Light control elements as convex cylindrical lens and concave cylindrical mirror based on 2D high-index contrast gratings

Convex cylindrical lens and concave cylindrical mirror using 2D non-periodic high-index contrast gratings (HCGs) by introducing a parabolic cylinder phase front are proposed and numerically investigated, simulation results indicate that the transmitted or reflected light beam of the structures can be modulated by the grating blocks and will converge into a line of light or a linear spot on the image plane while maintaining high transmissivity or reflectivity with low polarization dependence. An HCG convex cylindrical lens sample with a focal length of 250 mu m and a grating area of 400 mu m x 400 mu m are fabricated on an SOI wafer, which exhibits a liner focusing ability on the image side under normal incidence at the wavelength of 1.55 mu m.