Comparison of optical and electrical links

Our social habits have changed considerably in recent decades, and with them our "communicative" environment has evolved towards a more interactive and digital mode. Today's society is a ferocious consumer of data of all kinds. As proof, the number of "texts" exchanged (SMS, e-messages and others) between mobile terminals exceeds 150 texts/day and per individual, all age and function categories combined (source Experian on 2011 data).

Behind our messages, our "tweets" and other instantaneous exchanges lie the data processing and computing centers that have to ensure that this data is shuffled and transferred. If we take our 150 texts per person per day, and consider texts of 150 characters, that's over five hundred thousand billion bits per day to process! So we need to find the resources to meet this demand for very high-speed data processing and transfer, to ensure real-time operations.

Conventional transmission media such as copper are reaching their limits, and new transmission media such as fiber optics have emerged to overcome the intrinsic limitations of the former.

This article reviews the main transmission media, namely electrical cables and optical fibers. It presents the physical and system characteristics of these transmission media and details their main applications. It compares the various limiting factors associated with guided links and presents an analysis of these performances in relation to the system or application.

It also introduces unguided or free-space connections and compares them to guided connections.