2019
2019
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Record 421 of
Title:Three-dimensional space optimization for near-field ptychography
Author(s):Pan, An(1,2); Yao, Baoli(1,3)Source: Optics Express Volume: 27 Issue: 4 DOI: 10.1364/OE.27.005433 Published: 2019Abstract:A multiple slices approach in ptychography, termed 3ePIE algorithm, solves the multiple scattering problems of thick samples, which is crucial to biomedical imaging and in situ studies. However, it is unclear how many slices need to be separated and what the distance is between each layer respectively, while these two parameters are sensitive and crucial to the recovery of thick samples. The traditional method is to separate the sample with the same interval for convenience and to test the number of sections for the best reconstructions, which is reasonable for continuous samples and has achieved great results. But this kind of segmentation approach may not be scientific enough for those discrete samples with an uneven spatial distribution. The two inaccurate parameters may yield the algorithm to diverge or generate artifacts, and the empty slices may decrease the reconstruction quality and increase computation time. In addition, repeatedly testing the number of slices is tedious work even for a continuous sample. To this end, a genetic algorithm-based 3ePIE approach, termed the GA-3ePIE method, is proposed to retrieve both the interval between each layer and the number of slices. The performance is verified by both simulations and experiments. The maximum number of sections that can be resolved is also investigated in numerical analysis, which is associated with the sampling and overlap rate in a spatial domain. Our method can be also promoted to image thick samples with coherent Xrays and in the electron regime. The limitations of our method are also discussed. ? 2019 Optical Society of America.Accession Number: 20190906559972 -
Record 422 of
Title:A broadband enhanced plasmonic modulator based on double-layer graphene at mid-infrared wavelength
Author(s):Chi, Jiao(1,3); Liu, Hongjun(1,2); Huang, Nan(1); Wang, Zhaolu(1)Source: Journal of Physics D: Applied Physics Volume: 52 Issue: 44 DOI: 10.1088/1361-6463/ab36dc Published: August 13, 2019Abstract:Graphene is as an essential material for light modulation owing to controlling broadband absorption and plasmon excitation. Here, we propose a mid-infrared enhanced plasmonic modulator that integrates double-layer graphene in a reflective structure. It is demonstrated that double-layer graphene can support plasmonic resonances with higher oscillator intensity than single-layer in this modulator. The proposed modulator exhibits a modulation depth up to 21 dB and 3 dB bandwidth of 47.4 GHz over a wide range of wavelength (3.17 μm to 4.4 μm). Moreover, the maximum insertion loss of it is barely about 0.27 dB and the minimum of that is about 0.1 dB. This graphene-based modulator, with combined advantages of high modulation depth, low insertion loss and ultrafast modulation speed, holds potential in efficient manipulating MIR lights in free space communication. ? 2019 IOP Publishing Ltd.Accession Number: 20193807461464 -
Record 423 of
Title:Pulse signal restoration via stochastic resonance in a fabry-perot cavity with an intracavity nematic liquid crystal film
Author(s):Feng, Xingpan(1,3); Liu, Hongjun(1,2); Huang, Nan(1); Wang, Zhaolu(1); Zhang, Yongbin(1,3)Source: Optics Express Volume: 27 Issue: 10 DOI: 10.1364/OE.27.014931 Published: 2019Abstract:We theoretically propose a method to restore weak pulse signals submerged in noise via stochastic resonance, which is based on the optical bistability induced by the molecule reorientation in a Fabry-Perot cavity with an intracavity nematic liquid-crystal film. The bistable properties of this cavity are analyzed with different reflectance of the mirrors, initial phase shift and initial angle between the phase propagation vector and the director. The cross-correlation coefficient between pure input pulses and output is calculated to quantitatively evaluate the influence of noise intensity on output. The simulation results show a cross-correlation gain of 3.2 and that the buried signal can be recovered effectively by this device. It proves the potential of using this structure to recover noise-hidden pulse signals in an all-optical system. ? 2019 Optical Society of America under the terms of the OSA Open Access Publishing AgreementAccession Number: 20192106955334 -
Record 424 of
Title:Design of mirror assembly and surface simulation for CPA
Author(s):Xu, Guangzhou(1); Zhao, Xiaodong(1); Liu, Minxia(2); Liu, Ying(3)Source: Optik Volume: 192 Issue: DOI: 10.1016/j.ijleo.2019.162939 Published: September 2019Abstract:Mirror assembly is the important front module for the coarse pointing element of satellite laser communication. The structural and environmental adaption of the mirror assembly has a great influence for the performance of the laser communication system. To solve the design problem of the mirror assembly, the design of SiC mirror assembly and surface simulation for CPA is researched. First, the lightweight structure of SiC mirror is designed. Besides, to reduce the influence for the mirror surface change caused by the mismatching of different linear expansion coefficient, the flexible supporting structure is designed to realize the connection between the mirror and supporting structure. Second, the high-precision algorithm based on discrete error elimination technique for surface parameter of mirror is proposed and the correctness of the algorithm is validated. The validation result demonstrated the precision of proposed algorithm is higher and can satisfy the engineering demands. At last, the surface data of finite element analysis for the SiC mirror is processed by the developed program with high-precision algorithm; the surface parameter of mirror is obtained under the loadcases with gravity and thermal deformation. Based on the calculation result of surface parameter, the structural design of mirror assembly for CPA is verified and the fundamental data is provided to revise the structural design parameter of the mirror. A new technical reference is presented for the supporting structure design of mirror and the simulation technique of optical surface. ? 2019 Elsevier GmbHAccession Number: 20192607092268 -
Record 425 of
Title:Method of encapsulating silver nanodots using porous glass and its application in Qswitched all solid-state laser
Author(s):Zhang, Guodong(1,2); Li, Guangying(1,2); Zhang, Yunjie(3); Wang, Xu(1,2); Cheng, Guanghua(1)Source: Optics Express Volume: 27 Issue: 4 DOI: 10.1364/OE.27.005337 Published: 2019Abstract:Here, we report on a packaging method for silver nanodots (SNDs) by using highsilicate porous glass. Millions of nanopores, which are randomly distributed in porous glass, are used as cells for SND nucleation and growth during the initial chemical-reduction process. Then, the sample is annealed at a high-temperature in a reducing atmosphere to impel the further SND growth and nanopore collapse. The compact SND-embedded transparent glass is synthesized in the end. Morphology characterization shows that the SNDs that are encapsulated in the sample have a uniform size of 1.5 to 4.5 nm. Both the sample's saturable and reverse saturable absorptions are observed under the irradiation of 100 fs laser pulses at 800 nm. Saturable absorption's threshhold is characterized to be 1.4 × 1011 W/cm2, which is much lower than what was ever reported. Furthermore, the SNDs-embedded silica as a saturable absorber (SA) has been demonstrated in the Q-switched Nd:YVO4 laser. The pulse duration as short as 53 nanoseconds is obtained. To our knowledge, it is the first time that SNDs are used as a SA in the passively Q-switched all solid-state laser. ? 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.Accession Number: 20190906560873 -
Record 426 of
Title:Nd3+: Photo-thermo-refractive Glass Waveguides Written by Femtosecond Laser
Author(s):Zhang, Ze-Yu(1); An, Hai-Tao(1); Wang, Xu(2); Xie, Ying-Wu(1); Zhang, Hua(1); Liu, Qing(3); Chen, Li-Gong(1); Yang, Bo(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 48 Issue: 3 DOI: 10.3788/gzxb20194803.0314002 Published: March 1, 2019Abstract:Femtosecond laser with central wavelength of 1 028 nm, repetition rate of 50 kHz and pulse width of 220 fs is used to write double line and tubular depressed cladding waveguides in Nd3+ doped photo-thermo-refractive glass. The influences of laser power, double line separation and diameters of tubular depressed cladding waveguide on the near-field modes of waveguides are investigated, and the waveguides with better guiding mode are obtained. Refractive index profile is reconstructed by intensity distribution of the near-field mode, the largest positive refractive index change for these two types of waveguides is +7.0×10-4 and +5.5×10-4, respectively. By using the scattering technique, the propagation loss of double line waveguide is about 1.29 dB/cm. The loss of tubular depressed cladding waveguide is less than 1.95 dB/cm by testing the insert loss. Therefore, waveguides inscribed directly by femtosecond laser in Nd3+ doped photo-thermo-refractive glass are promising candidates for the development of integrated optical device. ? 2019, Science Press. All right reserved.Accession Number: 20192206992428 -
Record 427 of
Title:Tunable Fiber Laser Using an Er/Yb Codoped Fiber Based Modal Interferometer Filter
Author(s):Yang, Hening(1,2,3,4); Dong, Bo(1,2); Zhao, Wei(1,2); Chen, Enqing(4); Li, Yang(4); Si, Jinhai(5)Source: Journal of Lightwave Technology Volume: 37 Issue: 21 DOI: 10.1109/JLT.2019.2933703 Published: November 1, 2019Abstract:A tunable erbium-doped fiber laser (EDFL) is proposed and demonstrated experimentally. It is based on a tunable fiber filter using the pump induced refractive index change characteristics of the Er/Yb codoped phosphosilicate fiber (EYDF) based modal interferometer (MI). The laser achieves a tunability of 2.39 nm and 1.60 nm, with the wavelength linearly tuned from 1534.05 nm to 1536.44 nm and from 1554.36 nm to 1555.96 nm by changing the pump power injected into the MI. Its side mode suppression ratios are 30 dB and 33 dB, respectively. The stability of the tunable EDFL is getting better with the continuous improvement of the power of pump 1, and the dual-wavelength power fluctuations are less than 0.22 dB and 0.12 dB within 20 min at 250 mW of pump 1, respectively. ? 1983-2012 IEEE.Accession Number: 20200207993745 -
Record 428 of
Title:High energy femtosecond laser micromachining with hollow core photonic crystal fiber delivery
Author(s):Li, Feng(1); Yang, Zhi(1); Lv, Zhiguo(1); Wang, Yishan(1); Li, Qianglong(1); Wei, Yufeng(1); Yang, Yang(1); Yang, Xiaojun(1); Zhao, Wei(1)Source: Optik Volume: 194 Issue: DOI: 10.1016/j.ijleo.2019.163093 Published: October 2019Abstract:In this paper, we demonstrate a new way to deliver the high energy femtosecond laser with Kagome-type hollow core photonic crystal fiber for micromachining compared to the traditional free space laser delivery. To achieve the high coupling efficiency and overcome the nonlinear effect in the delivery, the coupling system is optimized and the fiber is vacuum pumped to less than 5 mbar. High delivery efficiency more than 90% is achieved. To our best knowledge, this is the highest efficiency of femtosecond laser delivered by Kagome type hollow core fiber. With vacuum pump, we lowered the nonlinear effect and make the laser beam have good beam profile and slightly pulse duration change even in the delivery of laser with the pulse energy of 100 μJ, average power of 20 W, and pulse duration of 234 fs. The whole system is also used to make micromachining of aluminum and stainless steel with good processing quality. ? 2019 Elsevier GmbHAccession Number: 20193007220859 -
Record 429 of
Title:An antenna array initial condition calibration method for integrated optical phased array
Author(s):Zhang, QiHao(1,2); Zhang, LingXuan(1,2); Li, ZhongYu(1); Wu, Wei(1,2,3); Wang, GuoXi(1,3); Sun, XiaoChen(1,3); Zhao, Wei(1,3); Zhang, WenFu(1,3)Source: arXiv Volume: Issue: DOI: null Published: February 16, 2019Abstract:This paper presents a modified rotating element electric field vector (modified REV) method to calibrate the antenna array initial condition of an optical phased array (OPA) device. The new method follows a similar sequential individual antenna phase calibration process while it modifies the algorithm to avoid possible π phase error in traditional REV when large initial phase distribution and finite optical power measurement accuracy present. We show that the method produces statistically more accurate and predictable calibration result which is highly desired in practice. Copyright ? 2019, The Authors. All rights reserved.Accession Number: 20200187649 -
Record 430 of
Title:An X-ray frequency modulation method and its application in X-ray communication
Author(s):Su, Tong(1,2); Tang, Liangyu(3); Li, Yao(1,2); Sheng, Lizhi(1); Zhao, Baosheng(1)Source: Optik Volume: 199 Issue: DOI: 10.1016/j.ijleo.2019.163263 Published: December 2019Abstract:X-ray communication (XCOM) is a novel space communication method with great potential. X-rays have much shorter wavelengths than both infrared and radio. In principle, XCOM can send more data for the same amount of transmission power, which could permit more efficient gigabits-per-second data rates for deep space missions. Besides, X-rays can pierce the hot plasma sheath that builds up as spacecraft hurdle through Earth's atmosphere at hypersonic speeds. However, some current technical limitations have made X-ray communication unable to fully release its theoretical advantages in space communications. Among them, the modulation of X-ray emission impacts significantly. For the requirements of high-flux, collimation, quasi-monochromatic X-ray emissions, as well as the exploration of X-ray frequency modulation, we propose an X-ray frequency modulation method for generating different energy X-rays by controlling the electron beam deflection based on an external electrostatic field. Different from all traditional on-off control methods, this scheme uses two specific X-ray energies indicate the digital signal 0 and 1, which makes X-ray frequency modulation possible. Based on this, we simulated the emission flux and energy distribution of two different targets. Simulation results indicate that this X-ray modulation method produce X-rays with up to 50 GHz modulation frequency, 1014 cps X-ray emission flux, 99% monochrome, and 1.5 mrad divergence angle. Through this modulator, not only the communication distance and communication speed experience significant increases, but also the concept of X-ray communication, X-ray ranging and X-ray navigation can be realized as a three-in-one mission. ? 2019 Elsevier GmbHAccession Number: 20193807444482 -
Record 431 of
Title:Biomimetic anti-adhesive surface microstructures on electrosurgical blade fabricated by long-pulse laser inspired by pangolin scales
Author(s):Li, Chen(1); Yang, Yong(2); Yang, Lijun(1); Shi, Zhen(1)Source: Micromachines Volume: 10 Issue: 12 DOI: 10.3390/mi10120816 Published: December 1, 2019Abstract:The electrosurgical blade is the most common invasive surgical instrument in a cutting and hemostasis process; however, the blade easily leads to the adhesion of overheated soft tissues on the blades and induces a potential danger for the patients. To minimize the adhesive tissues, we proposed the one-step surface texturing method to fabricate anti-adhesive biomimetic scales on stainless steel 316L rapidly based on the self-organized surface microstructures induced by the long-pulse fiber laser, which was inspired by the excellent performances of anti-adhesion and anti-friction in the pangolin scales. The optimal formation parameters, chemical components, and crystal structures of the laser-induced self-organized surface microstructures were investigated in the experiments. Moreover, the underlying formation mechanism was revealed. The electrosurgical blades with biomimetic scales have hydrophobicity and a smaller frictional coefficient, which effectively reduced the adhesion of soft tissue. ? 2019 by the authors. Licensee MDPI, Basel, Switzerland.Accession Number: 20200608149072 -
Record 432 of
Title:Real-time optical manipulation of particles through turbid media
Author(s):Peng, Tong(1,2,3); Li, Runze(1,2,3); An, Sha(1,2); Yu, Xianghua(1); Zhou, Meiling(1,2); Bai, Chen(1); Liang, Yansheng(1); Lei, Ming(1); Zhang, Chunmin(3); Yao, Baoli(1); Zhang, Peng(1)Source: Optics Express Volume: 27 Issue: 4 DOI: 10.1364/OE.27.004858 Published: 2019Abstract:Complex diffusive scattering media pose significant challenges for light focusing as well as optical imaging to be implemented in practice. Recently, it has been demonstrated that the wavefront shaping technique can be applied to realize focusing and imaging through scattering medium. Here we report dynamic optical manipulation of particles through turbid media by employing the interleaved segment wavefront correction method, which is an improved genetic algorithm providing faster convergence speed and higher peak to background ratio. Manipulating micro-beads behind a scattering medium along both one and two dimensional predesigned trajectories in real time has been successfully demonstrated. ? 2019 Optical Society of America.Accession Number: 20190906560075