Semi-conductor optical amplifier

A semiconductor optical amplifier includes a master source of input radiation, an amplifying component optically coupled to the master source. The amplifying component includes a semiconductor heterostructure that includes an active layer positioned between two cladding layers and an ohmic contact formed to at least one sublayer of the semiconductor heterostructure. The amplifying component also includes an input-output region for radiation that comprises at least one additional layer on at least one side of the heterostructure. This additional layer adjacent to the heterostructure comprises one or more sublayers having refractive indices nIORq and optical loss factors alpha IORq (cm) selected to provide for enhanced output power and a reduced angle of divergence.