| 摘要 |
An electrically tunable optical modulator includes a substrate having an electrooptical effect, an optical waveguide having first, second, and third cascading portions in the substrate, and transmitting an optical field, a first coplanar waveguide electrode having a first part over the first cascading portion and second and third parts extending beyond the first cascading portion, a second coplanar waveguide electrode having a fourth part over the second cascading portion and fifth and sixth parts extending beyond the second cascading portion, a third coplanar waveguide electrode having a seventh part over the third cascading portion and eighth and ninth parts extending beyond the third cascading portion, a fourth coplanar waveguide electrode formed to have a first distance from the first coplanar waveguide electrode, a fifth coplanar waveguide electrode formed between the first and second coplanar waveguide electrodes to have second and third distances, respectively, a sixth coplanar waveguide electrode formed between the second and third coplanar waveguide electrodes to have fourth and fifth distances, respectively, a seventh coplanar waveguide electrode formed to have a sixth distance from the third coplanar waveguide electrode, and a voltage source supplying voltages to the first, second, and third coplanar waveguide electrodes, wherein the fourth to seventh coplanar waveguide electrodes are grounded and the first to sixth distances are substantially the same, so that electrooptic overlap integrals of each cascading portion of the optical waveguide are the same.
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