Patent ID: 8849084

Claim:
A single-mode optical fiber, comprising: a core layer; and claddings surrounding the core layer, wherein a relative refractive index difference Δ1 of the core layer ranges from −0.1% to +0.1%, a radius R 1 of the core layer ranges from 4.0 μm to 6.0 μm; wherein the claddings surrounding the core layer comprises a first cladding layer, a second cladding layer, and a third cladding layer; wherein the first cladding layer immediately surrounds the core layer, and has a relative refractive index difference Δ2 ranging from −0.2% to −0.6%, and a radius R 2 ranging from 10 μm to 22 μm; wherein the second cladding layer immediately surrounds the first cladding layer, and has a relative refractive index difference Δ3 being less than Δ2, and wherein the relative refractive index difference Δ2 and the radius R 2 of the first cladding layer and the relative refractive index difference Δ3 and a radius R 3 of the second cladding layer satisfy the relationship of V=(Δ2−Δ3)×(R 3 −R 2 ), wherein a value of V ranges from 0.15% μm to 0.8% μm; and wherein the third cladding layer comprises one or more sub-layers immediately surrounding the second cladding layer, and wherein a relative refractive index difference of each sub-layer of the third cladding layer is greater than Δ3.