High-power semiconductor laser device having current confinement structure and index-guided structure and stably oscillating in single mode

A semiconductor laser device comprising:

• a GaAs substrate of a first conductive type;
• a lower cladding layer of said first conductive type, formed on said GaAs substrate;
• a lower optical waveguide layer formed on said lower cladding layer;
• a compressive strain quantum well active layer made of Inx3Ga1−x3As1−y3Py3 and formed on said lower optical waveguide layer, where 0<x3≦0.4, 0≦y3≦0.1, and an absolute value of a product of a strain and a thickness of said compressive strain quantum well active layer is equal to or smaller than 0.25 nm;
• an upper optical waveguide layer formed on said compressive strain quantum well active layer;
• a first etching stop layer made of Inx6Ga1−x6P of a second conductive type, and formed on said upper optical waveguide layer, where 0≦x6≦1;
• a second etching stop layer made of Inx1Ga1−x1As1−y1Py1 of said second conductive type, and formed on said first etching stop layer other than a stripe area of said first etching stop layer so as to form a first portion of a stripe groove realizing a current injection window, where 0≦x1≦0.4, and 0≦y1≦0.5;
• a first InxGa1−xP layer of said second conductive type, and formed on said second etching stop layer so as to form a second portion of said stripe groove, where x=0.49±0.01;
• a current confinement layer made of InxGa1−xP of said first conductive type, and formed on said first InxGa1−xP layer so as to form a third portion of said stripe groove;
• an upper cladding layer made of Inx4Ga1−x4As1−y4Py4 of said second conductive type, and formed over said current confinement layer and said stripe groove, where x4=0.49y4±0.01, and x−0.04≦x4≦x−0.01;
• and
• a contact layer of said second conductive type, formed on said upper cladding layer;
• wherein each of layers constituting said semiconductor laser device other than the compressive strain quantum well active layer and the first and second etching stop layers has such a composition as to lattice-match with GaAs.