An edge emitting semiconductor laser (1) is specified, comprising an n-side waveguide region (21) and a p-side waveguide region (22); an active zone (20) for generating electromagnetic radiation; at least one reflection layer (24) in the n-side waveguide region (21), wherein the active zone (20) is arranged between the two waveguide regions (21, 22), the thickness of the n-side waveguide region (21) is greater than that of the p-side waveguide region (22), the refractive index of the reflection layer (24) is less than the refractive index of the n-side waveguide region (21) adjoining the reflection layer (24).