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Generation of a Dark Hollow Beam inside a Cavity

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Chinese Physics Letters 2004年第2期21卷 298-301页

作者：张蕾陆璇辉陈许敏何赛灵 centreforopticalandelectromagneticresearch StateKeyLaboratoryofModernOpticalInstrumentationZhejiangUniversityHangzhou310027 OpticsInstitute DepartmentofPhysicsZhejiangUniversityHangzhou310027

A new method is introduced to generate a hollow beam inside a cavity. Using a matrix eigenvalue method, the laser resonator with optical diffraction elements is theoretically analysed and simulated. The hollow beam can be obtained theoretically by controlling the parameters of the diffraction functions. After designed the diffraction components in the cavity, a hollow beam of good quality is realized experimentally using a YAG solid state laser.

关键词： Solid state lasers

An Electro—Optical Modulator Based on GeO2—Doped Silica Ridge Waveguides with Thermal Poling

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Chinese Physics Letters 2003年第7期20卷 1081-1083页

作者：曹霞何赛灵 centreforopticalandelectromagneticresearch StateKeyLaboratoryofModernOpticalInstrumentationzhejiangUniversityHangzhou310027

Obtaining the band structure of a complicated photonic crystal by linear operations

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Chinese Physics B 2003年第6期12卷 642-648页

作者：吴良叶卓何赛灵 StatekeyLaboratoryformodernOpticalInstrumentation CentreforOpticalandElectromagneticResearchzhejiangUniversityHangzhou310027China StatekeyLaboratoryformodernOpticalInstrumentation CentreforOpticalandElectromagneticResearchzhejiangUniversityHangzhou310027China DepartmentofElectromagneticTheory RoyalInstituteofTechnologyS-10044StockholmSweden

Absolute band gaps can be created by lifting the degeneracy in the bands of a photonic *** calculate the band structure of a complicated photonic crystal generated by *** breaking,general forms of all possible linear operations are presented in terms of matrices and a procedure to combine these operations is *** forms of linear operations(such as the addition,subtraction,and translation transforms) are also presented to obtain an explicit expression for the Fourier coefficient of the dielectric function in the plane-wave expansion *** the present method,band structures for various complicated photonic crystals(related through these linear operations) can be obtained easily and *** a numerical example,a large absolute band gap for a complicated photonic crystal structure of GaAs is found in the high region of normalized frequency.

关键词： photonic crystal plane-wave expansion method linear operation Fourier coefficients

Dark decay behaviours of photorefractive grating induced by two deep-trap levels in Ce：BaTiO3

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Chinese Physics B 2005年第5期14卷 995-998页

作者：张明徐英洪治 centreforopticalandelectromagneticresearch StateKeyLaboratoryofModernOpticalInstrumentationZhejiangUniversityHangzhou310027China

Dark decay behaviours of photorefractive grating in Ce:BaTiO3 crystal are studied experimentally. It is observed that two deep-trap levels, i.e. Fe-ion deep level and Ce-ion deep level, both participate in the photorefractive process. A simplified two-deep model is presented based on the one-deep trap model and the shallow-deep trap model, with which we analyse quantitatively the contribution of each deep level to the whole space-electric field and thus the photorefractive grating varying with the different grating wave vectors and different writing intensities.

关键词： dark decay photorefractive grating Ce:BaTiO3 simplified two-deep model

How to realize a negative refractive index material at the atomic level in an optical frequency range?

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Journal of Zhejiang University Science 2004年第11期5卷 1322-1326页

作者：沈建其阮智超何赛灵 centreforopticalandelectromagneticresearch JointResearchCentreofPhotonicsoftheRoyalInstituteofTechnology（Sweden）andZhejiangUniversityZhejiangUniversityHangzhou310027China LaboratoryofPhotonicsandMicrowaveEngineering DepartmentofMicroelectronicsandInformationTechnologyRoyalInstituteofTechnologyElectrum229SE-16440KistaSweden

The theoretical mechanism for realizing a negative refractive index material in an optical frequency range with an atomic gas system of electromagnetically induced transparency (EIT) is studied. It is shown that under certain conditions such a dense gas can exhibit simultaneously negative permittivity and negative permeability, and negligibly small loss.

关键词： Negative refractive index Left-handed medium Electromagnetically induced transparency Atomic level Optical frequency