Fiber Optic Training - Fundamentals of Optical Fiber Communication
An important aspect of fiber communication speed growth is that the increase results
from changing the electronics, not the single mode fibers, at either end of the system. The capacity of a single mode system is limited by the capabilities of the electronics, not of the fiber. One advantage of single mode fibers is that once they are installed, the system's capacity can be increased as newer, higher-capacity transmission electronics becomes available.
Fiber Optic Training - Fundamentals of Optical Fiber Communication