NEW RECORD IN DATA TRANSFER

New record set for data-transfer speeds

In the foreground are 2 Chalmers VCSELs. The one on the left has a 6 μm aperture and could operate error free up to 62 Gb/s while the one on the right has a 5 μm aperture and set the equipment limited record of 64 Gb/s. Behind the two VCSELs is IBM's BiCMOS8HP VCSEL driver IC. On either side of the IC are the decoupling capacitors and connecting wirebonds. Image: IBMResearchers at IBM have set a new record for data transmission over a multimode optical fiber, a type of cable that is typically used to connect nearby computers within a single building or on a campus. The achievement demonstrated that the standard, existing technology for sending data over short distances should be able to meet the growing needs of servers, data centers and supercomputers through the end of this decade, the researchers said.

Sending data at a rate of 64 gigabits per second (Gb/s) over a cable 57-m long using a type of laser called a vertical-cavity surface-emitting laser (VCSEL), the researchers achieved a rate that was about 14% faster than the previous record and about 2.5 times faster than the capabilities of today's typical commercial technology.

To send the data, the researchers used standard non-return-to-zero (NRZ) modulation. “Others have thought that this modulation wouldn't allow for transfer rates much faster than 32 Gb/s,” said researcher Dan Kuchta of the IBM T.J. Watson Research Center in New York. Many researchers thought that achieving higher transmission rates would require turning to more complex types of modulation, such as pulse-amplitude modulation-4 (PAM-4).

"What we're showing is that that's not the case at all," Kuchta said. Because he and his colleagues achieved fast speeds even with NRZ modulation, he added, "this technology has at least one or two more generations of product life in it."

Kuchta will describe these results at the 2014 OFC Conference and Exposition, being held March 9-13 in San Francisco.

To achieve such high speeds, the researchers used the VCSEL lasers developed at Chalmers University of Technology in Sweden and custom silicon-germanium chips developed at IBM Research. “The receiver chip is a unique design that simultaneously achieves speeds and sensitivities well beyond today’s commercial offerings,” Kuchta explained. “The driver chip incorporates transmit equalization, which widens the bandwidth of the optical link. While this method has been widely used in electrical communication, it hasn't yet caught on in optical communication,” he said.

“Researchers typically rely on a rule of thumb that says the usable data-transfer rate is about 1.7 times the bandwidth,” Kuchta explained. “That means that with the VCSEL laser, which has a bandwidth of about 26 GHz, the rate would be only about 44 Gb/s.”

"What we're doing with equalization is we're breaking the historical rule of thumb," Kuchta said.

The fast speeds only worked for a distance of 57 m, so this technology isn't designed for sending data across continents. Instead, it's most suitable for transmitting data within a building, he said. About 80 percent of the cables at data centers and most, if not all, of the cables used for typical supercomputers are less than 50 meters long.

This new technology, Kuchta added, is ready for commercialization right now.

Presentation Th3C.2, titled “64Gb/s Transmission over 57m MMF using an NRZ Modulated 850nm VCSEL,” will take place Thursday, March 14 at 1:30 p.m. in room 121 of the Moscone Center.

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30,000-year-old virus from permafrost is reborn

30,000 year old virus from permafrost

An ultrathin section of a Pithovirus particle in an infected Acanthamoeba castellanii cell observed by transmission electron microscopy with enhancement using the artistic filter "plastic packaging" provided by Adobe Photoshop CS5. Credit: Julia Bartoli and Chantal Abergel, IGS and CNRS-AMU.

French scientists said Monday they had revived a giant but harmless virus that had been locked in the Siberian permafrost for more than 30,000 years.

Wakening the long-dormant virus serves as a warning that unknown pathogens entombed in frozen soil may be roused by global warming, they said.

Dubbed Pithovirus sibericum, the virus was found in a 30-metre (98-foot) -deep sample of permanently frozen soil taken from coastal tundra in Chukotka, near the East Siberia Sea, where the average annual temperature is minus 13.4 degrees Celsius (7.8 degrees Fahrenheit).

The team thawed the virus and watched it replicate in a culture in a petri dish, where it infected a simple single-cell organism called an amoeba.

Radiocarbon dating of the soil sample found that vegetation grew there more than 30,000 years ago, a time when mammoths and Neanderthals walked the Earth, according to a paper published in the US journal Proceedings of the National Academy of Sciences (PNAS).

P. sibericum is, on the scale of viruses, a giant—it has 500 genes, whereas the influenza virus has only eight.

It is the first in a new category of viral whoppers, a family known as Megaviridae, for which two other categories already exist.

An ultrathin section of a Pithovirus particle in an infected Acanthamoeba castellanii cell observed by transmission electron microscopy. The length of the particle is ~1.5 µm with a 0.5 µm diameter. Credit: Julia Bartoli and Chantal Abergel, IGS and CNRS-AMU.

The virus gets its name from "pithos," the ancient Greek word for a jar, as it comes in an amphora shape. It is so big (1.5 millionths of a metre) that it can be seen through an optical microscope, rather than the more powerful electron microscope.

Unlike the flu virus, though, P. sibericum is harmless to humans and animals, for it only infects a type of amoeba called Acanthamoeba, the researchers said.

The work shows that viruses can survive being locked up in the permafrost for extremely long periods, France's National Centre for Scientific Research (CNRS) said in a press statement.

"It has important implications for public-health risks in connection with exploiting mineral or energy resources in Arctic Circle regions that are becoming more and more accessible through global warming," it said.

"The revival of viruses that are considered to have been eradicated, such as the smallpox virus, whose replication process is similar to that of Pithovirus, is no longer limited to science fiction.

"The risk that this scenario could happen in real life has to be viewed realistically."

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