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In this paper, we report a study on Si nanopatterns, fabricated as a one-dimensional (1D) Si nanograting with a sub-wavelength (≈200 nm) period. Unpolarized light normally incident on the nanopatterned Si becomes partially polarized and chiral over the entire visible range of 380–740 nm. The degree and the state of polarization of light were measured using polarimetric and ellipsometric techniques. The analysis showed that the reflected light is partially linearly polarized and at the same time a slight chirality (Ŝ3≠0) is observed. Although the polarization of the reflected light is related to the 1D nanograting anisotropy, the chiral transformation of the light could be related to a micrometer-scale chiral substructure on the Si nanopatterned surface. This structure results from the dynamic polarization rotation of the femtosecond laser pulses in their filaments in liquid carbon disulfide near the Si surface during the interferential plasmonic self-organization of the surface nanorelief. These results could underline a key enabling process for the fabrication of polarization-sensitive metasurface-based sensors or devices within the common complementary metal-oxide semiconductor (CMOS)-compatible technology.

This paper investigated the diffraction of a Gaussian laser beam on a binary mask and a refractive axicon. The principles of the formation of a zero-order Bessel beam with sharp drops of the axial field intensity edges were discussed. A laser optical system based on an axicon for the formation of a Bessel beam with quasi-uniform distribution of axial field intensity was proposed. In the laser optical system, the influence of the axicon apex did not affect the output beam. The results of theoretical and experimental studies are presented. It is expected that the research results will have practical application in optical tweezers, imaging systems, as well as laser technologies using high-power radiation.