Patent ID: 7991021

Claim:
A multimode optical fiber that favors lower order modes, the fiber comprising: a core comprising a single core region, the single core region having a longitudinal optical axis and incorporating radially dependent amounts of dopant material and selected transparent oxides at each given radius from the longitudinal optical axis, the dopant material and the selected transparent oxides being selected to provide a measure of independent control over both a desired refractive index profile and a desired radially dependent Raman gain coefficient profile that favors lower order modes and discriminates against higher order modes, the refractive index and the Raman gain coefficient have their highest values along the optical axis of the fiber; and a cladding region surrounding the core and having a refractive index different from that of the core material; wherein light launched into an end of the fiber is subject to higher Raman gain along the optical axis, which promotes lower order modes and discriminates against higher order modes.