Method for preparing plastic optical fiber preform

Abstract

The present invention relates to a method for preparing a GI (graded index) plastic optical fiber preform having a radial refractive index gradient, the refractive index increasing gradually from the outer periphery of the preform toward the center thereof, comprising inserting a 1st plastic tube (inside diameter: d, outside diameter: d) () made of a first polymer (refractive index: n) in a cylinder reactor (inside diameter: d, d≦d) and inserting a 2nd plastic tube (inside diameter: d, outside diameter d, d≦d) () made of a second polymer (refractive index: n, n≧n) in the 1st plastic tube, the reactor, the 1st and 2nd plastic tubes are positioned coaxially, injecting a precursor of a third polymer (refractive index: n', n′≧n) into the 2nd plastic tube, injecting a precursor of a fourth polymer (refractive index: n″, n≦n″≦n) into the space between the 1st and 2nd plastic tubes.