployed a home-made THz time-domain system and experimentally investigated the influence of impairment on photoconductive antenna. The low temperature grown GaAs photoconductive antenna (PCA) was used as THz emitter and a ?110? ZnTe crystal modulating the probe beam to detect the THz field based on electro-optic sampling. By adjusting the position of laser spot on PCA gap, we found that the generated THz signal was quite different as the laser beam irradiating on different position of the antenna's gap. Moreover, we found that the small burned holes on the edge of both metal electrodes may affect the electric field of the antenna. Furthermore, we simulated the electric field of the PCA with a DC biased voltage applied across the electrodes, and found that the simulation results agreed with the experimental phenomenon, which can well demonstrated that the impairments on the antenna electrodes have a great influence on THz generation. ? 2013 Copyright SPIE.
Accession Number: 20141317501217
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Record 423 of
Title:Low-distortion plasmonic slow-light system at telecommunication regime
Author(s):Zeng, Chao(1); Cui, Yudong(1)
Source: Optics Communications Volume: 294 Issue: DOI: 10.1016/j.optcom.2012.12.037 Published: May 1, 2013
Abstract:On the basis of an analog of electromagnetically induced transparency (EIT), a metal-insulator-metal (MIM) plasmonic waveguide that has the capacity of realizing slow light with low distortion is proposed and investigated numerically. The transmission line results show that a quite flat dispersion curve with nearly constant group index over a broad bandwidth of 29.64 nm can be achieved by appropriately altering the grating depths. It is found that the group velocity dispersion (GVD) parameter of the proposed structure can approach zero. By means of Finite-Difference Time-Domain (FDTD) simulations, we find that the incident pulse centered at telecommunication regime (i.e., 1550 nm) could be dramatically slowed down with only 2.1% distortion due to the low dispersion. The proposed plasmonic slow-light system may find potential applications for optical buffers and all-optical signal processors in future highly integrated circuits. ? 2012 Elsevier B.V.
Accession Number: 20131416178329
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Record 424 of
Title:Numerical analysis of large mode area segmented cladding fibers
Author(s):Shao, Hongmin(1); Duan, Kailiang(1); Zhu, Yonggang(1); Yang, Hening(1)
Source: Proceedings - 2013 Wireless and Optical Communications Conference, WOCC 2013 Volume: Issue: DOI: 10.1109/WOCC.2013.6676417 Published: 2013
Abstract:We analyze numerically the dependence of segmented cladding fibers (SCF) characters, including the effective V-number, the effective fundamental mode area and the permissible bending radius of fundamental mode, on the structure parameters of the fiber and the signal wavelength with the methods of radial effective index and transmission matrix. The results show that a single mode and large mode area fiber with an acceptable permissible bending radius can be obtained when we design SCF with optimized structure parameters. The effective fundamental area is as large as 1948.93μm2 with proper fiber parameters. It will benefit the fabrication of the SCF for applications in high power fiber lasers. ? 2013 IEEE.
Accession Number: 20140717299194
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Record 425 of
Title:Observations of bound states of two and three dissipative solitons in a figure-eight laser in a normal dispersion regime
Author(s):Yun, Ling(1)
Source: Laser Physics Volume: 23 Issue: 4 DOI: 10.1088/1054-660X/23/4/045106 Published: April 2013
Abstract:Dissipative bound-state solitons exhibiting a trapezoid spectral profile and a regular modulation pattern are observed experimentally in a figure-eight fiber laser with large normal cavity dispersion for the first time, to the best of the author's knowledge. The soliton pairs have a pulse duration T0 of about 800 fs and a peak-to-peak separation of about 8T0. With the appropriate increase of the pumping strength, the proposed laser generates a bound state of three solitons with a pulse duration T0 of about 460 fs and a separation between adjacent pulses of about 15T0. Experimental results show that the bound-state solitons are strongly stable and suggest that they are formed by direct soliton interaction. ? 2013 Astro Ltd.
Accession Number: 20132616444962
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Record 426 of
Title:Investigation of various fabrics in terahertz time-domain spectroscopy
Author(s):Liu, Jia(1); Fan, Wenhui(1)
Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 42 Issue: 6 DOI: Published: June 2013
Abstract:The spectral properties of various fabrics were investigated by using terahertz time-domain spectroscopy. Through measuring the time-domain spectra in experiments and calculating frequency- domain spectra by applying the fast Fourier-transform (FFT) to each pulse waveform, the spectral information of fabrics in terahertz region, especially the transmission and absorbance, was obtained and analyzed. It is well demonstrated that the fabrics, which are opaque in visible light, are almost transparent in terahertz region and no special absorption spectra. This research has a great influence on identifying the concealed danger and terahertz imaging.
Accession Number: 20133216587675
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Record 427 of
Title:Design and characteristics of cycloolefin copolymer porous terahertz fiber
Author(s):Ma, Tian(1); Kong, Depeng(1); Ji, Jiangjun(1); Wang, Guangzhen(1); Wang, Lili(1)
Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 42 Issue: 3 DOI: Published: March 2013
Abstract:Terahertz fiber is one of the essential components in the terahertz system. In order to realize minimum low loss and dispersion of terahertz transmittion, a novel hollow terahertz fiber was designed and optimizated, which was based on Topas COC. Using the commercial software COMSOL based on the full-vector finite element method, the transmitting characters of this hollow terahertz fiber were calculated and the effects of the structural parameters on transmitting THz wave in the porous fiber core were analyzed. The research shows that adopting designed porous structure can confine the mode energy in porous core, and obtain small mode area, low propagation loss and nearly zero ultra-flattened dispersion. Increasing rate of the hole diameter to the hole spacing, the more mode energy can be confined in the porous fiber core, and the effective mode area and effective mode loss were reduced, but the confine loss and dispersion would be enlarged simultaneously.
Accession Number: 20132616448350
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Record 428 of
Title:Optical bistability in subwavelength compound metallic grating
Author(s):Lu, H.(1); Liu, X.M.(1)
Source: Optics Express Volume: 21 Issue: 11 DOI: 10.1364/OE.21.013794 Published: June 3, 2013
Abstract:We have investigated the optical bistability behavior based on an electromagnetically induced reflection (EIR) effect in a compound metallic grating consisting of subwavelength slits and Kerr nonlinear nanocavities embedded in a metallic film. The theoretical and simulation results show that a narrow peak in the broad reflection dip possesses a red-shift with increasing the refractive index of coupled nanocavities. Importantly, we have obtained an obvious optical bistability with threshold intensity about ten times lower than that of metallic grating coated by nonlinear material. The results indicate that our structure may find excellent applications for nonlinear plasmonic devices, especially optical switches and modulators. ? 2013 Optical Society of America.
Accession Number: 20132516425823
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Record 429 of
Title:Nondestructive scheme for measuring the attenuation coefficient of polymer optical fiber
Author(s):Lin, Xiao(1); Ren, Liyong(1); Liang, Jian(1)
Source: Optics Letters Volume: 38 Issue: 4 DOI: 10.1364/OL.38.000528 Published: February 15, 2013
Abstract:Based on the fiber macrobending and the refractive index matching technologies, a measurement scheme is proposed to gauge the attenuation coefficient of polymer optical fibers in this Letter. It is noteworthy that, by realizing both the light injecting into and the light extracting out the fiber core via the fiber cladding, this scheme will not induce any destruction during the whole measurement. Some related experiments and the theoretical verifications are given together with the nondestructive measurement principle. The comparison between the experimental results of this scheme and that of the cut-back scheme indicates a good feasibility of our scheme. As a result, it is promised to have a potential application for achieving the on-line attenuation monitoring that has never been introduced. ? 2013 Optical Society of America.
Accession Number: 20130916050933
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Record 430 of
Title:Next generation of space wireless communication technology based on X-ray
Author(s):Zhao, Bao-Sheng(1); Wu, Chuan-Xing(1); Sheng, Li-Zhi(1); Liu, Yong-An(1)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 42 Issue: 7 DOI: 10.3788/gzxb20134207.0801 Published: July 2013
Abstract:In the field of space wireless communication, laser and microwave technology have become mature, but bottleneck problems such as the limited transmission distance, the limited communication rate and so on already exist, which restrict the future applications in deep space. As a result of its short wavelength and great penetrability, X-ray has no attenuation for transmission in space when its photon energy is more than 10 keV (λ
Accession Number: 20133416646439
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Record 431 of
Title:High-temperature solar cell for concentrated solar-power hybrid systems
Author(s):Yang, Yang(1); Yang, Wenzheng(1); Tang, Weidong(1); Sun, Chuandong(1)
Source: Applied Physics Letters Volume: 103 Issue: 8 DOI: 10.1063/1.4819201 Published: August 19, 2013
Abstract:A high-temperature solar cell is proposed that harvests solar energy at elevated temperatures. Carrier separation is achieved by selective contacts that preferentially extract electrons or holes. The theoretical conversion efficiency of the proposed device is 38.6% at 600 K and an incident solar radiation concentration of 1000. The waste heat of this cell could be used by a secondary thermal converter boosting the total efficiency of the hybrid system above 55%. ? 2013 AIP Publishing LLC.
Accession Number: 20133716717843
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Record 432 of
Title:Coexistence and evolution of bright pulses and dark solitons in a fiber laser
Author(s):Wang, Leiran(1)
Source: Optics Communications Volume: 297 Issue: DOI: 10.1016/j.optcom.2013.02.009 Published: June 15, 2013
Abstract:Bright pulses and dark solitons coexisting and evolving in a fiber laser with strong normal dispersion have been observed. Experimental results show that there exists a transitional pulse regime with the pulse duty cycle of ～0.5 that connects the bright pulse and dark soliton regimes. On adjusting polarization states and pump power, the duty cycle of pulses varies so that the laser emits bright, transitional, and dark pulses alternately. It is found that dark solitons are composed of two antiphase square pulses with very large durations and duty cycles. The experimental observations reveal that the bright and dark solitons are not completely isolated from each other. This work could provide a new perspective to the understanding of bright and dark soliton formations as well as their transformations. ? 2013 Elsevier B.V.
Accession Number: 20131616218954
