Patent ID: 6940884

Claim:
A semiconductor laser device comprising an n-type first cladding layer, an active layer, and a p-type second cladding layer stacked on or above an n-type semiconductor substrate, wherein the second cladding layer contains carbon as a p-type impurity at a concentration of 2×10 17 cm −3 to 2×10 18 cm −3 ; wherein the active layer comprises at least one quantum well layer, and the semiconductor laser device further comprises a ridge-shaped p-type third cladding layer and an n-type current block layer which are provided on or above the second cladding layer in a manner that the third cladding layer extends in a stripe-like shape and that the n-type current block layer holds the third cladding layer from laterally opposite sides thereof; and wherein the third cladding layer contains carbon as a p-type impurity at a concentration of 2×10 17 cm −3 or higher and wherein carbon concentration of the third cladding layer is different than the carbon concentration of the second cladding layer.