2015
2015
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Record 421 of
Title:Theoretical and experimental research of polarization insensitive optical wavelength convertor in a photonic crystal fiber
Author(s):Hu, Hui(1,2,3); Duan, Tao(1); Qian, Fengchen(1,2); Huang, Xinning(1,2); Su, Yulong(1,2,3); Wang, Wei(1,2); Han, Biao(1,2); Feng, Huan(1,2); Xie, Xiaoping(1)Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 42 Issue: DOI: 10.3788/CJL201542.s105002 Published: September 10, 2015Abstract:A single pump polarization-insensitive and widely tunable all-optical wavelength conversion for 10 Gbit/s non-return-to-zero (NRZ) signal is experimentally demonstrated by means of four-wave-mixing (FWM) in highly nonlinear photonic crystal fiber (PCF). The residual birefringence in the 50 m dispersion-flattened guarantees the FWM-based wavelength conversion to be polarization insensitive when the pump polarization is exactly at 45° to the birefringent axes of the PCF. Experimental results show that the polarization dependence of FWM in the PCF can be decreased to be less than 1 dB over 28 nm of wavelength tunable operation. The conversion efficiencies are better than -13 dB and the Q factor of idler signal is larger than 7 over the conversion range with signal polarization change. ? 2016, Chinese Lasers Press. All right reserved.Accession Number: 20161502223252 -
Record 422 of
Title:Passively Q-switched Nd:YAG laser with a MoS2 solution saturable absorber
Author(s):Lin, Tao(1); Sun, Hang(1); Wang, Xi(2); Mao, Dong(3); Wang, Yonggang(2); Li, Lu(2); Duan, Lina(2)Source: Laser Physics Volume: 25 Issue: 12 DOI: 10.1088/1054-660X/25/12/125805 Published: December 2015Abstract:This study presents a passively Q-switched Nd:YAG laser using a MoS2 solution as a saturable absorber. The prepared MoS2 solution saturable absorber features adjustable optical absorption, high heat dissipation, and non-contact damage. By inserting the MoS2 solution saturable absorber into a Z-type Nd:YAG laser cavity, a stable Q-switched laser with the maximum repetition rate of 20.8 KHz centered at 1064.24 nm was achieved, with the shortest pulse width at 2.8 μs. The results experimentally confirm the potential application of a MoS2 solution saturable absorber for high performance Q-switched solid-state lasers. ? 2015 Astro Ltd.Accession Number: 20154801610316 -
Record 423 of
Title:Linkage of Dual Frequency Combs Based on All Polarization-Maintaining Femtosecond Fiber Lasers
Author(s):Xu, Xin(1); Feng, Ye(1); Liu, Yuanshan(1); Hu, Xiaohong(1); Li, Feitao(1); Zhang, Ting(1); Zhang, Wei(1); Yang, Zhi(1); Cheng, Zhao(2); Zhao, Wei(1); Wang, Yishan(1)Source: IEEE Photonics Technology Letters Volume: 27 Issue: 23 DOI: 10.1109/LPT.2015.2462080 Published: December 1, 2015Abstract:Perfect linkage of dual frequency combs based on all polarization-maintaining femtosecond fiber lasers is demonstrated. By employing two independent tracking feedback controlling circuits, the repetition frequency (fr) and the carrier-envelope offset frequency (fceo) of the slave frequency comb track the master's fr and fceo , respectively. The correlation coefficients of the dual fr 's and the dual fceo 's are up to 0.99 and 0.98, which indicate an ideal linkage between the dual frequency combs. To the best of our knowledge, this is the first report about linkage of dual frequency combs. ? 2015 IEEE.Accession Number: 20154201394493 -
Record 424 of
Title:Reflector designed for light-emitting-diode lighting source in three-dimensional space
Author(s):Wang, Guangzhen(1); Hou, Yu(2); Hu, Lichun(1); Tang, Wanwei(1); Gao, Jian(1); Wang, Lili(3)Source: Optik Volume: 126 Issue: 23 DOI: 10.1016/j.ijleo.2015.08.069 Published: 2015Abstract:Reflectors used for light-emitting-diode (LED) light source are designed in three-dimensional space to produce uniform illuminance effect. Reflector's surfaces are calculated by the source-target mapping method in Geometrical Optics. Ignoring scattering and absorption loss of the material, reflectors' performances are investigated. The simulation results show that the light efficiency which is the ratio of light flux in the target surface to that from LED light source can reach above 95%. And the illuminance uniformity which is the ratio of minimum illuminance (min E) to average illuminance (ave E) also can reach above 95%. Finally, the array of reflectors is investigated and the result shows it still has good performance. ? 2015 Elsevier GmbH. All rights reserved.Accession Number: 20160101753584 -
Record 425 of
Title:Hyperspectral band selection by multitask sparsity pursuit
Author(s):Yuan, Yuan(1); Zhu, Guokang(1); Wang, Qi(2)Source: IEEE Transactions on Geoscience and Remote Sensing Volume: 53 Issue: 2 DOI: 10.1109/TGRS.2014.2326655 Published: February 2015Abstract:Hyperspectral images have been proved to be effective for a wide range of applications; however, the large volume and redundant information also bring a lot of inconvenience at the same time. To cope with this problem, hyperspectral band selection is a pertinent technique, which takes advantage of removing redundant components without compromising the original contents from the raw image cubes. Because of its usefulness, hyperspectral band selection has been successfully applied to many practical applications of hyperspectral remote sensing, such as land cover map generation and color visualization. This paper focuses on groupwise band selection and proposes a new framework, including the following contributions: 1) a smart yet intrinsic descriptor for efficient band representation; 2) an evolutionary strategy to handle the high computational burden associated with groupwise-selection-based methods; and 3) a novel MTSP-based criterion to evaluate the performance of each candidate band combination. To verify the superiority of the proposed framework, experiments have been conducted on both hyperspectral classification and color visualization. Experimental results on three real-world hyperspectral images demonstrate that the proposed framework can lead to a significant advancement in these two applications compared with other competitors. ? 2014 IEEE.Accession Number: 20143518100095 -
Record 426 of
Title:Characterization of far field of diode laser by three dimensional measurement
Author(s):Liu, Hui(1,2); Yuan, Zhiyuan(1); Cui, Long(1); Wu, Di(1); Liu, Xingsheng(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9346 Issue: DOI: 10.1117/12.2076548 Published: 2015Abstract:In this paper three dimensional characterization of the far field of diode laser beam is proposed. Both the divergence angle and intensity distribution can be extracted and analyzed from the measurement results with obliquity factor correction and power transmission correction. The instrument provides high resolution and fast measurement. ? 2015 SPIE.Accession Number: 20152600969169 -
Record 427 of
Title:Threshold automatic selection hybrid phase unwrapping algorithm for digital holographic microscopy
Author(s):Zhou, Meiling(1); Min, Junwei(1); Yao, Baoli(1); Yu, Xianghua(1); Lei, Ming(1); Yan, Shaohui(1); Yang, Yanlong(1); Dan, Dan(1)Source: Journal of Modern Optics Volume: 62 Issue: 2 DOI: 10.1080/09500340.2014.954649 Published: January 19, 2015Abstract:Conventional quality-guided (QG) phase unwrapping algorithm is hard to be applied to digital holographic microscopy because of the long execution time. In this paper, we present a threshold automatic selection hybrid phase unwrapping algorithm that combines the existing QG algorithm and the flood-filled (FF) algorithm to solve this problem. The original wrapped phase map is divided into high- and low-quality sub-maps by selecting a threshold automatically, and then the FF and QG unwrapping algorithms are used in each level to unwrap the phase, respectively. The feasibility of the proposed method is proved by experimental results, and the execution speed is shown to be much faster than that of the original QG unwrapping algorithm. ? 2014 Taylor & Francis.Accession Number: 20150400446909 -
Record 428 of
Title:Switchable dual-wavelength fiber laser mode-locked by monolayer graphene on D-shaped fiber
Author(s):Yang, H.R.(1)Source: Journal of Modern Optics Volume: 62 Issue: 17 DOI: 10.1080/09500340.2015.1039616 Published: October 7, 2015Abstract:A switchable mode-locking fiber laser is demonstrated by means of a monolayer graphene saturable absorber (SA) based on a D-shaped fiber. The monolayer graphene, which is grown by chemical vapor deposition, is transferred onto the D-shaped fiber and then the light-graphene interaction via the evanescent field of the fiber is enhanced greatly. Using such a graphene-based SA, the single-wavelength mode locking can be switched from 1531.5 to 1559.1 nm by appropriately adjusting the polarization controller (PC). In addition, the stable dual-wavelength mode-locking operation is also observed at the proper state of PC. ? 2015 Taylor & Francis.Accession Number: 20152100876209 -
Record 429 of
Title:Projection-based NMF for hyperspectral unmixing
Author(s):Yuan, Yuan(1); Feng, Yachuang(1); Lu, Xiaoqiang(1)Source: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Volume: 8 Issue: 6 DOI: 10.1109/JSTARS.2015.2427656 Published: June 1, 2015Abstract:As a widely concerned research topic, many advanced algorithms have been proposed for hyperspectral unmixing. However, they may fail to accurately identify endmember signatures when coming across insufficient spatial resolution. To deal with this problem, an algorithm based on semisupervised linear sparse regression is proposed, in which unmixing procedure is reduced to seeking an optimal subset from the spectral library to best model mixed pixels in the scene. However, the number of the spectra with nonzero abundance is much more than that of the true endmember signatures. Furthermore, the selection of library spectra as endmember signatures is undesirable due to the divergent imaging conditions. In this paper, a novel projection-based nonnegative matrix factorization (NMF) (PNMF) algorithm is proposed by importing spectra library into the NMF framework. The main novelties of this paper are listed as follows. 1) By introducing the spectral library, the extraction of endmember signatures is no longer restricted by spatial resolution. 2) Related spectra are selected and projected onto a subspace containing the endmember signatures. So that the number of endmember signatures is controlled by dimension of the subspace. 3) In PNMF, the endmember signatures are adaptively generated from the spectral library, and are matched with the observed hyperspectral images. This overcomes the difficulty caused by diverse imaging conditions, and makes the proposed algorithm more practical for real applications. The experimental results, conducted on both synthetic and real hyperspectral data, illustrate the advantages of the proposed algorithm when compared with the state-of-the-art algorithms. ? 2008-2012 IEEE.Accession Number: 20153401185595 -
Record 430 of
Title:Hydrothermal synthesis of TiO2 nanostructure films and their photoelectrochemical properties
Author(s):Miao, Hui(1,2); Hu, Xiaoyun(1,2); Fan, Jun(3); Li, Chaoben(1); Sun, Qian(1); Hao, Yuanyuan(1); Zhang, Guowei(1); Bai, Jintao(1,2); Hou, Xun(1,2,4)Source: Applied Surface Science Volume: 358 Issue: DOI: 10.1016/j.apsusc.2015.08.212 Published: December 15, 2015Abstract:In this study, anatase TiO2 nanostructured films were successfully prepared via Ti foil-assisted hydrothermal synthesis method without any surfactants. With the increase of hydrothermal time from 3 to 12 h, the surface morphologies of the films changed from nanotubes to nanoflowers and the thickness of the films increased from 2.5 to 4.2 μm. The nanoflowers were seated on a layer of oriented nanotubes and consisted of nanosheets. Both nanotubes and nanosheets were multi-walled, comprising interconnected [TiO6] octahedra. Ti foil and acid-treated Ti foil both formed pieces of thin films on the surface with nanotubes and nanoflowers, respectively. Photoelectrochemistry tests showed that the photocurrent response of the nanotube film was nearly 13.8 μA/cm2, which was approximately three times higher than that of nanoflowers film. This indicates that the nanotubes more successfully transferred electrons to the surface of the film as a result of nanotubes providing direct pathways for electrons from the point of injection to the Ti foil electrode. The ultraviolet (UV)-visible-near infrared (NIR) absorption spectra indicated that the nanotube film had a narrower band gap as compared to the nanoflower film. In other words, a relatively low hydrothermal treatment temperature or relatively short hydrothermal treatment time is better for preparing excellent photocurrent response films. ? 2015 Elsevier B.V. All rights reserved.Accession Number: 20153601247445 -
Record 431 of
Title:Optical quantum random number generator based on parity of the number of photons detected in equal time intervals
Author(s):Yan, Qiu-Rong(1); Zhao, Bao-Sheng(2); Zhang, Hua(1); Liao, Qing-Hong(1); Chen, Rong-Ling(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 44 Issue: 6 DOI: 10.3788/gzxb20154406.0627003 Published: June 1, 2015Abstract:An optical quantum random number generator based on parity of the number of photons detected in the equal time intervals was proposed. Light emitted from a continuous wave laser diode is attenuated into discrete single-photon sequence. The single photon is detected by a single-photon avalanche photodiode module. Random bit is extracted by measuring the parity of number of photons detected in equal time interval. The random bit extraction circuit based on field programmable gate array was developed. The influences of the size of time interval and the performance parameters of single photon module on performance of the designed random number generator were analyzed. In order to achieve a random bit generator with small deviation and fast generation rate, a method of setting time interval automatically according to average counting rate was proposed. A random bit generation rate of 2 Mbit/s was obtained when the designed random number generator works on a counting rate of 20 Mcps and the equal time interval is set as 0.5 μs. The random bit sequences were tested by random number test program ENT and STS. The test results show that the generated random bit sequences fully meet the standards of true random numbers, and do not require post-processin ?, 2015, Chinese Optical Society. All right reserved.Accession Number: 20152901043477 -
Record 432 of
Title:Design of spun high-birefringent fiber for fiber optic current sensor
Author(s):Wang, Yingli(1); Kang, Menghua(1,2); Ren, Liyong(1,2); Ren, Kaili(1,2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 44 Issue: 1 DOI: Published: January 25, 2015Abstract:The residual linear birefringent of sensing fiber, temperature and vibration sensitivity severely influence the accuracy of Sagnac fiber optic current sensor (S-FOCS). A sensing fiber can be used in FOCS with spun high birefringent fiber (S Hi-Bi fiber) was designed. This S Hi-Bi fiber includes three sections: two terminal sections with variable spin-rate along fiber were utilized to substitute the fiber quarter-wave plates, respectively converting the light polarization state from the linear one to the circle one, and vice versa; and the middle section with a uniform spin-rate was utilized as the current sensing fiber which maintains the circular polarization state and compress the residual linear birefringent during the light propagation. In addition, the sensing fiber was wound into a special geometric structure so that the Sagnac phase shift was inherently eliminated and the sensing result did not depend on the position of the current conductor. In theory, used the coupled-mode theory the evolution of the light polarization state was simulated when linear polarization states light incident into the sensing fiber. A novel Sagnac fiber optic current sensor with vibration insensitivity based on this spun high birefringent fibers was proposed. ?, 2015, Chinese Society of Astronautics. All right reserved.Accession Number: 20151000594574