厄米-高斯模和拉盖尔-高斯模及它们之间的转换

介绍了厄米-高斯模和拉盖尔-高斯模的特点,基于厄米多项式与拉盖尔多项式之间的关系,给出了拉盖尔-高斯模用对角的厄米-高斯模的展开式表示,进而讨论了利用模式转换器使厄米-高斯光束转化为拉盖尔-高斯光束的方法。     

利用振幅光栅生成拉盖尔-高斯光束的实验研究

拉盖尔高斯(Laguerre-Gaussian,LG)光束由于其独特的相位结构和轨道角动量特性在微粒旋转操纵和信息处理等方面得到了越来越多的重视.对利用振幅型叉状衍射光栅产生LG光束进行了理论分析,采用计算全息图的方法制作了振幅型叉状衍射光栅,实验上获得了角量子数为±1的LG光束,并对光束变换过程中影响光束特性的主要因素进行了讨论. 关键词： 信息光学 拉盖尔高斯光束 计算全息光栅 光束轨道角动量     

利用液晶空间光调制器产生高阶拉盖尔高斯光束

本文采用反射式纯相位液晶空间光调制器产生了实验需要的高阶拉盖尔高斯光束。理论上详细计算了生成高阶拉盖尔高斯(Laguerre-Gaussian)光束的最优参数选择,用MATLAB编写程序,制作产生高阶LG光束的相息图。通过CCD采集图像数据,观测了以平面波入射生成拉盖尔高斯光束的强度分布,并利用干涉法验证了产生高阶拉盖尔高斯光束的螺旋相位分布。在此基础上,对实验测得一维强度轮廓进行拟合分析并估算了实验产生LG光束的纯度。     

涡旋光束与相位全息光栅不对准时的衍射特性研究

研究了涡旋光束与相位全息光栅不对准时衍射光束的解析特性.利用理论推导的方法得出涡旋光束经相位全息光栅接收后一阶衍射光束的解析表达式.然后通过仿真分析分别得出在发生正常对准、横向偏移、角向倾斜及横向偏移和角向倾斜两者同时出现时衍射光束的质心偏移特性和中心强度变化特性.研究表明: 拉盖尔-高斯光束经相位全息光栅衍射后得到的光场表达式为合流超几何函数形式.光束与相位全息光栅间的不对准会引起衍射光束质心的偏移,而且光束质心的偏移量随入射光束偏移距离和偏离角的增加而增加,与入射光束的偏移方向和方位角无关.角向倾斜时 关键词： 拉盖尔-高斯光束 相位全息光栅 横向偏移 角向倾斜     

高阶模高斯光束整形方法研究

研究了高阶模高斯光束的整形方法.在高阶模高斯光束和平顶光束理论模型的基础上,分别选择了平项洛仑兹函数和费米狄拉克函数作为平顶光分布函数,利用能量守恒定律,分别推导针对拉盖尔-高斯光束和厄米特-高斯光束整形系统中入射光与出射光的映射函数.最后利用ZEMAX软件设计了针对TEM01模高斯光束进行整形的非球面透镜元件.结果表...     

厄米-高斯模与拉盖尔-高斯模的图像比较

简要地叙述了厄米-高斯模与拉盖尔-高斯模的一些理论,画出了具有代表性的厄米-高斯模与拉盖尔-高斯模在z=0平面的三维图像。为了了解厄米-高斯模与拉盖尔-高斯模的各种模态的关系,分别画出了它们的模态从(0,0)到(2,2)的强度等高线,并从模阶数与峰值、峰值的变化、延伸面积和对称性得到了它们各自的特性,然后进行对比得到它们之间的相同点和不同点。另外通过图像和公式说明了厄米-高斯与拉盖尔-高斯最低阶模(0,0)是一致的,即高斯模。对比了它们之间的电(磁)场和平均坡印廷矢量,不同点与模态有很大关系。画出横截面中振幅强度随传输距离增加而变化的图像,从中得到了束宽和峰值强度与传输距离之间的关系。     

用光学相关识别方法测量单模光纤的折射率分布和色散

介绍了一种测量单模光纤剖面折射率分布和色散的新方法－－光学相关识别方法。应用计算全息制作高斯－拉盖尔模的匹配滤波器，根据光学相关识别原理测出单模光纤场分布的展开系数，由此推得剖面折射率分布和色散，给出了实际测量结果。     

基于拉盖尔-高斯光束的单光子捕获理论研究

基于TEM10模拉盖尔-高斯光束,推导自由空间量子密钥分配中单光子捕获概率表达式.针对低轨卫星-地面站间激光链路进行单光子捕获分析.结果表明:采用可高度衰减激光脉冲的TEM10模拉盖尔-高斯光束作为单光子源,单光子捕获采用前驱波参考脉冲设置时间窗口的方法,可使卫星上接收机以最大概率捕获光子.与基模高斯光束相比,采用TEM10模拉盖尔-高斯光束的优点是,不会由于卫星运动而增加单光子捕获概率的损耗.     

基于拉盖尔-高斯光束的单光子捕获理论研究

基于TEM₁₀模拉盖尔-高斯光束,推导自由空间量子密钥分配中单光子捕获概率表达式。针对低轨卫星-地面站间激光链路进行单光子捕获分析。结果表明：采用可高度衰减激光脉冲的TEM₁₀模拉盖尔-高斯光束作为单光子源,单光子捕获采用前驱波参考脉冲设置时间窗口的方法,可使卫星上接收机以最大概率捕获光子。与基模高斯光束相比,采用TEM₁₀模拉盖尔-高斯光束的优点是,不会由于卫星运动而增加单光子捕获概率的损耗。     

光纤激光器反馈耦合损耗分析

将双包层光纤基模LP01模近似表示为拉盖尔-高斯光束的线性叠加,前六阶的拉盖尔-高斯光束包含了LP01模能量的99.99％.利用拉盖尔-高斯光束的传输特性计算了腔镜分别为球面镜和透镜加平面反射镜时的反馈耦合损耗.结果表明,腔镜为球面镜时,只有当球面镜和到达球面镜光束的曲率半径匹配时才能获得最小的耦合损耗,特别是当平面镜紧贴光纤端面时,耦合损耗为0;当腔镜为透镜加平面反射镜时,将平面镜放置在透镜焦平面时获得最小反馈耦合损耗为0.25％.     

用叉形光栅实现光子轨道角动量的叠加态的测量

Laguerre-Gaussian(LG)模是光子的轨道角动量的本征态.提出了用一种特殊的光栅——“分数阶叉形光栅”来实现两种LG模的叠加，它在以光子角动量为编码空间的高维量子通信领域存在潜在的应用. 关键词： Laguerre-Gaussian(LG)模 叉形光栅     

相反拓扑指数的Laguerre-Gaussian模的产生和模间相互作用的实验研究

实验研究了带有相反拓扑指数的Laguerre-Gaussian(LG)模间的相互作用，发现含有相反拓扑指数的两个LG模在传播过程中其光场发生变化，观察到随着传播距离的增加，两个LG模的中心位相奇点会逐渐连成为一个弧形暗线形状.实验上验证了带有相反拓扑指数的光学涡流中的螺旋位错在传播过程中会演变为边位错这一理论结果.     

拉盖尔-高斯模叠加而成的部分相干光的相干涡旋

对Bogatyryova等人近来提出的一种可分离位相的部分相干光的相干涡旋作了详细研究.这类新的光束由相同角向指数的拉盖尔-高斯(LG)模非相干叠加而成.研究表明，叠加LG模式的模指数，权重因子和参考点位置的选择都会影响圆刃型位错出现的位置，使得涡旋消失或出现多个相干涡旋.而且，LG模叠加而成的位相不可分离的部分相干光也存在相干涡旋. 关键词： 奇点光学 一类新的部分相干光束 相干涡旋 圆刃型位错     

Laguerre-Gaussian modes selection in diode-pumped solid-state lasers

Over the last twenty years, diode pumping of solid-state lasers has opened new prospects for the mode control and formation of Laguerre-Gaussian (LG) beams, enabling a large variety of applications. Experiments on scalar and vector LG modes selection in Nd³⁺- and Yb³⁺-doped ceramics and crystal lasers carried out at the Institute for Laser Science, Tokyo are reviewed. Selection of LG modes from low to high orders using intra-cavity elements, polarization-selective mirrors, or shaping the pump beam profile, is considered. Illustrations of record-high-order LG hollow modes, multiring modes with highly directional propagation properties, characteristics of cw and pulsed lasers with radially or azimuthally polarized beams of high polarization purity are presented. General solutions of the wave equation for the axi-symmetric electric field, which describe LG beams of various profiles, are proposed for data analysis. In parallel, a short review on LG modes selection studies carried out at other laboratories is given.     

Manifestation of the rotational Doppler effect by use of an off-axis optical vortex beam

We report what is to our knowledge the first all-optical detection of the frequency beats between Gaussian and Laguerre-Gaussian LG0(1) modes in their axial superposition, caused by the rotational Doppler effect. The relation between the observable off-axis optical vortex rotation and the rotational frequency shift of the Laguerre-Gaussian component is ascertained. The results can be used as a physical basis for recognition of Laguerre-Gaussian mode spectra along their orbital angular momenta.     

Universal generation of higher-order multiringed Laguerre-Gaussian beams by using a spatial light modulator

Laguerre-Gaussian (LG) beams of various higher-order radial modes are generated by using a reflective phase-only liquid crystal on silicon (LCOS) spatial light modulator (SLM). Because of the LCOS SLM's phase-modulation characteristic of a wide spatial bandwidth, a phase modulation scheme effectively generates higher-order LG beams of up to the fifth-order radial mode. We also perform correlation analyses between the observed and the theoretical two-dimensional mode profiles to universally obtain correlation coefficients of more than 0.946, which suggest mode generations of high quality.     

Observing quantum correlation of photons in Laguerre-Gauss modes using the Gouy phase

The effect of the Gouy phase, which is one of the geometrical phases of photons, is observed through quantum correlation in Laguerre-Gaussian (LG) modes. In an experiment, the relative phase of two different LG modes of measurement basis states is manipulated via the Gouy phase, and the observed coincidence count rates agree well with theoretical predictions. This result suggests that the Gouy phase can be used as a new tool to manipulate multidimensional photonic quantum states.     

Geometric transformations of optical orbital angular momentum spatial modes

With the aid of the bosonic mode conversions in two different coordinate frames, we show that (1) the coordinate eigenstate is exactly the EPR entangled state representation, and (2) the Laguerre-Gaussian (LG) mode is exactly the wave function of the common eigenvector of the orbital angular momentum and the total photon number operator. Moreover, by using the conversion of the bosonic modes, theWigner representation of the LG mode can be obtained directly. It provides an alternative to the method of Simon and Agarwal.     

Rotation of laser beams with zero of the orbital angular momentum

We show that among the multitude of rotating light beams whose complex amplitude can be represented as a linear superposition of the Laguerre-Gaussian (LG) modes with definite numbers there are light beams with zero orbital angular momentum (OAM) and vice versa, multi-mode LG beams that show no rotation and are lacking the radially symmetric intensity distribution can possess the non-zero OAM. Also, we give examples of the rotating light beams with zero OAM, represented as a superposition of the Bessel and new hypergeometric modes. Using an SLM, we generate a rotating Bessel beam with zero OAM for the first time.     

Generation of super-high-order petal-like laser beam using Theon-sieve resonator

The Laguerre-Gaussian(LG) mode beam has very important applications in many research fields.Here,the Theon sieve is first introduced into the laser resonator to generate petal-like laser beams by coherently superimposing two high-order LG modes.The effectiveness was verified by GLAD software.The petal-like laser beam is derived from the light field redistribution and coherent superposition caused by the diffraction effect of the Theon sieve.The relationship between the order of the petal-like laser and the cavity structures has also been investigated in detail.Light field operation in the laser cavity greatly simplifies the optical structure and is more beneficial to optical diagnostics and imaging.