Focusing of beams into subwavelength area in an inhomogeneous medium.
Propagation and focusing of nonparaxial Gaussian beams with spherical wavefront in a graded-index medium are investigated using quantum-theoretical method of coherent states. Explicit expressions for the trajectory and width of a beam taking into account all correction terms to the paraxial approximation have been obtained. Electromagnetic field distributions in longitudinal and lateral directions are simulated. Diffraction of strongly focused high-aperture wave beams is investigated theoretically. The ratio of intensities of evanescent and propagating fields is calculated for different values of focused spot.
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Petrov