Patent ID: 7282455

Claim:
A method of producing a diffraction grating comprising: a first mask forming step of forming, on a main surface of a first member, a first mask having a plurality of resist patterns arranged at a Bragg diffraction period in a direction along the main surface; a first etching step of etching the first member by use of the first mask formed in the first mask forming step, thereby providing the first member with a diffraction grating; a first mask removing step of removing the first mask after the first etching step; a second member forming step of forming a second member of which an etching rate is lower than that of the first member, on the diffraction grating after the first mask removing step; a second mask forming step of 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 in the direction; a second etching step of etching the first member and the second member by use of the second mask formed in the second mask forming step; a second mask removing step of removing the second mask after the second etching step; and a second member removing step of removing the second member after the second mask removing step.