IBM researchers have set a record for data transmission over a multimode optical fiber. By sending data at a rate of 64 Gbit/s over a cable 57 meters long using a vertical-cavity surface-emitting laser (VCSEL), the researchers achieved a rate that was around 14% faster than the previous record and about 2.5 times faster than the capabilities of 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 Gbit/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."
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