Optical transmission fiber comprising: - a central core having an index difference Dn 1 with an outer optical cladding, wherein the central core has a radius r 1 comprised between 3.5 μm and 4.5 μm for an index difference with the outer optical cladding Dn 1 comprised between 5.0×10 -3 and 5.6x10 -3; - a first intermediate cladding having an index difference Dn 2 with the outer optical cladding, wherein the first intermediate cladding has a radius r 2 comprised between 9 μm and 12 μm; - a first depressed cladding having an index difference Dn 3 with the outer optical cladding which is between -5×10 -3 and -95×10 -3, wherein the first depressed cladding has a radius r 3, comprised between 14 μm and 16 μm; - a second intermediate cladding having an index difference Dn 4 with the outer optical cladding; - a second depressed cladding having an index difference Dn 5 with the outer optical cladding which is inferior, in absolute value, to the index difference Dn 3 of the first depressed cladding with the outer optical cladding, and wherein the index difference Dn 5 between the second depressed cladding and the outer optical cladding is comprised between -0.3x10 -3 and -3x10 -3 and wherein the second depressed cladding has a radius r 5 comprised between 25 μm and 40 μm; and wherein the index difference between the central core and the first intermediate cladding (Dn 1 - Dn 2) is comprised between 4.5x10 -3 and 6.0X10 -3; the optical fiber having a cable cut-off wavelength being less than or equal to 1260 nm and having, at a wavelength of 1625 nm, bending losses inferior or equal to 0.1 dB/10turns for a bending radius of 15 mm and bending losses inferior or equal to 0.5 dB/turn for a bending radius of 7.5 mm. - a central core having an index difference Dn 1 with an outer optical cladding, wherein the central core has a radius r 1 comprised between 3.5 μm and 4.5 μm for an index difference with the outer optical cladding Dn 1 comprised between 5.0×10 -3 and 5.6x10 -3; - a first intermediate cladding having an index difference Dn 2 with the outer optical cladding, wherein the first intermediate cladding has a radius r 2 comprised between 9 μm and 12 μm; - a first depressed cladding having an index difference Dn 3 with the outer optical cladding which is between -5×10 -3 and -95×10 -3, wherein the first depressed cladding has a radius r 3, comprised between 14 μm and 16 μm; - a second intermediate cladding having an index difference Dn 4 with the outer optical cladding; - a second depressed cladding having an index difference Dn 5 with the outer optical cladding which is inferior, in absolute value, to the index difference Dn 3 of the first depressed cladding with the outer optical cladding, and wherein the index difference Dn 5 between the second depressed cladding and the outer optical cladding is comprised between -0.3x10 -3 and -3x10 -3 and wherein the second depressed cladding has a radius r 5 comprised between 25 μm and 40 μm; and wherein the index difference between the central core and the first intermediate cladding (Dn 1 - Dn 2) is comprised between 4.5x10 -3 and 6.0X10 -3; the optical fiber having a cable cut-off wavelength being less than or equal to 1260 nm and having, at a wavelength of 1625 nm, bending losses inferior or equal to 0.1 dB/10turns for a bending radius of 15 mm and bending losses inferior or equal to 0.5 dB/turn for a bending radius of 7.5 mm.