Patent ID: 8093581

Claim:
An optical semiconductor device comprising: a substrate including a first region and a second region, the first region and the second region being adjacent to each other; a first optical semiconductor element including a lower cladding layer formed on the substrate, a lower optical guide layer which is formed on the lower cladding layer in the first region and is composed of AlGaInAs, an active layer which is formed on the lower optical guide layer in the first region and has a multiple quantum well structure where a barrier layer that is formed of AlGaInAs and a well layer are alternately stacked, an upper optical guide layer which is formed on the active layer in the first region and is composed of InGaAsP, and an upper cladding layer formed on the upper optical guide layer in the first region; and a second optical semiconductor element which is formed on the lower cladding layer in the second region and is formed so as to be in contact with the first optical semiconductor element.