A process is disclosed to improve the performance of plastic optical fibers to operate at high data rates (eg, at least 1 gigabit per second) at high temperatures (eg, 100 degrees Celsius) for avionics systems in aircraft. The gigabit plastic optical fiber 18 has a core 52 comprising a dopant 44 that enables data transmission at gigabit speeds. The enhancement process uses rapid thermal cooling of gigabit plastic optical fibers to stabilize the polymeric matrix 40 of the fibers. This rapid cooling treatment blocks dopant diffusion in a high temperature environment, thereby avoiding deterioration of the bandwidth and light loss characteristics of the fiber. This deterioration typically occurs in gigabit plastic optical fibers having a core and cladding 54 made of a transparent carbon-hydrogen-free perfluorine-based polymer.