Patent ID: 7065123

Claim:
A distributed feedback semiconductor laser comprising: a semiconductor substrate; first and second diffraction grating layers disposed above the semiconductor substrate and spaced from each other in an output direction of a beam so as to configure part of a virtual diffraction grating having a constant grating pitch and a continuous phase; a flat connecting layer sandwiched between the first and second diffraction grating layers; an active layer disposed above the first and second diffraction grating layers and the connecting layer; and a cladding layer disposed above the active layer, wherein a diffraction grating of each of the first and second diffraction grating layers has a plurality of slits penetrating from an upper surface to a lower surface and perpendicular to the output direction of the beam, and the connecting layer is formed from two layers grown epitaxially in a direction perpendicular to the output direction of the beam, one of the two layers being formed of the same material as the first and second diffraction grating layers.