US Patent 7856046 Surface emitting laser diode including grating layer

A surface emitting laser diode includes a ring-shaped first semiconductor layer including an n-type clad layer, a ring-shaped active layer provided on the first semiconductor layer, and a ring-shaped second semiconductor layer which is provided on the active layer and includes a p-type clad layer and a grating layer including grating units continuously arranged in a circumferential direction, each grating unit including a plurality of regions having different refractive indices and being adjacent to each other in the circumferential direction.