A single-mode optical fiber, comprising: a central core surrounded by an outer cladding, said central core having (i) a radius r 1, (ii) a positive, maximum refractive-index difference Δn 1 with respect to said outer cladding, and (iii) an alpha refractive-index profile with an alpha parameter α of between 1.5 and 2.5; an intermediate cladding positioned between said central core and said outer cladding, said intermediate cladding having a radius r 2 and a refractive-index difference Δn 2 with respect to said outer cladding; and a buried trench positioned between said intermediate cladding and said outer cladding, said buried trench having a radius r 3 and a negative refractive-index difference Δn 3 with respect to said outer cladding; wherein the optical fiber has (i), at a wavelength of 1310 nanometers, a mode field diameter with a nominal value of between 8.2 microns and 9.9 microns, (ii) a cable cut-off wavelength of 1260 nanometers or less, and (iii), for a bending radius of 15 millimeters at a wavelength of 1550 nanometers, bending losses of 0.003 dB/turn or less, wherein the mean ((r 2 +r 3)/2) of said intermediate cladding's radius r 2 and said buried trench's radius r 3 is between about 9.5 microns and 15.5 microns, wherein said central core has a surface integral V 01 of between about 22 x 10 -3 micron and 25 x 10 -3 micron, the surface integral V 01 being defined according to the following equation: V 01 = ∫ 0 r 1 Δ n r. dr ≈ r 1 × alpha ⋅ Δ ⁢ n 1 + Δ ⁢ n 2 / alpha + 1, wherein said buried trench has a surface integral V 03 of between about -45 x 10 -3 micron and -25 x 10 -3 micron, the surface integral V 03 being defined according to the following equation: V 03 = ∫ r 2 r 3 Δ n r. dr ≈ r 3 - r 2 × Δ ⁢ n 3. a central core surrounded by an outer cladding, said central core having (i) a radius r 1, (ii) a positive, maximum refractive-index difference Δn 1 with respect to said outer cladding, and (iii) an alpha refractive-index profile with an alpha parameter α of between 1.5 and 2.5; an intermediate cladding positioned between said central core and said outer cladding, said intermediate cladding having a radius r 2 and a refractive-index difference Δn 2 with respect to said outer cladding; and a buried trench positioned between said intermediate cladding and said outer cladding, said buried trench having a radius r 3 and a negative refractive-index difference Δn 3 with respect to said outer cladding; wherein the optical fiber has (i), at a wavelength of 1310 nanometers, a mode field diameter with a nominal value of between 8.2 microns and 9.9 microns, (ii) a cable cut-off wavelength of 1260 nanometers or less, and (iii), for a bending radius of 15 millimeters at a wavelength of 1550 nanometers, bending losses of 0.003 dB/turn or less, wherein the mean ((r 2 +r 3)/2) of said intermediate cladding's radius r 2 and said buried trench's radius r 3 is between about 9.5 microns and 15.5 microns, wherein said central core has a surface integral V 01 of between about 22 x 10 -3 micron and 25 x 10 -3 micron, the surface integral V 01 being defined according to the following equation: V 01 = ∫ 0 r 1 Δ n r. dr ≈ r 1 × alpha ⋅ Δ ⁢ n 1 + Δ ⁢ n 2 / alpha + 1, wherein said buried trench has a surface integral V 03 of between about -45 x 10 -3 micron and -25 x 10 -3 micron, the surface integral V 03 being defined according to the following equation: V 03 = ∫ r 2 r 3 Δ n r. dr ≈ r 3 - r 2 × Δ ⁢ n 3.