A semiconductor laser element including a ridge extending along a laser
output direction of the laser element. The ridge has a central portion,
two peripheral portions sandwiching the central portion, and two
transitional portions. Window regions that are non-gain regions are
located in corresponding peripheral portions. A difference in an
equivalent refractive index between the central portion of the ridge and
the peripheral portions on both sides is larger than a difference in an
equivalent refractive index between the central portion of the ridge and
transitional portions on both sides of the central portion in a gain
region.