US 12,392,684 B2 · Multimode optical fiber core cane classification method

Abstract

Methods for classifying a core cane of an multimode optical fiber are disclosed. In embodiments, the method includes determining a relative refractive index profile Δ(r) of the core cane; fitting the relative refractive index profile Δ(r) to an alpha profile Δfit(r) defined by: Δ fit ( r ) = Δ o , fit ( 1 - ( r a fit ) α fit ) where Δo,fit is a relative refractive index at a longitudinal centerline of the core cane, αfit is a core shape parameter, and afit is an outer radius of the core cane; generating a non-alpha residual profile Δdiff(r)=Δ(r)−Δfit(r) for the core cane; computing one or more metrics from Δdiff(r), and using the one or metrics in a classification of the core cane, the classification comprising a prediction of whether a bandwidth at a pre-determined wavelength of an optical fiber drawn from a preform comprising the core cane exceeds a pre-determined bandwidth at the pre-determined wavelength.

Claims20

Dependent claims

A method of classifying a core cane for use in forming a multimode optical fiber, the method comprising:

determining a relative refractive index profile Δ(r) of the core cane;
fitting the relative refractive index profile Δ(r) to an alpha profile Δfit(r) defined by
Δ
fit
(
r
)
=
Δ
o
,
fit
(
1
-
(
r
a
fit
)
α
fit
)
where Δo,fit is a relative refractive index at a longitudinal centerline of the core cane, αfit is a core shape parameter, and afit is an outer radius of the core cane;
generating a non-alpha residual profile Δdiff(r)=Δ(r)−Δfit(r) for the core cane;
computing one or more metrics from Δdiff(r), and
using the one or metrics in a classification of the core cane, the classification comprising a prediction of whether a bandwidth at a pre-determined wavelength of an optical fiber drawn from a preform comprising the core cane exceeds a pre-determined bandwidth at the pre-determined wavelength.

24 more elements

A method of fabricating a multimode optical fiber, the method comprising:

fabricating a core cane comprising an up-dopant concentration that varies from a centerline of the core cane to an outer radius of the core cane in accordance with a predetermined relative refractive index profile Δt(r) for the core cane;
measuring a relative refractive index profile Δ(r) of the core cane;
fitting the relative refractive index profile Δ(r) to an alpha profile Δfit(r) defined by
Δ
fit
(
r
)
=
Δ
o
,
fit
(
1
-
(
r
a
fit
)
α
fit
)
where Δo,fit is a relative refractive index at the longitudinal centerline and afit is an outer radius of the core cane;
generating a non-alpha residual profile Δdiff(r)=Δ(r)−Δfit(r) for the core cane;
determining that the core cane meets one or more selection criteria based on Δdiff(r), wherein the one or more selection criteria comprise one or more numerical ranges associated with one or more of a plurality of selection parameters, wherein the plurality of selection parameters comprises:
(i) Δdiff−sum, neg=∫r=0r=x+αfitΔdiff,neg(r) dr, where x defines an analysis region and Δdiff,neg is Δdiff(r) multiplied by a weighting function z(r) that is 1 when Δdiff(r) is negative and 0 when Δdiff(r) is positive;
(ii) Δdiff−sum, pos=∫r=0r=x+αfitΔdiff,pos(r) dr, where Δdiff,pos is Δdiff(r) multiplied by a weighting function y (r) that is 1 when Δdiff(r) is positive and 0 when Δdiff(r) is negative;
(iii) a minimum negative value of Δdiff(r) between r=0 and r=x*afit, Δdiff−neg, max;
(iv) a maximum positive value of Δdiff(r) between r=0 and r=x*afit, Δdiff−pos, max;
and
(v) a weighted summation τerr computed by
τerr=∫r=0αfitg(r)*Δdiff(r)dr
where g(r) is a predetermined weighting function;
and
in response to determining that the core cane meets the one or more selection criteria, either discarding the core cane from further processing or selecting the core cane for the further processing into the multimode optical fiber.

34 more elements

Dependencies are inferred from the claim text.

Multimode optical fiber core cane classification method

Life of this patent

Multimode optical fiber core cane classification method

Life of this patent

Abstract

Claims20