Fiber-Optic Cabling

Without question, the bandwidth-carrying capacity of modern fiber-optic cabling greatly exceeds that of any form of copper cabling. Unfortunately, the transceiver technology required to fully realize the performance advantages of fiber remains quite costly. Additionally, fiber suffers from some practical drawbacks that limit its utility. For example, fiber connectors are difficult to assemble and must be kept clean and free from scratches. Copper insulation-displacement connectors, on the other hand, are rugged and wipe clean upon insertion. Copper connections may be assembled anywhere , even in dirty environments. [89]

[89] This is not an issue to be taken lightly. Anyone who has spent time crawling around in attics and switch rooms knows that they are not clean, well-lighted places to work.

I'll not dwell further on the cost or convenience problems you will encounter with fiber. That's something you'll have to evaluate in the context of your own application. Any discussion here would soon be moot anyway, as the cost and convenience of using fiber cabling are improving steadily with the passage of time. I look forward to the day when fiber-optic connections are as ubiquitous and easy to use as copper connections.

What we discuss in this chapter are the physics of optical transmission. The following sections present the optical performance characteristics of both multimode and single-mode glass fiber data links. The cables used in the examples are selected from the TIA/EIA-568-B and ISO/IEC-11801 building wiring standards. Before we get to the detailed technical information, though, I should like to present a few pages of information about the general construction of fibers. If you're already familiar with fiber-optic cable construction, this might be a good time to step out for a cup of tea.

POINT TO REMEMBER

• The bandwidth-carrying capacity of modern fiber-optic cabling greatly exceeds that of any form of copper cabling, an advantage counterbalanced by the high costs and practical difficulties associated with fiber.