The laser beams formation with an extended light focal segment by subwavelength silicon microaxicons

The diffraction of Laguerre-super-Gaussian (1,0) modes with circular polarization by sub-wavelength silicon optical micro-axicons with relief height change has been studied in this paper. The height of the all relief of the microelements was varied and only the central part. Modeling by the finite difference time domain method showed that, depending on the height of the element, it is possible to form the required size of the focal segment. It was also shown that by adjusting the height of the central part of the axicon relief, the size of the focal spot can be reduced from 0.51λ to 0.24λ.