A semiconductor light emitter includes a substrate, a semiconductor multilayer structure including a light emission unit that emits light in an oblique direction with respect to the substrate, a base on which the substrate is disposed, a holding member that holds the substrate at an angle set in advance with respect to the base, a temperature control unit disposed parallel to the substrate to adjust a temperature of the substrate, and a shaping optical system held against the substrate to shape a luminous flux emitted from the semiconductor multilayer structure.

Provided is an optical semiconductor element including: a stacked structure body 20 formed of a first compound semiconductor layer 21, a third compound semiconductor layer (active layer) 23, and a second compound semiconductor layer 22. A fundamental mode waveguide region 40 with a waveguide width W.sub.1, a free propagation region 50 with a width larger than W.sub.1, and a light emitting region 60 having a tapered shape (flared shape) with a width increasing toward a light emitting end surface 25 are arranged in sequence.

Provided is an optical semiconductor element including: a stacked structure body 20 formed of a first compound semiconductor layer 21, a third compound semiconductor layer (active layer) 23, and a second compound semiconductor layer 22. A fundamental mode waveguide region 40 with a waveguide width W.sub.1, a free propagation region 50 with a width larger than W.sub.1, and a light emitting region 60 having a tapered shape (flared shape) with a width increasing toward a light emitting end surface 25 are arranged in sequence.