We present a model for a Monte-Carlo simulation of polymer optical fiber fabrication based on a novel method using heat treatment after melt spinning. The polymer is modeled using three-dimensional bond-fluctuation with the Leonard-Johns potential for non-bonded interactions of different polymers alongside the bond, bend and torsion potential for the bonded interactions within the same polymer. The studied fabrication parameters were different cooling rates, pressure and the polymer chain length. Their influence is investigated on properties such as the radius of gyration RG, physical and optical density ρ and n, and the isothermal compressibility, which will be affected e.g. by the phase-transition temperature Tg. They influence both mechanical and optical properties of the produced fiber.