A photoreactive material layer includes an upper portion and a lower portion each including a uniformly aligned crosslinked photoreactive material, wherein the upper portion includes a first portion of the crosslinked photoreactive material and a second portion of the crosslinked photoreactive material, wherein the first portion of the photoreactive material and the second portion of the crosslinked photoreactive material are crosslinked with each other and aligned in a first direction, and the lower portion includes a third portion of the crosslinked photoreactive material and a fourth portion of the crosslinked photoreactive material, wherein the third portion of the crosslinked photoreactive material and the fourth portion of the crosslinked photoreactive material are crosslinked with each other and aligned in the first direction.