DESIGN OF COMPATIBLE GLASS COMPOSITIONS FOR HEAVY-METAL FLUORIDE FIBERS

Although a large amount of information is separately available on the refractive indexes and thermal expansion coefficients of heavy metal fluoride glasses, it is necessary to consider both properties simultaneously, in order to find compatible core and cladding glass pairs. By placing limits on the range of the constituent metal fluoride concentrations and plotting refractive index as a function of expansion coefficient, a powerful fibre-preform design procedure is possible. Thus, for a given refractive index difference, a thermomechanically stable preform for fibre drawing can be readily devised.