Patent ID: 8199399
Filing Date: 2012-06-12
Classification: B29C,H01S

Abstract:
1. A method comprising: providing a plurality of amplifying fiber segments including a first amplifying segment and a second amplifying segment, wherein the first amplifying segment includes a first core that amplifies light of a signal-light wavelength and that is surrounded by a first inner cladding, wherein the first inner cladding is surrounded by a first outer cladding, wherein the first inner cladding includes a first defined absorbing structure that is doped with a species that absorbs light of the signal-light wavelength, wherein the second segment includes a second core that amplifies light of a signal-light wavelength and that is surrounded by a second inner cladding, wherein the second inner cladding is surrounded by a second outer cladding; coupling pump light into the first core from the first inner cladding along a length of the first core; coupling pump light into the second core from the second inner cladding along a length of the second core; coupling signal light of a signal-light wavelength into the first core; amplifying the signal light in the first amplifying segment to generate first-amplified signal light; coupling the first-amplified signal light from the first core into the second core; further amplifying the first-amplified signal light in the second amplifying segment to generate second-amplified signal light, wherein at least some light having the signal-light wavelength travels in the second amplifying segment as backwards-traveling second-segment signal-wavelength light; coupling at least some of the backwards-traveling second-segment signal-wavelength light into the first inner cladding from the second core; and absorbing, in the first defined absorbing structure, at least some of the backwards-traveling second-segment signal-wavelength light that was coupled into the first inner cladding from the second core.