Abstract:
Methods for forming optical fiber preforms are disclosed. According to one embodiment, a method for forming an optical fiber preform includes forming a preform core portion from silica-based glass soot. The silica-based glass soot may include at least one dopant species for altering an index of refraction of the preform core portion. A selective diffusion layer of silica-based glass soot may be formed around the preform core portion to form a soot preform. The selective diffusion layer may have an as-formed density greater than the density of the preform core portion. A diffusing species may be diffused through the selective diffusion layer into the preform core portion. The soot preform may be sintered such that the selective diffusion layer has a barrier density which is greater than the as-formed density and the selective diffusion layer prevents diffusion of the at least one dopant species through the selective diffusion layer.
Abstract:
La fibre comprend un cœur (2) d'indice N et de diamètre 10 µm ou plus, entouré par un anneau (4) d'indice N+Δn et d'épaisseur ΔR, et une gaine (6) entourant l'anneau et comportant par exemple des trous d'air (8). Selon l'invention : Δn ≥ 10 -3 et ΔR = α/(Δn) β [1] avec : 5x10 -4 µm≤α≤5x10 -2 µm et 0,5≤β≤1,5. Les nombres α et β dépendent de la longueur d'onde λ de la lumière guidée par la fibre, du nombre de trous manquants dans celle-ci, du diamètre d des trous, de leur espacement Λ et de N. Pour concevoir la fibre, on choisit λ, le nombre de trous manquants, d/Λ, le taux de dopage du cœur, Λ et Δn; et l'on détermine ΔR par la relation [1] de façon à obtenir un mode fondamental aplati.
Abstract:
Multi-core optical fiber ribbons and methods for making multi-core optical fiber ribbons are described herein. In one embodiment, a multi-core optical fiber ribbon (100) includes at least two core members (102) formed from silica-based glass and oriented in parallel with one another in a single plane. Adjacent core members have a center-to-center spacing ≥ 15 microns and a cross-talk between adjacent core members is ≤ -25 dB. In this embodiment each core member is single-moded with an index of refraction n c , and a core diameter d c . In an alternative embodiment, each core member is multi-moded and the center-to-center spacing between adjacent core members is ≥ 25 microns. A single cladding layer (104) is formed from silica-based glass and surrounds and is in direct contact with the core members. The single cladding layer is substantially rectangular in cross section with a thickness ≤ 400 microns and an index of refraction n cl c .
Abstract:
An optical fiber comprising: (i) a core (12); (ii) a cladding (16) surrounding the core; wherein the cladding comprises a cladding ring (18) that: (a) has a width W equal to or less than 10 microns; (b) includes at least 50 airlines, each airline having a maximum diameter or a maximum width of not more than 2 microns and more than 50% of said airlines have a length of more than 20 m; (c) has an air fill fraction of 0, 1% to 10%, and (d) has an inner radius R 1n , and an outer radius R out , wherein 6 μm in , out
Abstract:
An improved flame-hydrolysis process is disclosed, for manufacturing large optical fiber core preforms, useful in the production of low water, single-mode optical fibers. In one feature of the invention, the preform is manufactured using a vapor axial deposition (VAD) apparatus to form an inner core and an outside vapor deposition (OVD) apparatus to form an outer core, wherein the VAD and OVD apparatus both are located within the same housing. In another feature of the invention, the concentration of a germanium dopant in the inner and outer cores is substantially uniform, but increases immediately adjacent the outer surface of the outer core. Further, the concentration of a fluorine dopant in a surrounding cladding layer decreases from a maximum value immediately adjacent to the outer core. These variations in dopant concentrations are selected to offset the effect on refractive index caused by diffusion of the germanium dopant while the preform is subsequently being processes.