Semiconductor laser device

A semiconductor laser device, comprising:

• a GaAs substrate, a first cladding layer, which has either one of p-type electrical conductivity and n-type electrical conductivity, a first optical waveguide layer, an In.sub.x2 Ga.sub.1-x2 As.sub.1-y2 P.sub.y2 first barrier layer, an In.sub.x3 Ga.sub.1-x3 As.sub.1-y3 P.sub.y3 quantum well active layer, an In.sub.x2 Ga.sub.1-x2 As.sub.1-y2 P.sub.y2 second barrier layer, a second optical waveguide layer, and a second cladding layer, which has the other electrical conductivity, the layers being overlaid in this order on the GaAs substrate,
• wherein each of the first cladding layer and the second cladding layer has a composition, which is lattice matched with the GaAs substrate,
• each of the first optical waveguide layer and the second optical waveguide layer has a composition, which is lattice matched with the GaAs substrate,
• each of the first barrier layer and the second barrier layer has a tensile strain with respect to the GaAs substrate and is set such that a total layer thickness of the first barrier layer and the second barrier layer may fall within the range of 10 nm to 30 nm, and such that a product of a strain quantity of the tensile strain and the total layer thickness may fall within the range of 0.05 nm to 0.2 nm, and
• the In.sub.x3 Ga.sub.1-x3 As.sub.1-y3 P.sub.y3 quantum well active layer has a composition selected from the group consisting of a composition, which is lattice matched with the GaAs substrate, and a composition, which has a tensile strain of at most 0.003 with respect to the GaAs substrate.