Patent ID: 8477820

Claim:
A semiconductor laser device comprising: a semiconductor substrate having a main surface; a first semiconductor stack portion that includes a grating layer provided on the main surface and an active layer provided on the grating layer, the grating layer having a first region and a second region; a diffraction grating provided in the first region of the grating layer; a semiconductor ridge structure portion provided on the first semiconductor stack portion, the semiconductor ridge structure portion including a cladding layer and extending in a first direction; a pair of first trenches provided in the first semiconductor stack portion along both side faces of the semiconductor ridge structure portion, the first region of the grating layer being located between the pair of first trenches; and a pair of second trenches defining both side faces of the semiconductor ridge structure portion, wherein the pair of first trenches penetrates through the active layer and the grating layer, the pair of first trenches defines both side faces of the active layer and the grating layer in the first semiconductor stack portion, the side faces of the first semiconductor stack portion are separated from the side faces of the semiconductor ridge structure portion in a second direction that intersects the first direction, the first region of the grating layer has an end extending in the second direction, and the end of the first region of the grating layer reaches the first trench.