An optical diffusion structure includes an optical diffusion structure comprising a plurality of convex portions and a plurality of concave portions. Each convex portion is adjacent to a plurality of concave portions and each concave portion is adjacent to a plurality of convex portions. The convex portions, the concave portions and each junction of the convex and concave portions have a curvature different from 0. The optical diffusion structure further includes a diffusion plate having a first surface, wherein the optical diffusion structure is formed on the first surface, and the convex portions are arranged in a two dimensional array along a first direction and a second direction, and the concave portions are arranged in a two dimensional array along a third direction and a fourth direction.