Single-mode optical fiber

An optical transmission fiber, comprising:

• a central core having an index difference Dn1 with an outer optical cladding that is between about 5.0×10−3 and 5.6×10−3;
• a first intermediate cladding having an index difference Dn2 with the outer optical cladding that is between about −1.0×10−3 and 1.1 ×10−3, wherein the maximum index difference between the central core and the first intermediate cladding (Dn1-Dn2) is between about 4.5×10−3 and 6.0×10−3;
• a first depressed cladding having an index difference Dn3 with the outer optical cladding that is less than or equal to about −5×10−3;
• a second intermediate cladding having an approximately zero index difference Dn4 with the outer optical cladding;
• and
• a second depressed cladding having an index difference Dn5 with the outer optical cladding that (i) is between about −0.3×10−3 and −3×10−3 and (ii) in absolute value, is less than the index difference Dn3 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.

An optical transmission fiber, comprising:

• a central core having a radius r1 between about 3.5 μm and 4.5 μm and an index difference Dn1 with an outer optical cladding;
• a first intermediate cladding having a radius r2 between about 9 μm and 12 μm and an index difference Dn2 with the outer optical cladding, wherein the maximum index difference between the central core and the first intermediate cladding (Dn1-Dn2) is between about 4.5×10−3 and 6.0×10−3;
• a first depressed cladding having a radius r3 between about 14 μm and 16 μm and an index difference Dn3 with the outer optical cladding that is less than or equal to −5×10−3;
• a second intermediate cladding having a radius r4 between about 18 μm and 20 μm an index difference Dn4 with the outer optical cladding;
• and
• a second depressed cladding having a radius r5 between about 25 μm and 40 μm and an index difference Dn5 with the outer optical cladding that, in absolute value, is less than the index difference Dn3 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 0.1 dB/10 turns for a bending radius of 15 mm and bending losses less than or equal to 0.5 dB/turn for a bending radius of 7.5 mm.