| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical modulator with a reduced RF driving voltage as well as a reduced DC bias voltage.SOLUTION: The light modulator includes: a substrate; an optical waveguide formed on the substrate; a traveling wave electrode having a center electrode for high frequency electric signals and a ground electrode, in which a high frequency electric signal propagates; and a bias electrode which applies a bias voltage. The optical waveguide has an interaction part for high frequency electric signals and an interaction part for bias, and ridge parts are formed by concave portions formed by partially digging the substrate along the optical waveguide in both the interaction part for high frequency electric signals and the interaction part for DC bias. The concave portions in the interaction part for high frequency electric signals and the concave portions in the interaction part for DC bias are formed to have the same depth substantially, and at least one sub-ridge part is provided in the concave portion between ridge parts, where the bias electrode is formed, in the interaction part for DC bias, so that an electric power line of a DC bias passes the sub-ridge part. |
