High-bandwidth multimode optical fiber having reduced bending losses
AssigneeDraka Comteq B.V.
InventorsDenis Molin, Marianne Bigot-Astruc, Pierre Sillard, Koen de Jongh
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Abstract
The present invention embraces a multimode optical fiber that includes a central core having an alpha-index profile, an inner cladding, a depressed trench, and an outer cladding (e.g., an outer optical cladding). Typically, the central core's alpha-index profile has a minimum refractive index at the central core's radius that corresponds to a 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.
Claims35
A multimode optical fiber, comprising:
- a central core having (i) a radius r1, (ii) an alpha-index profile, and (iii) at said radius r1, a negative refractive index difference Δnend with respect to an outer cladding of greater than about −1×10−3;
- an inner cladding positioned between said central core and said outer cladding, said inner cladding having (i) a 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) a radius rout, (ii) a width w3, (iii) a refractive index difference Δn3 with respect to said outer cladding of between about −15×10−3 and −3×10−3, and (iv) a volume v3.
A multimode optical fiber, comprising:
- a central core having (i) a radius r1, (ii) an alpha-index profile, and (iii) at said radius r1, a negative refractive index difference Δnend with respect to an outer cladding of greater than about −1×10−3;
- an inner cladding positioned between said central core and said outer cladding, said inner cladding having (i) a 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) a radius rout of about 32 microns or less, (ii) a width w3, (iii) a refractive index difference Δn3 with respect to said outer cladding of between about −15×10−3 and −3×10−3, and (iv) a volume v3;
- wherein said inner cladding's refractive index difference Δn2 and said depressed trench's refractive index difference Δn3 satisfy the following inequality:
- 1000×Δn3<−1.29×(1000×Δn2)2−1.64×1000×Δn2−2.51.
A multimode optical fiber, comprising:
- a central core having (i) a radius r1, (ii) an alpha-index profile, and (iii) at said radius r1, a negative refractive index difference Δnend with respect to an outer cladding of greater than about −1×10−3;
- an inner cladding positioned between said central core and said outer cladding, said inner cladding having (i) a 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) a radius rout, (ii) a width w3, (iii) a refractive index difference Δn3 with respect to said outer cladding of between about −15×10−3 and −3×10−3, and (iv) a volume v3;
- wherein, at a wavelength of 850 nanometers, the optical fiber has an effective modal bandwidth (EMB) of at least 2,000 MHz·km;
- and
- wherein said inner cladding's refractive index difference Δn2 and said depressed trench's refractive index difference Δn3 satisfy both of the following inequalities:
- −1.89×(1000×Δn2)2−7.03×(1000×Δn2)−9.91<1000×Δn3;
- and
- 1000×Δn3<−1.53×(1000×Δn2)2−3.34×1000×Δn2−4.25.
Dependencies are inferred from the claim text.