Patent ID: 7058271

Claim:
A plastic optical fiber comprising at least a core and a clad surrounding the core, wherein the core has a refractive index which gradually decreases from the core center towards the outside in the radial direction of the plastic optical fiber, and the refractive index of the clad is lower than the refractive index of the core center and higher than the refractive index of the core periphery and wherein the plastic optical fiber has a refractive index distribution curve represented by the following formula (1): n ⁡ ( r ) = n 1 ⁢  1 - 2 ⁢ ρΔ ⁡ ( r R ) g ] 1 / 2 ⁢ ⁢ 0 ≤ r ≤ R Formula ⁢ ⁢ ( 1 ) where r is the distance in the radial direction from the core center; n(r) is the refractive index of the core or an intermediate portion of the position r; n 1 is the refractive index at the core center; ρ is the refractive index coefficient of the intermediate portion of the plastic optical fiber; Δ is a relative refractive index difference; R is the radius of the core and g is a refractive index distribution coefficient.