Polarization-maintaining optical fiber, method of manufacturing polarization-maintaining optical-fiber connecting portion, and polarization-maintaining optical-fiber connecting portion
First Claim
Patent Images
1. A polarization-maintaining optical fiber comprising:
- a core region; and
a cladding region formed around the core region, the cladding region having a refractive index lower than a refractive index of the core region, whereina refractive index profile of the core region is either one of a step shaped or a concave shaped, andthe cladding region includes two holes formed in such a manner that a shortest distance W between the core region and a hole represented by W=L−
(a+b)/2 is −
0.1 μ
m to 0.2 μ
m, where L is a distance between centers of the core region and the hole, a is a core diameter of the core region, and b is a diameter of the hole, at locations in opposite to each other across the core region,the cladding region, except the two holes, is formed of a uniform material,a relation a ≧
−
24.221×
Δ
3+51.718×
Δ
2−
40.786×
Δ
+16.878 is satisfied and Δ
is equal to or larger than 0.32%, where Δ
is a relative refractive index difference in percent of the core region with respect to the cladding region, and a is a core diameter in μ
m of the core region,noncircularity of the core region is smaller than 10%, anda leakage loss at a wavelength of 1550 nm is 0.01 dB/km or less.
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Abstract
A polarization-maintaining optical fiber includes a core region and a cladding region formed around the core region. The cladding region has a refractive index lower than a refractive index of the core region. A refractive index profile of the core region is either one of a step shaped or a concave shaped. The cladding region includes two holes formed in such a manner that a shortest distance from the core region is virtually zero at locations in opposite to each other across the core region.
236 Citations
18 Claims
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1. A polarization-maintaining optical fiber comprising:
-
a core region; and a cladding region formed around the core region, the cladding region having a refractive index lower than a refractive index of the core region, wherein a refractive index profile of the core region is either one of a step shaped or a concave shaped, and the cladding region includes two holes formed in such a manner that a shortest distance W between the core region and a hole represented by W=L−
(a+b)/2 is −
0.1 μ
m to 0.2 μ
m, where L is a distance between centers of the core region and the hole, a is a core diameter of the core region, and b is a diameter of the hole, at locations in opposite to each other across the core region,the cladding region, except the two holes, is formed of a uniform material, a relation a ≧
−
24.221×
Δ
3+51.718×
Δ
2−
40.786×
Δ
+16.878 is satisfied and Δ
is equal to or larger than 0.32%, where Δ
is a relative refractive index difference in percent of the core region with respect to the cladding region, and a is a core diameter in μ
m of the core region,noncircularity of the core region is smaller than 10%, and a leakage loss at a wavelength of 1550 nm is 0.01 dB/km or less. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of manufacturing a polarization-maintaining optical-fiber connecting portion comprising:
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forming an elliptic core region at a facet of a polarization-maintaining optical fiber that includes a core region and a cladding region formed around the core region, the cladding region having a refractive index lower than a refractive index of the core region, wherein a refractive index profile of the core region is either one of a step shaped or a concave shaped, and the cladding region includes two holes formed in such a manner that a shortest distance W between the core region and a hole represented by W=L−
(a+b)/2 is −
0.1 μ
m to 0.2 μ
m, where L is a distance between centers of the core region and the hole, a is a core diameter of the core region, and b is a diameter of the hole, at locations in opposite to each other across the core region, by collapsing the holes at the facet,wherein a relation a≧
−
24.221×
Δ
3+51.718×
Δ
2−
40.786×
Δ
+16.878 is satisfied and Δ
is equal to or larger than 0.32%, where Δ
is a relative refractive index difference in percent of the core region with respect to the cladding region, and a is a core diameter in μ
m of the core region,noncircularity of the core region is smaller than 10% a leakage loss at a wavelength of 1550 nm is 0.01 dB/km or less, and the cladding region, except the two holes, is formed of a uniform material; and fusion splicing the polarization-maintaining optical fiber and a stress-applying polarization-maintaining optical fiber after aligning polarization axes of the elliptic core region and the stress-applying polarization-maintaining optical fiber.
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10. A method of manufacturing a polarization-maintaining optical-fiber connecting portion comprising:
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fusion splicing a polarization-maintaining optical fiber that includes a core region and a cladding region formed around the core region, the cladding region having a refractive index lower than a refractive index of the core region, wherein a refractive index profile of the core region is either one of a step shaped or a concave shaped, and the cladding region includes two holes formed in such a manner that a shortest distance W between the core region and a hole represented by W=L−
(a+b)/2 is −
0.1 μ
m to 0.2 μ
m, where L is a distance between centers of the core region and the hole, a is a core diameter of the core region, and b is a diameter of the hole, at locations in opposite to each other across the core region, and a stress-applying polarization-maintaining optical fiber after aligning polarization axes of the polarization-maintaining optical fiber and the stress-applying polarization-maintaining optical fiber in such a manner that the holes at a facet of the polarization-maintaining optical fiber are not collapsed,wherein a relation a ≧
−
24.221×
Δ
3+51.718×
Δ
2−
40.786×
Δ
+16.878 is satisfied and Δ
is equal to or larger than 0.32%, where Δ
is a relative refractive index difference in percent of the core region with respect to the cladding region, and a is a core diameter in μ
m of the core region, andnoncircularity of the core region is smaller than 10%, a leakage loss at a wavelength of 1550 nm is 0.01 dB/km or less, and the cladding region, except the two holes, is formed of a uniform material; and forming an elliptic core region at the facet by heating the facet of the fusion spliced polarization-maintaining optical fiber so that the holes are collapsed.
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11. A polarization-maintaining optical-fiber connecting portion manufactured by a method comprising:
-
forming an elliptic core region at a facet of a polarization-maintaining optical fiber that includes a core region and a cladding region formed around the core region, the cladding region having a refractive index lower than a refractive index of the core region, wherein a refractive index profile of the core region is either one of a step shaped or a concave shaped, and the cladding region includes two holes formed in such a manner that a shortest distance W between the core region and a hole represented by W=L−
(a+b)/2 is −
0.1 μ
m to 0.2 μ
m, where L is a distance between centers of the core region and the hole, a is a core diameter of the core region, and b is a diameter of the hole, at locations in opposite to each other across the core region, by collapsing the holes at the facet,wherein a relation a ≧
−
24.221×
Δ
3+51.718×
Δ
2−
40.786×
Δ
+16.878 is satisfied and Δ
is equal to or larger than 0.32%, where A is a relative refractive index difference in percent of the core region with respect to the cladding region, and a is a core diameter in μ
m of the core region, andnoncircularity of the core region is smaller than 10% a leakage loss at a wavelength of 1550 nm is 0.01 dB/km or less, and the cladding region, except the two holes, is formed of a uniform material; and fusion splicing the polarization-maintaining optical fiber and a stress-applying polarization-maintaining optical fiber after aligning polarization axes of the elliptic core region and the stress-applying polarization-maintaining optical fiber, wherein in a fusion-splicing portion, a polarization crosstalk is equal to or smaller than −
30 dB, and a connection loss is equal to or smaller than 1.0 dB. - View Dependent Claims (12, 13, 14)
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15. A polarization-maintaining optical-fiber connecting portion manufactured by a method comprising:
-
forming an elliptic core region at a facet of a polarization-maintaining optical fiber that includes a core region and a cladding region formed around the core region, the cladding region having a refractive index lower than a refractive index of the core region, wherein a refractive index profile of the core region is either one of a step shaped or a concave shaped, and the cladding region includes two holes formed in such a manner that a shortest distance W between the core region and a hole represented by W=L−
(a+b)/2 is −
0.1 μ
m to 0.2 μ
m where L is a distance between centers of the core region and the hole, a is a core diameter of the core region, and b is a diameter of the hole, at locations in opposite to each other across the core region, by collapsing the holes at the facet,wherein a relation a ≧
−
24.221×
Δ
3+51.718×
Δ
2−
40.786×
Δ
+16.878 is satisfied and A is equal to or larger than 0.32%, where Δ
is a relative refractive index difference in percent of the core region with respect to the cladding region, and a is a core diameter in μ
m of the core region, andnoncircularity of the core region is smaller than 10%, a leakage loss at a wavelength of 1550 nm is 0.01 dB/km or less, and the cladding region, except the two holes, is formed of a uniform material; and fusion splicing the polarization-maintaining optical fiber and a stress-applying polarization-maintaining optical fiber after aligning polarization axes of the elliptic core region and the stress-applying polarization-maintaining optical fiber, wherein in a fusion-splicing portion, a polarization crosstalk is equal to or smaller than −
30 dB, and a connection loss is equal to or smaller than 0.5 dB. - View Dependent Claims (16, 17, 18)
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Specification
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Current AssigneeFurukawa Electric Company Limited
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Original AssigneeFurukawa Electric Company Limited
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InventorsMiyabe, Ryo, Mimura, Yu
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Primary Examiner(s)STAHL, MICHAEL J
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Application NumberUS12/169,182Publication NumberTime in Patent Office819 DaysField of SearchNoneUS Class Current385/123CPC Class CodesC03B 2203/12 Non-circular or non-ellipti...C03B 2203/22 Radial profile of refractiv...C03B 2203/29 Segmented core fibresC03B 2203/30 Polarisation maintaining [P...C03B 37/01466 Means for changing or stabi...G02B 6/024 with polarisation maintaini...
