Patent ID: 10048437

Abstract:
A low attenuation optical fiber having a core doped with Ge is offered. The optical fiber consists of a glass part and a covering part formed around the glass part. The glass part is made of silica glass and includes: a Ge-doped center core region; an optical cladding layer formed around the center core region; and an optical cladding layer formed around the cladding layer. The relationship of Δ1>Δ3≥Δ2 holds, where Δ1, Δ2, and Δ3 are the relative refractive index differences of the center core region, the cladding layer, and the cladding layer 30, respectively with respect to pure silica glass. The average outer diameter of the glass part is in the range of 125±0.5 μm in the longitudinal direction, and 3σ is in the range of 0.1 μm to 0.5 μm, where σ is the standard deviation of the outer diameter in the longitudinal direction.