Optimized Minimum-Forward Light Scattering by Dielectric Nanopillars

In this letter, silicon nanopillars (NPs) with an optimum aspect ratio are analyzed, in such a way that the overlapping of the electric and magnetic dipolar resonances provides a remarkable minimum forward (MF) scattering. This ideal shape is also related with the incident wavelength and the refractive index of the surrounding medium. We work in the frame of numerical simulations based on Maxwell equations solved by the finite-element method. When the aspect ratio implies an NP, a linear behavior for the MF condition is observed. An upper limit of the aspect ratio has been found to satisfy the MF condition. This aspect ratio is determinant in order to scale these systems with wavelength. A larger efficiency at the directional conditions is also shown with respect to silicon nanodisks. These results are promising for design and create novel CMOS integrated flat optical devices.