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US 8,406,593 B2Granted
Multimode optical fiber with low bending losses and reduced cladding effect
AssigneeDraka Comteq B.V.
InventorsDenis Molin, Marianne Bigot-Astruc, Pierre Sillard, Koen de Jongh
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Abstract
The present invention embraces an optical fiber that includes a central core having an alpha-index profile with respect to an outer cladding. The optical fiber also includes an inner cladding, a depressed trench, and an outer cladding. Typically, the alpha-index profile of the central core is interrupted at a point having a positive refractive index difference with respect to the outer cladding. The optical fiber achieves reduced bending losses and a high bandwidth with a reduced cladding effect for high-data-rate applications.
Claims39
A multimode optical fiber, comprising:
- a central core surrounded by an outer cladding, said central core having (i) an outer radius r1, (ii) a minimum refractive index difference Δnend with respect to said outer cladding that is greater than 0, and (iii) an alpha-index profile with respect to said outer cladding, the alpha-index profile being interrupted at said central core's outer radius r1, the alpha-index profile defining a theoretical radius r1zero;
- an inner cladding positioned between said central core and said outer cladding, said inner cladding having (i) an outer radius r2, (ii) a width w2, and (iii) a refractive index difference Δn2 with respect to said outer cladding;
- and
- a depressed trench positioned between said inner cladding and said outer cladding, said depressed trench having (i) an outer radius rout, (ii) a width w3, and (iii) a refractive index difference Δn3 with respect to said outer cladding;
- wherein the difference between said inner cladding's outer radius r2 and the alpha-index profile's theoretical radius r1zero is greater than about 0.5 micron and less than 2 microns;
- wherein said inner cladding's refractive index difference Δn2 and said depressed trench's refractive index difference Δn3 satisfy the following inequalities:
- −11.9×(1000Δn2)2−3.4×(1000Δn2)−7.2<1000Δn3;
- and
- 1000Δn3<−17.2×(1000Δn2)2+16.5×(1000Δn2)−8.0.
6 more elements
A multimode optical fiber, comprising:
- a central core surrounded by an outer cladding, said central core having (i) an outer radius r1, (ii) a maximum refractive index difference Δn1 of between about 11×10−3 and 16×10−3, (iii) a minimum refractive index difference Δnend with respect to said outer cladding that is greater than 0, and (iv) an alpha-index profile with respect to said outer cladding, the alpha-index profile being interrupted at said central core's outer radius r2, the alpha-index profile defining a theoretical radius r1zero;
- an inner cladding positioned between said central core and said outer cladding, said inner cladding having (i) an outer radius r2, (ii) a width w2, and (iii) a refractive index difference Δn2 with respect to said outer cladding of between about 0.2×10−3 and 2×10−3;
- and
- a depressed trench positioned between said inner cladding and said outer cladding, said depressed trench having (i) an outer radius rout, (ii) a width w3, and (iii) a refractive index difference Δn3 with respect to said outer cladding of between about −15×10−3 and −3×10−3;
- wherein the difference between said inner cladding's outer radius r2 and the alpha-index profile's theoretical radius r1zero is greater than about 0.5 micron and less than 2 microns;
- wherein said inner cladding's refractive index difference Δn2 and said depressed trench's refractive index difference Δn3 satisfy the following inequalities:
- −11.9×(1000Δn2)2−3.4×(1000Δn2)−7.2<1000Δn3;
- and
- 1000Δn3<−17.2×(1000Δn2)2+16.5×(1000Δn2)−8.0.
6 more elements
A multimode optical fiber, comprising:
- a central core surrounded by an outer cladding, said central core having (i) an outer radius r2, (ii) a minimum refractive index difference Δnend with respect to said outer cladding that is greater than 0, and (iii) an alpha-index profile with respect to said outer cladding, the alpha-index profile being interrupted at said central core's outer radius r1, the alpha-index profile defining a theoretical radius r1zero;
- an inner cladding positioned between said central core and said outer cladding, said inner cladding having (i) an outer radius r2, (ii) a width w2, and (iii) a refractive index difference Δn2 with respect to said outer cladding;
- and
- a depressed trench positioned between said inner cladding and said outer cladding, said depressed trench having (i) an outer radius rout of less than about 32 microns, (ii) a width w3, and (iii) a refractive index difference Δn3 with respect to said outer cladding;
- wherein the difference between said inner cladding's outer radius r2 and the alpha-index profile's theoretical radius r1zero is greater than about 0.5 micron and less than about 1.5 microns;
- wherein said inner cladding's refractive index difference Δn2 and said depressed trench's refractive index difference Δn3 satisfy the following inequalities:
- −11.9×(1000Δn2)2−3.4×(1000Δn2)−7.2<1000Δn3;
- and
- 1000Δn3<−17.2×(1000Δn2)2+16.5×(1000Δn2)−8.0.
6 more elements
Dependencies are inferred from the claim text.