Abstract: A method for manufacturing a preform for a multicore fiber, including stacking (S1) a plurality of core rods and a plurality of silica-based filler rods in a tube; collapsing (S2) the tube around the stack of core rods and silica-based filler rods, forming a collapsed stack; depositing (S3) a layer of silica around the collapsed stack; removing (S4) at least part of the deposited layer of silica. The preferential process for depositing a layer of silica around the collapsed stack and removing at least part of the deposited layer of silica is Advanced Plasma and Vapor Deposition.

Abstract: According to one aspect, a few-mode amplifying fiber in a given spectral band of use is provided. The few-mode amplifying fiber comprises a cladding having a given refractive index (n0) and at least one core of refractive index and of dimensions suited to the propagation of a finite number of spatial modes in the spectral band of use of the fiber, a spatial propagation mode corresponding to a channel for transporting information. The core comprises a first solid material having a given first refractive index (n1) strictly greater than the refractive index of the cladding (n0), and, within said first material, inclusions spatially separated from one another, formed by longitudinal bars comprising a second solid material having a second refractive index (n2) strictly greater than the first refractive index (n1), at least one of said inclusions being actively doped.

Abstract: A few-mode optical fiber including a core's refractive-index profile ?n(r) of trapezoid-like shape. The optical core having a center part of radius R1 and a transition part ranges from the radius R1 to a radius R2, such that R2>R1 with R2 between 6.8 and 11.5 ?m, said refractive-index profile being defined by a surface integral of the core index profile of between 180×10?3 and 270×10?3 ?m; a transition slope S of between 1.7×10?3 and 12×10?3 ?m?1; with ?n1 and ?n2 the refractive-index difference respectively of the center part of the optical core and of the cladding part adjacent to the optical core, with respect to the outer optical cladding.

Abstract: According to one aspect, a few-mode amplifying fiber in a given spectral band of use is provided. The few-mode amplifying fiber comprises a cladding having a given refractive index (n0) and at least one core of refractive index and of dimensions suited to the propagation of a finite number of spatial modes in the spectral band of use of the fiber, a spatial propagation mode corresponding to a channel for transporting information. The core comprises a first solid material having a given first refractive index (n1) strictly greater than the refractive index of the cladding (n0), and, within said first material, inclusions spatially separated from one another, formed by longitudinal bars comprising a second solid material having a second refractive index (n2) strictly greater than the first refractive index (n1), at least one of said inclusions being actively doped.

Abstract: A few-mode optical fiber including a core's refractive-index profile ?n(r) of trapezoid-like shape. The optical core having a center part of radius R1 and a transition part ranges from the radius R1 to a radius R2, such that R2>R1 with R2 between 6.8 and 11.5 ?m, said refractive-index profile being defined by a surface integral of the core index profile of between 180×10?3 and 270×10?3 ?m; a transition slope S of between 1.7×10?3 and 12×10?3 ?m?1; with ?n1 and ?n2 the refractive-index difference respectively of the center part of the optical core and of the cladding part adjacent to the optical core, with respect to the outer optical cladding.