Plasmon mechanism of light transmission through a metal film or a plasma layer

It is shown that a smooth metal film (or a plasma layer) can be made transparent for an electromagnetic wave when two identical subwavelength diffraction gratings are placed on both sides of the film. The electromagnetic wave transmission through the metal film is caused by excitation of evanescent surface waves (plasmons) and their transformation into propagating waves at the gratings. A model which is developed analytically shows that the problem of the wave transmission is physically equivalent to the problem of excitation of two coupled resonators of evanescent waves which are formed at the two film surfaces.     

Thermocapillary waves in a liquid film

This paper investigates two-dimensional waves in a heated liquid film in the presence of the thermocapillary effect. The waves in the film are described using the integral model. The first part of the paper considers film instability for cases of fixed temperature of the plate and fixed heat flux in the plate. The liquid temperature disturbance is calculated from the energy equation for arbitrary values of Peclet number. In the second part, the evolution of waves in a heated film is modeled based on the system of equations for film thickness, flow rate, and the energy equation. In numerical modeling of the wave evolution, the boundary of the region of growing disturbances agrees well with results of stability analysis. The calculations show that for a vertical film the thermocapillary effect leads to broadening of the instability region only at low Peclet numbers.     

Stability of the viscous fluid film flow on a uniformly heated substrate

The linear stability is investigated of a viscous fluid film on a uniformly heated substrate under an arbitrary angle of inclination against the horizon. At the substrate, the heat flux is set; at the film surface, the fluid-gas heat transfer coefficient is specified. The waves are considered in the film propagating in an arbitrary direction. Within the frame of the integral model, the dispersion ratios are obtained for the wave increment and phase velocity. The analysis is performed of the dispersion ratios, and the flow instability range is determined. At the Marangoni numbers above a certain threshold, standing wave or traveling wave type disturbances take place; the waves increase in the horizontal direction. For the traveling waves, the Marangoni number threshold value is significantly lower than the same for the standing waves.     

Acoustic waves in structure "piezoelectric plate-polymeric nanocomposite film"

Paper is devoted to the investigation of SH(0) acoustic waves propagating in structure "piezoelectric plate-polymeric nanocomposite film". The analysis was carried out by the example of the polymeric nanocomposite film based on high-pressure polyethylene with various contents of CdS nanoparticles and lithium tantalate and lithium niobate plate. The resonant attenuation of investigated waves for the certain ratios of plate and film thicknesses was found. The obtained results open the prospects of the development of structures for SH(0) waves consisting of nanocomposite polymeric substrates and thin piezoelectric plates. Such structures may be useful for development of various thermostable chemical and biological sensors and signal processing devices.     

Hysteresis of the characteristics of magnetostatic waves in ferrite films with stripe domains whose magnetization vectors are oriented close to the plane of the film

The propagation of zero-exchange spin waves (magnetostatic waves) is investigated in yttrium iron garnet films having a regular stripe domain structure with almost in-plane orientation of the domain magnetization vectors. The characteristics of the waves are studied for magnetizations of the film parallel and perpendicular to projections of the [111] crystallographic axes onto the plane of the film. It is established, in contrast with films having the domain magnetization vectors oriented close to the normal to the plane of the film, that both the propagation of magnetostatic waves and the variation of the parameters of the domain structure exhibit a distinctly pronounced hysteretic character as the magnetizing field is varied. The hysteresis of the amplitude-frequency response, equiphase, and dispersion curves of the magnetostatic waves is investigated. The authors examine how the hysteresis of these parameters is related to the hysteresis of the domain structure. The spectrum of magnetostatic waves is found to have an interval of wavelengths (wave numbers) that are not excited in the unsaturated film when the applied field is close to the saturation value, and this phenomenon as well exhibits hysteresis. Zh. éksp. Teor. Fiz. 114, 1430–1450 (October 1998)     

Novelty Filtering Using Phase Conjugate Wave in Organic Dye-Doped Polymer Films

A real-time detection of a moving object was demonstrated by taking the subtraction between cross-polarized phase conjugate waves with fast and slow response times with two kinds of dye-doped phase conjugators. One consists of superposed films of an erythrosin-B-doped film and a methyl-orange-doped film, and the other is a film dispersed with both dyes. The relative phase between cross-polarized phase conjugate waves by the both dye-dispersed films was stable.     

偶氮苯液晶薄膜相位共轭的光学记录研究

利用间并四波混频研究了一种偶氮苯液昌聚合物的相位共轭和光学记录特性，在近共振条件下，用低功率Ｎｄ：ＹＡＧ倍频激光得到高效率的相位共轭光和高阶衍射光，当光强达到１０Ｗ／ｃｍ＾２量级时，薄膜显示出光记录效应，即在撒掉写入光之后，相位共轭波并不消失，进一步大光强到１０＾３Ｗ／ｃｍ＾２量级时，出现三组分别只与前向泵浦光，后向泵浦光和信号有关的高阶衍射光。其中观察到第三阶衍射光，且在撒掉任两束光后，所剩一束     

Theory of magnetostatic waves in a ferrite film with transition layers

A dispersion relation is derived for magnetostatic waves in a ferrite film with inhomogeneous layers near the interfaces. It is shown that the transition layers can be taken into account using a single integrated parameter, namely, the effective film thickness. It is established that the layered structure of the film causes an extra wave damping. The relations obtained can be used to analyze the dispersion and damping of the main modes of magnetostatic waves.     

薄膜和半无限大介质间的近场辐射换热研究

研究了硼掺杂硅(记为Si-19)薄膜和半无限大物体(Si-19和SiC)在100 nm真空间距下的近场辐射换热随薄膜厚度的变化。研究结果表明,当半无限大物体和薄膜为相同的Si-19材料时,由于表面波激发并相互耦合,使得近场辐射换热随薄膜的厚度变化比较复杂。当半无限大物体为SiC材料时,由于表面波的耦合遭到破坏以及辐射体的高发射率频率区和吸收体的高吸收率频率区不匹配,导致表面波的激发对不同材料间的近场辐射换热的增强程度降低,因此在相同计算区域内热流密度随厚度的增加单调增加,没有出现极值点。     

Two- and three-dimensional waves in falling film flow in the nonlaminar flow regime: an NMR study

Nuclear magnetic resonance (NMR) velocity-encoded imaging results as well as propagators are presented for the nonlaminar flow regime of falling films. The film is generated by a continuous flow of silicon oil along a vertical poly(methyl methacrylate) plate. While the film remains purely laminar for a film Reynolds number Re_f=0.5, it exhibits laminar-wavy behavior for 1.0≤Re_f≤2.5. In this range, a laminar residual film can be distinguished from averaged waves near the surface of the film from measurements of the flow velocity ν₂ along the direction of gravity as a function of the coordinatex normal to the plate. The perpendicular velocity components, ν _x and ν _y are zero within the accuracy of the measurement, indicating that the wave motion is two-dimensional in the laminar-wavy case. For higher Re_f the waves are found to be three-dimensional, a straightforward division into a residual film and waves in ν _z is lost and the waves extend over the whole thickness of the film.     

Observation of spin-wave envelope solitons in periodic magnetic film structures

The formation and propagation of light and dark microwave spin-wave envelope solitons in a periodic magnetic film structure have been observed. The periodic structure was manufactured on the basis of the single-crystal film of iron-yttrium garnet and a lattice of copper strips placed on the surface of the film perpendicularly to the propagation direction of carrying spin waves. The solitons are generated at frequencies corresponding to the band gap in the spectrum of the spin waves of the periodic structure, which is due to the first Bragg resonance.     

Spin-wave spectroscopy and application of its methods to heterostructures of silicon dioxide with Co nanoparticles on a GaAs substrate

A method has been developed for determining magnetic and electrical characteristics of film nanostructures containing magnetic nanoparticles from dispersion curves of surface spin waves propagating in these nanostructures. The dispersion curves of spin waves are determined by the dynamics of the spin component described by the generalized Landau-Lifshitz equations and an alternating electromagnetic field induced by a spin wave. Since spin waves are very sensitive to inhomogeneity of magnetic parameters, spin disorder, and conductivity of an object near or inside which these waves propagate, they can be used for determining magnetic and electrical characteristics of the objects under investigation. The developed calculation method, which can be employed both in spin-wave spectroscopy and in analysis of dispersion curves obtained by other methods, has been used for determining parameters of heterostructures consisting of a SiO₂ film with Co nanoparticles on a GaAs substrate. It has been found from the shape of dispersion curves of the surface spin waves that, in the film near the interface, spins of the nanoparticles are close to a ferromagnetic ordering, whereas near the free surface, the spin orientation of nanoparticles is more chaotic. It has been revealed that a conducting layer is formed in GaAs, and the SiO₂(Co) film near the interface has an increased conductivity.     

Waveguide interaction of light with spin waves in a ferromagnetic film

We discuss the results of a theoretical analysis of the waveguide interaction of light and spin waves. Both linear and quadratic magnetooptical effects are taken into account. The features of the interaction are considered for the three principal types of spin waves: waves in a normally magnetized ferromagnetic film, and longitudinal and transverse waves in a tangentially magnetized film. Isotropic and anisotropic diffraction processes are considered. Numerical estimates of the intensity and frequency properties of the diffraction scattering are given for a number of situations of practical interest. The effect of a strong constant magnetic field on the interaction of light and spin waves is considered.Translated from Izvestiya Vyssnikh Uchebnykh Zavednii, Fizika, No. 4, pp. 5–31, April, 1989.     

Mutual influence of wave motion and patterns of surfactant distribution

Patterns of wave propagation along the surface of a viscous liquid covered with an insoluble elastic surfactant film are studied analytically. The relationship between the damping decrement of capillary–gravitational waves and the distribution pattern of the surfactant concentration maxima relative to the crests of the waves is established as a function of the film’s elasticity.     

Effects of metal and “magnetic wall” on the dispersion characteristic of magnetostatic waves

The dispersion relation of magnetostatic waves tangentially magnetized to saturation ferrite film, with a “magnetic wall” condition (tangential component of microwave magnetic field is equal to zero) on one of the film surface and with a metal condition on the opposite surface is analyzed. The dispersion characteristics show that unidirectional magnetostatic waves appear in this structure: they can transfer energy in one direction only and fundamentally cannot transfer energy in the opposite direction. The dispersion-free propagation of magnetostatic waves also is possible in the structure in a wide frequency interval.     

SPECIFIC HEAT OF A HEISENBERG SYSTEM WITH FINITE SIZE

Based upon the spin wave theory, the influence of the size of a three-dimensional Heisenberg system on its thermodynamic properties was studied. It is found that the specific heat increases due to the finite size and free surface of the system. For a magnetic film with finite thickness, the interaction of spin waves was also discussed. There exist three additional scattering processes, namely, the scattering between spin waves with wave-vectors parallel to the surface of the film (two-dimensional spin wave), the scattering between two and three-dimensional waves, and the scattering between those waves with the same component in the direction along the thickness of the film. As a result, the T⁴ term, arising from the coupling of spin waves, in the expression of the specific heat of the system, splite into three parts proportional to T^5/2,T^7/2 and T⁴, respectively. Here T is the temperature.     

Anomalous absorption of TM electromagnetic waves by an ultrathin layer: optical analog of liquid friction

A strong maximum of absorption (as much as 100%) of bulk TM electromagnetic waves by an ultrathin film with imaginary dielectric permittivity is shown to exist at some optimal film thickness. This typical thickness is usually much smaller than the wavelength and the wave penetration depth in the material of the film. The absorptivity maximum increases and the typical thickness decreases with increasing dielectric permittivity of the layer. An optical analog of linear (liquid) friction is discussed. A frictional contact approximation for TM electromagnetic waves is analyzed, and relevant boundary conditions with an optical coefficient of friction are derived.     

Reflective optical bi-stability of antiferromagnetic films

We investigate one magnetically nonlinear response of antiferromagnetic (AF) films to incident electromagnetic waves, or the reflective optical bi-stability (ROB). Such geometry is used, where the AF anisotropy axis and external static magnetic field both are parallel to the film surfaces and normal to the incident plane. For TE incident waves with the electric component transverse to the incident plane, the ROB of the AF film with the absorption is calculated, but the case of TM incident waves is neglected since no magnetic nonlinearity is induced in this geometry. The bi-stability is completely different in the two resonant-frequency vicinities. Two kinds of bi-stability are found in the higher vicinity, and their features versus incident power are opposite. We also find that there are critical incident angle and critical film thickness for the existence of bi-stability. The bi-stability disappears when the film thickness or incident angle exceeds its critical value. Because the properties of bi-stable reflection sensitively depend on the external field and the incident angle, this bi-stability can be easily modulated by means of changing these quantities.     

Edge Effects on Growth of Ordered Stress Relief Patterns in Free Sustained Aluminum Films

An unusual form of ordered stress relief patterns is observed in a nearly free sustained aluminum film system deposited on liquid substrates by the therm~l evaporation method. The edge effects on the growth of the ordered patterns are systematically studied. It is found that the patterns initiate from the film edges, preexisting ordered patterns, or other imperfections of the film. When the patterns extend in the film regions, they decay gradually and finally disappear. If they develop along the boundaries, however, the sizes are almost unchanged over several millimeters. The stress relief patterns look like rectangular waves in appearance, which are proven to evolve from sinusoidal to triangular waves gradually. The morphological evolution can be well explained by the general theory of buckling of plates.     

Images of unstable Taylor-Sedov blast waves propagating through auniform gas

We present images from the first observation and measurements of an instability in Taylor-Sedov blast waves propagating through a uniform background gas. The instability occurs when the adiabatic index of the background gas is low. Images of the expanding blast waves are dark field shadowgraphs obtained using a frequency-doubled (527 nm) pulsed YAG laser and black and white photographic film. The film images are digitized, and image processing routines are used for analysis and presentation