Design and fabrication of 1[formula omitted]N polarization-insensitive beam splitters based on 2D subwavelength gratings

Abstract

Based upon the wave front control of transmitted light using 2D high index contrast subwavelength gratings, a kind of 1×N polarization-insensitive beam splitters are proposed and demonstrated, which could redistribute the incident light into N beams while each of them converges to a spot respectively in the relevant subregion. 1×3 and 1×4 beam splitters as typical instances are designed applying the rigorous coupled-wave analysis (RCWA) results, of which the characterizations are tested by numerical simulation and the samples are fabricated on a silicon-on-insulator (SOI) wafer. Both numerical and experimental results demonstrate that good splitting ability without polarization sensitivity can be achieved while simultaneously maintaining high transmissivity under normal incidence at a wavelength of 1.55μm.