Investigation of the Effect of the Formation of Subwavelength Microcylinders in the Process of Pulsed Laser Action on the Cr/ZrO2 Bilayer

The effect of the formation of microcylinders during laser treatment (λ = 532 nm) of the surface of a chromium–zirconium dioxide bilayer in a pulsed low-frequency mode is studied. An unusual formation of microcylinders was observed, which was explained by the effect of micro wrinkles. It was found that in this way it is possible to form a quasi-periodic matrix of microcylinders, the size of which is on the order of the diffraction limit, which is approximately 6 times smaller than the effective diameter of the laser spot. It is shown that the matrix of elements can have a fill factor of about 0.5, with a period up to 2.5 times smaller than the diameter of the laser spot. Numerical simulation of diffraction of Gaussian beams and optical vortices with circular polarization on arrays of subwavelength microcylinders has shown that a decrease in the diameter of microcylinders leads to a decrease in the size of the focal spot and light needle for a Gaussian beam, and an increase in height leads to the formation of the main intensity peaks inside the element for both the Gaussian beam and the Laguerre-Gauss mode. Based on the simulation results, a focusing meander matrix of microcylinders with a minimum element size of about 350 nm and a height of 0.21 λ was made.