Patent ID: 8705166

Claim:
An apparatus comprising: an optical-fiber amplifier having a plurality of optically coupled gain-fiber segments, including: a first gain-fiber segment, wherein the first segment has a first core that is surrounded by a first inner cladding, wherein the first inner cladding is surrounded by a first outer cladding; a second gain-fiber segment that is joined to the first segment via a first tapered segment, wherein the second segment includes a second core that is surrounded by a second inner cladding, wherein the second inner cladding is surrounded by a second outer cladding, wherein an outer diameter of the first inner cladding of the first gain-fiber segment at its connection to the first tapered segment is smaller than an outer diameter of the second inner cladding of the second gain-fiber segment at its connection to the first tapered segment, wherein signal light of a signal-light wavelength is coupled into the first core, and wherein the signal light is coupled from the first core into the second core; and a first plurality of pump-light-input ports joined to the optical-fiber amplifier.