Fiber optics cables might make people think they transfer data at the speed of light, but they really don't. The best-made cables work at 40 Gb at most, and have relatively low latencies.True, the latencies are actually quite high compared to copper wires, and whatever other alternatives were tried over the years.
Still, it is nothing compared to the real speed of light, which researchers at the University of Southampton, in England, claim to have finally attained.
A team of scientists have created optical fibers that can transfer data at 99.7% of the speed of light. In bits, that means 73.7 terabits per second.
That's around 10 Terabytes per second and 1,000 times faster than the 40 Gb cables we have written about above.
The key to this achievement came from analyzing the speed of light in a vacuum and how it changes in another medium.
In a vacuum, light travels at 299,792,458 meters per second (or 186,282 miles per second), but it slows down dramatically in air or water, or whatever else.
Strangely enough, light travels faster through air than glass. In normal optical fibers (silica glass), light speed is 31% slower than in a vacuum.
What Francesco Poletti and the other members of his University of Southampton did was make a hollow optical fiber made mostly of air.
They had to improve the hollow core design first though, because, unlike glass cables, hollow cables don't have the refractive index to cause light to bounce around and not be lost when, say, the cable is bent around a corner. They used an ultra-thin photonic-bandgap rim.
The result of that combined with wave division multiplexing (WDM) and mode division multiplexing is what we've already described: a 73.7 terabits per second (three modes of 96 channels of 256Gbps).
Mode division multiplexing is a new technology that rotates signals with a polarizer, so that more fiber can be used. It sounds a lot like spatial filtering.
Normal fiber glass probably won't be replaced by this new invention, but data centers and supercomputer interconnects should prove quite quick to adopt it.