Optical fiber comprising an optical core and an optical cladding surrounding the optical core, characterized in that the optical core comprises a first core region and a second core region surrounding the first core region, said optical fiber being characterized in that the first and second core regions is such that the optical core has a refractive index profile n(r) defined either by the equation: n r = { n 0 ⋅ 1 − 2 ⋅ Δ ⋅ r a α + Δ s r < a s n 0 ⋅ 1 − 2 ⋅ Δ ⋅ r a α − Δ d a s ≤ r < a s + w d n 0 ⋅ 1 − 2 ⋅ Δ ⋅ r a α a s + w d ≤ r < a or by the equation: n r = { n 0 + Δ s r < a s n 0 ⋅ 1 − 2 ⋅ Δ ⋅ r a α − Δ d a s ≤ r < a s + w d n 0 ⋅ 1 − 2 ⋅ Δ ⋅ r a α a s + w d ≤ r < a wherein: a s is the radius of the first core region comprised between 1,5 and 4,5 μm; a is the radius of the second core region; Δ s is a step-index defined by the refractive index difference between the first core region and the second core region; A d is a depressed index area defined by the refractive index difference with respect to the second core region; n 0 is the maximal refractive index of the second core region; α is a non-dimensional parameter that defines the index profile shape of the second core region, and α ≥ 1; Δ is the normalized refractive index difference, and Δ = n 0 2 − n 1 2 2 n 0 2, n 1 being the minimal refractive index of the second core region, and in that the depressed index area is positioned to the periphery of the first core region and has a given width w d with a given width between 1 and 8 um and a refractive index difference Δ d with respect to the second core region such that said depressed index area refractive index difference Δ d, said refractive index difference Δ s between the first core region and the second core region and said first core region radius a s satisfy the following inequality: 0.0549 ⋅ a s 4 − 0.9053 ⋅ a s 3 + 5.483 ⋅ a s 2 − 14.39 ⋅ a s + 13.75 < 1000 ⋅ Δ s + Δ d < 1.11 ⋅ a s 2 − 6.9145 ⋅ a s + 17.94 a s is the radius of the first core region comprised between 1,5 and 4,5 μm; a is the radius of the second core region; Δ s is a step-index defined by the refractive index difference between the first core region and the second core region; A d is a depressed index area defined by the refractive index difference with respect to the second core region; n 0 is the maximal refractive index of the second core region; α is a non-dimensional parameter that defines the index profile shape of the second core region, and α ≥ 1; Δ is the normalized refractive index difference, and Δ = n 0 2 − n 1 2 2 n 0 2, n 1 being the minimal refractive index of the second core region, and in that the depressed index area is positioned to the periphery of the first core region and has a given width w d with a given width between 1 and 8 um and a refractive index difference Δ d with respect to the second core region such that said depressed index area refractive index difference Δ d, said refractive index difference Δ s between the first core region and the second core region and said first core region radius a s satisfy the following inequality: 0.0549 ⋅ a s 4 − 0.9053 ⋅ a s 3 + 5.483 ⋅ a s 2 − 14.39 ⋅ a s + 13.75 < 1000 ⋅ Δ s + Δ d < 1.11 ⋅ a s 2 − 6.9145 ⋅ a s + 17.94