文献类型：期刊文献

中文题名：像散正弦-高斯光束的分数傅里叶变换与椭圆空心光束产生

英文题名：Fractional Fourier transform of astigmatic sine-Gaussian beams and generation of dark hollow light beams with elliptic geometry

作者：朱洁 朱开成

第一作者：朱洁

通信作者：Zhu, KC[1]

机构：[1]贵州理工学院理学院;[2]中南大学物理与电子学院

第一机构：贵州理工学院理学院

通信机构：corresponding author), Cent S Univ, Sch Phys Sci & Technol, Changsha 410083, Hunan, Peoples R China.

年份：2016

卷号：0

期号：20

起止页码：92-97

中文期刊名：物理学报

外文期刊名：Acta Physica Sinica

收录：CSTPCD;;EI(收录号：20164302956569);Scopus(收录号：2-s2.0-84992145736);WOS:【SCI-EXPANDED(收录号:WOS:000389465700012)】；北大核心:【北大核心2014】；CSCD:【CSCD2015_2016】；

基金：Project supported by the High Level Introduction of Talent Research Start-up Fund of Guizhou Institute of Technology, China.

语种：中文

中文关键词：像散正弦-高斯光束;分数傅里叶变换;椭圆暗空心光束;位相奇异性

外文关键词：astigmatic sine-Gaussian beams; fractional Fourier transform（FrFT）; dark hollow beam with elliptic geometry; phase singularity;

摘要：基于分数傅里叶变换(FrFT)关系,推导了像散正弦-高斯光束场分布的解析表达式,利用所得结果和数值方法研究了像散正弦-高斯光束在FrFT平面上的光强分布与位相特性.理论和数值分析结果都表明:像散的存在使得正弦-高斯光束在FrFT过程中从初始输入具有边缘位错的多斑花样转换为具有涡旋的暗空心椭圆花样,且其拓扑荷指数为一,而在这种转换中像散起着关键控制作用.此外,适当选择光束参数与FrFT系统结构参数,暗空心椭圆花样的长轴可以是短轴的百余倍,因此利用这一方案可获得相当细长的暗空心椭圆光束.
In this work, we develop a novel method of creating dark hollow beam with vortex by converting a sine-Gaussian beam（SeGB） with edge-dislocation and astigmatism through using fractional Fourier transform（FrFT） optical system.On the basis of the definition of the FrFT, an analytical transformation formula is derived for an astigmatic Se GB passing through such a transform system. By use of the derived formulae, the changes of the intensity distribution and the corresponding phase properties associated with the transforming astigmatic Se GBs are analytically discussed in detail. It is found that for an input Se GB without astigmatism, there is still a dark line or an edge dislocation associated with the intensity distribution of the FrFT beam along the initial dislocation line, similar to that of the input Se GB.However, when the input Se GB astigmatically passes through an FrFT optical system, the dark line of the intensity distribution of the input SeGB can be converted into a solitary zero point, or in other words, a dark hollow beam with a single-charge vortex can be produced by SeGB with an edge dislocation. The results reveal that the astigmatism plays a critical role in transforming a SeGB into a dark hollow one through the FrFT optical system. Furthermore, some numerical calculation results based on the derived formula are presented and discussed graphically. It is shown that for appropriate beam parameters and carefully adjusting the transform angle of FrFT, dark hollow beams with single-charge vortex and elongated elliptic geometry can be realized with astigmatic SeGBs. The influences of the beam parameters and the transform angle of FrFT optical system on the generation of perfect dark hollow beams are also investigated.The results demonstrate that the linear eccentricity of the dark hollow beam, which is roughly defined as the ratio of semi-minor axis to semi-major one of the intensity pattern, mainly depends on the Fresnel number. And the optimal linear eccentricity may be relatively large under carefully selecting the beam and optical system parameters. Moreover,optimal parameter values corresponding to perfect dark hollow beam configurations which can be experimentally accessed are presented. As is well known, there are two types of pure phase defects or dislocations in the optical fields： one is screw dislocation or vortex and the other is edge-dislocation. Due to their important applications, the propagation dynamics of optical vortices or edge dislocations are extensively studied both theoretically and experimentally. The vortex-edge dislocation interaction is investigated in detail. However, there are fewer reports on the direct conversion between a single edge dislocation and a vortex. Therefore, the results obtained in this paper represent a significant step forward in understanding the transformation dynamics between beams with pure edge dislocation and vortex, and also opens possibilities for their potential applications, e.g., in generating dark hollow beams with elliptic geometry using FrFT systems.