a method and a device are disclosed for reducing ultraviolet and infrared degradation of a polymer core of large core polymer fiber . the method comprises coupling a large core polymer fiber with a glass rod resulting in the placement of the glass piece in the path of the ultraviolet and infrared radiation , thus intercepting the same and keeping the polymer core from being degraded due to long term exposure to low densities of ultraviolet or infrared radiation or from being destroyed in applications involving high density exposure to such radiation . the device comprises a large core polymer fiber having a glass rod incorporated therein to prevent exposure of the core of the fiber to ultraviolet and infrared radiation .