On the Angular Width of Diffractive Beam in Anisotropic Media

TL;DR

This paper presents a universal analytical formula for calculating the angular width of diffractive beams in 2-D anisotropic media, revealing that the width can vary widely, including becoming zero under certain conditions.

Contribution

It introduces a universal analytical formula for diffractive beam width in anisotropic media, applicable to various wave types and geometries, extending beyond isotropic cases.

Findings

Angular width can be less than, greater than, or equal to zero.

The formula applies to waves of different natures in 2-D anisotropic geometries.

The study uses magnetostatic surface wave diffraction as an example.

Abstract

2-D diffraction patterns arising in the far-field region were investigated theoretically for the case, when the plane wave with non collinear group and phase velocities is incident on the wide slit in opaque screen with arbitrary orientation. This investigation was carried out by consideration as an example of magnetostatic surface wave diffraction in tangentially magnetized ferrite slab. It was deduced the universal analytical formula, which one can use to calculate the angular width of diffractive beam in any 2-D anisotropic geometries for the waves of various nature. It was shown, that in 2-D anisotropic geometries this width may be not only more or less then the value L/D (L - wavelength of incident wave, D - length of slit), but it also may be equal to zero in certain conditions.