Abstract: A monolithically integrated multiple-wavelength laser structure includes an array of lasing structures each having a cavity length chosen to correspond to a desired lasing wavelength. The array is suitable for use as a transmitter in a wavelength division multiplexing communication system. The lasing structures preferably include quantum well active regions.

Abstract: An optical preamplifier includes a semiconductor optical amplifier monolithically integrated with an optical detector and electrically isolated from the detector by an isolation region. The isolation region consists of a low-loss, preferably transparent, insulating material whose index of refraction is matched to at least the refractive index of the amplifier, leading to reduced facet reflectivity at the amplifier output facet. Alternative device structures may include a waveguiding layer in the isolation region, a grating integrated with or following the optical amplifier, and a tuning region positioned between the amplifier and isolation region for filtering spontaneous emission.

Abstract: A monolithically integrated optical preamplifier comprises an amplifying region, an optical detection region for detecting amplified light, and an optically transparent and electrically insulating isolation region interposed between the amplifying and optical detection regions. The amplifying region achieves reduced facet reflectivity by being designed to have a large spot size, single-traverse mode waveguide amplifier oriented at an angle with respect to a crystal plane through the preamplifier. The isolation region is preferably an air gap.