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提出了一种利用双周期弧向非满额相位调制的方法产生双空心光束的方案. 当准直氦氖激光通过1.5 mm半径透光孔照射到该相位图样时, 在200 mm成像透镜像空间获得长30 mm, 间距57.6μm, 单管束宽度0.11–0.14 mm的双空心光束. 该方案结构简单, 产生的双空心光束具有较好的可控性, 双光管间距由相位调制因子p决定, 能够实现从双空心光束到单空心光束的双向演化. 对所提出的方案进行了实验研究并得到与理论相符的结果. 利用多种组合方式讨论了将该方案拓展到蓝失谐光学囚禁势阱, 可以实现可控的空心双光阱、四光阱与光学晶格等, 有望在冷原子、冷分子囚禁与操控等领域的实验研究中发挥重要作用. 相似文献
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为了调控艾里光束的传播,提出一种广义艾里光束.在传统立方相位基础上引入两个可变旋转角因子θ_1和θ_2,形成新改进的可调谐相位,加载该相位的高斯光束经傅里叶变换后可以产生广义艾里光束.基于衍射突变理论,分析讨论了该光束的双曲抛物线传播行为.重点研究了当旋转角θ_1=π/3和θ_2=7π/6时,该光束在传播距离0、3、6、10cm处的无衍射传播特性;以及旋转因子θ_1=3π/2和θ_2=π/4时,该光束在传播距离0、3、6、10cm处的自愈特性.理论研究表明该光束并非傍轴波动方程的特解,但数值模拟及实验证实其在一定程度上拥有无衍射及自愈特性.该光束不仅可沿任意指定的抛物线轨迹传播,同时还具有与传统艾里光束明显不同的空间强度分布,使其在光学操纵与生物医学等方面有潜在的应用. 相似文献
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提出了一种对称艾里涡旋光束.在对称立方相位的基础上引入螺旋相位因子形成新的相位图,加载该相位的高斯光束经傅里叶变换后产生对称艾里涡旋光束.研究表明:对称艾里涡旋光束出现自聚焦现象,且由于轴上涡旋的存在,其中心呈现中空现象,涡旋结构携带的轨道角动量使光束在初始平面处发生旋转,拓扑荷数越大,中空结构越大,旋转角度也越大,而拓扑荷数的正负仅改变光束的旋向.理论分析表明,离轴涡旋在初始平面处,因与光轴中心距离较远,并不会影响对称艾里光束主瓣的能量,即中心并无光强为零区域,但随着传播距离的增加,离轴涡旋逐渐出现在对称艾里光束其中的一个主瓣上.此外,对称艾里光束还可以加载多个离轴涡旋,能同时无损伤地捕获多个微粒.该光束不仅具有自聚焦特性,并且其中心呈中空结构,同时还携带轨道角动量,在光学微操纵与生物医学等方面有潜在应用. 相似文献
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Analysis of factors affecting beam shaping quality of geometric steady-phase method based on SLM北大核心 下载免费PDF全文
基于几何稳相法求解调制相位,使用傅里叶透镜进行傅里叶变换,在后焦面处聚焦,得到对应的平顶光束,从而将圆形高斯光束整形为方形平顶光束,其中光路参数对整形质量将产生较大影响。实验中发现,方形平顶光束受零级光影响均匀性较差,因此详细分析了零级光产生的原因,提出了有效的解决方法,并对实验结果中出现的零级光通过叠加闪耀光栅直接移除。实验结果表明:移除零级光后方形平顶光束的能量利用率为72.3%,光束均匀性高达97.2%,优于传统整形方法。最后进一步分析了全息图与入射光束偏移量、离焦以及入射光束束腰半径对几何稳相法整形质量的影响,为几何法光束整形的应用提供了便利。 相似文献
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利用全息技术,采用二元相位处理后的离散型艾里涡旋相位,制作了一种双复合离散型艾里涡旋加速光.理论模拟和实验探究了该加速光的传输特性,以及线性因子(s)、径向层数(N)和拓扑荷梯度(ΔL)对光场的调控机制.结果表明,双加速光在传输过程中,由于离散和旋转效应,逐渐分离为多个类艾里光;通过调节传输距离及ΔL,可实现二维类艾里光至一维类艾里光之间的演化.此外,N和s可分别调节双加速光的强度分布及其在初始截面(z=0处的x-y平面)中的位置分布;ΔL也可调节分离的类艾里光之间的强度分布. 相似文献
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实验验证了一种利用幂指数相位涡旋光束(PEPV)操控微粒的方法。该方法基于幂指数相位涡旋光束理论,产生不同拓扑荷数与方位角幂指数大于1的涡旋光场的相位全息图,并将该全息片经计算机输入到空间光调制器(SLM)上用于调制入射激光光束。利用透镜对被调制光束进行傅里叶变换,利用光阑在频域对衍射光斑进行筛选和过滤,并利用倒置高倍光学显微镜将光束成像于载物台样品上。利用该幂指数相位涡旋光束对微米级粒子实现了定向光学输运。研究结果表明,该光束在粒子的定向输送与收集方面有独特的功能,将进一步拓展光学涡旋光束的实际应用范围。 相似文献
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设计了一种周期型正交二元相位板,其具有周期型矩形调制单元,各单元的相位调制量为0或π。该相位板的空间频谱具有中心直流分量为0的特点,分别对该频谱中心区域的4个一级频谱点和8个二级频谱点进行相位调制,可得到正方阵列光斑和正方阵列涡旋。阵列涡旋中各涡旋光束的拓扑荷数l=±1,在空间交错分布。由于两个正方阵列光场在垂直传播方向的横向周期恰好重合,且两个光场沿光轴方向的波数不同,因此叠加之后可以形成强度分布随传输距离旋转的正方阵列螺旋,阵列中存在两种具有相反螺旋方向的螺旋光束,同样在空间呈交错分布。此外,讨论了产生最佳螺旋光束的相位板设计条件,并给出理想情况下系统的能量利用率,所得实验结果验证了该方法的可行性。 相似文献
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本文提出了一种基于叠层衍射成像(ptychography)的二元光学元件的检测方法,该方法可实现对二元光学元件表面微观轮廓的检测以及特征尺寸的标定.相比于传统的二元光学元件检测方法,其使用无透镜成像技术,简化了系统结构并可适用于特殊环境下的检测.该方法可直接通过采集多幅衍射图,利用叠层衍射成像迭代算法可精确地复原大尺寸待测元件的表面微观轮廓,提高大尺寸器件的检测效率.本文模拟仿真了台阶高度与噪声大小对纯相位台阶板复原结果的影响,并在光学实验中选取计算全息板为样品,复原样品的表面微观轮廓信息以及得到台阶高度.以白光干涉仪检测结果为标准,该方法在精度要求不太高的前提下,可获得令人满意的成像质量. 相似文献
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Multiple bottle beams based on metasurface optical field modulation and their capture of multiple atoms 下载免费PDF全文
Xichun Zhang 《中国物理 B》2022,31(8):88103-088103
Compared to conventional devices, metasurfaces offer the advantages of being lightweight, with planarization and tuning flexibility. This provides a new way to integrate and miniaturize optical systems. In this paper, a metasurface capable of generating multiple bottle beams was designed. Based on the Pancharatnam-Berry (P-B) phase principle, the metasurface lens can accurately control the wavefront by adjusting the aspect ratio of the titanium dioxide nanopillars and the rotation angle. When irradiated by left-handed circularly polarized light with a wavelength of 632.8 nm, the optical system can produce multiple micron bottle beams. Taking two bottle beams as examples, the longitudinal full widths at half-maximum of the optical tweezers can reach 0.85 μ and 1.12 μ, respectively, and the transverse full widths at half-maximum can reach 0.46 μ and 0.6 μ. Also, the number of generated bottle beams can be varied by controlling the size of the annular obstacle. By changing the x-component of the unit rotation angle, the metasurface can also change the shape of the bottle beam — the beam cross-section can be changed from circular to elliptical. This paper also analyzes the trapping of ytterbium atoms by the multi bottle beam acting as optical tweezers. It is found that the multi bottle beam can cool and trap multiple ytterbium atoms. 相似文献
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A theoretical method based on the quantum scattering theory is presented to evaluate the performances of a two-dimensional (2-D) focusing square multilayer Bragg–Fresnel lens. The numerical application results of the square multilayer Bragg–Fresnel lens working at 0.7 nm wavelength (W/Si 25 periods with a double layer thickness of 5.38 nm, the size of the diffraction pattern is about 291×291 μm, the size of the center square in the diffraction pattern is 21.4×21.4 μm, and the size of the smallest square in the diffraction pattern is 0.39×0.39 μm) are given. Our theoretical results are compared with the experimental results of the linear Bragg–Fresnel lens reported by other researchers; an analysis and a discussion are carried out regarding the advantages of an optical system based on the 2-D focusing square multilayer Bragg–Fresnel lens, in contrast to a Kirkpatrick–Baez optical system on the basis of a two-linear Bragg–Fresnel lens. 相似文献
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We demonstrate the generation of hollow laser beams by using a binary spatial light modulator and compare the results with those for a continuous modulator. The binary phase modulator produces beams that have continuous, azimuthally varying phase profiles and can be dynamically changed with kilohertz refresh rates. The intensity and phase profiles are recorded through the focus of an imaging lens and are compared with scalar diffraction theory. We highlight properties of the beams relevant to optical dipole traps. 相似文献
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Lei Wu Hongru Yang Xudong Li Bin Yang Gaoping Li 《Journal of Quantitative Spectroscopy & Radiative Transfer》2007,108(1):54-64
The scattering patterns and optical properties of large spherical bubbles in water are calculated by both Geometrical-optics theory and Debye-series expansion of the Mie amplitudes. In the Geometrical-optics calculations, the wave-front spreading factor and phase information are all taken into consideration. A detailed comparison between the two methods is presented. It is found that scattering patterns calculated from the Geometrical-optics approach agree reasonably with those obtained by Debye series when the size parameter is larger than approximately 400. In the case of scattering properties, the Geometrical-optics method can produce reliable results with the Debye expansion for size parameters larger than approximately 50. The Geometrical-optics results without the phase interferences are also reliable, but it cannot display the oscillations and the ripple structure as a function of size parameter. 相似文献