Patent ID: 8195019

Claim:
A plastic glass optical fiber comprising: a glass core composed of glass; a polymer core composed of fluorine addition polymer, which is disposed around a periphery of the glass core, and has a refractive index lower than a refractive index of the glass core; and a polymer cladding composed of polymer, which is disposed around a periphery of the polymer core, and has a refractive index lower than the refractive index of the polymer core, wherein the plastic glass optical fiber satisfies following relations: a diameter a 1 of the glass core is within a range between 110 μm or more and 200 μm or less, and when the diameter of the glass core is set to be a 1 and a diameter of the polymer core is set to be a 2 , a parameter X defined as X=a 2 2 /a 1 2 is within a range of 1.8≦X≦2.9; when a relative refractive index difference between the glass core and the polymer core is set to be Δ 1 and a relative refractive index difference between the polymer core and the polymer cladding is set to be Δ 2 , a parameter Y defined as Y=Δ 2 /Δ 1 is within range of 0.25≦Y≦0.84X−0.68 when the parameter X is within a range of 1.8≦X≦2, and the parameter Y is within a range of 0.48X−0.71≦Y≦−(2/9)X+13/9 when the parameter X is within range of 2≦X≦2.9; and When the diameter of the polymer core is set to be a 2 , the refractive index of the glass core is set to be n 1 , the refractive index of the polymer core is set to be n 2 , and the refractive index of the polymer cladding is set to be n 3 , a ratio Z R =Z 2core /Z 1core of parameters Z 2core and Z 1core is within a range of 1.25≦Z R ≦4, in which the parameter Z 2core is defined as Z 2core =a 2 2 π/4X√(n 1 2 −n 3 2 ) and the parameter Z 1core is defined as Z 1core =a 1 2 4X√(n 1 2 −n 2 2 ).