A new method for solving the problem of diffraction by a compact obstacle in a layered medium

We propose a new method for solving the two-dimensional problem of diffraction by a cylindrical body in a layered medium. Unlike the traditional methods, the boundary-value problem is reduced to solving the integral equation for the scattering pattern of the body. As an illustration of this method, we consider the problem of scattering by a round cylinder located in a dielectric layer between two homogeneous half-spaces. Technical University of Communication and Information Science, Moscow, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 7, pp. 874–888, July, 1998.     

Wave propagation and radiation in rectangular waveguides with laminar walls

Conclusions The property that dielectric laminar structures have of being good reflectors or almost complete transmitters of waves incident on them, as a function of the parameters of the layers (or the frequency), is well-known and widely used. These structures possess the same properties (for constant parameter values and frequency) in the case of oblique ray incidence, when the grazing angle changes. This property of laminar dielectrics [4] can be utilized to thin out the wave spectrum in transmission lines. In this paper we have investigated an open rectangular waveguide in which a laminar dielectric of this type is employed. Such lines can be employed in remote-control systems. We should note, of course, that the field of application of such transmission lines can be more extensive. By increasing the transverse dimensions, we can readily achieve extremely low losses for the lowest-order modes (on the order of 1 dB/km or less), while, by reducing the thickness of the dielectric layer, we can expand the working frequency band. In this case these waveguides are promising as transmission lines with low losses and a sparse spectrum; they can also be of interest in the optical range [15, 16].Institute of Physical Problems, Academy of Sciences of the USSR. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 22, No. 11, pp. 1365–1376, November, 1979.     

Laser-induced damage and light scattering in solids

The article deals with the present-day status of the problem of damage to transparent solid dielectrics such as crystals, glasses, and others. The role of the absorbing inclusions and of self-focusing in the laser damage mechanism is discussed, as are also the limiting mechanisms connected with the electron avalanche.Translated from Trudy Ordena Lenina Fizicheskogo Instituta im. P. N. Lebedeva, Vol. 101, pp. 3–8, 1978.     

Applicability of scalar theory for analysis of mode reflection from an optical dielectric waveguide end

Scalar and vector theories are compared for weakly guided modes reflected from a planar optical dielectric waveguide end or laser facet. By utilizing the free space radiation mode method the range of validity of the scalar theory over a wide range of reflectivities is given explicitly for the first time.     

Two Approaches to Solving the Problem of Diffraction on a Janus Sphere

Acoustical Physics - Based on the method of continued boundary conditions, two algorithms for the numerical solution of the problem of plane wave diffraction by a Janus sphere in the form of a...     

Orthogonality Conditions for Leaky Modes

We consider various approaches for normalization of leaky modes of open waveguides. General properties of such modes and their relation to continuous-spectrum modes are studied. Applicability of perturbation theory for calculating the shift of mode propagation constants in the case of small variations in the waveguide structure is discussed. General relations are illustrated by an example of a waveguide in the form of a channel inside a dielectric. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 5, pp. 388–401, May 2005.     

Solution of the three-dimensional problem of plane wave diffraction by a two-period plane grating

Using the discrete source method, we develop an algorithm for solving the three-dimensional problem of wave scattering by a plane grating consisting of acoustically soft or acoustically stiff bodies. An efficient algorithm is proposed for determining the periodic Green’s function of the grating. Numerical results are obtained for different geometries of the grating elements. The fulfillment of the energy conservation law is verified along with the fulfillment of the boundary condition at the surface of the central grating element.     

Abruptly terminated planar left-handed material waveguide

The problem of guided mode reflection from an abruptly terminated planar metamaterial waveguide is studied by the variational technique. The theory is illustrated by examples of abruptly terminated three-layer waveguides with step permittivity and permeability profiles. Differences in the scattering characteristics for systems with metamaterials and usual media are discussed.     

Measurement of nonlinear optical coefficients by the z-scan technique: Correctness of the technique and investigation of a new compound-lutetium diphthalocyanine complex

Correctness of z-scan measurements of nonlinear refractive indices for optical media is considered. It is shown that accuracy of these measurements is greatly affected by the thickness of the nonlinear medium layer (as compared with the diffraction length of the laser beam). Nonlinear refractive indices of nitrobenzene are measured at different laser pulse durations (7 ns and 350 ps); the nonlinearity mechanism is discussed. It is shown that at the pulse duration 350 ps the orientation mechanism of nonlinearity is less effective than at the pulse duration 7 ns due to its time lag. Nonlinear refractive indices are measured for the solution of a new synthesized compound-hexadecabutyl-substituted lutetium diphthalocyanine.     

The application of a modified method of discrete sources for solving the problem of wave scattering by group of bodies

A new universal and effective algorithm for solving the problems of wave diffraction on complicated structures composed of bodies of revolution is presented. The method is applied to diffraction on a group made of two impedance bodies of revolution. The method permits to get the pattern and the field with high accuracy.