| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical modulator having high performance in the optical modulation characteristics and improved stability. SOLUTION: In the optical modulator which includes a substrate 1, two optical waveguides 3a, 3b on the substrate, a buffer layer 2 formed on the substrate, a traveling wave electrode 4 including a center conductor 4a and ground conductors 4b, 4c disposed above the buffer layer, and a ridge part formed of a concave, provided by engraving at least a part of the substrate, in a region where an electric field intensity of high-frequency electrical signals propagating in the traveling wave electrode is strong, the ridge part including a ridge part 8a for the center conductor on which the center conductor is formed, and a ridge part 8b for the ground conductor on which the ground conductor is formed, and in the optical modulator which has an optical waveguide 3b, in at least the ridge part for the center conductor, the ground conductor includes a part 11a, in the concave 9c whose conductor is lacking, and the ratio of the volume of the ground conductor formed on a region other than the concave to the area of the region with the ground conductor formed thereon is made less than the ratio of the volume of the ground conductor formed on the concave to the area of the region with the ground conductor formed thereon. COPYRIGHT: (C)2009,JPO&INPIT
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