Optical fibre having low splice loss and method for making it
View Patent ↗A process for making a non-zero dispersion shifted optical fiber having low splice loss and low attenuation and to an optical fiber produced by this process. A reduction of the splice loss is observed with decreasing drawing tension. The optical fiber has a core region that includes three segments and an inner cladding segment, each having a maximum refractive index percent difference, Δdelta i %, i=0-3, the subscript i referring to a particular refractive index, the core segments being selected such that Δdelta 0 %>Δdelta 2 %>Δdelta 1 %≧0 and Δdelta 2 %>Δdelta 3 %≧0. Optical fibers exhibiting low splice loss were drawn at tensions not larger than 150 g, preferably not larger than 100 g.
1. A method for manufacturing a non-zero dispersion optical fibre comprising the steps of:
forming a glass preform from which an optical fibre can be drawn, the preform having a core and an outer cladding surrounding the core;
heating a region of the preform to permit drawing an optical fibre therefrom; and
drawing the preform into the optical fibre by applying a drawing tension to the heated region of the preform, the tension being not greater than 150 g,
wherein the drawn optical fibre comprises a central segment, a first annular segment, a second annular segment, an inner cladding segment, and an outer cladding segment, arranged in a sequence in a radial direction of the optical fibre, the central segment having a maximum refractive index percent difference Δ 0 %, the first annular segment having a maximum refractive index percent difference Δ 1 %, the second annular segment having a maximum refractive index percent difference Δ 2 %, the inner cladding segment having a maximum refractive index percent difference Δ 3 %, each of the maximum refractive index percent differences Δ 0 %, Δ 1 %, Δ 2 %, and Δ 3 % being defined with respect to the outer cladding segment, and
wherein Δ 0 %>Δ 2 %>Δ 1 %≧0 and Δ 2 %>Δ 3 %≧0, where Δ 0 % is between 0.64% and 0.80%, and the second annular segment has a centre radius r 2 in the range of 5.5 to 7.5 μm, and a width w 2 in the range of 1.7 to 3.0 μm.
2. The method of claim 1 , wherein r 2 is within the range of 6.7 to 7.5 μm.
3. The method of claim 1 , wherein the second annular segment has a Δ 2 % in the range of 0.11% to 0.17%.
4. The method of claim 1 , wherein the drawing tension is not more than 100 g.
5. The method of claim 4 , wherein the drawing tension is between 60 and 100 g.
6. The method of claim 4 , wherein Δ 0 % is between 0.64% and 0.73%.
7. The method of claim 4 , wherein r 2 is within the range of 7.1 to 7.5 μm.
8. The method of claim 1 , wherein the optical fibre is drawn at a speed in the range of 9 to 16 m/s.
9. The method of claim 1 , wherein the index profile of the second annular segment has a shape obtained using a super-Gaussian type function
Δ
2
%
·
exp
(
-
1
2
r
-
r
2
σ
2
α
)
with α in the range of 4 to 7.
10. The method of claim 1 , wherein the width of the central segment is in the range of 3.5 to 4.3 μm.
11. The method of claim 1 , wherein the maximum relative index of the inner cladding segment, Δ 3 %, is from 0.02% to 0.04%.
12. The method of claim 11 , wherein Δ 3 % is from 0.021% to 0.027%.