Semiconductor laser element

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.