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Determination of hyperfine splittings and Landé gJ factors of 5s2S1/2 and 5p2P1/2,3/2 states of Cd+111,113 for microwave frequency standards

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Physical Review A 2022年第1期106卷 012821-012821页

作者： J. Z. Han R. Si H. R. Qin N. C. Xin Y. T. Chen S. N. Miao C. Y. Chen J. W. Zhang L. J. Wang State Key Laboratory of Precision Measurement Technology and Instruments Key Laboratory of Photon Measurement and Control Technology of Ministry of Education Department of Precision Instrument Tsinghua University Beijing 100084 China Shanghai EBIT Lab Key Laboratory of Nuclear Physics and Ion-Beam Application Institute of Modern Physics Department of Nuclear Science and Technology Fudan University Shanghai 200433 China Department of Physics Tsinghua University Beijing 100084 China

Regarding microwave frequency standards based on trapped ions, we report on the determination of the hyperfine splittings and the Landé gJ factors of Cd+111,113. The hyperfine splittings and Landé gJ factors of the 5s2S1/2 and 5p2P1/2,3/2 states of Cd+111,113 are calculated using the multiconfiguration Dirac-Hartree-Fock scheme. Furthermore, the hyperfine splittings of the 5p2P3/2 state of Cd+111,113 are derived based on the laser-induced fluorescence spectroscopy. The Cd+ ions are confined in a linear Paul trap and sympathetically cooled by laser-cooled Ca+ ions. The calculated values and the derived values are cross-checked, thereby guaranteeing the reliability of our results. The results provided in this paper can improve the signal-to-noise ratio of the clock transition and the accuracy of the second-order Zeeman shift correction, thus further improving the stability and accuracy of the microwave frequency standards based on trapped Cd+111,113 ions.

关键词： Atomic & molecular structure Atomic spectra Atomic, optical & lattice clocks Cooling & trapping Electron correlation calculations for atoms & ions Fine & hyperfine structure Optical pumping

Dynamic dehydration observation based on terahertz in-line digital holography

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Dynamic dehydration observation based on terahertz in-line d...

Digital Holography and Three-Dimensional Imaging, DH 2015

作者： Rong, Lu Latychevskaia, Tatiana Zhou, Xun Huang, Haochong Wang, Dayong Wang, Yunxin College of Applied Sciences Beijing University of Technology No. 100 Pingleyuan Rd Beijing100124 China Beijing Engineering Research Center of Precision Measurement and Control Technology and Instruments Beijing University of Technology No. 100 Pingleyuan Rd Beijing100124 China Physics Department University of Zurich Winterthurerstrasse 190 Zurich8057 Switzerland Reserach Center of Laser Fusion CAEP Mianyang621900 China Terahertz Research Center CAEP Mianyang621900 China

We report here terahertz digital holography for dehydration observation of fresh-water algae. Temporal sequence of absorption images were obtained at the temporal resolution of 1 frame/sec.

ISBN: (纸本)9781557529916

We report here terahertz digital holography for dehydration observation of fresh-water algae. Temporal sequence of absorption images were obtained at the temporal resolution of 1 frame/sec.

关键词： Dehydration

Roundness measurement in Spring Clamps based on a Novel Particle Swarm Optimization

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Roundness Measurement in Spring Clamps based on a Novel Part...

SCIEI 2014 Hong Kong Conference

作者： Xia Zhu Ren-wen Chen the State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics & Astronautics Measurement and Testing Technology & Instruments at State Key Laboratory of Mechanics and Control of Mechanical Structures NUAA State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics & Astronautics

One important inspection step in spring clamp is the determination of roundness *** the circle from digital images is very important in computer *** view of clamp and the geometrical characteristics of the circular,a new optimization algorithm was proposed to extract image *** extraction is equivalent to the points search and extraction in the *** search strategy is an optimization *** swarm optimization(PSO) is an effective global optimization ***-tuning parameters were achieved by using the improved particle swarm algorithm along with the geometric properties of the round,and detected effective point of band image so as to realize the recognition and detection of the circle.A large number of tests show that the proposed algorithm has good robustness and precision compared with the existing PSO *** main advantages of this method as compared with other methods include the considerable lower cost of facilities,easier maintenance and getting more accurate.

关键词： image spring swarm Roundness measurement in Spring Clamps based on a Novel Particle Swarm Optimization Spring Swarm

Research on Image Enhancement Method of Impact Damage of Carbon Fiber Reinforced Plastics Based on Infrared Sequence Images

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Research on Image Enhancement Method of Impact Damage of Car...

China Instrument and control Society (ACCIS), Academic Conference of

作者： Lihua Yuan Jianlong Liu Yishun Jin Key Laboratory of Nondestructive Testing (Ministry of Education) Nanchang Hangkong University Nanchang China Department of Measurement and Control Technology and Instruments School of Testing and Optoelectronic Engineering Nanchang Hangkong University Nanchang China

ISBN: (数字)9798350350326

ISBN: (纸本)9798350350333

The long pulse reflection method was used to detect the internal defects of the impact damage of carbon fiber reinforced plastics. Under the excitation of halogen lamp, the thermal imager synchronized the change of the surface temperature field of the test block and stored in the form of infrared sequence images. In order to improve the imaging quality of infrared images, a variety of infrared sequence image processing algorithms were studied, including polynomial fitting method, robust principal component analysis, independent component analysis and pulse phase method. The performance of each sequence image processing algorithm was quantitatively analyzed by using peak signal-to-noise ratio, root mean square error and entropy. The results show that the image quality evaluation indexes of these four sequence image processing algorithms are better than those of the original image, indicating that these four algorithms are suitable for enhancing the infrared thermal image of impact damage. In particular, the peak signal-to-noise ratio and entropy of the robust principal component analysis enhancement results are optimal among all the processing methods, and the root mean square error is suboptimal.

关键词： PSNR Process control Independent component analysis Fiber reinforced plastics Entropy Polynomials Image sequences Carbon Root mean square Principal component analysis

Watt-level, kHz pulsed ASE source with pulse-width close to round-trip time based on Nd:GdVO4 bounce geometry

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arXiv 2018年

作者： Guo, Rui Nie, Mingming Gong, Mali State Key Laboratory of Precision Measurement and Instruments Tsinghua University Beijing100084 China Key Laboratory of Photon Measurement and Control Technology Ministry of Education Tsinghua University Beijing100084 China State Key Laboratory of Tribology Tsinghua University Beijing100084 China

We demonstrate a watt-level, kHz nanosecond-pulse ASE source with its pulse-width being close to its round-trip time. The ASE uses a Nd:GdVO4 high gain bounce geometry structure without an output coupler. Using an EOQ (electro-optics Q-switch) device with high extinction-ratio, the pulse-width reaches 2.28, 1.73 and 1.17 ns under three effective cavity lengths, respectively. All these pulse-widths are close to the round-trip time of the corresponding effective cavity lengths. With the pulse-width being 1.17 ns, maximum output energy of 120 μj and peak power of 100 kW are achieved. This study offers a convenient method to obtain high-peak-power short pulses, comparing with cavity-dumping method. Copyright © 2018, The Authors. All rights reserved.

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Short pulse close to round-trip time generated by cavityless high gain Nd:GdVO4 bounce geometry

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arXiv 2019年

作者： Rui, G.U.O. Mingming, N.I.E. Qiang, L.I.U. Gong, Mali State Key Laboratory of Precision Measurement and Instruments Tsinghua University Beijing100084 China Key Laboratory of Photon Measurement and Control Technology Ministry of Education Tsinghua University Beijing100084 China State Key Laboratory of Tribology Tsinghua University Beijing100084 China

In this paper, laser pulses with pulse-widths approach to the round-trip time are generated by utilizing a cavityless high gain Nd:GdVO4 bounce geometry. By adopting an EOQ (electro-optics Q-switch), pulse-widths of 1.36 ns, 1.82 ns, and 2.39 ns are achieved at three effective cavity lengths respectively. All these pulse-widths are close to the round-trip time of corresponding effective cavity lengths. Moreover, the output power reaches watt-level and the repetition rate is kHz-level, meanwhile the M2 factor is less than 1.3. Spectrally, the laser has a continuous spectrum with 10 dB linewidth of 0.2 nm. Copyright © 2019, The Authors. All rights reserved.

关键词：

Acoustic-optic Q-switched cavityless weak-feedback laser based on Nd:GdVO4 bounce geometry

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arXiv 2019年

作者： Rui, G.U.O. Qiang, L.I.U. Gong, Mali State Key Laboratory of Precision Measurement and Instruments Tsinghua University Beijing100084 China Key Laboratory of Photon Measurement and Control Technology Ministry of Education Tsinghua University Beijing100084 China State Key Laboratory of Tribology Tsinghua University Beijing100084 China

An AOQ (acoustic-optic Q-switched) laser with cavityless weak-feedback configuration is demonstrated based on a Nd:GdVO4 bounce geometry. The laser can operate at a repetition up to 500 kHz with the output power above 4W. The pulse-width at 100 kHz reaches 5.2 ns, which is 4.3 times the round-trip time. A theory of Q-switched cavityless weak-feedback laser is proposed for the first time, to our best knowledge. This theory is very suitable for analyzing short pulses comparable to round-trip time. By utilizing the theory, simulation is implemented for our experimental conditions. The consistence between the simulation and the experimental results proves the validity of our theory. Copyright © 2019, The Authors. All rights reserved.

关键词： Flow control

A continuous cold rubidium atomic beam with enhanced flux and tunable velocity

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arXiv 2023年

作者： Wang, Shengzhe Meng, Zhixin Yan, Peiqiang Liu, Yuanxing Feng, Yanying State Key Laboratory of Precision Measurement Technology and Instruments Tsinghua University Beijing China Department of Precision Instrument Tsinghua University Beijing China Beijing Institute of Aerospace Control Devices Beijing China

We present a cold atomic beam source based on a two-dimensional (2D)+ magneto-optical trap (MOT), capable of generating a continuous cold beam of 87Rb atoms with a flux up to 4.3 × 109 s−1, a mean velocity of 10.96(2.20) m/s, and a transverse temperature of 16.90(1.56) πK. Investigating the influence of high cooling laser intensity, we observe a significant population loss of atoms to hyperfine-level dark states. To account for this, we employ a multiple hyperfine level model to calculate the cooling efficiency associated with the population in dark states, subsequently modifying the scattering force. Simulations of beam flux at different cooling and repumping laser intensities using the modified scattering force are in agreement with experimental results. Optimizing repumping and cooling intensities enhances the flux by 50%. The influence of phase modulation on both the pushing and cooling lasers is experimentally studied, revealing that the mean velocity of cold atoms can be tuned from 9.5 m/s to 14.6 m/s with a phase-modulated pushing laser. The versatility of this continuous beam source, featuring high flux, controlled velocity, and narrow transverse temperature, renders it valuable for applications in atom interferometers and clocks, ultimately enhancing bandwidth, sensitivity, and signal contrast in these devices. © 2023, CC BY.

关键词： Atoms

Optical meta-waveguides for integrated photonics and beyond

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Light(Science & Applications) 2021年第12期10卷 2263-2306页

作者： Yuan Meng Yizhen Chen Longhui Lu Yimin Ding Andrea Cusano Jonathan A.Fan Qiaomu Hu Kaiyuan Wang Zhenwei Xie Zhoutian Liu Yuanmu Yang Qiang Liu Mali Gong Qirong Xiao Shulin Sun Minming Zhang Xiaocong Yuan Xingjie Ni State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua University100084 BeijingChina Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing and School of Information Science and TechnologyFudan UniversityShanghai 200433China School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China Department of Electrical Engineering Pennsylvania State UniversityUniversity ParkPA 16802USA Optoelearonic Division Department of EngineeringUniversity of Sannio1-82100 BeneventoItaly Department of Electrical Engineering Stanford UniversityStanfordCA 94305USA Nanophotonics Research Centre Shenzhen Key Laboratory of Micro-Scale Optical Information TechnologyShenzhen UniversityShenzhen 518060China Key Laboratory of Photonic Control Technology Ministry of EducationTsinghua University100084 BeijingChina Yiwu Research Institute of Fudan University Chengbei RoadYiwu City 322000 ZhejiangChina Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074 HubeiChina

The growing maturity of nanofabrication has ushered massive sophisticated optical structures available on a photonic *** integration of subwavelength-structured metasurfaces and metamaterials on the canonical building block of optical waveguides is gradually reshaping the landscape of photonic integrated circuits,giving rise to numerous metawaveguides with unprecedented strength in controlling guided electromagnetic ***,we review recent advances in meta-structured waveguides that synergize various functional subwavelength photonic architectures with diverse waveguide platforms,such as dielectric or plasmonic waveguides and optical *** results and representative applications are comprehensively *** physical models with explicit design tutorials,either physical intuition-based design methods or computer algorithms-based inverse designs,are cataloged as *** highlight how meta-optics can infuse new degrees of freedom to waveguide-based devices and systems,by enhancing light-matter interaction strength to drastically boost device performance,or offering a versatile designer media for manipulating light in nanoscale to enable novel *** further discuss current challenges and outline emerging opportunities of this vibrant field for various applications in photonic integrated circuits,biomedical sensing,artificial intelligence and beyond.

关键词： waveguides waveguide beyond