Patent ID: 8774571

Claim:
An optical device comprising: a substrate; a first optical waveguide including a mesa, where the mesa includes: a first lower clad layer portion, a first core layer portion, and a first upper clad layer portion, where the first lower clad layer portion, the first core layer portion, and the first upper clad layer portion are disposed in this order from the substrate side; a first etch stop layer configured to stop etching when the first optical waveguide is formed, the first etch stop layer being laminated over the substrate, and the first optical waveguide being laminated on the first etch stop layer; a second optical waveguide which includes a second lower clad layer portion, a second core layer portion, and a mesa-shaped second upper clad layer portion in this order from the substrate side, the second optical waveguide being laminated on the first etch stop layer, wherein the first core layer portion and the second core layer portion are optically connected to each other, and wherein the second core layer portion includes a second core layer configured to stop etching when the second optical waveguide is formed.