Patent ID: 6411762
Filing Date: 2002-06-25
Classification: C03B,G02B,H01S

Abstract:
An optical fiber, comprising:a centrally disposed core region adapted to absorb radiation at a first wavelength and provide gain at a second wavelength, the radiation having at least one mode; an intermediate cladding layer disposed around the core region, wherein the intermediate cladding layer comprises: an inner transparent region adjacent to the core region; and an outer absorbing region adjacent to the first cladding region, the outer absorbing region absorbing radiation at a predetermined wavelength, wherein the outer absorbing region selectively attenuates modes propagating in the core region in favor of propagation of a fundamental mode of the optical fiber; a first cladding layer having an outer boundary and disposed around the intermediate cladding layer, the first cladding layer having a plurality of irregularities formed at least along the outer boundary such that the outer boundary is radially constrained and quasi-circular; and a second cladding layer disposed around the first cladding layer, wherein the refractive index of the intermediate cladding layer is between that of the core region and the first cladding layer.