A light-emitting device and optical communication system based on the light-emitting device is disclosed. The light-emitting device is formed in a float-zone substrate. The light-emitting device includes on the substrate lower surface a reflective layer and on the upper surface spaced apart doped regions. The portion of the upper surface between the doped regions is textured and optionally covered with an antireflection coating to enhance light emission. The light-emitting device can operate as a laser or as a light-emitting diode, depending on the reflectivities of the antireflection coating and the reflective layer.