A plurality of Bragg gratings are formed at predetermined locations of a laminate including a mounting substrate, a clad layer provided on the mounting substrate and an optical material layer provided on the clad layer. Optical waveguides are formed each including at least each of the Bragg gratings. Masks are formed each covering a region corresponding to each of the grating elements on the optical material layer. The optical material layer and clad layer are etched to shape an end face of each of the grating elements.