Method for manufacturing a graded refractive index plastic optical-fiber and apparatus therefor

摘要

A plastic optical-fiber is provided having a desired length and a desired graded refractive index. To this end, a base polymer is mixed with a non-polymerizable compound having a higher refractive index, to obtain a fiber material. This material is then transformed continuously into a fiber (5) in a fiber-preparing unit (1). A plurality of diffusion tanks (T1 to Tn) are provided with a solution having a different level of viscosity to one another. This fiber is then dipped successively into the solutions in the order from the lowest viscosity level to a higher viscosity level. During this process, the non-polymerizable compound and polymerizable compound (17) diffuse inside the fiber (5) and form a graded refractive index distribution. The polymerizable compound (17) is then polymerized and hardened in a drying-and-heating unit (15). The fiber (5) thus obtained is drawn and coated with a cladding.