Patent ID: 8406593

Claim:
A multimode optical fiber, comprising: a central core surrounded by an outer cladding, said central core having (i) an outer radius r 1 , (ii) a minimum refractive index difference Δn end 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 r 1 , the alpha-index profile defining a theoretical radius r 1zero ; an inner cladding positioned between said central core and said outer cladding, said inner cladding having (i) an outer radius r 2 , (ii) a width w 2 , and (iii) a refractive index difference Δn 2 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 r out , (ii) a width w 3 , and (iii) a refractive index difference Δn 3 with respect to said outer cladding; wherein the difference between said inner cladding's outer radius r 2 and the alpha-index profile's theoretical radius r 1zero is greater than about 0.5 micron and less than 2 microns; wherein said inner cladding's refractive index difference Δn 2 and said depressed trench's refractive index difference Δn 3 satisfy the following inequalities: −11.9×(1000 Δn 2 ) 2 −3.4×(1000 Δn 2 )−7.2<1000 Δn 3 ; and 1000 Δn 3 <−17.2×(1000 Δn 2 ) 2 +16.5×(1000 Δn 2 )−8.0.