In order to give protection to a silica optical fiber it must be coated with some material, usually a polymer. Acrylate is the most commonly used and this restricts the maximum temperature of use to about 100 °C. Polyimide coated fibers can operate at temperatures up to 300 °C. For higher performance, metal-coated fibers using pure metals of copper, aluminium and gold have been available for some time. These give higher temperature use, better hermeticity, and higher strength than polymer coated fibers.

The new CuBALL coating allows use at temperatures up to 700 °C for short periods and 500 °C for long periods. This compares well with gold-coated fibers but at a fraction of the cost. In addition the fibers can be made in long lengths (several kilometres) and in a wide variety of fiber types such as single mode, graded index, and step index large core fibers in UV and IR grades of silica.