OPTO-IT

Numerical analysis of subwavelength focusing using a silicon cylinder

D. A. Savelyev^ab, S. N. Khonina<sup>ab

a</sup> Samara State Aerospace University
^b Image Processing Systems Institute, Russian Academy of Sciences

Abstract: The analysis of the impact of variations in the size of a silicon micro-cylinder with a subwavelength radius on the diffraction of circularly polarized Gaussian beams was performed using a finite-difference time-domain (FDTD) method. It is numerically shown that a Gaussian beam can be focused near the surface of the element in a light spot, whose size at full-width at half-maximum of the intensity is 0.25$\lambda$. It is demonstrated that the silicon cylinder illuminated by a laser beam with a vortex phase singularity of the first order forms a light spot, with its central part mainly formed by the longitudinal component of the electric field. (FWHM = 0.29$\lambda$).

Keywords: diffractive optics, optical vortices, binary optics, FDTD-method, micro-cylinder with subwavelength radius, sharp focusing of light, circular polarization, Meep software.

Received: 10.11.2014