Patent ID: 9515450
Filing Date: 2016-12-06
CPC Classification: G02B,H01S

Claim Text:
1. An amplifying optical fiber comprising: a plurality of cores to which an active element is doped; a first cladding enclosing the plurality of cores with no gap; and a second cladding enclosing the first cladding, wherein: the plurality of cores is disposed around a center axis of the first cladding in a state in which an inter-core distance between cores adjacent to each other is equal; a refractive index of the core is provided higher than a refractive index of the first cladding; the refractive index of the first cladding is provided higher than a refractive index of the second cladding; and an expression below is satisfied: where the inter-core distance is defined as Λ, a mode field diameter of the core is defined as MFD, a cutoff wavelength is defined as λc, and a wavelength of communication light incident on the core is defined as λop.