2020

• Record 37 of
  
  Title:Lensless computational imaging technology using deep convolutional network
  
  Author(s):Chen, Peidong(1,2); Su, Xiuqin(1); Liu, Muyuan(1,2); Zhu, Wenhua(1,2)
  Source: Sensors (Switzerland)  Volume: 20  Issue: 9  DOI: 10.3390/s20092661  Published: May 1, 2020  
  Abstract:Within the framework of Internet of Things or when constrained in limited space, lensless imaging technology provides effective imaging solutions with low cost and reduced size prototypes. In this paper, we proposed a method combining deep learning with lensless coded mask imaging technology. After replacing lenses with the coded mask and using the inverse matrix optimization method to reconstruct the original scene images, we applied FCN-8s, U-Net, and our modified version of U-Net, which is called Dense-U-Net, for post-processing of reconstructed images. The proposed approach showed supreme performance compared to the classical method, where a deep convolutional network leads to critical improvements of the quality of reconstruction. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
  Accession Number: 20202008646790
• Record 38 of
  
  Title:Fe3O4 nanoparticle-enabled mode-locking in an erbium-doped fiber laser
  
  Author(s):Li, Xiaohui(1); Peng, Jiajun(1); Liu, Ruisheng(1,2); Liu, Jishu(1); Feng, Tianci(1); Qyyum, Abdul(1); Gao, Cunxiao(2); Xue, Mingyuan(2); Zhang, Jian(2)
  Source: Frontiers of Optoelectronics  Volume: 13  Issue: 2  DOI: 10.1007/s12200-020-1057-4  Published: June 1, 2020  
  Abstract:In this paper, we have proposed and demonstrated the generation of passively mode-locked pulses and dissipative soliton resonance in an erbium-doped fiber laser based on Fe3O4 nanoparticles as saturable absorbers. We obtained self-starting mode-locked pulses with fundamental repetition frequency of 7.69 MHz and center wavelength of 1561 nm. The output of a pulsed laser has spectral width of 0.69 nm and pulse duration of 14 ns with rectangular pulse profile at the pump power of 190 mW. As far as we know, this is the firsttimethatFe3O4 nanoparticles have been developed as low-dimensional materials for passive mode-locking with rectangular pulse. Our experiments have confirmed that Fe3O4 has a wide prospect as a nonlinear photonics device for ultrafast fiber laser applications. [Figure not available: see fulltext.] © 2020, Higher Education Press.
  Accession Number: 20202908941737
• Record 39 of
  
  Title:Accelerating triangle-like singular beam
  
  Author(s):Yan, Shaohui(1,2); Li, Manman(1,2); Zhou, Yuan(1,2); Zhang, Yanan(1,2); Yao, Baoli(1,2)
  Source: Journal of the Optical Society of America A: Optics and Image Science, and Vision  Volume: 37  Issue: 12  DOI: 10.1364/JOSAA.408431  Published: December 1, 2020  
  Abstract:We demonstrate a type of singular beam that accelerates along a parabolic trajectory and has a cross-section intensity pattern exhibiting a dark central region surrounded by multiple rings with the innermost (main) ring resembling an equilateral triangle. The key to creating such beams is to replace the standard triangle with a rounded one, made up of six circular arcs connected end to end. The individual input phase mask for each arc can be analytically computed, and the whole input phase mask for the beam is thus obtained by piecing together these individual phases. Furthermore, the continuity of field forces of these triangle-like modes is discrete; that is, an index similar to the topological charge of vortex beams arises. Numerical results show that the energy flow in the beam’s cross section circulates around the dark center along the triangle-like main ring, suggesting a possible application in orbiting particles along an irregular path. © 2020 Optical Society of America
  Accession Number: 20204909569034
• Record 40 of
  
  Title:Digital Simulation of Topological Matter on Programmable Quantum Processors
  
  Author(s):Mei, Feng(1,2); Guo, Qihao(3); Yu, Ya-Fei(4); Xiao, Liantuan(1,2); Zhu, Shi-Liang(5,6); Jia, Suotang(1,2)
  Source: arXiv  Volume:   Issue:   DOI: null  Published: March 12, 2020  
  Abstract:Quantum circuits play a crucial role in quantum information processing and have been realized in various quantum computing platforms. Here, based on common single- and two-qubit elementary quantum gates, we theoretically propose and then experimentally demonstrate an approach to design topologically protected quantum circuits in which spin-orbital coupling and the related topological matter can be digitally simulated, and the hallmarks of topological matter, the edge states and the topological invariants can be directly measured. In particular, a low-depth topological quantum circuit is performed on both IBM and Rigetti quantum processors. In the experiments, we not only observe but also distinguish the 0 and π energy topological edge states through measuring the qubit excitation probability distribution at the output of the circuits. Copyright © 2020, The Authors. All rights reserved.
  Accession Number: 20200373601
• Record 41 of
  
  Title:Full-color optically-sectioned imaging by wide-field microscopy via deep-learning
  
  Author(s):Bai, Chen(1); Qian, Jia(1,2); Dang, Shipei(1,2); Peng, Tong(1); Min, Junwei(1); Lei, Ming(1); Dan, Dan(1); Yao, Baoli(1)
  Source: Biomedical Optics Express  Volume: 11  Issue: 5  DOI: 10.1364/BOE.389852  Published: May 1, 2020  
  Abstract:Wide-field microscopy (WFM) is broadly used in experimental studies of biological specimens. However, combining the out-of-focus signals with the in-focus plane reduces the signal-to-noise ratio (SNR) and axial resolution of the image. Therefore, structured illumination microscopy (SIM) with white light illumination has been used to obtain full-color 3D images, which can capture high SNR optically-sectioned images with improved axial resolution and natural specimen colors. Nevertheless, this full-color SIM (FC-SIM) has a data acquisition burden for 3D-image reconstruction with a shortened depth-of-field, especially for thick samples such as insects and large-scale 3D imaging using stitching techniques. In this paper, we propose a deep-learning-based method for full-color WFM, i.e., FC-WFM-Deep, which can reconstruct high-quality full-color 3D images with an extended optical sectioning capability directly from the FC-WFM z-stack data. Case studies of different specimens with a specific imaging system are used to illustrate this method. Consequently, the image quality achievable with this FC-WFM-Deep method is comparable to the FC-SIM method in terms of 3D information and spatial resolution, while the reconstruction data size is 21-fold smaller and the in-focus depth is doubled. This technique significantly reduces the 3D data acquisition requirements without losing detail and improves the 3D imaging speed by extracting the optical sectioning in the depth-of-field. This cost-effective and convenient method offers a promising tool to observe high-precision color 3D spatial distributions of biological samples. © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
  Accession Number: 20202008666797
• Record 42 of
  
  Title:Numerical analysis of light reflection and transmission in poly-disperse sea fog
  
  Author(s):Zhang, Chi(1); Zhang, Jianqi(1); Wu, Xin(1); Huang, Melin(1,2)
  Source: Optics Express  Volume: 28  Issue: 17  DOI: 10.1364/OE.400002  Published: August 17, 2020  
  Abstract:The presence of sea fog greatly affects both the reflected and transmitted detections when radiation propagates through targets and maritime backgrounds. Thus, the maritime target detections and the remote sensing in oceanic environments would be disturbed by the sea fog. In our work, a poly-disperse sea fog system is introduced. Such a sea fog layer comprises spherical water particles of different radii, where the radii are divided into eight radius regions. The attenuation, asymmetry factors, and absorption probabilities of the radiation interacting with sea fog particles in each radius region are computed using Mie theory. The scattering processes of the radiation in the poly-disperse sea fog layer are traced in our improved Monte Carlo (MC) simulation. This paper presents a new method (named "our method" hereafter) with the intention to provide more accurate calculations on the reflection and transmission when radiation propagates through poly-disperse sea fog media of two different refractive indices. Therein, we investigated the influence of liquid water contents and thicknesses of the poly-disperse sea fog layer on the reflectance and transmittance of the radiation. The results using our MC method compared with those using the previous MC method are also presented. Besides, with three different MC methods along with our method and the previous method, we also inspected how different MC methods affect the calculations of reflectance and transmittance, and it shows manifestation that our method has an advantage over the previous method. © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
  Accession Number: 20203809184702
• Record 43 of
  
  Title:Single-fiber computational endoscopic imaging
  
  Author(s):Ren, Liyong(1); Xu, Chengfang(2,3)
  Source: Optics InfoBase Conference Papers  Volume:   Issue:   DOI: null  Published: 2020  
  Abstract:By obtaining transmission matrix (TM) of multimode optical fiber (MMF) working in reflective mode, objects can be computationally reconstructed from their speckle fields. This method shows potential applications for wide-field and ultrathin single-fiber endoscopic imaging. © 2020 The Author(s)
  Accession Number: 20214511137888
• Record 44 of
  
  Title:Impact of third-order dispersion and three-photon absorption on mid-infrared time magnification via four-wave mixing in Si0.8Ge0.2 waveguides
  
  Author(s):Zheng, Aihu(1,2); Sun, Qibing(1,2); Wang, Leiran(1,2); Liu, Mulong(1,2); Zeng, Chao(1,2); Wang, Guoxi(1,2); Zhang, Lingxuan(1,2); Fan, Weichen(1,2); Zhao, Wei(1,2); Zhang, Wenfu(1,2)
  Source: Applied Optics  Volume: 59  Issue: 4  DOI: 10.1364/AO.379232  Published: February 1, 2020  
  Abstract:We investigate the influence of third-order dispersion of dispersive elements, three-photon absorption and free-carrier effects on mid-infrared time magnification via four-wave mixing (FWM) in Si0.8Ge0.2 waveguides. It is found that the magnified waveform is seriously distorted by these factors, and conversion efficiency is decreased, mainly because of nonlinear absorption. A time lens based on FWM in Si0.8Ge0.2 waveguides is proposed for time magnification of mid-infrared ultrashort pulses, in which the low-distortion, high-magnification in the time domain could be obtained by optimizing system parameters. These results make it possible to analyze the transient dynamic process through oscilloscopes and detectors with gigahertz bandwidth and have important applications in ultrafast process analysis, optical pulse sampling, and optical communications. © 2020 Optical Society of America.
  Accession Number: 20200508115511
• Record 45 of
  
  Title:Rapid tilted-plane Gerchberg-Saxton algorithm for holographic optical tweezers
  
  Author(s):Cai, Yanan(1,2); Yan, Shaohui(1); Wang, Zhaojun(1); Li, Runze(1); Liang, Yansheng(1); Zhou, Yuan(1,2); Li, Xing(1,2); Yu, Xianghua(1); Lei, Ming(1); Yao, Baoli(1,2)
  Source: Optics Express  Volume: 28  Issue: 9  DOI: 10.1364/OE.389897  Published: April 27, 2020  
  Abstract:Benefitting from the development of commercial spatial light modulator (SLM), holographic optical tweezers (HOT) have emerged as a powerful tool for life science, material science and particle physics. The calculation of computer-generated holograms (CGH) for generating multi-focus arrays plays a key role in HOT for trapping of a bunch of particles in parallel. To realize dynamic 3D manipulation, we propose a new tilted-plane GS algorithm for fast generation of multiple foci. The multi-focal spots with a uniformity of 99% can be generated in a tilted plane. The computation time for a CGH with 512×512 pixels is less than 0.1 second. We demonstrated the power of the algorithm by simultaneously trapping and rotating silica beads with a 7×7 spots array in three dimensions. The presented algorithm is expected as a powerful kernel of HOT. © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
  Accession Number: 20202108694776
• Record 46 of
  
  Title:Influence of amplified spontaneous emission on laser linewidth in a fiber amplifier
  
  Author(s):Xue, Mingyuan(1,2); Gao, Cunxiao(1); Niu, Linquan(1); Zhu, Shaolan(1); Sun, Chuandong(1)
  Source: Applied Optics  Volume: 59  Issue: 8  DOI: 10.1364/AO.383507  Published: March 10, 2020  
  Abstract:Spectral broadening due to amplified spontaneous emission (ASE) in a fiber amplifier is experimentally and theoretically investigated in this paper. By measuring and analyzing the variation in linewidth and noise of the fiber amplifier, the influence of ASE on laser linewidth is studied. The analysis shows that the ASE will cause broadening of the laser linewidth as noise, and the noise is introduced as an additive term rather than a multiplicative one. © 2020 Optical Society of America
  Accession Number: 20201108290600
• Record 47 of
  
  Title:Azimuthally phase-shifted Fibonacci zone plate
  
  Author(s):Rafighdoost, Jila(1); Zhou, Yuan(1,2); Li, Xing(1,2); Yan, Shaohui(1); Zhou, Meiling(1); Yao, Baoli(1,2)
  Source: Journal of the Optical Society of America B: Optical Physics  Volume: 37  Issue: 12  DOI: 10.1364/JOSAB.402866  Published: December 1, 2020  
  Abstract:We present a novel and straightforward Fibonacci lens, which is created by binarizing and adding a spiral phase to its radial phase function. It is shown that this new element yields a pair of petal-like modes due to several segments of the Fibonacci lens, where each segment is phase shifted by π compared to its adjacent segment. Also, the generated petals have highly controllable rotation, and their locations are adjustable, in which their focal distance ratio is equal to a mathematical parameter of the so-called golden ratio. Also, by changing the topological charge, an arbitrary even number of petals is obtained. © 2020 Optical Society of America
  Accession Number: 20204909573071
• Record 48 of
  
  Title:Investigations on Average Fluorescence Lifetimes for Visualizing Multi-Exponential Decays
  
  Author(s):Li, Yahui(1,2,3); Natakorn, Sapermsap(4); Chen, Yu(4); Safar, Mohammed(1); Cunningham, Margaret(1); Tian, Jinshou(2,3); Li, David Day-Uei(1)
  Source: Frontiers in Physics  Volume: 8  Issue:   DOI: 10.3389/fphy.2020.576862  Published: October 16, 2020  
  Abstract:Intensity- and amplitude-weighted average lifetimes, denoted as τI and τA hereafter, are useful indicators for revealing Förster resonance energy transfer (FRET) or fluorescence quenching behaviors. In this work, we discussed the differences between τI and τA and presented several model-free lifetime determination algorithms (LDA), including the center-of-mass, phasor, and integral equation methods for fast τI and τA estimations. For model-based LDAs, we discussed the model-mismatch problems, and the results suggest that a bi-exponential model can well approximate a signal following a multi-exponential model. Depending on the application requirements, suggestions about the LDAs to be used are given. The instrument responses of the imaging systems were included in the analysis. We explained why only using the τI model for FRET analysis can be misleading; both τI and τA models should be considered. We also proposed using τA/τI as a new indicator on two-photon fluorescence lifetime images, and the results show that τA/τI is an intuitive tool for visualizing multi-exponential decays. © Copyright © 2020 Li, Natakorn, Chen, Safar, Cunningham, Tian and Li.
  Accession Number: 20233514654860