Patent ID: 7587111

Claim:
An optical transmission fiber, comprising: a central core having an index difference Dn 1 with an outer optical cladding; a first intermediate cladding having an index difference Dn 2 with the outer optical cladding, wherein the maximum index difference between the central core and the first intermediate cladding (Dn 1 -Dn 2 ) is between about 4.5×10 −3 and 6.0×10 −3 ; a first depressed cladding having an index difference Dn 3 with the outer optical cladding that is less than or equal to about −5 ×10 −3 ; a second intermediate cladding having an index difference Dn 4 with the outer optical cladding; and a second depressed cladding having an index difference Dn 5 with the outer optical cladding that, in absolute value, is less than the index difference Dn 3 of the first depressed cladding with the outer optical cladding; wherein, at a wavelength of 1625 nm, the optical transmission fiber has bending losses less than or equal to about 0.1 dB/10 turns for a bending radius of 15 mm and bending losses less than or equal to about 0.5 dB/turn for a bending radius of 7.5 mm.