Patent ID: 6888863

Claim:
An optical communication system comprising an external cavity laser that comprises: a gain medium comprising an active region, the gain medium including an antireflective layer to prevent the laser from lasing off facets of the laser, the active region containing a quantum well to generate light, the quantum well having sides and cladding layers formed on the sides; a tapered beam expanding region, optically coupled to the active region, the beam expanding region and being wider than the active region, the beam expanding region shaped to provide lateral broadening and vertical broadening or both; one or more optical guiding layers to guide light from the gain media towards the beam expanding region; an optical waveguide located adjacent the gain medium such that at least a portion of the electromagnetic energy generated by the active region passes through the beam expanding region and through the antireflective layer into the optical waveguide; a Bragg grating integral with or coupled to the optical waveguide, wherein the gain medium and the optical waveguide exhibit a coupling efficiency which even without the presence of coupling optics located between the gain medium and the optical waveguide is great enough that during laser operation, substantially all optical resonance that occurs is resonance of the cavity defined between said reflective face and said grating; and wherein the grating bandwidth is selected such that the laser provides multimode output of at least two modes within the grating bandwidth.