2019
2019
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Record 481 of
Title:WS2 Passively Q-switched Er:SrF2 Laser at ～3 μm
Author(s):Xu, Jihua(1); Li, Ming(2); Chen, Yinqi(1)Source: Laser Physics Volume: 29 Issue: 5 DOI: 10.1088/1555-6611/aaf325 Published: March 26, 2019Abstract:A few-layer tungsten disulfide (WS2) nanosheet film on a YAG substrate was fabricated and used as saturable absorber in a passively Q-switched Er:SrF2 laser operating at 2.79 μm. Under an absorbed power of 2.42 W, a stable Q-switched laser operation was realized with an average output power of 428 mW and a pulse duration of 679 ns at a repetition rate of 38 kHz, corresponding to a pulse energy of 11.26 μJ. ? 2019 Astro Ltd.Accession Number: 20192607105911 -
Record 482 of
Title:Axial resolution enhancement of light-sheet microscopy by double scanning of Bessel beam and its complementary beam
Author(s):Jia, Hao(1,2); Yu, Xianghua(1); Yang, Yanlong(1); Zhou, Xing(1,2); Yan, Shaohui(1); Liu, Chao(1,2); Lei, Ming(1); Yao, Baoli(1)Source: Journal of Biophotonics Volume: 12 Issue: 1 DOI: 10.1002/jbio.201800094 Published: January 2019Abstract:The side lobes of Bessel beam will create significant out-of-focus background when scanned in light-sheet fluorescence microscopy (LSFM), limiting the axial resolution of the imaging system. Here, we propose to overcome this issue by scanning the sample twice with zeroth-order Bessel beam and another type of propagation-invariant beam, complementary to the zeroth-order Bessel beam, which greatly reduces the out-of-focus background created in the first scan. The axial resolution can be improved from 1.68 μm of the Bessel light-sheet to 1.07 μm by subtraction of the two scanned images across a whole field-of-view of up to 300 μm × 200 μm × 200 μm. The optimization procedure to create the complementary beam is described in detail and it is experimentally generated with a spatial light modulator. The imaging performance is validated experimentally with fluorescent beads as well as eGFP-labeled mouse brain neurons. ? 2018 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimAccession Number: 20183605778353 -
Record 483 of
Title:Application of Gaussian fitting to the fast search of pulsar periodic
Author(s):Xu, Neng(1,2,3); Sheng, Lizhi(1); Chen, Chen(1,3); Li, Yao(1,3); Su, Tong(1,3); Zhao, Baosheng(1); Zheng, Wei(4); Liu, Chunliang(2)Source: Optik Volume: 198 Issue: DOI: 10.1016/j.ijleo.2019.163253 Published: December 2019Abstract:In this paper, we provided a Gaussian fitting method for fast periodic search to improve the accuracy of chi-square method. And this method can be used for the pulse periodic search of X-ray Pulsar. Firstly, we built the fast search model based on the epoch folding procedure by employing the basic principle of the chi-square evaluation. Secondly, we simulated the distribution of chi-square value by applying the pulsar profile to the fast search model, and it is fitting well with the Gaussian function. Finally, the designed experiments indicated that applying Gaussian fitting to chi - square method can significantly improve period search accuracy. ? 2019 Elsevier GmbHAccession Number: 20193507370827 -
Record 484 of
Title:Semisupervised Learning with Parameter-Free Similarity of Label and Side Information
Author(s):Zhang, Rui(1); Nie, Feiping(1); Li, Xuelong(2)Source: IEEE Transactions on Neural Networks and Learning Systems Volume: 30 Issue: 2 DOI: 10.1109/TNNLS.2018.2843798 Published: February 2019Abstract:As for semisupervised learning, both label information and side information serve as pivotal indicators for the classification. Nonetheless, most of related research works utilize either label information or side information instead of exploiting both of them simultaneously. To address the referred defect, we propose a graph-based semisupervised learning (GSL) problem according to both given label information and side information. To solve the GSL problem efficiently, two novel self-weighted strategies are proposed based on solving associated equivalent counterparts of a GSL problem, which can be widely applied to a spectrum of biobjective optimizations. Different from a conventional technique to amalgamate must-link and cannot-link into a single similarity for convenient optimization, we derive a new parameter-free similarity, upon which intrinsic graph and penalty graph can be separately developed. Consequently, a novel semisupervised classification algorithm can be summarized correspondingly with a theoretical analysis. ? 2012 IEEE.Accession Number: 20182705408852 -
Record 485 of
Title:Three-dimensional thermal model of high-power semiconductor lasers
Author(s):Wu, Di-Hai(1,2,3); Zah, Chung-En(2); Liu, Xingsheng(2)Source: Applied Optics Volume: 58 Issue: 14 DOI: 10.1364/AO.58.003892 Published: 2019Abstract:In this paper, 3-D, steady-state, analytical thermal models of high-power single-emitter semiconductor lasers (SEs) and laser diode arrays (LDAs) are derived, considering the heat conduction in multi-layered laser structures. Heat flow in the laser chips for an epi-down bonded SE and LDA is described using this model, and it is observed that the laser chips contribute to 8% and 6% of total heat dissipation for the SE and LDA, respectively. The submount size requirement for this model is discussed by revealing the heat flow in the submount. Through finite element simulations, the solution accuracy for the lasers with non-ideal submounts is confirmed. Finally, the performance of our proposed analytical models is verified by finite element simulations and experimental measurements based on the wavelength shift method. ? 2019 Optical Society of America.Accession Number: 20192106950947 -
Record 486 of
Title:Aperture scalable liquid crystal optically duplicated array of phased array
Author(s):He, Xiaoxian(1); Wang, Xiangru(1); Wu, Liang(2); Liu, Xiaopeng(2); Guo, Hongru(1); Huang, Xinning(3); Xie, Xiaoping(3); Tan, Qinggui(4); Cao, Jie(5)Source: Optics Communications Volume: 451 Issue: DOI: 10.1016/j.optcom.2019.06.037 Published: 15 November 2019Abstract:To achieve non-mechanical laser beam steering in the scenario of long distance propagation such as free-space laser communication between satellites, large aperture size is an inevitable issue to be considered to narrow the divergence angle of the output beam. Liquid crystal optical phased array, to be one of the solutions of non-mechanical beam steering, has already shown its obvious potential to achieve a relative large aperture on the order of centimeter. To achieve even larger, its driving matrix becomes squared larger. In this paper, we proposed a novel architecture to realize an optical phased array with a scalable aperture. Meanwhile the driving matrix is almost not increased. It provides the feature of a cascade system with a device of spatial phased modulation and an array of duplicating units. Each unit of the duplicating array is consist of a polarization beam splitter and a half wave plate to have the same output optical field distribution as the input beam whose phase front is modulated by a small size spatial modulator. Not only the property of beam deflection is numerically simulated and experimentally verified, but also the property of divergence angle compression and grating lobes limitation are evaluated. Meanwhile, due to the high precision of the experimental alignment, the non-mechanical beam deflection property is still maintained no matter how many the duplicated unit number is. The relative standard derivation steering error is 0.025. ? 2019 Elsevier B.V.Accession Number: 20192607111767 -
Record 487 of
Title:Customizing supercontinuum generation via adaptive on-chip pulse splitting
Author(s):Wetzel, Benjamin(1,2); Kues, Michael(1,3); Roztocki, Piotr(1); Reimer, Christian(1,4); Godin, Pierre-Luc(1); Rowley, Maxwell(2); Little, Brent E.(5); Chu, Sai T.(6); Viktorov, Evgeny A.(7); Moss, David J.(8); Pasquazi, Alessia(2); Peccianti, Marco(2); Morandotti, Roberto(1,7,9)Source: Optics InfoBase Conference Papers Volume: Part F140-CLEO_Europe 2019 Issue: DOI: null Published: 2019Abstract:Modern optical systems increasingly rely on complex physical processes. Advanced light sources, such as supercontinuum (SC) [1], are highly sought for imaging and metrology, and are based on nonlinear dynamics where the output properties must often finely match target performance characteristics. However, in these systems, the availability of control parameters and the means to adjust them in a versatile manner are usually limited. Moreover, finding the ideal parameters for a specific application can become inherently complex. Here, we use an actively-controlled photonic chip to prepare and manipulate patterns of femtosecond optical pulses seeding supercontinuum generation [1]. Taking advantage of machine learning concepts [2], we exploit this access to an enhanced and tunable parameter space and experimentally demonstrate the customization of nonlinear interactions responsible for tailoring supercontinuum properties [3]. ? 2019 IEEEAccession Number: 20202008660968 -
Record 488 of
Title:Toward high contrast and high-resolution microscopic ghost imaging
Author(s):Sun, Zhe(1,2,3); Tuitje, Frederik(1,3); Spielmann(1,3)Source: Optics Express Volume: 27 Issue: 23 DOI: 10.1364/OE.27.033652 Published: November 11, 2019Abstract:In this study, the influence of speckle size on contrast-to-noise ratio (CNR) and resolution is examined based on the object dimensions in the macroscopic and microscopic regimes. This research shows that for microscopic samples the conventional scaling laws are no longer effective and the CNR does not counter-propagate in the same manner as the resolution. To our knowledge, a deviation in CNR scaling on speckle size is observed for the first time in the field of microscopic ghost imaging. This result was verified using two different sample shapes. In addition, numerical analysis revealed that the noise of the photodiode is a limiting factor for the CNR. Based on these findings, the conditions for identifying the parameter set that maximizes the CNR and provides high resolution images was defined, which achieving high-quality microscopic ghost images. ? 2019 Optical Society of America under the terms of the OSA Open Access Publishing AgreementAccession Number: 20194707727115 -
Record 489 of
Title:Elastic bending of variable curvature mirrors: Validation of a simplified analytical method
Author(s):Xie, Xiaopeng(1,2); Hugot, Emmanuel(3); Li, Chuang(1); Xu, Liang(1); Lemared, Sabri(3); Liu, Meiying(1); Fan, Xuewu(1); Zhao, Hui(1)Source: Applied Optics Volume: 58 Issue: 26 DOI: 10.1364/AO.58.007121 Published: September 10, 2019Abstract:This work explores the variable curvature mirror’s (VCM) elastic bending rules through modeling it as a thin elastic plate with an exponential thickness distribution actuated with a uniform pressure under simply supported boundary conditions. By using the small-parameter method, the general analytical expression of a plate’s deflection is worked out. The results calculated by the analytical solution are compared to the finite element analysis of a VCM model with the same specific parameters. We demonstrate that the two have a good correlation with the each other. This analytical solution is an effective way to predict a VCM’s deflection. ? 2019 Optical Society of America.Accession Number: 20193807459654 -
Record 490 of
Title:A single gold metasurface design capable of generating vortex beams with different topological charges
Author(s):Zhang, Xiaodong(1,2,3); Kong, Depeng(1,2); Yuan, Yuan(1,2); Mei, S.E.N.(1,2); Wang, Lili(1,2)Source: Optoelectronics and Advanced Materials, Rapid Communications Volume: 13 Issue: 11-12 DOI: null Published: November-December 2019Abstract:A simple approach is proposed to generate vortex beams using a metasurface composed of 31×31 array of sub-wavelength sized rectangular apertures in a ultrathin gold film. It operates at broadband (800~2000 nm) covering telecom wavelengths, topological charges of resultant vortex beams are from-4 to +4 and weight coefficient of the desired charge exceeds 0.95 under the incidence of circularly polarized light. Simulation results show that this design is logically coincidence. The designed metasurface also has advantage of favorable fabrication tolerance and may be a potential candidate in integrated optical communication system in future. ? 2019, National Institute of Optoelectronics. All rights reserved.Accession Number: 20203409069318 -
Record 491 of
Title:Nonmechanical two-user tracking method of space-polarization division using the liquid crystal optical phased array
Author(s):Guo, Hongru(1); Wang, Xiangru(1); Liu, Xiaopeng(2); He, Xiaoxian(1); Wu, Liang(2); Huang, Xinning(3); Xie, Xiaoping(3); Tan, Qinggui(4); Cao, Jie(5); Xie, Wen(6)Source: Optics Communications Volume: 447 Issue: DOI: 10.1016/j.optcom.2019.05.005 Published: 15 September 2019Abstract:We propose a two-user tracking method called space-polarization division to enable simultaneously multiple terminals tracking in the field of free space laser communications. This method is based on the nonmechanical beam steering device of liquid crystal optical phased array, which is capable of continuously laser beam pointing and multiple beams generating. An optical architecture of two-user access is presented to show a one-to-two communication link between the relay satellite terminal and user terminals. The two-user tracking strategy is modeled numerically and experimentally verified to show the feasible and agile two-user tracking with a good accuracy less than 50 microradians which meet the requirements of coarse tracking. ? 2019 Elsevier B.V.Accession Number: 20192006930191 -
Record 492 of
Title:Third harmonic generation in highly-doped silica glass micro ring resonator
Author(s):Li, Yuhua(1); Zhao, Jianguo(2); Davidson, Roy(2); Wang, Leiran(3); Wang, Shao Hao(4); Little, Brent E.(3); Chu, Sai T.(1)Source: Optics InfoBase Conference Papers Volume: Part F140-CLEO_Europe 2019 Issue: DOI: null Published: 2019Abstract:Visible emissions in microresonators by high-harmonic generation with input at telecom wavelengths have been demonstrated in a number of platforms, such as silica [1], silicon photonic-crystal [2], and silicon nitride [3]. In this work, we report the first observation of green emission by third-harmonic generation (THG) in a highly doped glass micro ring-resonator and show that the measured pump and emission dependence agrees with the theoretical prediction of the THG process. The ring resonator used in the experiment is composed of highly-doped silica glass with core refractive index of 1.7 and a radius of 135 μm. With waveguide dimensions of 2μm × 1μm, it corresponds to a free-spectral range (FSR) of 201.5 GHz. Fig. 1(a) shows the effective index mismatch between the pump mode and the various THG modes. With a measured Q factor of ~5.5×105 at 1550 nm and small mode volume, it contributes to the high conversion efficiency of the THG where the threshold pump power for THG is approximately 2.4 mW. The captured green emission from directly above the ring resonator (insert of Fig. 1(b)) when pumped with a continuous-wave (CW) laser at 1550 nm centred at 516.7 nm demonstrates that the green light is attributed to the THG process. ? 2019 IEEEAccession Number: 20202008661122