Many inventions that have changed the world have humble beginnings. Optical communications that enable the internet fit that category.

Have you wondered how it has been possible during the Covid-19 lockdowns for so many companies to function effectively with most of their employees working from home?

It is because we are the beneficiaries of a remarkable global telecommunications infrastructure built over the past 30 years that enables ubiquitous high data rate digital communications to individual homes.

The digital data is carried in the form of light pulses on glass fibers thinner than a human hair over thousands of kilometers at data rates of billions of bits per second. The optical pulses are generated by tiny lasers the size of pinheads attached to the optical fibers.

The light pulses are detected by tiny sensors that convert them into electrical bit pulses processed by computers.

What makes this possible are two key inventions: low-cost fiber optical fibers and reliable semiconductor lasers that enable ever-growing amounts of data to be transmitted at ever-decreasing costs.

There would be no Internet without optical communications. Billions of people around the world have access to the internet for modest monthly fees making ubiquitous communications possible.

We are so used to this inexpensive flow of digital data that few remember when a long-distance international phone call  (4 kilobits per second) cost one dollar per minute. Then telecommunications traffic was carried on copper lines and – over long distances – via satellite wireless links. Such a call is nearly free today and access to the internet at one gigabit per second is common in many homes.

Optical communications took decades to mature and had many skeptics who doubted it would ever be practical or economical because the problems were daunting. To begin, in the 1960s when research work began on optical fibers at Corning and other laboratories, the idea of long-distance optical pulse transmission was a far-fetched concept because early glass fibers absorbed too much light except in small “window regions” of relatively low absorption.

Also lacking were tiny powerful light sources that could be modulated at high rates and were small enough to launch powerful light pulses into hair-thin glass fibers.

But then good fortune intervened – nature gave us the answer. The tiny semiconductor lasers invented in the late  1960s emitted light in those low fiber loss spectral regions. These tiny lasers could also produce repeatable short light pulses.

The combination now made possible the transmission of short light pulses over many kilometer distances. In fact, in 1970 at RCA Labs we built a five-kilometer fiber length demonstration optical communications system using as a light source the semiconductor laser that we had invented at the RCA Laboratories and Corning fiber.

While communications companies tracked the technology through industry conferences, the public was generally unaware of this development that was far from commercial reality.

In September 1975, an article appeared in BusinessWeek describing the technology: “The light wave of the future – Hair-thin glass fibers could replace thick bunches of copper wires.”

At that time a great deal of progress had been made in various laboratories including Bell Labs, RCA and Corning on the reliability and cost of the technology. In the article, I was quoted: “The right way to go in communications is optical transmission.”

Modern society could not exist without optical communications which are everywhere in the world.

But it took many more years before cost-effective systems were commercialized because such systems had to be extremely reliable and such developments always are lengthy and costly and a great deal of public and private funding was needed to make optical systems fully deployable on land and undersea in the 1990s.

Skeptics doubted the magnitude of the market for such systems. At RCA in 1975, I demonstrated a prototype system to a visiting telecommunications expert. When I mentioned that gigabit optical communications links would eventually be possible, he commented: “There would be a small market. You will have one system between San Francisco and New York carrying all the data traffic ever needed.”

This prophetic comment of my visitor about the limited market reminds me of a note in the Talmud that modern day prophecy is the domain of fools.

Dr Henry Kressel is a technologist, inventor and long-term Warburg Pincus private equity investor. Among his technological achievements is the pioneering of the modern semiconductor laser device that enables modern communications systems. His most recent book (with Norman Winarsky) is: If you really want to change the world: A guide to creating and sustaining breakthrough ventures (Harvard Business Review Press, 2015).