检索结果-南通市图书馆

Linearly polarized operation of Yb-doped fiber laser by Brewster's angle-polished fiber end

在线全文

学校读者我要写书评

暂无评论

Chinese Optics Letters 2010年第2期8卷 184-186页

作者：刘侠杜松涛周军董景星魏运荣袁志军王炜苏宙平楼祺洪 Shanghai Key laboratory of All Solid-State Laser and Applied Techniques Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences Graduate University of Chinese Academy of Sciences School of Science Jiangnan University

A new method to obtain linear polarization operation by Brewster＇s angle-polished fiber end is demonstrated. By using the special polarization operation technique together with introducing a narrow-linewidth fiber grating into the laser cavity, a cladding-pumped linear polarization and single-transverse-mode （M2 〈 1.1） Yb-doped fiber laser with narrow linewidth whose full-width at half-maximm （FWHM） is less than 0.2 nm, is obtained in a simple configuration. The output power is up to 10 W which is continuous- wave output at 1085 nm, and the slope efficiency is 63% with respect to the coupled pump power and 75% with respect to the absorbed pump power, respectively. The measured 21-dB polarization extinction ratio does not degrade with the output power. The simplicity of such an approach is highly beneficial for a number of applications, including the use of a fiber laser for the nonlinear wavelength conversion （especially for the intracavity frequency doubling） and for the coherent and spectral beam combination.

关键词： Fibers Laser cladding Polarization Pumping (laser) Pumps Single mode fibers Solid state lasers Ytterbium

Grating imaging scanning lithography

在线全文

学校读者我要写书评

暂无评论

Chinese Optics Letters 2013年第8期11卷 11-13页

作者：俞斌贾伟周常河曹红超孙文婷 Information Optics laboratory Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences

We present a grating imaging scanning lithography system for the fabrication of large-sized gratings. In this technology, ±1-order diffractive beams are generated by a phase grating and selected by a spatial filter. Meanwhile, a 4f system enables the ±1-order diffractive beams to form a grating image with a clear jagged-edge boundary on the substrate. A high-precision two-dimensional （2D） mobile stage is used for complementary cyclical scanning, thereby effectively eliminating image stitching errors. The absence of such errors results in a seamless and uniform large-sized grating. Characterized by a simple structure, high energy use, and good stability, this lithography system is highly relevant to the high-speed and cost- effective production of large-sized gratings.

关键词： Errors Lithography

A New Type of Non-Noether Adiabatic Invariants for Disturbed Lagrangian Systems： Adiabatic Invariants of Generalized Lutzky Type

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2007年第9期24卷 2463-2466页

作者：罗绍凯 Institute of Mathematical mechanics and Mathematical Physics Zhejiang Sci-Tech University Hangzhou 310018 Key laboratory of Advanced Textile Materials and Manufacturing Technology (Ministry of Education) Zhejiang Sci-Tech University Hangzhou 310018

For a Lagrangian system with the action of small disturbance, the Lie symmetrical perturbation and a new type of non-Noether adiabatic invariant are presented in general infinitesimal transformation groups. On the basis of the invariance of disturbed Lagrangian systems under general infinitesimal transformations, the determining equations of Lie symmetries of the system are constructed. Based on the definition of higher-order adiabatic invariants of a mechanical system, a new type of adiabatic invariant, i.e. generalized Lutzky adiabatic invariants, of a disturbed Lagrangian system are obtained by investigating the perturbation of Lie symmetries t＇or a Lagrangian system with the action of small disturbance. Finally, an example is given to illustrate the application of the method and results.

关键词： coated conductor buffer layer self-epitaxy CeO2

A sixth-order wavelet integral collocation method for solving nonlinear boundary value problems in three dimensions

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2022年第2期38卷 81-92,I0003页

作者： Zhichun Hou Jiong Weng Xiaojing Liu Youhe Zhou Jizeng Wang Key laboratory of mechanics on Disaster and Environment in Western China the Ministry of EducationLanzhou 730000China College of Civil Engineering and mechanics Lanzhou UniversityLanzhou 730000China

A sixth-order accurate wavelet integral collocation method is proposed for solving high-order nonlinear boundary value problems in three *** order to realize the establishment of this method,an approximate expression of multiple integrals of a continuous function defined in a three-dimensional bounded domain is proposed by combining wavelet expansion and Lagrange boundary *** applying such an integral technique,during the solution of nonlinear partial differential equations,the unknown function and its lower-order partial derivatives can be approximately expressed by its highest-order partial derivative values at nodes.A set of nonlinear algebraic equations with respect to these nodal values of the highest-order partial derivative is obtained using a collocation *** validation and convergence of the proposed method are examined through several benchmark problems,including the eighth-order two-dimensional and fourth-order three-dimensional boundary value problems and the large deflection bending of von Karman *** demonstrate that the present method has higher accuracy and convergence rate than most existing numerical *** importantly,the convergence rate of the proposed method seems to be independent of the order of the differential equations,because it is always sixth order for second-,fourth-,sixth-,and even eighth-order problems.

关键词： Nonlinear boundary value problems Eighth-order derivative Coiflet wavelet Integral collocation method Von Karman plate

Volumetric fraction measurement in oil-water-gas multiphase flow with dual energy gamma-ray system

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2005年第12期6卷 1405-1411页

作者：李东晖吴应湘李志彪钟兴福 Institute of mechanics Chinese Academy of Sciences Beijing 100080 China

Volumetric fraction distribution measurement is a constituent part of process tomography system in oil-water-gas multiphase flow. With the technological development of nuclear radial inspection, dual-energy γ-ray techniques make it possible to investigate the concentration of the different components on the cross-section of oil-water-gas multiphase pipe-flow. The dual-energy gamma-ray technique is based on materials attenuation coefficients measurement comprised of two radioactive isotopes of 241Am and 241Cs which have emission energies at 59.5 keV and 662 keV in this project. Nuclear instruments and data acquisition system were designed to measure the material’s attenuation dose rate and a number of static tests were conducted at the Multiphase laboratory, Institute of mechanics, Chinese Academy of Sciences. Three phases of oil-water-gas media were inves- tigated for their possible use to simulate different media volumetric fraction distributions in experimental vessels. Attenuation intensities were measured, and the arithmetic of linear attenuation coefficients and the equations of volumetric fractions were studied. Investigation of an unexpected measurement error from attenuation equations revealed that a modified arithmetic was involved and finally the system achieved acceptable accuracy in experimental research.

关键词： Volumetric fraction Multiphase flow Dual-energy γ-ray Process tomography

Lie Symmetrical Perturbation and Adiabatic Invariants of Generalized Hojman Type for Disturbed Nonholonomic Systems

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2007年第11期24卷 3017-3020页

For a nonholonomic mechanics system with the action of small disturbance, the Lie symmetrical perturbation and adiabatic invariants of generalized Hojman type are studied under general infinitesimal transformations of groups in which the generalized coordinates and time are variable. On the basis of the invariance of disturbed nonholonomic dynamical equations under general infinitesimal transformations, the determining equations, the constrained restriction equations and the additional restriction equations of Lie symmetries of the system are constructed, which only depend on the variables t, qs and q^.s. Based on the definition of higher-order adiabatic invariants of a mechanical system, the perturbation of Lie symmetries for a nonholonomic system with the action of small disturbance is investigated, and the Lie symmetrical adiabatic invariants, the weakly Lie symmetrical adiabatic invariants and the strongly Lie symmetrical adiabatic invariants of generalized Hojman type of disturbed nonholonomic systems are obtained. An example is given to illustrate applications of the results.

关键词： coated conductor buffer layer self-epitaxy CeO2

Layered and isotropic acoustic cloak design based on conformal transformation acoustics

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,mechanics & Astronomy) 2011年第4期54卷 593-597页

作者： REN ChunYu XIANG ZhiHai CEN ZhangZhi Key laboratory of Applied mechanics Tsinghua University Chinese Ministry of Education Beijing 100084 China Department of Naval Architecture and Ocean Engineering Naval University of Engineering Wuhan 430033 China

The acoustic cloak can manipulate sound waves in surprising ways and enable us to guide the trajectories of waves at *** contrast to the existing approaches for designing such devices that need exotic material parameters,here we demonstrate how to design a layered and isotropic acoustic cloak based on conformal transformation acoustics.A petal-shaped layered acoustic cloak is designed from the reduction of material parameters of an approximate rectangular *** resultant material parameters span a narrow range,thus strongly facilitating the *** invisibility performance of the cloak for different shapes of acoustic wavefront is verified using a full-wave finite-element analysis.

关键词： Conformal transformation acoustics cloak isotropic material layered

Imprints of molecular orbitals using photoelectron angular distribution by strong laser pulses of circular polarization

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2013年第7期22卷 148-152页

作者：任向河吴艳张敬涛马慧许玉龙 School of Sciences Shandong Polytechnic University Department of Physics Zhejiang University of Science & Technology State Key laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences

We theoretically investigate the strong-field ionization of H＋2 molecules in four different electronic states by calculating photoelectron angular distributions in circularly polarized fields. We find that the structure of photoelectron angular distribution depends on the molecular orbital as well as the energy of the photoelectron. The location of main lobes changes with the symmetric property of the molecular orbital. Generally, for molecules with bonding electronic states, the photoelectron’s angular distribution shows a rotation of π/2 with respect to the molecular axis, while for molecules with antibonding electronic states, no rotation occurs. We use an interference scenario to interpret these phenomena. We also find that, due to the interference effect, a new pair of jets appears in the waist of the main lobes, and the main lobes or jets of the photoelectron’s angular distribution are split into two parts if the photoelectron energy is sufficiently high.

关键词： photoelectron angular distributions circular polarization laser field photoionization molecule

Field-free molecular orientation enhanced by tuning the intensity ratio of a three-color laser field

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2017年第5期26卷 183-187页

作者：黄志远王丁郑浪黎文开赵睿睿冷雨欣 State Key laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Jiangxi Provincial Education Examination Authority Nangchang 330038 China

We theoretically study the field-free molecular orientation induced by a three-color laser field. The three-color laser field with a large asymmetric degree can effectively enhance the molecular orientation. In particular, when the intensity ratio of the three-color laser field is tuned to a proper value of I3： I2： I1= 0.09 ： 0.5 ： 1, the molecular orientation can be improved by - 20% compared with that of the two-color laser field at intensity ratio I2： I1= 1 ： 1 for the same total laser intensity of 2×10^13W/cm^2. Moreover, we investigate the effect of the carrier-envelope phase（CEP） on the molecular orientation and use the asymmetric degree of the laser field to explain the result. We also show the influences of the laser intensity, rotational temperature, and pulse duration on the molecular orientation. These results are meaningful for the theoretical and experimental studies on the molecular orientation.

关键词： rotational tuning asymmetric meaningful tuned explain dipole intense envelope momentum