How the fibre communications revolution began

What if we had no Optical Fibre Communications today?

What if Charles Kao had been less determined, and had succumbed to the views of the majority who thought the fibre dream was impossible?

Many labs had committed their programmes and their reputations to the alternative technology of Long Haul Microwave Waveguide.Charles and his team experienced huge resistance over the early years.

What speculative communication technology could survive two decades of research investment today?

Without fibre we might have been committed to Long Haul Microwave Waveguide

Information Capacity:

Although the speculative predictions of information capacity seemed impressive at the time (early ’60s), its information capacity would have been fundamentally handicapped by its much lower carrier frequency.

Fibre today provides more than a thousand times the capacity potential of Long Haul Microwave Waveguide technology.


This was very expensive to make & install. It required plenty of physical material including expensive Copper. The cost of communicating over distance would have continued to be directly related to the distance.

Fibre itself is almost free. It has annihilated the cost of communicating over distance, enabling the World Wide Web.


The benefits of guiding the energy through a gas-filled pipe were that low loss might result. It was suggested that a figure of 3 dB per mile might be achieved and this looked good at the time (every mile loses half the power).

Optical fibre now achieves one tenth that figure, so half the power is lost in ten miles. This enables the repeaters (required to regularly boost the signal), to be spaced much further apart.


Fibre is more flexible than microwave waveguide

Optical fibre flexibility versus microwave waveguide

It was physically inflexible, so its use would have been confined to a few major trunk routes.

Fibre is now ubiquitous, reaching everywhere including our homes. It is used in our cars, planes ships etc..

Undersea and Transoceanic

This is where the biggest difference would have been seen. In Long Haul Microwave Waveguides the energy propagates through a pipe, with a large hollow central region, filled with gas or air.  Five miles down on the ocean floor, any pipe would require a massive steel pressure tube if it were to avoid being squashed flat by the pressure of all that water above. Any transoceanic pipe would be far too expensive, heavy, inflexible to install. It would have made intercontinental communication impossible.

Optical fibre has revolutionised communication between continents. Oceans are no impediment. It is often cheaper to communicate from London to New York, than to almost anywhere within a country itself.

So we would have no World Wide Web

Fibre has annihilated the cost of distance, and spanned continents & oceans. The Web / Internet is only possible because the cost of communicating is:

  • Very low
  • Independent of distance

If Optical Fibre had never happened, we would live in a more parochial world today, confined to our islands of information.

*Information from “Trunk Waveguide Communication”, by A.E.Karboviak, Chapman & Hall Ltd., 1965.

2016: Half a Century of Optical Fibre Communications

2016 is the 50th anniversary of the publication that started it all.

Optical Fibre has transformed our world yet is now almost completely ignored.

The reasons?:

  • It is largely hidden (beneath our streets and oceans).
  • No surviving commercial organisation has an interest in promoting the STL history.
  • Few remember just how poor global communications used to be.

Useful Links

For anyone who enjoyed STL

STL Quarter Century Club

For the full story of optical communication see

"City of Light - The Story of Fiber Optics" by Jeff Hecht

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