Patent ID: 7783149

Claim:
A large mode area, gain-producing optical fiber comprising: a core region having a longitudinal axis, and a cladding region surrounding said core region, said core and cladding regions configured to support and guide the propagation of signal light in a fundamental transverse mode in said core region in the direction of said axis, said core region having a graded index profile in a radial cross-section thereof, a core radius R c a core contrast Δn c , and a grading depth Δn g , and said mode having an effective mode-field area A° eff when said fiber is straight, wherein Δn c , Δn g , and R c are selected such that when said fiber is bent to a radius R b , said fiber has sufficiently suppressed higher-order modes, and resists bend-induced degradation of gain interaction while exhibiting no less than a predetermined level of effective mode area A eff , and exhibiting no more than a predetermined level of bend loss, said suppression of higher-order modes (HOM) being roughly 10 dB or more relative to the fundamental mode, wherein said resistance to bend-induced degradation of gain interaction is achieved by configuring Δn g such that the bend-induced displacement of the fundamental transverse mode is less than about 0.85 times the radius of the mode.