According to an aspect of the present invention, there is provided an edge emitting laser including: a substrate; a first dielectric layer disposed on the substrate; a semiconductor structure on the substrate at a first direction, extending in a second direction, and protruding from the substrate through the first dielectric layer in a third direction, perpendicular to the first and second directions; a hard mask layer disposed on top of the semiconductor structure; a first, a second and a third III-V optical layers sequentially and laterally grown on and from a sidewall of the semiconductor structure, and extending in the second direction; a cladding semiconductor layer disposed on the substrate next to the third III-V optical layer and electrically connected to the third III-V optical layer; a second dielectric layer disposed on the substrate to cover the first dielectric layer, the hard mask layer, the semiconductor structure, the cladding semiconductor layer, and the first, second and third III-V optical layers; and a first contact structure and a second contact structure disposed on and electrically connected to the semiconductor structure and the cladding semiconductor layer, respectively.