Iq optical modulator

An IQ optical modulator, comprising:

• a parent Mach-Zehnder type (MZM) optical waveguide functioning as a parent;
• child MZM optical waveguides functioning as a child that constitute two arms of the parent MZM optical waveguide;
• two electrode transmission lines that are provided along the two arms of the child MZM optical waveguides, respectively, and that receive a modulation signal to thereby phase-modulate an optical signal propagating in the child MZM optical waveguide;
• an RF extension line that is connected to the two electrode transmission lines, respectively, and that is used to input the modulation signal applied to the two electrode transmission lines;
• a first optical splitter for branching light into the two arms of the parent MZM optical waveguide;
• second optical splitters for branching light into the two arms of the child MZM optical waveguides;
• and
• first optical multiplexers for multiplexing light from the two arms of the child MZM optical waveguides,
• wherein:
• the child MZM optical waveguide including the two electrode transmission lines has a stripe direction that is the same as the stripe direction of the RF extension line, the stripe direction of the second optical splitter, and the stripe direction of the first optical multiplexer, and that is orthogonal to the stripe direction of the first optical splitter.