Patent ID: 8041172

Claim:
A transmission optical fiber, comprising: a central core having a radius r 1 ; an intermediate cladding having a radius r 2 , said intermediate cladding surrounding said central core; a depressed cladding having a radius r 3 , said depressed cladding surrounding both said intermediate cladding and said central core; and an outer optical cladding surrounding said depressed cladding, said intermediate cladding, and said central core; wherein the refractive index difference (Δn 3 ) between said depressed cladding and said outer optical cladding is less than the refractive index difference (Δn 2 ) between said intermediate cladding and said outer optical cladding; wherein the refractive index difference (Δn 3 ) between said depressed cladding and said outer optical cladding is less than about −3.5×10 −3 ; and wherein said optical fiber possesses (i) an effective area (S eff ) of more than about 120 μm 2 at a wavelength of 1550 nm and (ii) an effective cutoff wavelength (λ Ceff ) of less than 1600 nm.