Large core area single mode optical fiber
First Claim
1. A single-mode optical fiber for guiding an optical signal, said optical fiber having a longitudinal, optical axis and a cross section perpendicular thereto, said optical fiber comprising:
- a core region being capable of guiding an optical signal in a fundamental core mode with an effective refractive index, nc, at an optical signal wavelength, λ
1;
a cladding region surrounding the core region, the cladding region comprising an inner cladding region and an outer cladding region, said inner cladding region comprising a background material having a refractive index, nb, and a plurality of inner cladding features arranged in said background material, wherein at least a plurality of said plurality of inner cladding features are of a first type of feature, said first type of feature comprising an air hole surrounded by a high-index region comprising a high-index material having a refractive index, nr, that is larger than the refractive index of the inner cladding background material, said first type of feature supports an optical mode with an effective refractive index, n1, which is lower than or equal to the effective refractive index of the fundamental core mode, nc, at said optical signal wavelength, λ
1,wherein said core region has a maximum cross-sectional dimension of more than about 40 μ
m,and wherein the index difference between the high-index material and the background material of the inner cladding is below about 1.10−
2.
1 Assignment
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Accused Products
Abstract
A single-mode optical fiber for guiding an optical signal, wherein the core region is capable of guiding an optical signal in a fundamental core mode at an optical signal wavelength. A cladding region is arranged to surround the core region and includes an inner cladding region and an outer cladding region. The inner cladding region includes a background material and a plurality of inner cladding features arranged in the background material, wherein a plurality of the plurality of inner cladding features are of a first type of feature that includes an air hole surrounded by a high-index region comprising a high-index material that is larger than the refractive index of the inner cladding background material.
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Citations
17 Claims
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1. A single-mode optical fiber for guiding an optical signal, said optical fiber having a longitudinal, optical axis and a cross section perpendicular thereto, said optical fiber comprising:
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a core region being capable of guiding an optical signal in a fundamental core mode with an effective refractive index, nc, at an optical signal wavelength, λ
1;a cladding region surrounding the core region, the cladding region comprising an inner cladding region and an outer cladding region, said inner cladding region comprising a background material having a refractive index, nb, and a plurality of inner cladding features arranged in said background material, wherein at least a plurality of said plurality of inner cladding features are of a first type of feature, said first type of feature comprising an air hole surrounded by a high-index region comprising a high-index material having a refractive index, nr, that is larger than the refractive index of the inner cladding background material, said first type of feature supports an optical mode with an effective refractive index, n1, which is lower than or equal to the effective refractive index of the fundamental core mode, nc, at said optical signal wavelength, λ
1,wherein said core region has a maximum cross-sectional dimension of more than about 40 μ
m,and wherein the index difference between the high-index material and the background material of the inner cladding is below about 1.10−
2. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 17)
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15. A cladding pumped optical fiber for amplifying an optical signal, said optical fiber having a longitudinal, optical axis and a cross section perpendicular thereto, said optical fiber comprising:
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a core region comprising a material doped with at least one active element;
said core region being capable of guiding an optical signal in a fundamental core mode with an effective refractive index, nc, at an optical signal wavelength, λ
1;a cladding region surrounding the core region, the cladding region comprising an inner cladding region and an outer cladding region, the inner cladding region being capable of guiding a pump signal at a pump wavelength, λ
p, said inner cladding region comprising a background material having a refractive index, nb, and a plurality of inner cladding features arranged in said background material, wherein at least a plurality of said plurality of inner cladding features are of a first type of feature, said first type of feature comprising an air hole surrounded by a high-index region comprising a high-index material having a refractive index, nr, that is larger than the refractive index of the inner cladding background material, said plurality of said first type of inner cladding feature being arranged to provide at least one cladding mode that suppresses higher order core modes.
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16. A method for producing an optical fiber, said method comprising:
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I. providing at least one core preform element, and a plurality of inner cladding preform elements; II. arranging said core preform element and said inner cladding preform elements in a preform such that said inner cladding preform elements surround said core preform element, and optionally arranging a plurality of outer cladding preform elements and/or an outer cladding preform tube to surround the core preform element and the inner cladding preform elements; III. drawing said preform to an optical fiber; wherein said inner cladding preform elements comprise a plurality of a first type of preform elements comprising an air hole surrounded by a region with a higher index of refraction than the outer cladding preform elements.
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Specification