Specialty Optical Fibers Handbook

fluoroaluminate glasses are more durable, with leach rates that are more than

three times lower than those for the fluorozirconate glasses. The strength of

HMFG fibers is less than that for silica fibers. From Table 13.1, we see that

Young’s modulus E for fluoride glass is 51 GPa compared to 73 GPa for silica

glass. Taking the theoretical strength to be about one-fifth that of Young’s

modulus gives a theoretical value of strength of 11 GPa (R ¼ 1:198r

E

s

max

) for

fluoride glass. The largest bending strength measured has been about 1.4 GPa,

well below the theoretical value. To estimate the bending radius R, we may use

the approximate expression, where ...