| 摘要 |
PROBLEM TO BE SOLVED: To suppress bias shift which is the shift in a phase relation between output signal light and monitor light.SOLUTION: An optical device includes: a substrate 91 having electro-optical effect; an optical waveguide 41 for modulation that is formed in the surface layer part of the substrate 91 and configures an interference type optical modulator for modulating input light; an output optical waveguide 42 that is formed in the surface layer part of the substrate 91 and connected to the downstream portion of the optical waveguide 41 for modulation; and a branch monitor part for monitoring branched light of light that is transmitted in the output optical waveguide 42 to be output from the output end surface 91a of the substrate 91. The output optical waveguide 42 has a narrow width area 42a in which a waveguide width is narrowed. |
