Single mode optical fiber with large effective area

An optical fiber with a large effective area, comprising a core layer and a cladding layer, wherein

• said core layer is clad with an intermediate cladding layer, and a depressed cladding layer is provided outside said intermediate cladding layer;
• said core layer comprises a first sub core layer and a second sub core layer;
• a radius r1 of said first sub core layer ranges from 1.5 μm to 5 μm, and a relative refractive index difference Δn1 thereof ranges from 0.05% to 0.22%;
• a unilateral radial width (r2−r1) of said second sub core layer ranges from 1.5 μm to 5 μm, and a relative refractive index difference Δn2 thereof ranges from 0.15% to 0.34%;
• the relative refractive index difference Δn1 of said first sub core layer is less than the relative refractive index difference Δn2 of said second sub core layer, i.e., Δn1<Δn2;
• a unilateral radial width (r3−r2) of said intermediate cladding layer ranges from 2.5 μm to 6 μm, and a relative refractive index difference Δn3 thereof ranges from −0.10% to 0.10%;
• and
• a unilateral radial width (r4−r3) of said depressed cladding layer ranges from 2.5 μm to 10 μm, and a relative refractive index difference Δn4 thereof ranges from −1.5% to −0.2%.