偏振光的杨氏干涉

在基础光学框架内,通过杨氏双孔干涉实验中线偏振光的干涉及线偏振光经过两任意厚度晶片的干涉等几个实例,说明了基于矢量波叠加概念的电磁干涉的基本思想、基本分析方法和基本现象.偏振光干涉时,观测平面上可以出现或不出现光强的周期性空间调制,但一般都产生光场偏振态的周期调制.它表明了光的矢量性对干涉的重要影响,并可揭示只分析强度条纹时被掩盖的一些物理效应.     

New effects in Young's interference experiment with partially coherent light

We analyze the coherence properties of a partially coherent optical field emerging from two pinholes in a plane opaque screen. We show that at certain pairs of points in the region of superposition the light is fully coherent, regardless of the state of coherence of the light at the pinholes. In particular, this result also holds if each pinhole is illuminated by a different laser.     

Contrasts of Stokes parameters in Young's interference experiment and electromagnetic degree of coherence

We analyze the modulation of the Stokes parameters in Young's two-pinhole interference experiment with a random electromagnetic beam. We demonstrate that the electromagnetic (spectral) degree of coherence put forward in Opt. Lett.29, 328 (2004) [or its space-time analog in Opt. Express 11, 1137 (2003)] is physically related to the contrasts of modulation in the four Stokes parameters. More explicitly, the electromagnetic degree of coherence is a measure of both the visibility of the intensity fringes and the modulation contrasts of the three polarization Stokes parameters. We also show that by using suitable wave plates the modulation in any Stokes parameter can be transformed into the form of intensity variation, and hence the electromagnetic degree of coherence can be obtained experimentally by four visibility measurements.     

Generation of complete coherence in Young's interference experiment with random mutually uncorrelated electromagnetic beams

The recently developed theory that unifies the treatments of polarization and coherence of random electromagnetic beams is applied to study field correlations in Young's interference experiment. It is found that at certain pairs of points the transmitted field is spatially fully coherent, irrespective of the state of coherence and polarization of the field that is incident on the two pinholes.     

Enhancement of spatial coherence by surface plasmons

We report on a method to generate a stationary interference pattern from two independent optical sources, each illuminating a single slit in Young's interference experiment. The pattern arises as a result of the action of surface plasmons traveling between subwavelength slits milled in a metal film. The visibility of the interference pattern can be manipulated by tuning the wavelength of one of the optical sources.     

The effects of longitudinal spatial coherence of light in interference experiments

The physical conditions needed to observe the effects of longitudinal spatial coherence of emission of an extended thermal source are considered. Results of experiments on observation of interference pulses of longitudinal spatial coherence, performed using a scanning longitudinal shearing Michelson interferometer, are presented. Distinctions between the effects of temporal and longitudinal spatial coherence of light are established. It is shown that the presence of a noncompensated optical layer in one of the arms of the interferometer makes the interference pulses of the temporal and spatial coherence of light shift relative to each other (“recession”).     

Phase singularities of the coherence functions in Young's interference pattern

We analyze the coherence properties of a partially coherent field emerging from two pinholes in an opaque screen and show that the spectral degree of coherence possesses phase singularities on certain surfaces in the region of superposition. To our knowledge, this is the first illustration of the singular behavior of the spectral degree of coherence, and the results extend the field of singular optics to the study of phase singularities of correlation functions.     

Young's interference in light scattering by spheres

Young's interference pattern was observed in laser light scattering by spheres on the backside of a glass plate, but not on the frontside of the substrate. This was because that former method eliminated or reduced the influence of light scattering from a substrate on interference fringes. Young's interference makes the prediction of integrated scattering cross section of spheres complicated for the case of high number density of deposited particles. A modified Bohbert-Vlieger model that takes interference effect into consideration is proposed. Analysis shows that this model is reasonable to describe light scattering cross section of spheres.     

Young's two-slit interference of vector light fields

We explore the peculiar interference behaviors of the vector fields in the Young's two-slit configuration. The interference patterns have a chessboard structure in the middle region and depend on the topological charge and the initial phase of the input vector field. The results have potential applications such as characterizing the topological properties of the arbitrary vector fields.     

Stokes parameters and polarization contrasts in Young's interference experiment

We derive a spectral interference law that governs the behavior of the four Stokes parameters in Young's two-pinhole experiment with a random electromagnetic beam. In addition to the visibility of intensity fringes, we introduce three new contrast parameters that describe the interference-induced changes in the field's state of partial polarization. The polarization modulation depends on the electric field correlations at the pinholes and is closely related to the two-point Stokes parameters. The results are expected to be particularly useful in polarization interferometry and electromagnetic coherence theory. The formalism is demonstrated with specific examples.     

涡旋光束经杨氏双缝干涉后的光谱变化

从完全相干光的传输定理出发,研究了完全相干涡旋光照射在双缝上,干涉场中的光谱变化。研究结果表明,和普通的完全相干光(平面波)经双缝干涉的光谱变化相比较,涡旋光束的光谱变化情况显得更加丰富。研究了相对平均频率的变化,发现相对平均频率将随着源光谱的宽度,拓扑荷数以及观察点位置的变化而变化。给出了对应于不同拓扑荷数,一个固定观察面的相对平均频率的分布情况。     

Spatial coherence properties of surface plasmon investigated by Young's slit experiment

In this Letter, we present an original method to extract the optical properties of surface plasmon polaritons (SPPs) on silver surfaces. A two Young's slit experiment combined with a leakage radiation microscope has been built. By correlating both imagery and coherence measurements on the same area, we are able to address the evolution of the SPP spatial coherence along its propagation. The proposed method could also be useful to explore the properties of complex plasmonic systems.     

折射率调制深度误差对切趾啁啾光纤光栅特性的影响

从耦合模方程出发,用一种矩阵方法分析了折射率调制深度误差对切趾啁啾布拉格光纤光栅传输特性的影响。结果表明:折射率调制深度误差的分布频率越高,光栅传输特性受到的危害越小;误差平均幅值越高,光栅传输特性的劣化程度越大。因此,在光栅的制作过程中,应注意避免和减小高幅值误差,并注意减少低空间频率分布的误差。     

双棱镜干涉实验中干涉光场的调控

针对双棱镜干涉实验存在的问题,在分析双棱镜分波前干涉原理和讨论双棱镜干涉光场的结构及其相干性的基础上,探讨了怎样通过优化实验参数调控干涉光场获得适于观测的干涉条纹.使学生更好地领略物理思想和学会实验方法,培养研究能力和启迪创新意识,促进光学教学的改革.     

一个新颖的白光干涉实验的开发与研究

开发了一个获得白光条纹的新实验.把劳埃镜干涉和光栅衍射结合起来,有可能使白光源产生的不同颜色的条纹彼此重合,从而能观察到清晰的黑白条纹.讨论了有关的实验原理、装置和方法,介绍了主要的实验关键并提供了相应的测量数据.     

白光干涉实验中的一种现象及其分析

分析了迈克耳孙实验中白光干涉的原理，介绍了在测定透明介质折射率的过程中侧梭出现彩色条纹的特殊现象，并分析了其成因，     

Longitudinal purely spatial coherence of a light field

The effects of longitudinal purely spatial coherence of light and the results of observation of these effects in an interference experiment are considered under the condition that the length of temporal coherence l _c is considerably smaller than the length of longitudinal spatial coherence ρ_‖ of the field. It is shown that, for l _c ? ρ_‖, the longitudinal purely spatial coherence of the light field in fact governs the coherence of the wave train in the process of its propagation. The length and the time of coherent (“free”) path of the wave train are considered as new spatial and temporal scales of a partially coherent light field.     

物理最值三趣题

用数学中不等式a b c≥3(abc开立方）的基本性质，可以求解某些物理问题的最值．下面介绍3道电磁场的趣题．     

Decrease in spatial coherence of light propagating in free space

It is shown that a highly spatially incoherent light distribution may be generated from a highly coherent one on propagation in free space. This result essentially demonstrates that there exists an inverse of a classic result of optical coherence theory, namely, the van Cittert-Zernike theorem. The analysis also indicates that the technique of phase conjugation may be used to reverse changes in the coherence properties of light, at least those which are generated on propagation in free space.