Solution:

A halide glass fiber contains fluorine, chlorine, bromine, and iodine. The most common Halide glass fiber is heavy "metal fluoride glass". It uses ZrF4 as a major component. This fluoride glass is known by the name ZBLAN Since it is constituents are ZrF4, BaF2, LaF3 A1F3, and NaF.

The percentages of these elements to form ZBLAN fluoride glass is shown as follows:

$ \begin{array}{|l|c|} \hline \text { Materials } & \text { Molecular percentage } \\ \hline \mathrm{BaF}_2 & 20 \% \\ \mathrm{A1F}_3 & 3.5 \% \\ \mathrm{LaF}_3 & 4.5 \% \\ \mathrm{ZrF}_4 & 54 \% \\ \hline \end{array} $

These materials add up to make the core of a glass fiber. By replacing ZrF4 by HaF4, the lower refractive index glass is obtained.

The intrinsic losses of these glasses is 0.01 to 0.001 dB/km