Why is Mylar tape used in fiber optical cable?

Answer 1

There are a few reasons that optical fibers are wrapped with aluminized Mylar. The Mylar acts to reduce signal loss by reflecting lost light back into the fiber, rather than absorbing or refracting it. It also serves to physically reinforce the fiber, even though optical fibers are relatively robust on their own; the wrapping of aluminized Mylar tape serves as a buffer to physical friction, shock, and pressure (as seen during handling and installation), adds some strain relief/protection (as the fibers typically are least resistant to strain), and also adds some measure of environmental protection, to slow degradation of the fiber from environmental contaminants near the ends, where the cable bundles "break out" for connection to endpoints or repeaters.