US Patent 8009713 Semiconductor laser

A semiconductor laser includes an active layer, a first GaAs layer formed on the active layer, the first GaAs layer including a plurality of recessed portions periodically arranged, each of the recessed portions including a bottom surface of a (100) crystal surface and a slope including a (111) A crystal surface at least in parts, the recessed portion being disposed in contact with each other or with a minimal gap between each of adjacent ones of the recessed portions, the width of the bottom surface being greater than the minimal gaps, an InGaP layer formed on the recessed portion, and a second GaAs layer formed on the InGaAs layer over the recessed portion.