What are the disadvantages of optical fiber versus copper cables?

The major disadvantage of fiber optic versus metal cable is that it is difficult to make connections to fiber optic cable. Single-mode optical cable (the type used for communications) has a core as fine as a human hair (although the entire fiber is thicker). When making splices, the fiber cores must be perfectly aligned. Also, the ends of the optical fiber must be highly polished to allow light to pass with little loss. There is also the problem of converting back and forth from a light signal to an electrical signal. However, the advantages of fiber-optics far outweigh the problems. One single mode fiber can replace a metal cable that is thousands of times larger and heavier. Multi-mode optical cable has a larger diameter and can be used to carry signal over short distances.