A bending-loss insensitive single mode optical fibre having a Mode Field Diameter greater than or equal to 9.0μm at a 1310nm wavelength, said optical fibre having a core surrounded by a cladding , the core refractive index profile having a trapezoid-like shape, wherein a centre part of said core has a radius r 0 and a refractive index n 0 and a transition part of the trapezoid-like core refractive index profile ranges from radius r 0 to a radius r 1 >r 0 with a trapezoid ratio r 0 / r 1 of said centre part of said core's radius r 0 to said transition part's radius r 1 between 0.1 and 0.6, wherein said cladding comprises at least one region of depressed refractive index, called a trench , ranging from radius r 2 ≥ r 1 to radius r 3 >r 2 and having a refractive index n t , and an outer cladding ranging from radius r 3 to the end of a glass part of the single mode fibre and having a refractive index n 4 , characterized in that the refractive-index difference of said trench with respect to said outer cladding Δ n t = n t - n 4 is between -2×10 -3 and -0.9×10 -3 , and in that said core has a surface integral V 01 of between about 20×10 -3 μm and 24×10 -3 μm, the surface integral being defined according to the following equation: V 01 = ∫ 0 r 1 Δn r . dr , where Δ n ( r ) is the refractive-index difference of said core with respect to said outer cladding as a function of the radius r, wherein said cladding has a surface integral V 02 of between about - 25×10 -3 μm and -9×10 -3 μm, the surface integral being defined according to the following equation: V 02 = ∫ r 1 ∞ Δn r . dr , where Δ n ( r ) is the refractive-index difference of said cladding with respect to said outer cladding as a function of the radius r, and wherein said single mode optical fibre fulfils the following criterion: 25.7 × 10 -3 ≤ V 01 - 0.2326 V 02 ≤ 26.8 × 10 -3 . wherein a centre part of said core has a radius r 0 and a refractive index n 0 and a transition part of the trapezoid-like core refractive index profile ranges from radius r 0 to a radius r 1 >r 0 with a trapezoid ratio r 0 / r 1 of said centre part of said core's radius r 0 to said transition part's radius r 1 between 0.1 and 0.6, wherein said cladding comprises at least one region of depressed refractive index, called a trench , ranging from radius r 2 ≥ r 1 to radius r 3 >r 2 and having a refractive index n t , and an outer cladding ranging from radius r 3 to the end of a glass part of the single mode fibre and having a refractive index n 4 , characterized in that the refractive-index difference of said trench with respect to said outer cladding Δ n t = n t - n 4 is between -2×10 -3 and -0.9×10 -3 , and in that said core has a surface integral V 01 of between about 20×10 -3 μm and 24×10 -3 μm, the surface integral being defined according to the following equation: V 01 = ∫ 0 r 1 Δn r . dr , where Δ n ( r ) is the refractive-index difference of said core with respect to said outer cladding as a function of the radius r, wherein said cladding has a surface integral V 02 of between about - 25×10 -3 μm and -9×10 -3 μm, the surface integral being defined according to the following equation: V 02 = ∫ r 1 ∞ Δn r . dr , where Δ n ( r ) is the refractive-index difference of said cladding with respect to said outer cladding as a function of the radius r, and wherein said single mode optical fibre fulfils the following criterion: 25.7 × 10 -3 ≤ V 01 - 0.2326 V 02 ≤ 26.8 × 10 -3 . <EOS>