Patent ID: 8472760

Claim:
An integrated semiconductor optical device comprising: a semiconductor substrate that includes a main surface including first and second areas, the first and second areas being arranged next to each other in a predetermined direction; a first semiconductor optical device including a first mesa portion extending in the predetermined direction, a first buried layer surrounding the first mesa portion, and a first adjusting layer provided between the first mesa portion and the first buried layer, the first buried layer containing an insulating material, and the first mesa portion including a first region of a first cladding layer provided on the first area, a first core layer provided on the first region of the first cladding layer, and a first region of a second cladding layer provided on the first core layer; and a second semiconductor optical device including a second mesa portion extending in the predetermined direction, the second mesa portion having a width different from a width of the first mesa portion, the second mesa portion including a second region of the first cladding layer provided on the second area, a second core layer provided on the second region of the first cladding layer, and a second region of the second cladding layer provided on the second core layer, wherein the first core layer is joined to the second core layer by a butt joint, the first adjusting layer extends from one end facet to another end facet of the first semiconductor optical device in the predetermined direction, and the first adjusting layer has a refractive index lower than a refractive index of the first core layer and higher than a refractive index of the first buried layer.