Patent ID: 6254808
Filing Date: 2001-07-03
Classification: B29C,B29D,B29L

Abstract:
A process for fabricating graded index plastic optical fiber, comprising the steps of:introducing a first polymer material into a first nozzle;introducing a second polymer material into a second nozzle concentrically located around the first nozzle, wherein at least one of the first polymer material and the second polymer material comprises at least one refractive index-altering diffusible dopant;directing the first and second polymer materials from the first and second nozzles into a diffusion section in a concentric manner such that diffusion of the dopant is possible between and within the first and second polymer materials, wherein the materials flow through a diffusion zone having a length of at least 33 cm;extruding the first and second polymer materials from the diffusion section through an exit die at a flow rate of at least 0.5 cm.sup.3 /min; anddrawing the materials from the exit die to form the optical fiber,wherein the first and second polymer materials encounter two distinct temperature regions after exiting the first and second nozzles and prior to drawing, the temperature of the distinct temperature regions being at least 50.degree. C. above the higher of the glass transition temperature of the first polymer material and the glass transition temperature of the second polymer material.