Image Number 3 for United States Patent #8063408.
In an integrated semiconductor optical device, a first cladding layer is made of a first conductivity type semiconductor. A first active layer for forming a first semiconductor optical device is provided on the first cladding layer in a first area of a principal surface of a substrate. A second active layer for forming a second semiconductor optical device is provided on the first cladding layer in a second area of the principal surface. A second cladding layer made of a second conductivity type semiconductor is provided on the second active layer. A third cladding layer made of a first conductivity type semiconductor is provided on the first active layer. A tunnel junction region is provided between the first active layer and the third cladding layer. The first active layer is coupled to the second active layer by butt joint. The second and third cladding layers form a p-n junction.