Abstract: A semiconductor laser device of low operating current and low noise for the 780 nm band to be used as the light source for an optical disc and its fabrication method. The device comprises: a certain conduction type Ga.sub.1-Y1 Al.sub.Y1 As first light guide layer, a Ga.sub.1-Y2 Al.sub.Y2 As second light guide layer of said certain conduction type, or an In.sub.0.5 Ga.sub.0.5 P or an In.sub.0.5 (GaAl).sub.0.5 P or an InGaAsP second light guide layer, successively formed one upon another at least in one side of the principal plane of an active layer; an opposite conduction type Ga.sub.1-Z Al.sub.Z As current blocking layer formed on the second light guide layer and provided with a stripe-like window; and a Ga.sub.1-Y3 Al.sub.Y3 As cladding layer of the same conduction type a said light guide layers formed on said stripe-like window, wherein relations of Z>Y3>Y2 and Y1>Y2 are established among Y1, Y2 Y3 and Z that define the AlAs mole-fractions.

Abstract: A semiconductor laser device suitable as a light source for an optical disk may be operated at a low operating current with low noise for the 780 nm band. The device comprises: a certain conduction type Ga.sub.1-Y1 Al.sub.Y1 As first light guide layer, a Ga.sub.1-Y2 Al.sub.Y2 As second light guide layer of said certain conduction type, or an In.sub.0.5 Ga.sub.0.5 P or an In.sub.0.5 (GaAl).sub.0.5 P or an InGaAsP second light guide layer, successively formed one upon another at least in one side of the principal plane of an active layer; an opposite conduction type Ga.sub.1-Z Al.sub.Z As current blocking layer formed on the second light guide layer and provided with a stripe-like window; and a Ga.sub.1-Y3 Al.sub.Y3 As cladding layer of the same conduction type as the light guide layers formed on the stripe-like window. The relations of Z>Y3>Y2 and Y1>Y2 define the AlAs mole fractions.