Patent ID: 7471853

Claim:
An optical modulator comprising: a substrate having an electrooptic effect; an optical input port and an optical output port arranged on the same end face of the substrate; a first optical waveguide unit formed on the substrate and having one end connected to the optical input port; a second optical waveguide unit formed on the substrate, at a location separated from the first optical waveguide, and having one end connected to optical output port; a curved folded waveguide which is formed on the substrate and connects the other ends of the first and second optical waveguide units to each other; a first signal electrode arranged along the first optical waveguide unit; a second signal electrode arranged along the second optical waveguide unit; and a ground electrode arranged with a distance to the first and second signal electrodes, wherein a portion of the first signal electrode extending along a longitudinal direction of the first optical waveguide unit is obliquely arranged to a portion of the second electrode extending along a longitudinal direction of the second optical waveguide unit, the portion of the first signal electrode and the portion of the second signal electrode being arranged so as to not intersect one another; a curvature radius of the curved folded waveguide is larger than a half of an interval between the optical input port and the optical output port; and input portions of the first and second signal electrodes to which electric signals are applied are arranged at a side surface, closer to the optical output port than the optical input port, of opposing side surfaces of the substrate.