Semiconductor laser element having great bandgap difference between active layer and optical waveguide layers, and including arrow structure formed without P-As interdiffusion

A semiconductor laser element comprising:

• a GaAs substrate of a first conductive type;
• a lower cladding layer formed above said GaAs substrate and made of AlxGa1−xAs of said first conductive type, where 0.57≦x≦0.8;
• a lower optical waveguide layer formed above said lower cladding layer and made of In0.49Ga0.51P which is undoped or said first conductive type;
• a compressive-strain quantum-well active layer formed above said lower optical waveguide layer and made of undoped Inx1Ga1−x1As1−y1Py1, where 0.49y1<x1≦0.4 and 0≦y1≦0.1;
• an upper optical waveguide layer formed above said compressive-strain quantum-well active layer and made of In0.49Ga0.51P which is undoped or a second conductive type;
• a first etching stop layer formed above said upper optical waveguide layer and made of GaAs of said second conductive type;
• a second etching stop layer made of Inx8Ga1−x8P of said second conductive type and formed above said first etching stop layer other than stripe areas of the first etching stop layer corresponding to at least one current injection region and low-refractive-index regions located on outer sides of the at least one current injection region and separated from the at least one current injection region or outermost ones of the at least one current injection region by a predetermined interval, where 0≦x8≦1, and said stripe areas of the first etching stop layer extend in a direction of a laser resonator;
• a first current confinement layer made of GaAs of said first conductive type and formed above said second etching stop layer;
• a third etching stop layer made of Inx9Ga1−x9P of said second conductive type and formed over said first current confinement layer and said stripe areas of said first etching stop layer, where 0≦x9≦1;
• a fourth etching stop layer made of GaAs of said second conductive type and formed above said third etching stop layer other than at least one stripe area of the third etching stop layer corresponding to said at least one current injection region;
• a second current confinement layer made of In0.5(Ga1−zAlz)0.5P of said first conductive type and formed above said fourth etching stop layer, where 0.1≦z≦1;
• a first upper cladding layer of said second conductive type, formed above said second current confinement layer and said at least one stripe area of the third etching stop layer, and made of one of AlGaAs and In0.5(Ga1−zAlz) 0.5P, where 0.1≦z≦1;
• and
• a contact layer made of GaAs of said second conductive type and formed above said first upper cladding layer.