OPTICAL ELEMENT AND METHOD FOR MANUFACTURING OPTICAL ELEMENT

An object is to realize an optical characteristic based on periodic structure of optical waveguide layer of optical element, while reducing the number of grooves in the periodic structure in the optical waveguide layer. An optical element 5 includes an optical waveguide layer 53 that is provided with a periodic structure 6 of grooves 61. The optical waveguide layer 53 has a layer-thickness equal to or greater than 1.5µm and is made of material selected from a group consisting of TaO, AlO, LiNbO, LiTaO, AlN, GaN, SiC, and Yttrium aluminum garnet (YAG). (D/0.5Λ)≧2.5 is satisfied, where D indicates the depth of the groove; and A indicates the pitch of the arranged grooves, the unit of A being identical to the unit of D.