Optical modulator including electro-optic polymer in grooves having multiple widths

An optical device comprising:

• a groove on a waveguide formed on a substrate, the groove being formed in a longitudinal direction and having electro-optic (EO) polymer placed in the groove;
• and an optical modulator that modulates light propagated through the waveguide by changing phase of the light propagated through the waveguide through change of a refractive index of the EO polymer placed in the groove by means of an electric signal, the optical device further comprising:
• a first terminal groove formed on the substrate and having a width larger than a width of the groove in the optical modulator, the width of the groove in the optical modulator being along a direction perpendicular to a direction in which the light is propagated;
• and
• a relay groove formed on the substrate and communicating with the groove in the optical modulator and the first terminal groove, wherein
• the EO polymer is placed in the groove in the optical modulator, the relay groove, and the first terminal groove.