Patent attributes
In an embodiment, a method of producing a diffraction grating comprises steps of: forming, on a man surface of a first member, a first mask having a plurality of resist patterns arranged at a Bragg diffraction period; etching the first member by use of the first mask, thereby providing the first member with a diffraction grating; removing the first mask; forming, on the diffraction grating, a second member of which an etching rate is lower than that of the first member; forming a second mask on a first region in a surface of the second member, the first region and a second region in the surface being adjacent to each other; and etching the first member and the second member by use of the second mask.