What is typically used as insulation in optical fiber cables?

Optical fiber cables use plastic as insulation primarily because it provides a necessary layer of protection and support for the delicate glass core of the fiber. The plastic insulation helps to maintain the integrity of the glass fibers, reduce the risk of physical damage, and prevent water ingress, all of which are crucial for the performance and longevity of optical fibers. Furthermore, plastic is lightweight and can be manufactured in various forms, which adds flexibility to the installation and application of optical fiber cables.

While glass is the primary material for the core where light transmission occurs, it does not serve as insulation. Copper is used in traditional electrical wiring, not in optical fibers. Polyethylene can be used as an outer sheath material for environmental protection but is not the main insulating layer around the fiber itself. Therefore, plastic is the most appropriate choice for insulation in optical fiber cables.