Gradient-index polymer optical fiber preparation through a co-extrusion process

The preparation of gradient index polymer optical fiber through a co-extrusion process is analyzed theoretically. The effects of the essential parameters of the system under consideration on the radial distribution of the refractive index (RI) of the optical fiber are examined through numerical simulation. These include the ratio (volume of inner layer/volume of outer layer), the diffusivity and the initial concentration of monomer, the length of diffusion zone, and the mass transfer coefficient of monomer at the outer boundary of the outer layer. We show that these parameters can play a significant role in the design of a co-extrusion process. If they are chosen appropriately, about 80% of an optical fiber can have an approximate parabolic RI distribution in its radial direction.