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Focusing of high polarization order axially-symmetric polarized beams

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Chinese Optics Letters 2009年第10期7卷 938-940页

作者：周哲海谭峭峰金国藩 State Key Laboratory of Precision Measurement Technology and Instruments Tsinghua University Department of Optical Information Science & Technology Beijing Information Science & Technology University

We study the high numerical aperture focusing properties and typical applications of axially-symmetric polarized beams （ASPBs） with high polarization orders. We calculate the field distribution near focus of an aplanatic system for incident ASPBs with different polarization orders and initial azimuthal angles, and based on the simulation results, we find some unique focusing properties of the beams, such as ever on-axis energy null, strong longitudinal field, and flowerlike intensity distribution at focus. In addition, we can manipulate the three-dimensional （3D） focused field distribution flexibly by use of diffractive optical elements （DOEs）, which will give rise to some interesting applications, and we also discuss possible applications and present an example of a 3D optical chain at last.

关键词： particle beams Polarization

Deep silicon grating as high-extinction-ratio polarizing beam splitter

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Chinese Optics Letters 2009年第4期7卷 325-328页

作者：冯吉军周常河王博郑将军 Information Optics Lab Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

A deep binary silicon grating as high-extinction-ratio reflective polarizing beam splitter （PBS） at the wavelength of 1550 nm is presented. The design is based on the phenomenon of total internal reflection （TIR） by using the rigorous coupled wave analysis （RCWA）. The extinction ratio of the rectangular PBS grating can reach 2.5~105 with the optimum grating period of 397 nm and groove depth of 1.092 μm. The efficiencies of TM-polarized wave in the 0th order and TE-polarized wave in the -1st order can both reach unity at the Littrow angle. Holographic recording technology and inductively coupled plasma （ICP） etching could be used to fabricate the silicon PBS grating.

关键词： Inductively coupled plasma Optical instruments particle beams Prisms Refractive index

One-dimensional Doppler laser collimation of chromium beam with a novel pre-collimating scheme

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Chinese Optics Letters 2008年第10期6卷 782-784页

作者：张宝武李同保马艳 Department of Physics Tongji UniversityShanghai 200092

A novel pre-collimating scheme in laser-focused chromium （Cr） atomic deposition is presented. It consists of three apertures, which are one main pre-collimating aperture at centre and two probing apertures with uniform dimension at both sides of the central one. The calculations show that the Cr atomic beam is divided into three parts accordingly after going through this scheme, and the full-width at half-maximum （FWHM） of each part decreases while the peak value increases after one-dimensional （1D） Doppler laser collimation, subsequently. Compared with that before laser collimation, the central part does not have displacement, but each part of the other two has the same displacement to the centre after laser collimation. These phenomena which are agreed with experiment prove that the novel pre-collimating scheme is a feasible means to solve the problem which we cannot observe the collimation of Cr atomic beam after substrate in laser-focused deposition with a pre-collimating scheme of only one aperture, because the atoms will be obstructed completely by the substrate.

关键词： Atomic beams Atomic physics Atoms Chromium particle beams

Adiabatic Passage Based on the Calcium Active Optical Clock

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Chinese Physics Letters 2010年第7期27卷 105-107页

作者：解晓鹏庄伟陈景标 Institute of Quantum Electronics and State Key Laboratory of Advanced Optical Communication System & Network School of Electronics Engineering & Computer Science Peking University Beijing 100871

We propose a new application of the optical adiabatic passage effect for the excitation of a thermal atomic beam, which will be used in the calcium active optical clock to produce population inversion. A comparison between the optical adiabatic passage effect and the Rabi π pulse is investigated, 99% of the calcium atoms in the atomic beam that has a wide velocity distribution will be excited to the upper state for population inversion using the adiabatic passage, while 76% at most will be excited to the excited state using the π pulse with suitable parameters.

关键词： ATOMIC beams OPTICAL properties NUCLEAR excitation MATRIX inversion CALCIUM particle beams

Theoretical Research on a D-Band Traveling Wave Extended Interaction Amplifier

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Chinese Journal of Electronics 2024年第6期33卷 1487-1491页

作者： Zhongtao CUI Xuesong YUAN Xiaotao XU Dongrui CHEN Yifan ZU Matthew Thomas Cole Qingyun CHEN Yang YAN Terahertz Science and Technology Key Laboratory of Sichuan Province School of Electronic Science and EngineeringUniversity of Electronic Science and Technology of China Department of Electronic and Electrical Engineering University of Bath

A traveling-wave, extended interaction amplifier is herein investigated for use in millimeter-wave and terahertz amplification sources. By placing engineered extended interaction cavities between the traveling wave structures, higher gain is obtained with a shorter high frequency circuit, compared with conventional traveling wave tubes architectures. The bandwidth of the device is significantly increased relative to extended interaction klystrons. A Dband beam wave interaction circuit of 26 mm long has been designed. particle-in-cell simulations at 21.5-kV operating voltage, 0.3-A beam current, and 5-mW input power show that the maximum output power reaches 351 W, with a gain of 48.4 dB and 3-dB bandwidth of 1.42 GHz.

关键词： particle beams Millimeter wave circuits Traveling wave tubes Power amplifiers Bandwidth Voltage Terahertz radiation Gain Power generation Magnetic circuits

Proposal of an Ultracompact Triplexer Using Photonic Crystal Waveguide with an Air Holes Array

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Chinese Physics Letters 2010年第8期27卷 84-87页

作者：何灵娟徐旭明刘念华于天宝方利广廖清华 Department of Physics Nanchang University Nanchang 330031 Institute for Advanced Study Nanchang University Nanchang 330031 State Key Laboratory on Integrated Optoelectronics Institute of Semiconductors Chinese Academy of Sciences Beijing 100083

We propose an ultracompact triplexer based on a shift of the cutoff frequency of the fundamental mode in a planar photonie crystal waveguide （PCW） with a triangular lattice of air holes. The shift is realized by modifying the radii of the border holes adjacent to the PCW core. Some defect holes are introduced to control the beam propagation. The numerical results obtained by the finite-difference time-domain method show that the presented triplexer can separate three specific wavelengths, i.e. 1310, 1490 and 1550nm with the extinction ratios higher than -18 dB. The designed device with a size as compact as 12 μm × 6.5μ m is feasible for the practical application, and can be utilized in the system of fiber to the home.

关键词： CRYSTAL optics OPTICAL waveguides CRYSTAL lattices particle beams FINITE differences TIME-domain analysis

A New High-Spin Level Scheme of ^128I

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Chinese Physics Letters 2010年第8期27卷 58-61页

作者：王海霞张玉虎丁兵周小红张宁涛柳敏良马英君 Y. Sasakiz K. Yamada H. Ohshima S. Yokose M. Ishizuka T. Komatsubara K. Furuno Insititute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 Graduate School of the Chinese Academy of Sciences Beijing 100049 Department of Physics Jilin University Changehun 130021 Institute of Physics and Tandem Accelerator Center University of Tsukuba Ibaraki 305-0006 Japan

High-spin states in the beam energies. A new and 72 γ transitions odd-odd nucleus ^128I are investigated via the ^124 Sn（^7 Li,3n）^128 I reaction at 28 and 32 Me V level scheme of 12sI is established up to high-spin states at I^π = 16, including 48 levels The present level scheme is largely different from the one in a recent publication due to identification of several doublet and triplet γ transitions and their proper placements in the level scheme. The high-spin level structure exhibits no obvious collective properties and is possibly associated with two and multi-quasiparticle configurations.

关键词： ENERGY levels (Quantum mechanics) PHASE transformations (Physics) NUCLEAR reactions particle beams QUASIparticleS (Physics)

Tunneling-induced π-phase shift with a single-photon signal field in asymmetric double quantum wells

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Chinese Optics Letters 2009年第10期7卷 886-890页

作者：郭洪菊汪丽春钮月萍金石琦龚尚庆 State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences Graduate University of Chinese Academy of Sciences

A theoretical investigation is carried out into the cross phase modulation （XPM） in an asymmetric double A1GaAs/GaAs quantum wells structure with a common continuum. It is found that, combining resonant tunneling-induced transparency and constructive interference in the third-order Kerr effect, a giant XPM can be achieved with vanishing linear and nonlinear absorptions, accompanied by the velocities of the probe and signal fields being matched. Furthermore, this giant XPM could induce a π-phase shift at a single-photon level which is favorable for the applications in two-qubit quantum logic gates.

关键词： Kerr magnetooptical effect Magnetic field effects particle beams Phase shift Photons Quantum theory Wind tunnels

Correction of ultraviolet single photon counting image distortion

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Chinese Optics Letters 2008年第9期6卷 661-664页

作者：张兴华赵宝升缪震华李伟朱香平刘永安邹玮 State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision MechanicsChinese Acaderny of Sciences State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision MechanicsChinese Academy of Sciences

Single photon counting imaging technology has been widely used in space environment detection, astronomy observation, nuclear physics, and ultraweak bioluminescence. However, the distortion of the single photon counting image will badly affect the measurement results. Therefore, the correction of distortion for single photon counting image is very significant. Ultraviolet single photon imaging system with wedge and strip anode is introduced and the influence factor leading to image distortion is analyzed. To correct original distorted image, three different image correction methods, namely, the physical correction, the global correction, and the local correction, are applied. In addition, two parameters, i.e., the position index and the linearity index, are defined to evaluate the performance of the three methods. The results suggest that the correction methods can improve the quality of the initial image without losing gray information of each counting light spot. And the local correction can provide the best visual inspections and performance evaluation among the three methods.

关键词： Image reconstruction Light measurement Nuclear physics Optoelectronic devices particle beams Photons Visual communication