A semiconductor laser device comprises a laminate consisting of a semiconductor
layer of first conductivity type, an active layer and a semiconductor layer of
second conductivity type, which is different from the first conductivity type,
that are stacked in order, with a waveguide region being formed to guide a light
beam in a direction perpendicular to the direction of width by restricting the
light from spreading in the direction of width in the active layer and in the proximity
thereof, wherein the waveguide region has a first waveguide region and a second
waveguide region, the first waveguide region is a region where light is confined
within the limited active layer by means of a difference in the refractive index
between the active layer and the regions on both sides of the active layer by limiting
the width of the active layer, and the second waveguide region is a region where
the light is confined therein by providing effective difference in refractive index
in the active layer.
