Analysis of focusing light by a harmonic diffractive lens taking into account the refractive index dispersion

The work is devoted to the theoretical and numerical investigation of the focusing properties of a harmonic lens with due regard for the refractive index dispersion. It is shown that the harmonic lens has hybrid refractive-diffractive properties, which are expressed not only in the appearance of additional local foci, but also in the displacement of the main focus even for aliquot wavelengths. The latter effect arises precisely because of the dispersion of the refractive index of the lens material.