Patent ID: 7474683

Claim:
A distributed feedback semiconductor laser comprising: a first cladding layer; a first optical guide layer provided on the first cladding layer; an active layer of AlGaInAs provided on the first optical guide layer; a second optical guide layer provided on the active layer and made of AlGaInAs semiconductor; an InP semiconductor layer provided on the second optical guide layer; an InGaAsP semiconductor layer provided on the InP semiconductor layer; a second cladding layer provided on the InGaAsP semiconductor layer and made of InP semiconductor; and a current blocking semiconductor region burying a stripe mesa, the stripe mesa including the first optical guide layer, active layer, second optical guide layer, InP semiconductor layer and InGaAsP semiconductor layer, and the stripe mesa extending in a predetermined direction; and a diffraction grating for the distributed feedback semiconductor laser in the stripe mesa, the diffraction grating being at an interface of the InGaAsP semiconductor layer and the second cladding layer, and the interface having a periodic shape to provide the diffraction grating.