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 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.     

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.     

Negative shift of a light beam reflected from the interface between optically transparent and resonant media

The lateral shift of a light beam reflected from the interface between an optically transparent dielectric and a medium for which the frequency dependences of the real and imaginary parts of the permittivity have a resonant form is investigated. At certain radiation frequencies and angles of incidence, a negative displacement of the reflected beam along the interface takes place.     

Net lateral shift of reflected beam due to surface plasmon resonance in Kretschmann configuration

When surface plasmon resonance is excited in Kretschmann configuration, the maximum Goos–Hänchen shift occurs at the resonant angle which is associated with the minimum value of reflectivity, but the maximum angular shift occurs at two incident angles beside the resonant angle. When the reflected beam is detected at Rayleigh range, the maximum net lateral shift of the reflected beam does not encounter the resonant angle and its magnitude is lager than that of Goos–Hänchen shift. Numerical simulation shows that theory agrees well with numerical results when the beam width is large enough.     

Lateral beam shift at transmission through layered structures with negative index material

We studied electromagnetic wave transmission through layered structures that include negative index materials. The excitation of leaky guided modes leads to the formation of anomalous lateral shifts in the reflected beam with a double-peak structure and in the transmitted beam with a single-peak structure. In the absence of losses, we demonstrate that the total transparency (i.e. zero reflection) of the slab waveguide with the negative index material can be achieved under conditions in which high reflectivity is normally expected. We demonstrate the trade-off effect between the high transmission and the high lateral shift. This peculiar effect exists not only for the pure TE or the pure TM polarization of the obliquely incident radiation, but also under certain circumstances for both of them simultaneously i.e. for the nonpolarized radiation.     

Lateral shifts of an optical beam in an anisotropic metamaterial slab

The lateral shift of a light beam at the surface of an anisotropic metamaterial slab is investigated. Analytical expressions of the lateral shifts are derived using the stationary-phase method, in the case that total reflection does and does not occur at the first interface. The sign of the lateral shift in two situations is discussed, and the necessary conditions for the lateral shift to be positive or negative are given. It is shown that the thickness and physical parameters of the anisotropic metamaterial slab, as well as the incident angle of the light beam, strongly affect the properties of the lateral shift, and numerical results validate these conclusions. The effect of a lossy metamaterial on the lateral shift is also investigated. A restriction on the thickness of the slab is obtained, which is necessary for the stationary-phase method to remain valid.     

激光等离子体对反射波频移影响的实验研究

 研究了微波被激光等离子体反射时反射波的频率变化。实验中微波发生器产生的微波入射到激光等离子体并被等离子体反射,反射波的频率由频谱分析仪测量,发现反射波的频率与入射波的频率明显不同,分析了在激光等离子体膨胀和熄灭两种情况下激光功率密度和入射波频率对反射波频移影响的原因。结果表明：在等离子体膨胀和熄灭过程中,反射波频移的最大值随激光功率密度的增加而增加;随入射微波频率的增加而减小。     

激光等离子体对反射波频移影响的实验研究

研究了微波被激光等离子体反射时反射波的频率变化。实验中微波发生器产生的微波入射到激光等离子体并被等离子体反射,反射波的频率由频谱分析仪测量,发现反射波的频率与入射波的频率明显不同,分析了在激光等离子体膨胀和熄灭两种情况下激光功率密度和入射波频率对反射波频移影响的原因。结果表明：在等离子体膨胀和熄灭过程中,反射波频移的最大值随激光功率密度的增加而增加;随入射微波频率的增加而减小。     

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.     

Lateral inhomogeneity of unoccupied states for PbPc films

Micro-spot two-photon photoemission (micro-2PPE) spectroscopy is used to probe unoccupied electronic levels at sub-monolayer (ML) films of lead phthalocyanine (PbPc) on graphite (HOPG). The high-energy resolution (30 meV) 2PPE spectra with high-lateral resolution (0.4 μm) show well-resolved features due to molecule-derived occupied/unoccupied levels and the image potential state (IPS). The surface images based on photoemission from the highest occupied molecular orbital (HOMO) become laterally uniform after an annealing procedure. By contrast, the images based on the peak due to the lowest unoccupied molecular orbital (LUMO) and the next LUMO (LUMO + 1) are laterally inhomogeneous even after the annealing. The IPS peak is broadened to higher energy by 0.3 eV for sub-ML films and becomes sharp when a 1 ML film is formed. The broadening indicates that the electron in the IPS is scattered by molecules within the mean free path in the range from 1 to 10 nm. PbPc molecules are randomly distributed including nm-clusters. The LUMO and LUMO + 1 levels are stabilized as the cluster size increases. The inhomogeneity of the surface image due to the LUMO + 1 peak arises from the size distribution of the nm-clusters. The present results demonstrate that the unoccupied levels are more sensitive to the environment than the occupied levels.     

Directional tunneling escape from nearly spherical optical resonators

We report the surprising observation of directional tunneling escape from nearly spherical fused-silica optical resonators, in which most of the phase space is filled with nonchaotic regular trajectories. Experimental and theoretical studies of the dependence of the far-field emission pattern on both the degree of deformation and the excitation condition show that nonperturbative phase-space structures in the internal ray dynamics profoundly affect tunneling leakage of the whispering-gallery modes.     

Analysis of the positive or negative lateral shift of the reflected beam in Otto configuration under grazing incidence

We investigate the lateral shift of a TM-polarized light beam reflected from Otto configuration under grazing incidence. It is found that the lateral shift is strongly dependent on the thickness of the air-gap layer. By employing the pole-null representation, we demonstrate that the lateral shift is closely related to the null of the reflection function. The numerical simulations for a Gaussian beam are performed to demonstrate the validity of our theoretical analysis.     

Energy spectrum of an electron beam multiply reflected from the target

The effect of inelastically scattered electrons on the pulsed-beam energy spectrum are studied for the case where they hit back the target upon reflection from the accelerating region. The beam is formed in a vacuum diode and transported to the target by the guiding magnetic field. The formulas for the total and differential fluxes of different-order absorbed and backscattered electrons are presented. It is shown that account of multiple electron backscattering gives rise to a considerable change in the behavior of the normalized heat-source function in the target: the energy loss near the surface of the irradiated target increases markedly due to its reduction in the deep layers of the material. High-Current Electronics Institute, the Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshykh Uchebnykh Zavedenii, Fizika, No. 2, pp. 49–53, February, 2000.     

Large positive and negative lateral optical beam shift due to long-range surface plasmon resonance

In this paper, we examine theoretically the beam shift at visible wavelengths on a long-range surface plasmon (LRSP) configuration by using the stationary-phase approach. We report that the lateral beam shift at the resonance of LRSP can be two orders of magnitude greater than a wavelength. It is also found that the sign of the lateral beam shift depends on the magnitude of the intrinsic damping relative to that of the radiative damping. Negative lateral beam shift occurs when the former is larger than the latter.     

Electronic inhomogeneity and optical response of Bi2212

We measured the in-plane optical reflectivity spectra of Bi₂Sr₂CaCu₂O_8+δ single crystals from under-to overdoped regime. Appreciable residual conductivity is observed in the low energy region even in the superconducting state well below T_c. Comparing with the results of the Scanning Tunneling Microscope/Scanning Tunneling Spectroscopy (STM/STS) measurement made on the same set of crystals, we discuss how the observed gap inhomogeneity in the CuO₂ plane affects the optical spectrum.     

Self-focusing of a Gaussian laser beam reflected from a thermocapillary liquid surface

Self-focusing of laser radiation reflected from the surface of liquid heavy hydrocarbons is reported. Close agreement of experimental data with theoretical previsions suggests that thermocapillarity is the main physical phenomenon involved. The focus appears at 40 cm of the sample surface after 1 s of irradiation at 350 mW.     

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     

Radiation reflection from an optical inhomogeneity moving in a right- and left-handed medium

The parametric Doppler effect in a medium whose dielectric permittivity and magnetic permeability become negative in some spectral range is analyzed with respect to uniform plane waves. The regime in which the medium is right-handed (the refractive index is positive) for incident radiation and left-handed (the refractive index is negative) for reflected wave is demonstrated. The possibility of the occurrence of additional branches in the dispersion dependences is demonstrated.