An improved optical communication system is provided, the system particularly
suited for so-called short-haul applications, e.g., applications involving transmission
over distances less than 100 km, such as metro applications. The system uses an
external cavity laser made up of a gain medium that comprises an active region,
a beam expanding region, and an antireflective layer, an optical waveguide located
adjacent the gain medium, and a Bragg grating integral with or coupled to the optical
waveguide. The medium and the optical waveguide, due to the beam expanding region,
exhibit a coupling efficiency of at least 40%, advantageously at least 50%, even
in the absence of coupling optics, and the laser is configured and operated to
emit at least two modes.
