Surface plasmon polariton at the interface of dielectric and graphene medium using Kerr effect

We theoretically investigate the control of surface plasmon polariton(SPP) generated at the interface of dielectric and graphene medium under Kerr nonlinearity. The controlled Kerr nonlinear signal of probe light beam in a dielectric medium is used to generate SPPs at the interface of dielectric and graphene medium. The positive, negative absorption, and dispersion properties of SPPs are modified and controlled by the control and Kerr fields. A large amplification(negative absorption) is noted for SPPs under the Kerr nonlinearity. The normal/anomalous slope of dispersion and propagation length of SPPs is modified and controlled with Kerr nonlinearity. This leads to significant variation in slow and fast SPP propagation. The controlled slow and fast SPP propagation may predict significant applications in nano-photonics, optical tweezers, photovoltaic devices, plasmonster, and sensing technology.     

Reflections of light by the gradient of refractive-index distributions

We report the results of observation of weakly luminous rays produced by the gaussian beam incidence on the surface of inhomogeneous dielectric materials. These rays are experimentally distinguished from the ordinary geometrical optics rays that are reflected at the air-dielectric interface. The results are consistent with the theoretical prediction that the luminous phenomenon is caused by the reflection of the incident ray at every point in the inhomogeneous medium.     

Effects of surface and interface energies on the bending behavior of nanoscale multilayered beams

A modified continuum model of the nanoscale multilayered beams is established by incorporating surface and interface energies. Through the principle of minimum potential energy, the governing equations and boundary conditions are obtained. The closed-form solutions are presented and the overall Young's modulus of the beam is studied. The surface and interface energies are found to have a major influence on the bending behavior and the overall Young's modulus of the beam. The effect of surface and interface energies on the overall Young's modulus depends on the boundary condition of the beam, the values of the surface/interface elasticity constants and the initial surface/interface energy of the system. The results can be used to guide the determinations of the surface/interface elasticity properties and the initial surface/interface energies of the nanoscale multilayered materials through nanoscale beam bending experiments.     

Transient radiation induced by a modulated flow of charged particles on a perfectly conducting surface with random roughness

The excitation of surface waves by a modulated electron flow in a medium whose surface has random inhomogeneities is studied. It is shown that the energy flux density of a surface wave (polariton) exhibits oscillations determined by the ratio of the period of oscillations of the electron beam and the time of flight of a charged particle in the space between the beam modulation plane and the interface between the media.     

Excitation of surface elasticity waves in piezoelectric media by ion beams∗

Kinetically it has been shown that by considering a semi-bounded piezoelectric medium with hexagonal symmetry with an ion beam flowing on its free surface, the surface elasticity waves can be excited on their surface-vacuum interface as a result of the piezoelectric effect.     

Control of direction of Goos–Hänchen shift on reflection from a weakly absorbing medium

The Goos–Hänchen effect of reflected beams at the interface between isotropic medium and weakly absorbing medium was studied. We find that there is a lateral shift when a light beam travels through the interface for reflected beam for TM wave. The influence of permeability and permittivity on the Goos–Hänchen shift was discussed, respectively. When the weakly absorbing medium is right-handed material the imaginary of magnetic permeability will control the direction and magnitude of the shift. On the contrary, when the weakly absorbing medium is left-handed material, the refractive index of the isotropic medium determines the direction and magnitude of the shift.     

Analytical modelling of end thermal coupling in a solid-state laser longitudinally bonded by a vertical-cavity top-emitting laser diode

The intrinsic features involving a circularly symmetric beam profile with low divergence, planar geometry as well as the increasingly enhanced power of vertical-cavity surface-emitting lasers (VCSELs) have made the VCSEL a promising pump source in direct end bonding to a solid-state laser medium to form the minimized, on-wafer integrated laser system. This scheme will generate a surface contact pump configuration and thus additional end thermal coupling to the laser medium through the joint interface of both materials, apart from pump beam heating. This paper analytically models temperature distributions in both VCSEL and the laser medium from the end thermal coupling regarding surface contact pump configuration using a top-emitting VCSEL as the pump source for the first time. The analytical solutions are derived by introducing relative temperature and mean temperature expressions. The results show that the end contact heating by the VCSEL could lead to considerable temperature variations associated with thermal phase shift and thermal lensing in the laser medium. However, if the central temperature of the interface is increased by less than 20~K, the end contact heating does not have a significant thermal influence on the laser medium. In this case, the thermal effect should be dominated by pump beam heating. This work provides useful analytical results for further analysis of hybrid thermal effects on those lasers pumped by a direct VCSEL bond.     

Surface dark screening solitons

We report on the existence of surface dark screening solitons at the interface between a dielectric medium (air) and a self-defocusing nonlinear material, taking advantage of photorefractive diffusion and drift nonlinearities. It is very interesting that a surface dark soliton is just like half of a dark soliton in bulk, but not a whole dark soliton propagating along surface. The excitation, propagation, and stability of this type of soliton are studied by using the beam-propagation method. Another interesting thing is that this type of dark soliton can be excited by a planar light beam without a necessary dark notch.     

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.     

Laser-induced coherent modulation of solid and liquid surfaces

The interaction of a single spatially coherent, polarized laser beam with an interface possessing microscopic roughness leads to inhomogeneous energy deposition due to the interference between the incident beam and scattered interface fields. At high intensities this can lead to spatially periodic melting or vaporization of solid or liquid layers, and temporary or permanent modification of the interface. We review our experimental and theoretical work and discuss the detailed electrodynamics, spatial spectra, surface structure and temporal growth characteristics of this phenomenon.     

平顶光束经表面有缺陷的厚非线性介质后的光强分布

基于非线性薛定谔方程和分步傅里叶算法, 研究了高功率平顶高斯光束经过厚非线性介质后在自由空间传输的光强演变过程, 详细分析了介质表面缺陷对光强演化规律的影响.研究结果表明, 平顶阶数越大, 光束的自聚焦效果越差, 最大光强点越靠近介质后表面.入射光束的初始场强越强, 介质的厚度和非线性系数越大, 光束的自聚焦越强, 且极值点越靠近介质后表面.介质表面的缺陷使得光束在靠近介质后表面有较大的光强. 并且相位调制型缺陷比振幅调制型缺陷对光强的影响更大. 关键词： 平顶光束 自聚焦 缺陷 光强分布     

Multipole surface solitons supported by the interface between linear media and nonlocal nonlinear media

We address multipole surface solitons occurring at the interface between a linear medium and a nonlocal nonlinear medium. We show the impact of nonlocality, the propagation constant, and the linear index difference of two media on the properties of the surface solitons. We find that there exist a threshold value of the degree of the nonlocality at the same linear index difference of two media, only when the degree of the nonlocality goes beyond the value, the multipole surface solitons can be stable.     

高斯光束经表面有缺陷的厚非线性介质的传输特性

光学元件上存在的缺陷会对传输光束产生局域振幅和位相调制. 基于衍射理论模型和分步傅里叶算法,模拟分析了高斯光束经过表面有缺陷的非线性介质的传输过程中于介质内及从介质出射后在自由空气的传输特性, 并详细研究了在厚介质前表面有缺陷的情况下,介质中和自由空气中的光强分布演化规律. 研究表明,介质厚度越长、介质的非线性折射率越大,光束整体聚焦越厉害, 聚焦点离介质后表面越近.光束受调制点的位置离中心越近,光束分裂成丝产生的局部光强越大, 且介质表面存在缺陷将使通过的光束在介质后表面处产生一个很大的光强, 相位调制型缺陷产生的这一光强点比振幅调制型缺陷产生的光强点更强.     

Modeling of the interrelation of mechanical and electrical parameters of the surface of solids

A mathematical model for the determination of physical constants in equations of state at the interface between a metal and an inert gas medium has been developed in terms of the surface physics and thermodynamics of nonequilibrium processes with due regard for internal stresses induced by a redistribution of conduction electrons. Physical characteristics of a surface layer, in particular, at the copper-inert gas medium interface and the silicon-inert gas medium interface, have been determined using experimental values of surface tensions and energies for contacting media.     

On the Theoretical Basics of Charged-Particle-Beam Stochastic Optics

The distribution function describing the process of multiple Coulomb scattering is used to investigate the charged-particle-beam dynamics in scattering media. Formulae are presented that describe the phase portrait of the scattered beam through the incident beam and scattering medium parameters. The notion of a beam matched to the target is introduced. The refraction and reflection phenomena at the tilt interface between the medium and vacuum are studied. A mathematical model of flow tubes is suggested to carry out the appropriate calculations.     

Speckle from a rough surface when the illuminated region contains few correlation areas: The effect of changing the surface height variance

We report speckle contrast measurements taken at the centre of the far-field diffraction pattern of weak, medium and strong diffusers illuminated by a focused laser beam. We study the evolution of curves of speckle contrast as a function of the radius of the laser spot as the variance of surface height is steadily increased for a fixed correlation length. We also present experimental curves of speckle contrast as a function of the distance of the rough surface from the beam focus for three of the diffusers.     

Reflection and transmission of strongly focused vector beams at a dielectric interface

The reflection and transmission of tightly focused azimuthally and linearly polarized electromagnetic wave beams with subwavelength spot size at a dielectric interface are investigated. A substantial increase of the reflectance of a light beam that is normally incident from a higher-index medium to a lower-index medium and a decrease of the reflectance of a beam that is incident from a lower-index medium to a higher-index dielectric medium in comparison with the Fresnel reflectance are predicted.     

Enhancement of circular differential deflection of light in an optically active medium

In this letter, we investigate the circular differential deflection of a light beam refracted at the interface of an optically active medium. We show that the difference between the angles of deviation of the two circularly polarized components of the transmitted beam is enhanced manyfold near total internal reflection, which suggests a simple way of increasing the limit of detection of chiro-optical measurements.     

Reflected image of a strongly focused spot

We describe the reflection of a strongly focused beam from an interface between two dielectric media. If the beam is incident from the optically denser medium, the image generated by the reflected light is strongly aberrated. This situation is encountered in high-resolution confocal microscopy and data sampling based on solid immersion lenses and oil immersion objectives. The origin of the observed aberrations lies in the nature of total internal reflection, for which there is a phase shift between incident and reflected waves. This phase shift displaces the apparent reflection point beyond the interface, similarly to the Goos-H?nchen shift.     

Surface solitons at the interface between semi-infinite linear and thermal nonlinear optical media

We investigate numerically surface-wave solitons occurring at the interface between semi-infinite linear and thermal nonlinear optical media, with the refractive index of the linear medium being greater than that of the nonlinear medium (in the absence of light). We find that the threshold energy flows of the existence of the surface solitons depend on the linear refractive index difference of the two media. Their fitting empirical formula has been obtained. Furthermore, we elucidate that the optical beams propagating in thermal nonlinear optical media, either as a single surface soliton or as a dipole surface soliton, can be attracted to the surface, even when launched from far away.