Abstract: A multilayered crystal structure in a semiconductor laser device contains an active layer for laser oscillation on a V-stripe channeled substrate having a current-blocking layer thereon. The active layer further includes regions by means of which carriers within the active layer are prevented from diffusing outside of the active layer. These regions are disposed facing each other with an optical waveguide therebetween which is formed by the absorption of light by the portions of the current-blocking layer which are positioned at both sides of the striped channel. The distance between the regions is narrower than the width of the optical waveguide in the vicinity of both facets and wider than the width of the optical waveguide inside of both facets.