| 摘要 |
PURPOSE:To easily produce a waveguide type mode splitter and to obtain superior mode separating characteristics by forming a proton replacing part for changing only an abnormal optical waveguide on a part of a mode separating area in an optical waveguide. CONSTITUTION:Two waveguides 2, 3 are formed on the surface of a base board 1 consisting of a Z-cut plate of LiNbO3 by Ti diffusion so as to be mutually crossed and a proton replacing part 6 is formed on the intersected part. The part 6 has characteristics changing only the refractive index of abnormal light. At the formation of the waveguides 2, 3, the concentration of Ti is controlled so that the branching ratio of TE mode light becomes the maximum value '1' or a value close to '1'. On the other hand, the part 6 is formed so that the branching ratio of TM mode light becomes the minimum value '0' or a value close to '0'. In said constitution, the TM mode light of incident light L is not refracted and branched at the intersected part, but goes straight through the waveguide 3. On the other hand, almost 100% the TM mode light is refracted and branched and almost complete mode separation can be attained. |
