Norway


Fiber transmission could be more efficient, go farther, carry more traffic and be cheaper to implement if the work of scientists in Sweden and Estonia is successful.

In a recent demonstration, researchers at Chalmers University of Technology, Sweden, and Tallinn University of Technology, Estonia, used new, ultra-low-noise amplifiers to increase the normal fiber-optic transmission link range six-fold.

And in a separate experiment, researchers at DTU Fotonik, Technical University of Denmark used a unique frequency comb to push more than the total of all internet traffic down one solitary fiber link.

Fiber transmission limits

Signal noise and distortion have always been behind the limits to traditional (and pretty inefficient) fiber transmission. They’re the main reason data-send distance and capacity are restricted using the technology. Experts believe, however, that if the noise that’s found in the amplifiers used for gaining distance could be cleaned up and the signal distortion inherent in the fiber itself could be eliminated, fiber could become more efficient and less costly to implement.

Plus, if fiber could carry more traffic in single strands, it would be cheaper to power, and it would also keep up with rapidly escalating future internet growth.

Those two areas of improvement are where many scientists are concentrating their fiber development efforts.

The researchers at Chalmers University of Technology and Tallinn University of Technology said they can now send data 4,000 kilometers (nearly 2,500 miles) — or roughly the air-travel distance from Los Angeles to New York.

The team is using special, phase-sensitive amplifiers that handle both the noise and the distortion. The special amplifier functions using multiple pulses of different, very bright, compressed colors, polarized and then formatted into division multiplexing, Chris Lee of Ars Technica explains in coverage of the research.

“The amplifiers can provide a very significant reach improvement over conventional approaches,” Chalmers University says in its news release.

Increasing the amount of data fiber can carry

In more progress, another group has been concentrating on increasing the amount of data the fiber can carry. That multi-scientist team, from DTU Fotonik, Technical University of Denmark, said it can show that it can pump 661 terabits per second down a piece of fiber. That’s “equivalent to more than the total Internet traffic today,” the publication Nature explains in an abstract on its website.

Worry over the amount of data being generated globally, and how to carry it, is behind the work.

“The Internet today transmits hundreds of terabits per second, consumes nine percent of all electricity worldwide and grows by 20 percent to 30 percent per year,” according to the article in Nature.

Multiple, parallel links handle the traffic now, but they’re not energy efficient. That’s primarily because each side-by-side stream needs its own power. The researchers think that if they can stuff all the traffic into one pipe, they would solve the electricity issue — you wouldn’t need so much power-hungry equipment.

They DTU researchers are using a frequency comb made up of non-resonant aluminium-gallium-arsenide-on-insulator nanowaveguide. They seed the chip with gigahertz-per-picosecond pulses.

Frequency combs measure and detect disparate frequencies and map them. In this case: light. The tools are getting common, and might even become used in RF-based Wi-Fi, too, say researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences.

In this case, though, the optical, fiber-based frequency comb produced “unprecedented high data-rate transmission,” the Nature article says. The Danes used single-mode 30-core fiber for the six-mile experiment.

It’s “robust to temperature changes, is energy efficient and facilitates future integration with on-chip lasers or amplifier.” Importantly, too, the technique reduces bulk for the transmission equipment — less data center or telco space will ultimately be needed.

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