Negative and positive lateral shift of a light beam reflected from a grounded slab

We consider the lateral shift (LS) of a light beam reflecting from a dielectric slab backed by a metal. It is found that the LS of the reflected beam can be negative while the intensity of reflected beam is almost equal to the incident one under a certain condition. The explanation for the negativity of the LS is given in terms of the interference of the reflected waves from the two interfaces. It is also shown that the LS can be enhanced or suppressed under some other conditions. The numerical calculation on the LS for a realistic Gaussian-shaped beam confirms our theoretical prediction.     

Transformation and shift of a Gaussian light beam upon reflection from a resonant medium

The specific features of the transformation and shift of a Gaussian beam reflected from a resonant absorbing medium are analyzed numerically. The study is based on the expansion of the field of the incident Gaussian beam into plane-wave components by using the Fourier integral transform. The calculations are performed for a frequency range covering the resonance region. The conditions for the splitting of the profile of the reflected beam and for its negative shift are established.     

Formation of a quasi-regular interference pattern in a speckle-modulated laser beam reflected from a transparent optically nonuniform layer

Conditions for the formation of a quasi-regular interference pattern in the speckle-modulated radiation reflected from a rough transparent layer irradiated by a focused laser beam are found. A laser method for determining the optical thickness of the transparent coating deposited onto the rough surface is proposed.     

部分偏振光经界面反射时的偏振度分析

定量计算了轴外点光源发出的部分偏振光束经界面反射后反射光偏振度与空间坐标及点光源坐标间关系，定量计算了特定参数的入射部分偏振光束经界面反射后的偏振度分布，给出了偏振度变化的数量级。计算表明一定偏振度的入射部分偏振光束经界面反射后，反射光束偏振度由于界面反射在反射光束截面上将产生一定分布。偏振度的变化不仅与光线入射角有关，还与点光源位置有关     

Lateral displacement of a Gaussian beam reflected from absorbing media

Lateral displacements of well-focused beams reflected from absorbing media are demonstrated in this paper. The incident beam is modeled as a tapered wave with a Gaussian spectrum. The field solutions are obtained on both sides of the interface by solving analytically from Maxwell's equations and by matching the boundary conditions at the interface. Numerical simulations are presented and the field values as well as the time-averaged power densities are computed. The influences of the polarization, the angle of incidence and the beam width on the displacement are discussed. The origin of the displacement lies in the absorption of the media, for which there is a phase shift between the incident and reflected waves. Because of this phase shift, the center of the reflected beam does not coincide with that of the incident one, similar to the Goos-Hänchen shift.     

Transformation of singular light beam transverse structure in resonant media

The peculiarities of transformation of transverse structure for singular light beams propagating in a resonant medium have been analyzed theoretically. The influence of nonlinear absorption, self-focusing, and defocusing on the characteristics of optical vortices with different topological structure has been studied. The formation conditions and parameters for singular spatially localized structures have been characterized. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 509–515, July–August, 2008.     

Experimental observation of spin-independent transverse shift of the centre of gravity of a reflected Laguerre-Gaussian light beam

We report experimental observation of a transverse shift of the centre of gravity of partially reflected optical beam having non-zero orbital angular momentum. The results are in reasonable agreement with the theoretical predictions. Possibility of using such shift for measurement of orbital angular momentum state of photon is discussed.     

吸收媒质反射束Goos-Hnchen位移的直接计算公式

本文导出了从吸收媒质上反射的s和p两种偏振的Goos-Hnchen位移的一般表达式。若令消光系数等于零,它们就简化成McGuilk和Carniglia给出的仅用于非吸收媒质的公式。吸收媒质的位移,在任何不为零的入射角度时都有。在镓的表面上,位移有几个波长。     

Lateral shift and tunneling of optical beam reflected from gradient-induced inhomogeneity

Two effects have been analytically and numerically studied: Goos-Hänchen shift, which is acquired by an optical beam reflected from a gradient inhomogeneity, and tunneling of radiation through a narrow induced inhomogeneity. A possibility of increasing the lateral beam shift in comparison with total internal reflection from a homogeneous medium is revealed. The dependence of the tunneling coefficient on the inhomogeneity parameters is determined and the critical inhomogeneity width at which the tunneling effect arises is found.     

Fedorov lateral shift at the interface between left-handed and right-handed media

The Fedorov lateral shift of a polarized beam upon the total internal reflection of light from an interface between media with positive and negative refractive indices is investigated. It is shown that the Fedorov lateral shift depends substantially on the polarization of the incident beam. The prediction is made that the Fedorov lateral shift can be completely compensated upon the total internal reflection of linearly polarized modes from two boundaries of a planar waveguide with a substrate prepared from a left-handed material.     

Negative lateral shift of a light beam transmitted through a dielectric slab and interaction of boundary effects

It is found that when a light beam travels through a slab of optically denser dielectric medium in air, the lateral shift of the transmitted beam can be negative. This is a novel phenomenon that is reversed in comparison with the geometrical optic prediction according to Snell's law of refraction. A Gaussian-shaped beam is analyzed in the paraxial approximation, and a comparison with numerical simulations is made. Finally, an explanation for the negativity of the lateral shift is suggested, in terms of the interaction of boundary effects of the slab's two interfaces with air.     

Principles of controlling a single-photon radiation state using optically thick resonant media

The propagation of a single-photon wave packet in a thick resonant absorber if it undergoes rapid displacement at a certain instant after the beginning of a wave packet emission is investigated theoretically and experimentally. This displacement was found to yield a radiation burst at the absorber output.     

Second-harmonic generation in a sound beam reflected and transmitted at a curved interface

This article presents a model for second-harmonic generation in a sound beam that is reflected from or transmitted through a curved interface. Propagation in homogeneous fluids is assumed. Simple analytic solutions are derived for the case of focused Gaussian beams. The solutions are used to illustrate the effects of focusing or defocusing due to curvature of the interface, in combination with impedance change at the interface, on energy transfer from the fundamental to the second harmonic.     

Transverse instability of one-dimensional transparent optical pulses in resonant media

It is shown analytically that a transparent optical pulse in a resonant medium, i.e the SIT soliton, is unstable with respect to long transverse perturbations. In this limit, the growth rate as a function of the amplitude and phase of the pulse is derived.     

Measurement of elastic light scattering from two optically trapped microspheres and red blood cells in a transparent medium

Optical tweezers can be used to manipulate small objects and cells. A trap can be used to fix the position of a particle during light scattering measurements. The places of two separately trapped particles can also be changed. In this Letter we present elastic light scattering measurements as a function of scattering angle when two trapped spheres are illuminated with a He-Ne laser. This setup is suitable for trapping noncharged homogeneous spheres. We also demonstrate measurement of light scattering patterns from two separately trapped red blood cells. Two different illumination schemes are used for both samples.     

拉盖尔-高斯光束在界面反射和折射的质心偏移特性研究

在圆柱坐标系中研究了傍轴线偏振拉盖尔-高斯光束在两种各向同性介质界面反射和折射后光强质心的偏移. 基于菲涅耳近似和泰勒级数展开,分别得到了部分反射和全反射两种情形下,质心的横向偏移和纵向偏移与光束拓扑荷的解析关系式. 研究表明,部分反射时,反射和折射光束的横向偏移的大小与光束的拓扑荷成正比,方向由拓扑荷的符号决定;而纵向偏移仅仅大小与光束的拓扑荷有关. 全反射时,反射光束质心偏移不受拓扑荷影响. 通过数值模拟验证了解析结果的正确性,并得到了解析公式的适用条件. 拉盖尔-高斯光束的质心偏移特性可应用于测量光 关键词： 拉盖尔-高斯光束 横向偏移 纵向偏移 拓扑荷     

Transformation of a Gaussian light beam reflected in the vicinity of the Brewster angle

Variations in the profile and shift of a Gaussian light beam upon reflection from a plane interface between a transparent dielectric and a medium with a complex refractive index are studied. The beam is assumed to be incident at angles close to the Brewster’s angle, where the effects of transformation of the beam profile are most substantial. Based on numerical analysis, the reflected beam profiles are obtained for different properties of the media, parameters of the incident beam, and positions of the plane of observation.     

Photoacoustic-guided convergence of light through optically diffusive media

We demonstrate that laser beams can be converged toward a light-absorbing target through optically diffusive media by using photoacoustic-guided interferometric focusing. The convergence of light is achieved by shaping the wavefront of the incident light with a deformable mirror to maximize the photoacoustic signal, which is proportional to the scattered light intensity at the light absorber.