Overview

In the past few years, several major improvements have been made in the use of optical fiber communications. In earlier discussions regarding the use of SONET (see Chapter 29, "Synchronous Optical Network [SONET]"), the issue of bandwidth surfaced. Not only does the issue of bandwidth keep coming up but also the problem of just how quickly we consume all the bandwidth that is made available. No matter how much or how fast we improve our spectrum availability, newer applications crop up that literally eat up all the capacity available to us.

To solve this problem, the use of frequency division multiplexing (FDM) with our light-based systems became a topic of research. What ensued was the ability to introduce various wavelengths (frequencies) of light on the same fiber cable and the resultant increase in possible throughput. We have seen increases that approximate between 16 to 30 times the original capacity of a single fiber. These capacities are now being pushed to the limit with variations being promised of up to 128 times the capacity of the existing fiber technologies. What this means is that the old days of having to replace the in-place fibers with new technology have been replaced with newer technology that uses the in-place fiber, necessitating only the change in electronics on the line. We can expect to see these advances provide virtually unlimited bandwidth without en masse changes in the infrastructure. The future holds the promise of reduced costs, increased bandwidth utilization, and ease...