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US 9,541,704 B2Granted
Multi-core optical fiber and multi-core optical fiber cable
AssigneeSumitomo Electric Industries, Ltd.
InventorTetsuya Hayashi
Life of this patent
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Abstract
The present embodiment relates to a multi-core optical fiber and others having an excellent transmission capacity per unit cross-sectional area and spectral efficiency and being easy to manufacture. The multi-core optical fiber has a plurality of cores, a cladding, and a coating and has an appropriately-set neighboring core pitch, cable cutoff wavelength, confinement index of light into each core, cladding outer diameter, and neighboring intercore power coupling coefficient, and a relationship among a minimum of Formula Λ/(rclad−OCTmin), a maximum of the Formula, and a core count is present under a predetermined relationship.
Claims9
A multi-core optical fiber comprising:
- a plurality of cores each extending along a central axis and comprised of silica-based glass;
- a common cladding covering each of the plurality of cores and comprised of silica glass;
- and a coating provided on an outer peripheral surface of the common cladding and comprised of a material different from silica glass,
- wherein in a cross section of the multi-core optical fiber perpendicular to the central axis, the plurality of cores are arranged in an equilateral-triangular lattice pattern and a neighboring core pitch Λ [μm] being a distance between centers of neighboring cores is constant,
- wherein a cable cutoff wavelength λcc [μm] of each of the plurality of cores is not more than 1.53 μm,
- wherein when a theoretical cutoff wavelength is represented by λcth [μm] and a mode field diameter by MFD [μm], MFD/(λcc)0.657 as a confinement index of light into each of the plurality of cores is not more than 8.2 at the wavelength of 1.55 μm, or, MFD/(λcth)0.720 as a confinement index of light into each of the plurality of cores is not more than 6.9 at the wavelength of 1.55 μm,
- wherein an outer diameter 2rclad [μm] of the common cladding is from 115 μm to 250 μm,
- wherein when the multi-core optical fiber is bent in a radius of curvature R in the range of 0.3 m to 3 m over the entire length thereof, both of a neighboring intercore power coupling coefficient and a neighboring identical intercore power coupling coefficient are not more than 2.3×10−6/km at the wavelength of 1625 nm and at least either one of the neighboring intercore power coupling coefficient and the neighboring identical intercore power coupling coefficient is not less than 3.6×109/km at the wavelength of 1530 nm,
- wherein when OCT represents a shortest distance from a center of a core located at an outermost periphery out of the plurality of cores, to an outer peripheral surface of the common cladding, OCT0.01 dB/km [μm] by which a transmission loss increase in the coating theoretically becomes 0.01 dB/km and OCT0.001 dB/km [μm] by which the transmission loss increase in the coating theoretically becomes 0.001 dB/km, are values obtained by Formula (1) or Formula (2) below using MFD [μm] at the wavelength of 1625 μm,
- {
- OCT
- 0.01
-
-
- dB
-
- /
-
- km
- =
- 1.625
-
- [
- -
- 7.78
- ×
- 10
- -
- 2
-
- (
- MFD
- (
- λ
- bc
- )
- 0.869
- )
- 2
- +
- 3.02
-
- (
- MFD
- (
- λ
- bc
- )
- 0.869
- )
- ]
- OCT
- 0.001
-
-
- dB
-
- /
-
- km
- =
- 1.625
-
- [
- -
- 8.48
- ×
- 10
- -
- 2
-
- (
- MFD
- (
- λ
- cc
- )
- 0.869
- )
- 2
- +
- 3.31
-
- (
- MFD
- (
- λ
- cc
- )
- 0.869
- )
- ]
- (
- 1
- )
- {
- OCT
- 0.01
-
-
- dB
-
- /
-
- km
- =
- 1.625
-
- [
- -
- 2.90
- ×
- 10
- -
- 2
-
- (
- MFD
- (
- λ
- cth
- )
- 0.703
- )
- 2
- +
- 2.81
-
- (
- MFD
- (
- λ
- cth
- )
- 0.703
- )
- ]
- OCT
- 0.001
-
-
- dB
-
- /
-
- km
- =
- 1.625
-
- [
- -
- 3.06
- ×
- 10
- -
- 2
-
- (
- MFD
- (
- λ
- cth
- )
- 0.703
- )
- 2
- +
- 3.08
-
- (
- MFD
- (
- λ
- cth
- )
- 0.703
- )
- ]
- (
- 2
- )
- wherein when permissible minimum OCT is represented by OCTmin, the OCTmin is a value from OCT0.01 dB/km to OCT0.001 dB/km and actual OCT is not less than OCTmin,
- wherein with a definition of a parameter represented by a formula of Λ(rclad−OCTmin) which is a ratio of the neighboring core pitch Λ to a core-arrangeable radius of the common cladding, a relationship of [a core count:a minimum of the parameter:a maximum of the parameter] is one of [19:0.450:0.500], [27:0.378:0.397], [31:0.351:0.378], [37:0.315:0.333], [42:0.297:0.311], [48:0.278:0.285], [55:0.255:0.277], [63:0.240:0.248], [69:0.229:0.240], [73:0.222:0.229], [85:0.203:0.218], [102:0.189:0.195], [109:0.182:0.189], [121:0.173:0.180], and [151:0.154:0.160].
180 more elements
Dependencies are inferred from the claim text.