OPTICAL SEMICONDUCTOR DEVICE

An optical semiconductor device includes: a semiconductor multilayer structure, an active region interposed between a first facet on a light emitting side and a second facet opposing to the first facet, and a first electrode layer provided on a top of the semiconductor multilayer structure and a second electrode layer provided on a bottom of the semiconductor multilayer structure; and an electrical connection region connected to at least one of the first electrode layer and the second electrode layer of the optical semiconductor device and used for injecting a current to the active region, and α > β and β > 0 are satisfied, where in a contact area between the electrical connection region and the optical semiconductor device, the contact area included in a half region on the first facet side in a top area of the optical semiconductor device is denoted as α, and the contact area included in a half region on the second facet side is denoted as β.