Patent ID: 8474287

Claim:
A method of making an optical fiber comprising randomly distributed voids therein, the method comprising the step of drawing said fiber from a preform comprising randomly distributed voids therein under conditions effective to result in process parameter Ω which is less than 5×10 −7 , where Ω = D gas ( T avg ) ⁢ ϕ f ⁢ L root V f ⁢ R f 2 and wherein D gas in cm 2 /sec is the void gas diffusivity at T avg , wherein T avg is the average of the softening point temperature of the optical fiber preform and the peak draw furnace temperature in ° C., φ f is the regional void area fraction, L root is the draw root length in cm as measured from the beginning of the neck down region and ending when the preform has reached the final fiber draw diameter, V f is the fiber draw speed in cm/sec and R f is the final fiber radius in cm.