Low-dispersion single-mode optical fiber

A low-dispersion single-mode fiber, comprising:

• core layer and claddings, wherein
• the core layer has a radius R1 in a range from 3 μm to 3.98 μm and a relative refractive index difference Δ1 in a range from 0.15% to 0.45%, and
• the claddings comprise a first depressed cladding, a raised cladding, a second depressed cladding, and an outer cladding from inside to outside, wherein
• the first depressed cladding has a unilateral width (R2−R1) in a range from 2 μm to 7 μm and a relative refractive index difference Δ2 in a range from −0.4% to 0.03%;
• the raised cladding has a unilateral width (R3−R2) in a range from 2 μm to 7 μm and a relative refractive index difference Δ3 in a range from 0.05% to 0.20%;
• the second depressed cladding has a unilateral width (R4−R3) in a range from 0 μm to 8 μm and a relative refractive index difference Δ4 in a range from 0% to −0.2%;
• and
• the outer cladding is a layer made of pure silicon dioxide glass,
• wherein the core layer is a silicon dioxide glass layer co-doped with germanium Ge and fluorine F, and has a contribution amount of doped F, wherein ΔF1 is in a range from −0.2% to −0.02%.