Patent ID: 7860139

Claim:
A semiconductor laser device comprising: an n-type clad layer formed on a substrate; an active layer formed on the n-type clad layer; and a p-type clad layer formed on the active layer to have a striped ridge and wing regions, the wing regions being provided with a first trench present on one side of the ridge and a second trench present on the other side thereof being interposed therebetween, wherein a reflectivity Rf at a front end face as a light extraction side of a resonator, a reflectivity Rr at a rear end face of the resonator, a minimum value W 1 of a width of the first trench in a region adjacent to the front end face, a minimum value W 2 of a width of the second trench in the region adjacent to the front end face, a width W 3 of the first trench at the rear end face, and a width W 4 of the second trench at the rear end face satisfy: Rf<Rr, W1<W3, and W2<W4, a width Wf of the ridge at the front end face, and a width Wr of the ridge at the rear end face satisfy: Wf>Wr, and the ridge includes a region where a width decreases with distance from the front end side toward the rear end side.