标量和矢量空心激光束的产生与传输特性研究
发布时间：2018-10-16 20:49
【摘要】：空心光束是中心强度为零的一类环状激光束,螺旋波阵面、中心相位奇异和空间传播不变性等特性。这些特性使得空心光束在原子分子光学,微纳粒子操控,材料加工,量子信息等领域有广泛的应用。空心光束可以简单分为标量空心光束与矢量空心光束两大类,多年来发展了多种理论上或者实验上产生空心光束的技术。本文我们分别提出两个产生空心光束的新方案：一个方案是利用非线性晶体材料ZnSe的非线性效应产生标量空心光束。研究了基于非线性介质材料的空心光束的产生原理,光学系统参数对产生的空心光束质量的影响,并根据惠更斯-菲涅尔衍射积分计算产生了空心光束的强度分布以及其在自由空间的传输特性,同时研究了空心光束的暗斑尺寸(DSS)和最佳传输距离随着入射高斯光束的束腰半径的变化情况。研究表明,随着传播距离的增大,空心光束的强度分布呈现出一种对称分布,随着入射高斯光束束腰半径的增大,最佳传播距离Zopt和DSS都变大。通过这种方法产生的空心光束可以用作原子、分子光阱。如果将入射光改为椭圆高斯光束或者平顶高斯光束,那么经过非线性晶体可以得到椭圆空心光束和平底空心光束,研究发现产生的椭圆空心光束在自由空间很长一段距离可以维持很好的空心特性。另一个方案是利用空心金属波导产生矢量空心光束。将高斯光束通过2π相位板和透镜相位调制产生的标量空心光束,入射到空心金属波导的空心区域激发出TEo1模式的矢量空心光束,并在自由空间传输。根据矢量瑞利-索末菲衍射积分我们计算了通过空心金属波导之后模式光强的矢量分布。结果发现经过空心金属波导产生的矢量光束在自由空间的场强分布是环状的空心光束,而且在空间传输时一直都是空心分布,另外随着传输距离的增大还会有类自聚焦现象出现。同时,我们还研究了由不同半径的空心金属波导得到的矢量空心光束在自由空间传输时类自聚焦位置和发散角情况,计算得到空心金属波导空心半径越大,类自聚焦位置越远,而得到的矢量空心光束在类自聚焦之后发散角越小。另外金属波导激发得到的TEol模,在自由空间传输时保持角向偏振不变。方案产生的角向偏振矢量空心光束可以用于原子分子透镜。
[Abstract]:Hollow beam is a kind of ring laser beam with zero central intensity, helical wave front, center phase singularity and spatial propagation invariance. These properties make hollow beams widely used in the fields of atomic and molecular optics, micro and nano particle manipulation, material processing, quantum information and so on. Hollow beams can be divided into two categories: scalar hollow beams and vector hollow beams. In this paper, we propose two new schemes for the generation of hollow beams. One scheme is to generate scalar hollow beams by using the nonlinear effect of nonlinear crystal material ZnSe. The principle of hollow beam generation based on nonlinear dielectric material and the influence of optical system parameters on the quality of hollow beam are studied. Based on the Huygens-Fresnel diffraction integral, the intensity distribution of the hollow beam and its propagation characteristics in free space are calculated. At the same time, the variation of the dark spot size (DSS) and the optimum propagation distance of hollow beam with the beam waist radius of the incident Gao Si beam is studied. The results show that the intensity distribution of hollow beam exhibits a symmetrical distribution with the increase of propagation distance. With the increase of waist radius of incident Gao Si beam, the optimum propagation distance Zopt and DSS increase. The hollow beam produced by this method can be used as an atomic and molecular optical trap. If the incident light is changed to an elliptical Gao Si beam or a flat-topped Gao Si beam, then the elliptical hollow beam and the flat bottom hollow beam can be obtained through a nonlinear crystal. It is found that the elliptical hollow beam can maintain a good hollow characteristic at a long distance in free space. Another scheme is to generate vector hollow beams using hollow metal waveguides. The vector hollow beam of TEo1 mode is excited by introducing the scalar hollow beam of Gao Si beam through the 2 蟺 phase plate and lens phase modulation into the hollow region of the hollow metal waveguide and propagating in free space. According to the vector Rayleigh-Sommerfeld diffraction integral, we calculate the vector distribution of the mode light intensity after passing through the hollow metal waveguide. The results show that the field intensity distribution of the vector beam generated by the hollow metal waveguide in the free space is annular hollow beam, and it has always been hollow distribution in the space propagation. In addition, with the increase of transmission distance, there will be a similar self-focusing phenomenon. At the same time, we also study the quasi-self-focusing position and divergence angle of the vector hollow beam obtained from hollow metal waveguide with different radii in free space. The larger the hollow radius of hollow metal waveguide is, the farther the quasi-self-focusing position is. The smaller the divergence angle of the vector hollow beam is after the similar self-focusing. In addition, the TEol mode excited by metal waveguide keeps angular polarization invariant in free space transmission. The angular polarization vector hollow beam can be used in atomic and molecular lens.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN241
本文编号：2275594
[Abstract]:Hollow beam is a kind of ring laser beam with zero central intensity, helical wave front, center phase singularity and spatial propagation invariance. These properties make hollow beams widely used in the fields of atomic and molecular optics, micro and nano particle manipulation, material processing, quantum information and so on. Hollow beams can be divided into two categories: scalar hollow beams and vector hollow beams. In this paper, we propose two new schemes for the generation of hollow beams. One scheme is to generate scalar hollow beams by using the nonlinear effect of nonlinear crystal material ZnSe. The principle of hollow beam generation based on nonlinear dielectric material and the influence of optical system parameters on the quality of hollow beam are studied. Based on the Huygens-Fresnel diffraction integral, the intensity distribution of the hollow beam and its propagation characteristics in free space are calculated. At the same time, the variation of the dark spot size (DSS) and the optimum propagation distance of hollow beam with the beam waist radius of the incident Gao Si beam is studied. The results show that the intensity distribution of hollow beam exhibits a symmetrical distribution with the increase of propagation distance. With the increase of waist radius of incident Gao Si beam, the optimum propagation distance Zopt and DSS increase. The hollow beam produced by this method can be used as an atomic and molecular optical trap. If the incident light is changed to an elliptical Gao Si beam or a flat-topped Gao Si beam, then the elliptical hollow beam and the flat bottom hollow beam can be obtained through a nonlinear crystal. It is found that the elliptical hollow beam can maintain a good hollow characteristic at a long distance in free space. Another scheme is to generate vector hollow beams using hollow metal waveguides. The vector hollow beam of TEo1 mode is excited by introducing the scalar hollow beam of Gao Si beam through the 2 蟺 phase plate and lens phase modulation into the hollow region of the hollow metal waveguide and propagating in free space. According to the vector Rayleigh-Sommerfeld diffraction integral, we calculate the vector distribution of the mode light intensity after passing through the hollow metal waveguide. The results show that the field intensity distribution of the vector beam generated by the hollow metal waveguide in the free space is annular hollow beam, and it has always been hollow distribution in the space propagation. In addition, with the increase of transmission distance, there will be a similar self-focusing phenomenon. At the same time, we also study the quasi-self-focusing position and divergence angle of the vector hollow beam obtained from hollow metal waveguide with different radii in free space. The larger the hollow radius of hollow metal waveguide is, the farther the quasi-self-focusing position is. The smaller the divergence angle of the vector hollow beam is after the similar self-focusing. In addition, the TEol mode excited by metal waveguide keeps angular polarization invariant in free space transmission. The angular polarization vector hollow beam can be used in atomic and molecular lens.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN241
【参考文献】
相关期刊论文 前1条
1 吕百达,罗时荣,张彬;平顶高斯光束的相关概念和对称化变换[J];强激光与粒子束;1999年04期
，本文编号：2275594
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