Diffraction of a Gaussian beam in a three-dimensional smoothly inhomogeneous medium: an eikonal-based complex geometrical-optics approach.

摘要: We present an ab initio account of the paraxial complex geometrical optics (CGO) in application to scalar Gaussian beam propagation and diffraction a 3D smoothly inhomogeneous medium. The CGO deals with quadratic expansion eikonal reduces wave problem solution ordinary differential equations Riccati type. This substantially simplifies description as compared full-wave or parabolic (quasi-optics) equations. For propagating homogeneous medium along symmetry axis lenslike medium, possess analytical solutions; otherwise, they can be readily solved numerically. As nontrivial example we consider helical ray axially symmetric waveguide It is shown that major beam's elliptical cross section grows unboundedly; it oriented predominantly azimuthal (binormal) direction does not obey parallel-transport law.