Patent ID: 7852892

Claim:
A ridge stripe semiconductor laser device, comprising a first conductivity type cladding layer, an active layer, a second conductivity type first cladding layer, an etching stop layer, a second conductivity type second cladding layer formed as a stripe-shaped ridge, and a current blocking layer formed in a region except for at least a part on the ridge these layers being disposed on a compound semiconductor substrate, wherein an orientation of a surface of the semiconductor substrate on which these layers are disposed is tilted by a predetermined angle from a (100) plane, wherein in a cross-section perpendicular to a stripe direction of the ridge, each of both lateral surfaces of the ridge comprises a first surface that is substantially perpendicular to a surface of the semiconductor substrate and extends downward from an upper end of the ridge, and a second surface that is formed of a substantially linear skirt portion inclined surface that is inclined obliquely downward to an outside of the ridge in a skirt portion of the ridge, the first surface and the second surface are connected via a third intermediate surface, the third intermediate surface is on each of both lateral surfaces of the ridge, (b1) a substantially linear step surface that protrudes toward the outside of the ridge, is substantially parallel with the surface of the semiconductor substrate and has a length not greater than 0.2 μm in the cross-section, or (b2) an inclined intermediate surface that protrudes obliquely downward to the outside of the ridge, has a linear shape or a curved shape that is convex toward an inside of the ridge, and has a length not greater than 0.2 μm along the direction parallel with the substrate surface in the cross-section, and a (111) plane of a semiconductor constituting the second cladding layer is exposed in the second surface, and wherein the (111) plane is exposed in at least 50% of an area of the second surface.