Abstract: The optical semiconductor apparatus includes, on an n-GaAs substrate, a surface-emitting semiconductor laser device and a photodiode integrated on the periphery of the laser device with an isolation region interposed there between. The laser device is composed of an n-DBR mirror, an active region, and a p-DBR mirror and includes a columnar layered structure with its sidewall covered with an insulating film. The photodiode is formed on the substrate and has a circular layered structure wherein an i-GaAs layer and a p-GaAs layer surrounds the laser device with an isolating region interposed between the i-GaAs and p-GaAs layers and the laser device. The diameter of the photodiode is smaller than the diameter of the optical fiber core optically coupled with the optical semiconductor apparatus. Since the laser device and the photodiode are monolithically integrated, the devices do not require optical alignment, and thus, facilitate optical coupling with an optical fiber.

Abstract: A window structure type AlGaInP semiconductor laser able to suppress abnormal growth in the vicinity of a ridge and having good surface morphology, wherein a least one step-like structure is provided on a substrate having a surface tilted to a [0-1-1] direction from a (100) plane, a semiconductor stack is formed on the substrate and comprises an active layer including two types of Group III elements including at least indium (In) and Group V elements including phosphorus (P), a cladding layer of a first conductivity, a cladding layer of a second conductivity, end surfaces of an active layer serve as end surfaces of a resonator, a light guide is formed between and the end surfaces of the resonator, and the light guide is arranged at an upper step side of the step-like structure so that a portion of the light guide not including resonator end surfaces is positioned in the vicinity of the step-like structure and so that the resonator end surface portions of the light guide are farther from the step-lik