Optical modulator

An optical modulator comprising:

• an optical waveguide formed on a substrate,
• wherein the optical modulator modulates a light wave propagating through the optical waveguide,
• wherein the optical waveguide has a configuration in which a plurality of branching parts are connected to each other in multiple stages,
• wherein each of branched waveguides that are branched from a branch point of a first branching part among the plurality of branching parts has a transition curve of which a curvature changes,
• wherein, in a predetermined section from the branch point, each of the branched waveguides is formed by the transition curve starting from a curvature of 0, and a curvature change and a width change of the optical waveguide are set to be symmetric between the branched waveguides,
• wherein second branching parts formed in the respective branched waveguides are disposed at different positions between the branched waveguides in a direction along a propagation axis of the optical waveguide, and
• wherein an end point of the predetermined section is a position where a distance between the branched waveguides is equal to or higher than a mode diameter of a light wave propagating through each of the branched waveguides.