In various aspects, a semiconductor light emitting device provided between a first edge and a second edge opposite to the first edge and emitting laser from the first edge, may include: a first clad layer of a first conductivity type having a nitride semiconductor; an active layer provided on the first clad layer and having a nitride semiconductor; a second clad layer of a second conductivity type provided on the active layer having a nitride semiconductor and a ridge waveguide, the ridge waveguide having an activation region and a first edge region which is adjacent to the activation region and is extended from the first edge in a direction from the first edge to the second edge; an upper electrode provided on the ridge waveguide in the activation region; and a dielectric layer provided on a side surface of the ridge waveguide in the activation region, wherein the ridge waveguide in the first edge region has a lower activation ratio of a second conductivity type impurity than the ridge waveguide in the activation region.