| 摘要 |
<p>In the present invention, for example with regards to a Mach-Zehrider type LN modulator which uses a Z-cut LN substrate, by providing a step by forming an etching part (1A) on the surface of the LN substrate (1), and forming an optical waveguide so as to position a pair of branching waveguides (13A,13B) of a Mach-Zehnder interferométer in the step portion, a height difference (1A) is produced between the branching waveguides, in the perpendicular direction to the substrate surface. As a result, lines of electric field directed from a signal electrode provided above one branching waveguide towards a ground electrode provided above an other branching waveguide are hardly dispersed, and a desired electrooptic effect can be obtained at a lower drive voltage.</p> |
