Polarization-Insensitive High-Index Contrast Gratings Beam Splitter With Focusing Ability

A polarization-insensitive two-dimensional highindex contrast gratings (2D-HCGs) beam splitter based on silicon-on-insulator is proposed and demonstrated, which performs two independent functions-transmission focusing and power equalization at the wavelength of 1550 nm. The grating profile is optimized by the use of rigorous coupled-wave analysis and the finite-element method (FEM). Simple analytical expressions of phase and modal guidelines for the beam splitter design are given. The beam splitter based on the 2D-HCGs is experimentally studied at the distance of 600 and 190 μm from the transmitted plane, which are in good agreement with the designed values.