7. Multi-mode transmission

The considerable increase in data rates transmitted over optical fibers, in conjunction with advances in WDM technology, has led to interest in the fiber's capacity in terms of information theory, i.e. the maximum data rate it can transmit. This limit, which no-one considered in the early days of optical transmission, now appears to be a stumbling block that will be reached in the next few years. One solution for increasing the data rate transmitted over an artery is, of course, to lay a new cable alongside the saturated one. But researchers also wondered whether there was still a way of increasing the data rate transmitted over a single fiber. Since 2010, research has been very active in two directions: multi-mode transmission in a conventional fiber, and the use of multi-core fibers (known as MCF).