Biomedical subjects

Alexander B Manenkov

Publications and source records attributed to Alexander B Manenkov.

5 recordsLinked to original sources

PubMed2007

Reflectivity properties of an anisotropic slab waveguide with isolated substrate.

The scattering properties for both TE and TM modes of an abruptly ended two-layered slab waveguide with anisotropic core and isolated substrate are examined by an improved iteration technique, which is based on the integral equation method with accelerating parameters. The relative dielectric constants of the core for the three Cartesian directions are considered to be different, but cases with isotropic core are also considered. The electric field distribution on the terminal plane and the reflection coefficients of the dominant TE and TM guided modes, as well as the near-field distribution and the far-field radiation pattern, are computed, while numerical results are presented for several cases of the core anisotropy.

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PubMed2006

Metal iris influence on guided-mode diffraction.

The effects of the presence of metal irises on guided-mode propagation through a symmetrical three-layer slab waveguide are examined by using the integral equation method. The aperture electric field distribution is expressed in terms of a finite series of Chebyshev polynomials. The modal reflection and transmission coefficients, the near-field structure, and the far-field radiation pattern are calculated, while numerical results are presented for several iris apertures.

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PubMed2004

Calculation of radiation modes by the Lanczos-Fourier expansion.

For construction of the TE radiation modes of planar waveguides several methods are employed that are based on collocation techniques. The field representation in the core is based on the Lanczos-Fourier sinusoidal series. The numerical codes are very simple and give accurate results. The validity of these methods is checked for constant refractive-index profiles, while numerical results are also given for parabolic profiles. Furthermore, the validity of the orthogonality condition between the guided and the radiation modes is checked. These methods are demonstrated to be effective and can also be employed to study the TM case and waveguides of lossy media, as well as anisotropic and chiral structures.

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PubMed2004

Reflectivity of buried slab waveguides.

The scattering properties of an abruptly ended buried slab waveguide for both TE and TM modes are examined by an improved iteration technique that is based on the integral equation method with "accelerating" parameters. The waveguide is considered a symmetrical slab, for which the weakly guiding conditions are invalid, and it is embedded in a different dielectric material. The tangential electric field distribution on the terminal plane, the reflection coefficient of the first TE and TM guided modes, and the far-field radiation pattern are computed. Numerical results are presented for several ended waveguides, while special attention is given to the far-field radiation pattern rotation and the terminal field distributions.

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PubMed2002

Guided-mode analysis by the Lanczos-Fourier expansion.

The Lanczos-Fourier series expansion is employed to analyze the guided-mode field in an asymmetrical slab waveguide, the core of which has an anisotropic and inhomogeneous dielectric permittivity. A system of linear homogeneous equations is derived by the collocation technique with consideration of the wave equation and the appropriate boundary conditions at the interfaces between the core and cladding media. The propagation constants are found from a determinant equation that ensures the existence of a nontrivial solution of the system. Numerical results are presented for several cases of dielectric permittivity, including the constant, parabolic, linear, and anisotropic cases. This approach is found to converge reasonably fast, and Richardson's extrapolation technique is applied to accelerate the convergence further. The approach can be easily generalized from the scalar to the vector equation, and, as an example, we consider the guided modes of a circular fiber.

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