| 摘要 |
PURPOSE: To improve a wavelength selection characteristic in mode conversion by an electrooptic effect by causing a temp. distribution in which a temp. is changed along the direction of light propagation in an optical waveguide. CONSTITUTION: A mode converter 1 is constituted of a substrate 11, the optical waveguide 12, a comb shape electrode 13, tuning electrode 14 for heating the optical waveguide and an insulation layer 15. At this time, the plane view shape of the tuning electrode 14 is selected so that the temp. distribution in which the temp. is changed along the direction of light propagation occurs in the optical waveguide 12. That is, respective connection conductive parts 14b of the tuning electrode 14 are not parallel to the optical waveguide 12, and are curved so that the central part in the direction of light propagation comes near to the optical waveguide 12 than the end parts. Accompanying with that, the lengths of respective electrode pieces 14a of the tuning electrode 14 are not uniform, they are shortest in the central part in the direction of light propagation and become longer gradually according to come near to both ends. Thus, the temp. distribution in which the temp. becomes lower gradually according to facing from the central part in the direction of light propagation to the end part occurs in the optical waveguide 12. |
