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1.
基于Porras提出的光传输的非傍轴矢量矩理论,推导出初始圆偏振的非傍轴矢量拉盖尔-高斯(LG)光束的特征参数,包括束宽、远场发散角和M2因子等的公式,并表示为级数求和形式.非傍轴矢量高斯光束公式作为特例给出.研究表明,基于二阶矩定义的束宽按双曲线规律传输,当w0/λ→0(w0为束宽,λ为波长)时,远场发散角θ趋于90°,大于非傍轴标量理论预示的值63.435°.非傍轴矢量LG光束的M2因子不仅与模指数p有关,而且还与w0/λ有关.最后,对非傍轴矢量LG光束和非傍轴标量LG光束的传输作了比较,结果表明在w0/λ较小时,矢量效应对远场发散角的影响十分显著.对θ→90°引起的问题和非傍轴矢量矩理论的适用范围,以及解决问题的可能途径作了分析和讨论.
关键词:
非傍轴矢量拉盖尔-高斯光束
圆偏振
非傍轴矢量矩理论
光束参数 相似文献
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基于矢量Rayleigh-Sommerfeld衍射积分,推导出矢量非傍轴圆偏振厄米-拉盖尔-高斯(HLG)光束的远场解析表达式.矢量非傍轴圆偏振高斯光束可作为一般公式的特例给出.将桶中功率(PIB)概念推广到非傍轴范畴,用以描述矢量非傍轴光束的远场光束质量,其中光强用时间平均坡印廷矢量的z分量取代.数值计算和分析表明,矢量非傍轴HLG光束的PIB不仅与束腰宽度与波长之比w0/λ有关,而且还与α参数,模指数n和m以及所取桶的尺寸有关.
关键词:
矢量非傍轴厄米-拉盖尔-高斯光束
矢量Rayleigh-Sommerfeld衍射积分
桶中功率 相似文献
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提出了一种基于Pancharatnam-Berry(PB)相位调控产生混合偏振矢量光束的方法.按照光轴随空间坐标变化的规律,用相位延迟为π的PB相位元件对PB相位进行操控,获得局域偏振为线偏振的矢量光束,将此矢量光束入射到四分之一波片,产生混合偏振矢量光束.通过测定斯托克斯参数重构输出光场的偏振分布,实验结果表明:当以θ0=0的线偏振光入射时,输出光场包含庞加莱球上垂直于S3轴经线圆上所有偏振态的混合矢量光场;当以θ0=π/2的线偏振光入射时,输出光场包含庞加莱球上垂直于S1轴经线圆上所有偏振态的混合矢量光场. 相似文献
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利用稳相法和矢量结构理论, 导出了线偏振拉盖尔-高斯光束的矢量结构项TE项和TM项在远场的解析表达式. 进而利用TE项和TM项的远场能流分布, 给出了TE项和TM项的功率占总功率比例的度量式,同时还给出了线偏振拉盖尔-高斯光束、TE项和TM项三者远场发散角的解析式以及三者远场发散角间的关系式. 所得到的公式不仅适用于傍轴情形,而且还适用于非傍轴情形. 通过数值计算, 分析了TE项和TM项在远场的功率占总功率的比例与参数f和模数间的依赖关系;还分析了拉盖尔-高斯光束、TE项和TM项的远场发散角随参数f、模数和线偏振角的变化关系.这一研究从矢量结构本性揭示了线偏振拉盖尔-高斯光束的远场发散特性, 丰富了对其传输特性的认识. 相似文献
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利用强非局域非线性介质中傍轴光束传输的线性模型(修正的Snyder-Mitchell模型)讨论了两束共线(即光束中心和传输方向都相同)拉盖尔-高斯型光孤子的传输过程. 改变双光束的相对阶数和相对强度比,叠加光场在传输截面上的光强分布呈现出多样性,通过叠加的方法在该介质中产生了多环形光孤子. 一定条件下传输光束在传输过程中会出现旋转现象,叠加光场成为旋转光场,给出了旋转光束的旋转条件以及旋转速度. 进一步利用拉盖尔-高斯光束在传输过程中特有的螺旋相位特点分析了光场截面强度多样性产生的物理机理.
关键词:
强非局域非线性介质
拉盖尔-高斯型光孤子
共线传输
涡旋相位 相似文献
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环形光束的锥形衍射效应对于微粒的操控具有重要的应用价值.本文建立了环状高斯光束的锥形衍射模型,并基于Berry理论给出了线偏振态下环形光束锥形衍射出射光场的计算公式.理论仿真了环状光锥形衍射出射光场的偏振特性,得出环光锥形衍射出射光场的内、外亮环具有相互正交的偏振分布特性.搭建了线偏振态下环状高斯光锥形衍射的实验系统,实验验证了出射光场的偏振特性.针对环形光束锥形衍射出射光场具备的偏振特性,设计了一种组合偏振片,理论和实验研究了该组合偏振片对环光锥形衍射出射光场的调控.结果表明,随着组合偏振片方位角的变化,锥形衍射出射光场的内、外环强度发生周期性的变化. 相似文献
11.
X.P. Zhang W. Wang Y.J. Xie P.X. Wang Q. Kong Y.K. Ho 《Optics Communications》2008,281(15-16):4103-4108
The electric field intensity distribution and the phase velocity distribution of high-order Laguerre–Gaussian (LGρ?) mode laser beams are analyzed. Using three-dimensional test particle simulation, the numerical results of electrons accelerated by LG00, LG40 and LG41 mode laser beams are presented. Compared with the LG00 mode (the fundamental mode) laser beam, low-energy injection electrons can be more favorably accelerated in a high-order LG mode laser beam. Contrary to anticipation, a high-order LG mode laser beam with intense axial electric field distribution is inferior to the LG00 mode in capture acceleration for electrons with high injection energy. 相似文献
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The acceleration of electrons by using a Bessel-Gaussian (BG) beam in vacuum is studied. It is shown that the axial electric
field of a linearly or circularly polarized BG beam of order n = 1 can be used to accelerate electrons. The general features of the acceleration of electrons by using a linearly or circularly
polarized BG beam, such as the transversal and axial electric-field components, phase velocity, slippage distance, accelerating
potential, and energy gain etc., are analyzed. 相似文献
13.
We investigate the optical trapping effect of high-order Laguerre-Gaussian (LG) beams acting on a dielectric sphere in Rayleigh regime. For LG beams with the azimuthal mode index l=0, it is found that under the same input power, the transverse trapping effect can be enhanced several times with increasing the radial mode index p, compared with that of the Gaussian beam; while its axial trapping effect is exactly the same as that of Gaussian beam, although the central trapping region reduces as p increases. For LG beams with l≥1, we find that the maximal transverse gradient forces increase with the increasing of p and the axial radiation forces reduces slightly, therefore an optimal choose on p and l is necessary for obtaining an optimal optical guiding. Our result is useful for analyzing the trapping efficiency of LG beams applied in micromanipulation technologies. 相似文献
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《Current Applied Physics》2015,15(3):174-179
The acceleration of electrons by a plasma wave in the presence of density ripple in plasma has been investigated. Plasma density ripple can excite higher harmonics of different phase velocities of the fundamental plasma wave. The combined role of the different harmonics of the plasma wave contributes significantly in electrons energy gain during acceleration by the fundamental plasma wave. Our calculation shows that the plasma electrons gain considerable energy during the acceleration by the plasma waves in the presence of a density ripple in plasma. The initial electron energy and the ripple density play an important role for the acceleration of an electron. 相似文献
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等单元长度多间隙加速结构是一种非同步加速结构,当粒子在加速结构中的速度变化很明显时,粒子在每个间隙的相位是不相同的,薄透镜近似下的束流纵向运动方程没有考虑粒子在加速结构中的速度变化,这在单腔的能量增益相对于粒子能量很小的情况下是合理的,但是当粒子在加速结构中的速度有明显变化时,这种处理方式是不够的。本文从带电粒子在电磁场中的运动方程出发,通过目前普遍采用的理论建立了束流在这种加速结构中的纵向运动方程,通过数值方法得到了粒子在这种结构的相运动,计算了不同初始能量的粒子在不同的电场梯度及单元数的加速腔中运动的能量变化情况。结果显示:粒子相运动与不考虑粒子速度变化的薄透镜近似下的相运动轨迹有明显差异,当粒子速度变化超过一定值后,薄透镜近似下束流纵向运动方程在计算束流能量增益时与同步相位之间满足的余弦关系不再成立,并给出了能量增益变化曲线相对余弦曲线的偏离情况与电场梯度、间隙数、初始能量等参数的关系。 相似文献
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In this paper, a radially polarised cosh-Gaussian laser beam(CGLB) is used to study the electron acceleration produced in vacuum. A highly energetic electron beam can be achieved by a CGLB,even with comparatively low-powered lasers. The properties of a CGLB cause it to focus earlier,over a shorter duration than a Gaussian laser beam, which makes it suitable for obtaining high energies over small durations. It is found that the energy gained by the electrons strongly depends upon the decentering parameter of the laser profile. It is also observed that for a fixed value of energy gain, if the decentering parameter is increased, then the intensity of the laser field decreases. The dependence of the energy gained by electrons on the laser intensity and the laserspot size is also studied. 相似文献
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行波半导体光放大器的偏振特性研究 总被引:1,自引:0,他引:1
以有源法布里-珀罗谐振腔的增益特性为基础,研究了行波半导体光放大器的偏振特性。对行波半导体光放大器的偏振灵敏度与端面反射率、增益系数、光场限制因子等诸因素之间的关系进行了理论分析和实验研究。在此基础上,讨论了改善行波半导体光放大器偏振灵敏度的若干方法,并提出了新的偏振不灵敏行波半导体光放大器结构。 相似文献
20.
B. Yedierler S. Bilikmen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):367-371
The limits put by optical guiding, and channel guiding mechanisms on the Laser Wakefield Acceleration (LWFA) technique are
imposed on the Resonant Laser Wakefield Acceleration (RLWFA) scheme. Energy gained by the electrons in both schemes are calculated
and compared. It has presented that in the RLWFA case, the electrons gain more and more energy after each traversal of the
laser pulse and the electrons in a plasma gain about 3 GeV after 10 passages of the laser pulse. They gain 13 GeV when the
laser light makes 50 passages and 26 GeV after the laser beam traverses the plasma 100 times. Moreover, the channel guiding
mechanism is integrated to the RLWFA scheme and together with diffraction guiding a model for electron acceleration is proposed.
Received 13 September 2000 and Received in final form 27 October 2000 相似文献