| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a new optical waveguide element, having high reliability which will not cause shift of operating point. SOLUTION: A first and a second branched light waveguides 23-1 and 23-2, which constitute an optical waveguide of a Mach-Zehnder type is formed on a surface layer portion of a substrate 21. On a buffer layer 22, a first earth electrode 25-1, a signal electrode 24, and a second earth electrode 25-2 are formed. The second ground electrode 25-2 is divided in the longitudinal direction of the optical waveguide to have a groove part 26 and the electrode for modulation, consisting of a signal electrode 24, thereby the first and second ground electrode 25-1 and 25-2 become symmetrical with respect to the center II-II of the first and second branched light waveguides. Then, the ratio d2/d1 of the intervals d1 and d2 of the first and second branched light waveguide to the signal electrode is 3.5-7.5.</p> |
