That’s a good question. Especially for the optical and electrical engineers that design the evolving internet infrastructure and the money people that are going to have to pay for it.
Since 1980, the number of bits per second that can be sent down an optical fiber has increased some 10 millionfold. That’s remarkable even by the standards of late-20th-century electronics. It’s more than the jump in the number of transistors on chips during that same period, as described by Moore’s Law. There ought to be a law here, too. Call it Keck’s Law, in honor of Donald Keck. He’s the coinventor of low-loss optical fiber and has tracked the impressive growth in its capacity. Maybe giving the trend a name of its own will focus attention on one of the world’s most unsung industrial achievements.
Moore’s Law may get all the attention. But it’s the combination of fast electronics and fiber-optic communications that has created “the magic of the network we have today,” according to Pradeep Sindhu, chief technical officer at Juniper Networks. The strongly interacting electron is ideal for speedy switches that can be used in logic and memory. The weakly interacting photon is perfect for carrying signals over long distances. Together they have fomented the technological revolution that continues to shape and define our times.
Now, as electronics faces enormous challenges to keep Moore’s Law alive, fiber optics is also struggling to sustain the momentum. For the past few decades, a series of new developments have allowed communications engineers to keep pushing more and more bits down fiber-optic networks. But the easy gains are behind them. To keep moving forward, they’ll need to conjure up some fairly spectacular innovations.
New ideas continue to emerge. In June 2015, Nikola Alic of the University of California, San Diego, and colleagues reported a way of increasing fiber transmission distance by using optical frequency combs, which naturally lock laser wavelengths relative to one another, eliminating jitter and improving signal quality. “We can at least double the data rate of any system” by using a frequency comb, says Alic. “It is very nice and solid work,” says Winzer, but he doubts it would have much practical impact, because developers want a bigger increase.
What will come next? Today telecommunications carriers have their hands full installing 100-Gb coherent systems. Superchannels will boost maximum capacity by 30 percent or so, and spatial-division multiplexing looks like the best candidate for the next big jump in capacity. But beyond that, who knows?
Perhaps some new twist on an old idea might come along. Coherent transmission, which was finally adopted around 2010, was actually a hot topic in the 1980s, but it lost out then to other technologies that were ready to deploy. Something totally new might emerge from the fertile ground of photonics research. And we could always lay more fibers. In any case, the global thirst for data will keep engineers working very hard to keep pumping up the bandwidth.
Bandwidth drives everything and it looks as if there may be limitations on bandwidth just like there are limitations on just how much bandwidth is going to be available for the internet of things. The idea of connecting everything to the internet may seem great, but if you can’t carry the load, well, it’s just not going to work.