Patent ID: 6668002
Filing Date: 2003-12-23
Classification: H01S

Abstract:
A semiconductor laser device comprising:a GaAs substrate of a first conductive type; a first lower cladding layer formed above said GaAs substrate and made of In0.49Ga0.51P of said first conductive type; a lower optical waveguide layer formed above said first lower cladding layer and made of Inx1Ga1-x1As1-y1Py1 which is undoped or said first conductive type, where x1=0.49y1 and 0&lE;y1&lE;0.3; a compressive-strain quantum-well active layer formed above said lower optical waveguide layer and made of Inx3Ga1-x3As1-y3Py3, where 0.49y3an upper optical waveguide layer formed above said compressive-strain quantum-well active layer and made of Inx1Ga1-x1As1-y1Py1 which is undoped or a second conductive type, where x1=0.49y1 and 0&lE;y1&lE;0.3; a first upper cladding layer of said second conductive type, formed above said upper optical waveguide layer and made of one of In0.49Ga0.51P and AlxGa1-xAs which has an approximately identical refractive index to a refractive index of In0.49Ga0.51P, where 0.45&lE;x&lE;0.55; a first etching stop layer formed above said first upper cladding 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&lE;x8&lE;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&lE;x9&lE;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 In0.49Ga0.51P of said first conductive type and formed above said fourth etching stop layer; a second 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 In0.49Ga0.51P and AlxGa1-xAs which has an approximately identical refractive index to the refractive index of In0.49Ga0.51P, where 0.45&lE;x&lE;0.55; and a contact layer made of GaAs of said second conductive type and formed above said second upper cladding layer.