2012
2012
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Record 217 of
Title:Ghost interference with pseudo-thermal light
Author(s):Yao, Yin-Ping(1,2); Wan, Ren-Gang(1); Zhang, Shi-Wei(1,2); Song, Jia-Zheng(1); Zhang, Tong-Yi(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8554 Issue: DOI: 10.1117/12.999577 Published: 2012Abstract:Ghost imaging (correlated imaging) has been extensively investigated in recent years, both theoretically and experimentally. By using the second-order or high-order coherence properties of light field and the correlation measurement, ghost imaging was realized with quantum entangled light, pseudo-thermal light and even true thermal light. In this work, basing on the theory of statistical optics, we model the dynamic process of thermal variation, and obtain the ghost interference and ghost imaging by means of simulated calculation. In the later experiment, a pseudo-thermal source is firstly prepared by using a laser beam to pass through a rotating ground glass plate, and the parameters of the pseudo-thermal source are obtained via Hanbury-Brown-Twiss (HBT) experiment. With the pseudo-thermal light, we perform ghost interference. The experimental results demonstrate the accordance of numerical prediction. And our conclusion shows that the quality of ghost interference is influenced by the size of the pinhole in the reference path, the little pinhole due to a higher quality of ghost interference. ? 2012 SPIE.Accession Number: 20132916514915 -
Record 218 of
Title:Quantitative monitoring of relative clock wander between signal and sampling sources in asynchronous optical under-sampling system
Author(s):Zhang, Huixing(1,2); Zhao, Wei(1)Source: Chinese Optics Letters Volume: 10 Issue: 3 DOI: 10.3788/COL201210.030601 Published: March 2012Abstract:Optical performance monitoring using asynchronous optical or electrical sampling has gained considerable attention. Relative clock wander between data signal and sampling source is a typical occurrence in such systems. A method for the quantitative monitoring of the relative clock wander in asynchronous optical under-sampling system is presented. With a series of simulations, the clock wanders recovered using this method are in good agreement with the preset clock wanders of different amounts and frequencies for both RZ and NRZ signals. Hence, the reliability and robustness of the method are proven. ? 2012 Chinese Optics Letters.Accession Number: 20121514938098 -
Record 219 of
Title:High-power and widely tunable Tm-doped fiber laser at 2 μm
Author(s):Guo, Chengzheng(1,2); Shen, Deyuan(1); Long, Jingyu(1); Wang, Fei(1)Source: Chinese Optics Letters Volume: 10 Issue: 9 DOI: 10.3788/COL201210.091406 Published: September 2012Abstract:Efficient, high-power, and widely tunable Tm-doped fiber lasers cladding-pumped by diode lasers at 791 nm are demonstrated by use of an external cavity containing a diffraction grating. A maximum output power of 62 W is obtained at 2004 nm for 140 W of launched pump power, corresponding to a slope efficiency of 48% with respect to launched pump power. The operating wavelength is tunable over 200 nm (1895 to 2109 nm), with >52 W of output power over a tuning range of 140 nm (1926 to 2070 nm). Prospects for further improvement in output power, lasing efficiency, and tuning range are considered. ? 2012 Chinese Optics Letters.Accession Number: 20124515645477 -
Record 220 of
Title:Route of delivering 40-fs ultra-short laser pulses for gating photoconductive antenna in fiber-coupled terahertz time-domain spectroscopy
Author(s):Liu, Jia(1,2); Fan, Wen-Hui(1); Chen, Long-Chao(1,2)Source: Optical Engineering Volume: 51 Issue: 8 DOI: 10.1117/1.OE.51.8.085001 Published: August 2012Abstract:A route of delivering ultra-short laser pulses through a polarization- maintaining single-mode fiber has been investigated experimentally. The group velocity dispersion was well compensated, and the self-phase modulation was depressed in fiber. Finally, a 40-fs laser pulse with the energy of 70 pJ was obtained at the output of the transmitted fiber with the length up to 4 m in our fiber-delivery system. The route exhibits distinguishing features of compactness and flexibility, and this 40-fs laser pulse can be used not only to generate broadband terahertz (THz) radiation but also to detect broadband THz radiation, which is much better than the 150-fs laser pulse used previously. ? 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20140317194402 -
Record 221 of
Title:A neodymium fluid laser: Laser emission in circulating state
Author(s):Hou, Chaoqi(1,2); Guo, Haitao(1); She, Jiangbo(1,2); Cui, Xiaoxia(1); Qiao, Zebang(1); Gao, Fei(1); Lu, Min(1); Wei, Wei(1); Peng, Bo(1)Source: Optics and Laser Technology Volume: 44 Issue: 5 DOI: 10.1016/j.optlastec.2011.12.047 Published: July 2012Abstract:Differing from conventional liquid lasers, a novel concept of fluid laser was provided, which has attractively potential using in high average power lasers. The laser medium was prepared by dispersing Nd3: phosphate glass micro-balls in organic match liquid. Its optical properties were investigated and the radiative transition rate was calculated by JuddOfelt theory. The experiment of laser oscillation in static state indicates that the heat exchanging has limited effect on refractive index of the fluid laser medium in a short time. In circulating state, a laser oscillation occurred at 1058.1 nm when pumped by two 808 nm diode lasers. The maximum output energy is 2.58 mJ with the absorbed pumping energy of 460 mJ. This study offers a new way in the exploration of high average power laser. ? 2012 Elsevier Ltd. All rights reserved.Accession Number: 20120814786197 -
Record 222 of
Title:Review on quantum clock synchronization schemes
Author(s):Yao, Yin-Ping(1,2); Zhang, Tong-Yi(1); Wan, Ren-Gang(1); Zhao, Wei(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8332 Issue: DOI: 10.1117/12.918844 Published: 2012Abstract:Accurate remote clock synchronization is the backbone of applications such as high-accuracy satellite navigation, digital and/or cryptographic communication systems, space-based interferometric surveillance, coherent distributed-aperture sensing at high frequencies, and geolocation. During the last decade, several clock synchronization schemes have been proposed based on quantum mechanical concepts. Quantum clock synchronization promises more precision and better security. In this paper, the various proposed quantum clock synchronization schemes are reviewed. We compare and discuss several different quantum clock synchronization schemes. The advantages and disadvantages of these schemes are investigated with emphasis on the application in space-based satellite navigation systems. ? 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20121514939405 -
Record 223 of
Title:Study on high sensitivity and low noise electro-optic terahertz detector
Author(s):Chen, Long-Chao(1,2); Fan, Wen-Hui(1)Source: Tien Tzu Hsueh Pao/Acta Electronica Sinica Volume: 40 Issue: 9 DOI: 10.3969/j.issn.0372-2112.2012.09.001 Published: September 2012Abstract:An electro-optic terahertz (THz) detector with a newly-designed circuit was investigated. A pair of high-quality PIN photodiodes and a low-noise current-voltage conversion circuit were applied to convert the modulated probe laser to voltage signal. These two voltage signals were subsequently sent to a specially-designed differential amplifier with high common-mode-rejection-rate (CMRR) that largely restrain the noise of terahertz signal and avoid the disturbance of probe laser intensity. Then a band-pass filter was employed to control bandwidth and restrain noise of the detected signal. Finally, the weak THz signal was detected via a main amplifier. Experimental results show that the THz detector has high signal-to-noise-ratio (SNR), teeny distortion and wide bandwidth, which fully satisfy the requirement of terahertz time-domain spectroscopy (THz-TDS).Accession Number: 20124615671080 -
Record 224 of
Title:Optical quantum random number generator based on the time randomness of single-photon pulse
Author(s):Yan, Qiurong(1,2); Zhao, Baosheng(1); Liu, Yong'an(1); Sheng, Lizhi(1,2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 32 Issue: 3 DOI: 10.3788/AOS201232.0327001 Published: March 2012Abstract:An optical quantum random number generator based on the time randomness of single-photon pulse is proposed. A constant-intensity light source attenuating into single-photon state and a single photon detector are used to generate single-photon random pulses. The random bits are extracted by continuously comparing the time intervals between two adjacent pulses in the single-photon random pulses sequence. A random number generation rate of more than 10 M bit/s is obtained by designing high-speed single-photon detector based on micro-channel plate and field programmable gate arry (FPGA) based random bit extraction circuit. In order to reduce the correlation coefficient of random bit sequence, measurement accuracy of the time interval is improved by using a constant fraction discriminator and a frequency-multiplied counting clock. Correlation coefficient of the random bit sequence is less than 0.001, when the random bit generation rate is less than 10 k bit/s. The random bit sequences are tested by random number test program ENT and DIEHARD. The test results show that random bit sequences have good randomness, do not require post-processing and fully meet the standards of true random numbers.Accession Number: 20121514937623 -
Record 225 of
Title:Dual-mode, eye-safe MOPA all-fiber laser
Author(s):Yun, Jian(1,2); Sun, Chuan-Dong(1); Gao, Cun-Xiao(1); Zhu, Shao-Lan(1); He, Hao-Dong(1); Feng, Li(1); Niu, Lin-Quan(1,2); Dong, Li-Jun(1,2)Source: Shenzhen Daxue Xuebao (Ligong Ban)/Journal of Shenzhen University Science and Engineering Volume: 29 Issue: 4 DOI: 10.3724/SP.J.1249.2012.04311 Published: July 2012Abstract:An all-fiber laser which could work with either pulse or continuous wave (CW) mode is reported. The configuration of laser is master-oscillator power-amplifier (MOPA), the seeder of which is a single mode directly modulated laser diode operating in wavelength of 1550 nm, and the amplifier consists of two preamplifiers and one main amplifier. In pulse mode, the peak power of 5.1 kW and a pulse width of 1.7 ns are obtained when the repetition rate is 50 kHz and the pump power is 4 W. In CW mode, the average power of 0.5 W is obtained. By using this laser, the pulse and the phase laser ranging can be realized simultaneously.Accession Number: 20123715431305 -
Record 226 of
Title:Dual-wavelength slightly off-axis digital holographic microscopy
Author(s):Min, Junwei(1,2); Yao, Baoli(1); Gao, Peng(1); Guo, Rongli(1); Ma, Baiheng(1); Zheng, Juanjuan(1); Lei, Ming(1); Yan, Shaohui(1); Dan, Dan(1); Duan, Tao(1); Yang, Yanlong(1); Ye, Tong(1)Source: Applied Optics Volume: 51 Issue: 2 DOI: 10.1364/AO.51.000191 Published: January 10, 2012Abstract:We propose dual-wavelength digital holographic microscopy with a slightly off-axis configuration. The axial measurement range without phase ambiguity is extended to the micrometer range by synthesizing a beat wavelength between the two wavelengths with separation of 157 nm. Real-time measurement of the specimen is made possible by virtue of the high wavelength selectivity of the Bayer mosaic filtered color CCD camera. The principle of the method is exposed, and the practicability of the proposed configuration is demonstrated by the experimental results on a vortex phase plate and a rectangular phase step. ? 2012 Optical Society of America.Accession Number: 20120314698453 -
Record 227 of
Title:A-Optimal Non-negative Projection for image representation
Author(s):Liu, Haifeng(1); Yang, Zheng(2); Wu, Zhaohui(2); Li, Xuelong(2)Source: Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition Volume: Issue: DOI: 10.1109/CVPR.2012.6247851 Published: 2012Abstract:As a central problem in computer vision and pattern recognition, data representation has attracted great attention in the past years. Non-negative matrix factorization (NMF) which is a useful data representation method makes great contribution on finding the latent structure of the data and leads to a parts-based representation by decomposing the data matrix into a few bases and encodings with nonnegative constraints. However, non-negative constraint is insufficient for getting more robust data representation. In this paper, we propose a novel method, called A-Optimal Non-negative Projection (ANP) for image data representation and further analysis. ANP imposes a constraint on the encoding factor as a regularizer during matrix factorization. In this way, the learned data representation leads to a stable linear model no matter what kind of data label is selected for further processing. Thus, it can preserve more intrinsic characteristics of the data regardless of any specific labels. We demonstrate the effectiveness of this novel algorithm through a set of evaluations on real world applications. ? 2012 IEEE.Accession Number: 20124015484275 -
Record 228 of
Title:Soliton mode locking fiber laser with an all-fiber polarization interference filter
Author(s):Yan, Zhijun(1); Wang, Hushan(1,2); Zhou, Kaiming(1); Wang, Yishan(2); Li, Cheng(2); Zhao, Wei(2); Zhang, Lin(1)Source: Optics Letters Volume: 37 Issue: 21 DOI: 10.1364/OL.37.004522 Published: November 1, 2012Abstract:An erbium doped fiber ring laser achieving soliton mode locking by the use of an intra-cavity all-fiber polarization interference filter (AFPIF) has been demonstrated. To incorporate an AFPIF with relative narrow transmission bandwidth, the laser has produced clean soliton pulses of 1.2 ps duration at a repetition rate of 14.98 MHz with a polarization extinction ratio up to 25.7 dB. Moreover, we have demonstrated that the operating wavelength of the mode locking laser can be tuned over 20 nm range from 1545 to 1565 nm by thermally tuning the AFPIF cavity. ? 2012 Optical Society of America.Accession Number: 20124515650471