Focusing of beams into subwavelength area in an inhomogeneous medium

Propagation and focusing of nonparaxial Gaussian beams with spherical wavef ront in a graded-index medium are investigated using quantum-theoretical me thod of coherent states. Explicit expressions for the trajectory and width of a beam taking into account all correction terms to the paraxial approxim ation have been obtained. Electromagnetic field distributions in longitudin al and lateral directions are simulated. Diffraction of strongly focused hi gh-aperture wave beams is investigated theoretically. The ratio of intensit ies of evanescent and propagating fields is calculated for different values of focused spot. (C) 2001 Optical Society of America.