Patent ID: 9329340
Filing Date: 2016-05-03
CPC Classification: G02B,G02F

Claim Text:
1. An optical modulator having a Mach-Zehnder type waveguide on a surface of a dielectric substrate, wherein a waveguide, after multiplexing in a Y-multiplexer in an output side of the Mach-Zehnder type waveguide, includes only a multiple mode waveguide in its coupling portion, two subsidiary output waveguides that are high-order mode waveguides and that guide radiation-mode light are connected to a portion where the multiple mode waveguide is changed to a single mode waveguide that is a main output waveguide guiding signal output light, the two subsidiary output waveguides are arranged axisymmetrically with respect to the main output waveguide by interposing the main output waveguide therebetween, the multiple mode waveguide has a length equal to or longer than 150 μm, a distance between outer edges of two branching waveguides coupled in the Y-multiplexer is equal to a width (W a distance between outer edges of the two subsidiary output waveguides is equal to a width (W